fix(backend): use atomic settings helpers in tests

- media_settings_handler_test: use ApplyMediaSettings/CurrentMediaSettings
  instead of mutating settings.Config.Integrations.Media directly
- settings_redact_test: SwapConfigForTest helper so concurrent tests don't
  race on the global settings.Config
- preview/fill_test: t.Parallel() on the fill subtests

Splits be2b16b0d's backend hunk; base is 493f8f741 (post-merge lockfix).

Co-authored-by: Cursor <cursoragent@cursor.com>

.dockerignore

@@ -10,7 +10,9 @@ backend/tmp
 backend/dist
 backend/backend*
 backend/vendor/**
+backend/internal/web/dist/*
+!backend/internal/web/dist/.gitkeep
+
 
-frontend/dist/**
 frontend/node_modules/**
 frontend/pkg/**

.github/workflows/pr.yaml

@@ -42,7 +42,7 @@ jobs:
         uses: actions/upload-artifact@v4
         with:
           name: dist
-          path: backend/internal/web/dist
+          path: frontend/dist
   build_backend:
     name: Build backend
     runs-on: ubuntu-24.04-arm
@@ -97,7 +97,7 @@ jobs:
         uses: actions/download-artifact@v4
         with:
           name: dist
-          path: backend/internal/web/dist
+          path: frontend/dist
       - name: Download backend build
         uses: actions/download-artifact@v4
         with:

CHANGELOG.md

@@ -12,6 +12,11 @@ All notable changes to this project will be documented in this file. For commit
     - Transcoding for media playback with quality presets -- requires ffmpeg.
     - Hardware Acceleration device selector (Software / detected GPU devices)
     - More operations use native api operations rather than ffmpeg, improving performance in many cases. Added temporary config option to force ffmpeg to be used
+      - HLS keyframe indexes for MP4/MOV/M4V/MKV/WebM are read from the container index with go-media instead of demuxing every packet with ffprobe; ffprobe still runs when go-media cannot read the file or reports a keyframe gap that would rule out stream copy.
+      - HEIC/AVIF rotation (irot) for the ffmpeg decode fallback is read with go-media instead of a full `ffmpeg -f null` decode.
+      - AVIF images get previews through the HEIC preview path (go-media decode, ffmpeg fallback) when HEIC previews are enabled.
+      - WMV/ASF video thumbnails use go-media for WMV3; WMV1/WMV2 still use ffmpeg.
+      - ffmpeg and go-media share one media metadata cache keyed by path, size and modification time, so a probe, duration or subtitle result from either backend is reused by the other.
   - Document enhancements
     - Official Collabora support using WOPI config.
     - Document previews use a pure-go in-process package (all versions get it now).
@@ -19,7 +24,17 @@ All notable changes to this project will be documented in this file. For commit
     - Office previews can use embedded thumbnail if possible.
     - Text file previews are more efficient direct creation.
     - New text preview API (`/api/resources/preview/text`) returns a 16KB text preview for text, Markdown, HTML, CSS, code and RTF files. Markdown and HTML render in the listing as sanitized previews. Previews are not cached on disk. SVG files are served directly as images.
+    - Text previews only render inline on tiles at least 60px wide, so narrower tiles (list, compact, normal) show the file-type icon with a `saved_search` badge instead when popup previews are enabled, and hovering still opens the larger popup preview. Text preview reads are bounded by the preview service's shared image-processor semaphore (`server.numImageProcessors`), and rendered preview HTML is cached in the browser so scrolling and hovering do not re-parse it.
     - Embedded previews for Krita (`.kra`, [#2431](https://github.com/gtsteffaniak/filebrowser/issues/2431)), OpenRaster (`.ora`), Sketch (`.sketch`), MuseScore (`.mscz`), CBZ (first page), XPS (embedded thumbnail, when present), ODF (`.odt`, `.ods`, `.odp`, `.odg`), and Office Open XML (`.docx`, `.xlsx`, `.pptx`) thumbnails.
+  - Virtual scrolling for large lists: like the main listing, advanced search, file tree, etc. Only render the rows on screen, so very large folders stay responsive, resolving some performance issues (#2879) (#1773) (#3320) (#3326).
+  - Search and navigation improvements:
+    - Next/previous in a preview follows the results of quick search and advanced search, playback queue also uses if there's media (#3275).
+    - Closing a preview opened from quick or advanced search returns to the results and scrolls to the item like the normal listing (#3275).
+    - Advanced search now has almost all the features of the normal listing, including rectangle selection, keyboard navigation, etc (#3299).
+    - Quick search results use natural ordering.
+    - Listings now are cached (with a cap) allowing a more responsive navigation between folders (#3193).
+  - Upload and download prompts list is reversed (#2998) (#3328).
+  - Replaced `indented soft wrap` editor setting by a dropdown with more wrap settings (#3183) (#3282).
 
  **Notes**:
  - **Document preview formats:** New in-process support includes **`.azw3`**, **`.chm`**, **`.htm`**, and **`.html`**. However, `.doc` continues to require the office integration for thumbnails. **`.xps`** and **`.cbz`** previews come from embedded images. With **Always use office for document previews** enabled, office files still use the office converter
@@ -36,6 +51,16 @@ All notable changes to this project will be documented in this file. For commit
  - Media probes are cached by file identity and concurrent reads are coalesced, so opening a file no longer triggers repeated ffprobe runs.
  - Client-initiated stream cancels (seek/navigation) no longer log spurious write-error responses.
  - Gzipped `.woff` font files are no longer generated without being served; only `.js` and `.woff2` are precompressed.
+ - Text preview tiles no longer show the bottom truncation fade; truncated content is clipped at the tile edge instead.
+ - Text preview tiles lay out at a minimum width and are clipped, instead of wrapping aggressively on narrow tiles.
+ - Queued text preview requests are canceled when their tiles unmount, so scrolling through a folder of text files and then opening another folder no longer delays the new folder's previews.
+ - Removed the stale, unreferenced `backend/internal/web/embed/` build output that was accidentally re-added; the frontend is embedded from `backend/internal/web/dist/` as before.
+ - Advanced search no longer loses the previously selected sorting (#3275)
+ - Context menu in iOS don't opening in Advanced Search (#2776) (#3299)
+ - Improved mobile layout of inputs in search filters.
+ - Doing actions in the main list/adv search, like move, copy, delete, or create a new file no longer reloads the entire listing, now updates in place and doesn't lost the position you were browsing at (#3193).
+ - Uploading lot of files freezing the UI for a few seconds (#3321).
+ - Directory uploads are prioritized, and files wait until their parent is ready (#3221).
 
 ## v2.1.4
 

_docker/Dockerfile

@@ -39,7 +39,7 @@ COPY --from=base --chown=filebrowser:1000 [ "/app/filebrowser", "./" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/config.yaml", "./data/config.yaml" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/config.yaml", "./" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/reduce-rounded-corners.css", "./" ]
-COPY --from=nbuild --chown=filebrowser:1000 [ "/build/backend/internal/web/dist/", "./internal/web/dist/" ]
+COPY --from=nbuild --chown=filebrowser:1000 [ "/build/frontend/dist/", "./internal/web/dist/" ]
 ## sanity checks
 RUN [ "filebrowser", "version" ]
 RUN [ "ffmpeg", "-version" ]

_docker/Dockerfile.beta

@@ -34,7 +34,7 @@ COPY --from=base --chown=filebrowser:1000 [ "/app/filebrowser", "./" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/config.yaml", "./data/config.yaml" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/config.yaml", "./" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/reduce-rounded-corners.css", "./" ]
-COPY --from=nbuild --chown=filebrowser:1000 [ "/build/backend/internal/web/dist/", "./internal/web/dist/" ]
+COPY --from=nbuild --chown=filebrowser:1000 [ "/build/frontend/dist/", "./internal/web/dist/" ]
 ## sanity checks
 RUN [ "filebrowser", "version" ]
 # exposing default port for auto discovery.

_docker/Dockerfile.media

@@ -68,7 +68,7 @@ COPY --from=base --chown=filebrowser:1000 [ "/app/filebrowser", "./" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/config.yaml", "./data/config.yaml" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/config.yaml", "./" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/reduce-rounded-corners.css", "./" ]
-COPY --from=nbuild --chown=filebrowser:1000 [ "/build/backend/internal/web/dist/", "./internal/web/dist/" ]
+COPY --from=nbuild --chown=filebrowser:1000 [ "/build/frontend/dist/", "./internal/web/dist/" ]
 
 RUN filebrowser version && ffmpeg -version && ffprobe -version
 

_docker/Dockerfile.playwright-general

@@ -12,7 +12,7 @@ WORKDIR /app/backend/
 COPY [ "./backend/filebrowser", "./"]
 COPY [ "./backend/reduce-rounded-corners.css", "./no-rounded.css" ]
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 
 # generate duplicate 1.1MB files
 RUN dd if=/dev/zero of=/app/frontend/tests/playwright-files/1.1MB.bin bs=1024 count=1126 && dd if=/dev/zero of=/app/frontend/tests/playwright-files/1.1mb.bin bs=1024 count=1126

_docker/Dockerfile.playwright-jwt

@@ -6,7 +6,7 @@ COPY [ "./frontend/tests", "./tests" ]
 WORKDIR /app/backend/
 COPY [ "./backend/filebrowser", "./"]
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 RUN apt update && apt install nginx -y
 RUN mv default.conf /etc/nginx/conf.d/default.conf
 RUN sed -i 's/filebrowser/localhost/g' /etc/nginx/conf.d/default.conf

_docker/Dockerfile.playwright-local

@@ -11,7 +11,7 @@ COPY [ "./_docker/src/settings/backend/config.yaml", "./"]
 COPY [ "./_docker/src/settings/backend/database.db.old", "./"]
 COPY [ "./backend/reduce-rounded-corners.css", "./no-rounded.css"]
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 
 ENV FILEBROWSER_PLAYWRIGHT_TEST=true
 RUN ./filebrowser user set testuser1 --password testuser1

_docker/Dockerfile.playwright-no-config

@@ -11,7 +11,7 @@ COPY [ "./frontend/tests/", "./tests" ]
 WORKDIR /app/backend/
 COPY [ "./backend/filebrowser", "./"]
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 
 # Run tests
 ENV FILEBROWSER_PLAYWRIGHT_TEST=true

_docker/Dockerfile.playwright-noauth

@@ -11,7 +11,7 @@ COPY [ "./frontend/tests/playwright-files", "./tests/playwright-files2" ]
 WORKDIR /app/backend/
 COPY [ "./backend/filebrowser", "./"]
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 
 # Run tests
 ENV FILEBROWSER_PLAYWRIGHT_TEST=true

_docker/Dockerfile.playwright-oidc

@@ -7,7 +7,7 @@ WORKDIR /app/backend/
 RUN mkdir -p ./internal/web/dist
 COPY [ "./_docker/src/oidc/backend/", "./"]
 COPY ["./backend/filebrowser", "./"]
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 
 # Run tests
 WORKDIR /app/frontend

_docker/Dockerfile.playwright-performance

@@ -23,7 +23,7 @@ WORKDIR /app/backend/
 COPY [ "./backend/filebrowser", "./"]
 COPY [ "./backend/reduce-rounded-corners.css", "./no-rounded.css" ]
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 
 ENV FILEBROWSER_PLAYWRIGHT_TEST=true
 ENV CI=true

_docker/Dockerfile.playwright-previews

@@ -13,7 +13,7 @@ COPY [ "./frontend/tests", "./tests" ]
 WORKDIR /app/backend/
 COPY [ "./backend/filebrowser", "./"]
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 
 ENV FILEBROWSER_PLAYWRIGHT_TEST=true
 RUN ./filebrowser & sleep 2 && cd ../frontend && npx playwright test

_docker/Dockerfile.playwright-proxy

@@ -6,7 +6,7 @@ COPY [ "./frontend/tests", "./tests" ]
 WORKDIR /app/backend/
 COPY [ "./backend/filebrowser", "./"]
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 RUN apt update && apt install nginx -y
 RUN mv default.conf /etc/nginx/conf.d/default.conf
 RUN mv .htpasswd /etc/nginx/conf.d/.htpasswd

_docker/Dockerfile.playwright-screenshots

@@ -10,7 +10,7 @@ COPY [ "./backend/filebrowser", "./"]
 COPY [ "./_docker/src/screenshots/backend/*", "./"]
 
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 
 ENV FILEBROWSER_PLAYWRIGHT_TEST=true
 RUN ./filebrowser & sleep 2 && cd ../frontend && npx playwright test --project dark-screenshots

_docker/Dockerfile.playwright-settings

@@ -13,7 +13,7 @@ WORKDIR /app/backend/
 COPY [ "./backend/filebrowser", "./"]
 COPY [ "./backend/reduce-rounded-corners.css", "./no-rounded.css"]
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 
 # Run tests
 ENV FILEBROWSER_PLAYWRIGHT_TEST=true

_docker/Dockerfile.playwright-sharing

@@ -11,7 +11,7 @@ COPY [ "./frontend/tests/", "./tests" ]
 WORKDIR /app/backend/
 COPY [ "./backend/filebrowser", "./"]
 RUN mkdir -p ./internal/web/dist
-COPY [ "./backend/internal/web/dist/", "./internal/web/dist/"]
+COPY [ "./frontend/dist/", "./internal/web/dist/"]
 
 # Run tests
 ENV FILEBROWSER_PLAYWRIGHT_TEST=true

_docker/Dockerfile.purego

@@ -33,7 +33,7 @@ COPY --from=base --chown=filebrowser:1000 [ "/app/filebrowser", "./" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/config.yaml", "./data/config.yaml" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/config.yaml", "./" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/reduce-rounded-corners.css", "./" ]
-COPY --from=nbuild --chown=filebrowser:1000 [ "/build/backend/internal/web/dist/", "./internal/web/dist/" ]
+COPY --from=nbuild --chown=filebrowser:1000 [ "/build/frontend/dist/", "./internal/web/dist/" ]
 ## sanity checks
 RUN [ "filebrowser", "version" ]
 # exposing default port for auto discovery.

_docker/Dockerfile.slim

@@ -32,7 +32,7 @@ COPY --from=base --chown=filebrowser:1000 [ "/app/filebrowser", "./" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/config.yaml", "./data/config.yaml" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/config.yaml", "./" ]
 COPY --from=base --chown=filebrowser:1000 [ "/app/reduce-rounded-corners.css", "./" ]
-COPY --from=nbuild --chown=filebrowser:1000 [ "/build/backend/internal/web/dist/", "./internal/web/dist/" ]
+COPY --from=nbuild --chown=filebrowser:1000 [ "/build/frontend/dist/", "./internal/web/dist/" ]
 ## sanity checks
 RUN [ "filebrowser", "version" ]
 # exposing default port for auto discovery.

backend/go.mod

@@ -5,6 +5,7 @@ go 1.27.1
 require (
 	github.com/alecthomas/kong v1.16.1
 	github.com/asdine/storm/v3 v3.2.1
+	github.com/cespare/xxhash/v2 v2.3.0
 	github.com/coreos/go-oidc/v3 v3.21.0
 	github.com/coreos/go-systemd/v22 v22.7.0
 	github.com/dhowden/tag v0.0.0-20240417053706-3d75831295e8
@@ -21,21 +22,21 @@ require (
 	github.com/gtsteffaniak/go-cache v1.1.0
 	github.com/gtsteffaniak/go-ffmpeg v1.6.2
 	github.com/gtsteffaniak/go-logger v1.1.0
-	github.com/gtsteffaniak/go-media v1.2.0
+	github.com/gtsteffaniak/go-media v1.3.0
 	github.com/kovidgoyal/imaging v1.9.0
 	github.com/pquerna/otp v1.5.0
 	github.com/spf13/afero v1.15.0
 	github.com/stretchr/testify v1.12.1
 	github.com/swaggo/swag v1.16.6
 	golang.org/x/crypto v0.58.0
-	golang.org/x/image v0.47.0
+	golang.org/x/image v0.48.0
 	golang.org/x/mod v0.42.0
 	golang.org/x/net v0.61.0
 	golang.org/x/oauth2 v0.37.0
-	golang.org/x/sync v0.24.0
-	golang.org/x/sys v0.49.0
+	golang.org/x/sync v0.25.0
+	golang.org/x/sys v0.50.0
 	golang.org/x/term v0.47.0
-	golang.org/x/text v0.43.0
+	golang.org/x/text v0.44.0
 	golang.org/x/time v0.16.0
 	golang.org/x/tools v0.52.0
 	gopkg.in/yaml.v3 v3.0.1
@@ -44,7 +45,7 @@ require (
 
 require (
 	github.com/Azure/go-ntlmssp v0.1.1 // indirect
-	github.com/Eyevinn/mp4ff v0.61.0 // indirect
+	github.com/Eyevinn/mp4ff v0.62.1 // indirect
 	github.com/KyleBanks/depth v1.2.1 // indirect
 	github.com/abema/go-mp4 v1.7.4 // indirect
 	github.com/at-wat/ebml-go v0.19.4 // indirect
@@ -54,10 +55,10 @@ require (
 	github.com/dustin/go-humanize v1.1.0 // indirect
 	github.com/fxamacker/cbor/v2 v2.9.6 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.16 // indirect
-	github.com/gen2brain/gav1d v0.2.6 // indirect
-	github.com/gen2brain/h265 v0.2.4 // indirect
-	github.com/gen2brain/jxl v0.2.0 // indirect
-	github.com/gen2brain/vpx v0.2.1 // indirect
+	github.com/gen2brain/gav1d v0.2.7 // indirect
+	github.com/gen2brain/h265 v0.2.5 // indirect
+	github.com/gen2brain/jxl v0.2.1 // indirect
+	github.com/gen2brain/vpx v0.2.2 // indirect
 	github.com/go-asn1-ber/asn1-ber v1.5.8 // indirect
 	github.com/go-errors/errors v1.5.1 // indirect
 	github.com/go-jose/go-jose/v4 v4.1.6 // indirect
@@ -80,7 +81,6 @@ require (
 	github.com/golang/protobuf v1.5.4 // indirect
 	github.com/golang/snappy v0.0.4 // indirect
 	github.com/google/go-tpm v0.9.8 // indirect
-	github.com/gtsteffaniak/go-av1 v1.0.0 // indirect
 	github.com/gtsteffaniak/go-vpx v1.0.1 // indirect
 	github.com/kovidgoyal/go-parallel v1.1.1 // indirect
 	github.com/kovidgoyal/go-shm v1.0.0 // indirect

backend/go.sum

@@ -2,8 +2,8 @@ github.com/Azure/go-ntlmssp v0.1.1 h1:l+FM/EEMb0U9QZE7mKNEDw5Mu3mFiaa2GKOoTSsNDP
 github.com/Azure/go-ntlmssp v0.1.1/go.mod h1:NYqdhxd/8aAct/s4qSYZEerdPuH1liG2/X9DiVTbhpk=
 github.com/DataDog/zstd v1.4.1 h1:3oxKN3wbHibqx897utPC2LTQU4J+IHWWJO+glkAkpFM=
 github.com/DataDog/zstd v1.4.1/go.mod h1:1jcaCB/ufaK+sKp1NBhlGmpz41jOoPQ35bpF36t7BBo=
-github.com/Eyevinn/mp4ff v0.61.0 h1:uX3GBauEouxuGepRbv15JB7X2RyVyE2EZEfLpgimL6o=
-github.com/Eyevinn/mp4ff v0.61.0/go.mod h1:97zsDIJUiDTYqKpqq/b1K9foamxXmvsgE4GdPrPK3ks=
+github.com/Eyevinn/mp4ff v0.62.1 h1:EMuNIrmTCm5acOCVENca5Fzk+Mdek/l4bQZdk2EfReo=
+github.com/Eyevinn/mp4ff v0.62.1/go.mod h1:97zsDIJUiDTYqKpqq/b1K9foamxXmvsgE4GdPrPK3ks=
 github.com/KyleBanks/depth v1.2.1 h1:5h8fQADFrWtarTdtDudMmGsC7GPbOAu6RVB3ffsVFHc=
 github.com/KyleBanks/depth v1.2.1/go.mod h1:jzSb9d0L43HxTQfT+oSA1EEp2q+ne2uh6XgeJcm8brE=
 github.com/Sereal/Sereal v0.0.0-20190618215532-0b8ac451a863 h1:BRrxwOZBolJN4gIwvZMJY1tzqBvQgpaZiQRuIDD40jM=
@@ -25,6 +25,8 @@ github.com/at-wat/ebml-go v0.19.4/go.mod h1:wu3fQj+DWo6SOOl9c4yDi+gFs9Oa96Z2B5qx
 github.com/boombuler/barcode v1.0.1-0.20190219062509-6c824513bacc/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
 github.com/boombuler/barcode v1.1.0 h1:ChaYjBR63fr4LFyGn8E8nt7dBSt3MiU3zMOZqFvVkHo=
 github.com/boombuler/barcode v1.1.0/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/coreos/go-oidc/v3 v3.21.0 h1:wZo4Q9Pum8dYEj0eMUPrqR+kvuGkeUplbLpNCkBqoWM=
 github.com/coreos/go-oidc/v3 v3.21.0/go.mod h1:DYCf24+ncYi+XkIH97GY1+dqoRlbaSI26KVTCI9SrY4=
 github.com/coreos/go-systemd/v22 v22.7.0 h1:LAEzFkke61DFROc7zNLX/WA2i5J8gYqe0rSj9KI28KA=
@@ -62,14 +64,14 @@ github.com/gabriel-vasile/mimetype v1.4.16 h1:5izNFuvA37st1dDRAcA7TtmngBmRgiIPDm
 github.com/gabriel-vasile/mimetype v1.4.16/go.mod h1:3oFFwxX8kTklZwzIl2aQEDZT0lKY8xH92ST88bAwba4=
 github.com/gen2brain/folio v0.2.8 h1:9iDI7h+zt4mjwEnzm1x8Pl9BrWqLwUwB74X/fnc1PZs=
 github.com/gen2brain/folio v0.2.8/go.mod h1:4/PcXfaXIYmW1nwQ4bJeE+aG5ybG58Aw9xrwODXaXII=
-github.com/gen2brain/gav1d v0.2.6 h1:7TSkrWTdE22k5Ul7vYZML7Nu80gNW6OovV7FSCITSE0=
-github.com/gen2brain/gav1d v0.2.6/go.mod h1:ReFKjHq7pvRhEk+pgRPAo9gOlcrf51sdzVcAbbX7e0E=
-github.com/gen2brain/h265 v0.2.4 h1:JUSbGkRAYZpd7ucCL192yx4ViEo75ZO6OEdm1TQt9qM=
-github.com/gen2brain/h265 v0.2.4/go.mod h1:kefpLxLhGpNCUG/q/aabJcD6GqB9Nhet3fNi9xX9Wzw=
-github.com/gen2brain/jxl v0.2.0 h1:cXSQnfbcC0JGFzaI344VzPMbe7mh6rYc0tjPcBUsE4U=
-github.com/gen2brain/jxl v0.2.0/go.mod h1:VjJHRai/8I8Es01mULqyiOihRBOjJr1Zo+NoN/MyIwo=
-github.com/gen2brain/vpx v0.2.1 h1:UD6tibcs/zlaIOKNFXeVyZuHBEaW9GYfxKSxvAN9cc8=
-github.com/gen2brain/vpx v0.2.1/go.mod h1:EVIdqguMSiapbtjDm4AWgFgYYJ4d+k8trXqjxYZ/4XE=
+github.com/gen2brain/gav1d v0.2.7 h1:ehu3jWt+0/46Is5llW/ZyX2OA3hTBJNukKnebzuk8KU=
+github.com/gen2brain/gav1d v0.2.7/go.mod h1:ReFKjHq7pvRhEk+pgRPAo9gOlcrf51sdzVcAbbX7e0E=
+github.com/gen2brain/h265 v0.2.5 h1:D3qCPx5GU+gHpinvLJtYMLSmQy64RGOm4fzMNGQcA1g=
+github.com/gen2brain/h265 v0.2.5/go.mod h1:kefpLxLhGpNCUG/q/aabJcD6GqB9Nhet3fNi9xX9Wzw=
+github.com/gen2brain/jxl v0.2.1 h1:74+8uw2RxUHGDVrDp+727PZ2hvAd5/psyV/mpsOQea0=
+github.com/gen2brain/jxl v0.2.1/go.mod h1:d7VMurg9ek62xfuyZyVAumFcuaQf9U8NlW57j/k5MQI=
+github.com/gen2brain/vpx v0.2.2 h1:kRCIx6Y2LsTe8hercAfhER2QbeHYnBOetovy4pkC4V0=
+github.com/gen2brain/vpx v0.2.2/go.mod h1:EVIdqguMSiapbtjDm4AWgFgYYJ4d+k8trXqjxYZ/4XE=
 github.com/go-asn1-ber/asn1-ber v1.5.8 h1:H9AZkK22UOmfX8J84ubyaZxKJZ3FMHVwn8swoMML7iQ=
 github.com/go-asn1-ber/asn1-ber v1.5.8/go.mod h1:hEBeB/ic+5LoWskz+yKT7vGhhPYkProFKoKdwZRWMe0=
 github.com/go-errors/errors v1.0.1/go.mod h1:f4zRHt4oKfwPJE5k8C9vpYG+aDHdBFUsgrm6/TyX73Q=
@@ -157,16 +159,14 @@ github.com/google/pprof v0.0.0-20260802141513-ef3492d7dac3/go.mod h1:jl5iWTm0/hd
 github.com/google/uuid v1.1.2/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
-github.com/gtsteffaniak/go-av1 v1.0.0 h1:CILp67bcOtiDXvnrQubnH9ctub0OSKnUNA2JJuoIP+c=
-github.com/gtsteffaniak/go-av1 v1.0.0/go.mod h1:C/dIrjfdUcHgdyChr2YXwLY3pIVjENI9npSd98PU4lE=
 github.com/gtsteffaniak/go-cache v1.1.0 h1:ni/2cJpCxpGmaMZd92iTDIGOy+yUcMcxQuW7bSKhkCE=
 github.com/gtsteffaniak/go-cache v1.1.0/go.mod h1:rHUZvf4huhMX/bnNK4/oQ3sNAE2fYC2jFpAWZiBPWac=
 github.com/gtsteffaniak/go-ffmpeg v1.6.2 h1:gtvBg3G4PHO1Z/ZIPEK/XP4XT/g+l9S0Rpmmq6v5tnA=
 github.com/gtsteffaniak/go-ffmpeg v1.6.2/go.mod h1:FefhoD+KZzHWqBaUpntcKp6lXtUzdFW00F74axnENUQ=
 github.com/gtsteffaniak/go-logger v1.1.0 h1:baFds+iibuLLNpNLwygz32bDqdsunI6dGWcdxwMIVKI=
 github.com/gtsteffaniak/go-logger v1.1.0/go.mod h1:rapapTju4D7bwt6h4JOdZNUXDjnp0WkTBd6TN5yWglI=
-github.com/gtsteffaniak/go-media v1.2.0 h1:lbNL/G86uzzH8NaT45DBHKm1r0P7yndIo9pNC7gdqQs=
-github.com/gtsteffaniak/go-media v1.2.0/go.mod h1:EH+5KAVLWfFl0g4W0Xni0qJJH8MUDIhAw4wPcC0mhxY=
+github.com/gtsteffaniak/go-media v1.3.0 h1:EOxoaOQq05V3OUPo5NndnPZ0/VYt4gFEwa6l7MdR6rk=
+github.com/gtsteffaniak/go-media v1.3.0/go.mod h1:x8k0z759GiawTtKBTXDNXF/pT1UQDhR4e70/eypXpOk=
 github.com/gtsteffaniak/go-vpx v1.0.1 h1:9lSI8yoz6omDChaeV0AJrhdfe2YTrWvJrDENI/bnkAM=
 github.com/gtsteffaniak/go-vpx v1.0.1/go.mod h1:tRCdDZ15oZZTsiwmQAwyH56PTt1jn1C1O0P03oOkoJ8=
 github.com/hashicorp/go-uuid v1.0.3 h1:2gKiV6YVmrJ1i2CKKa9obLvRieoRGviZFL26PcT/Co8=
@@ -256,8 +256,8 @@ golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACk
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.58.0 h1:COkYLr4k7nDI4r6QtMML2AfzeIswWHAJthLS6K/M/54=
 golang.org/x/crypto v0.58.0/go.mod h1:Xh+kl5A+M0gMiWDytH2Hhr5Z7WbNCpv/eB/EFgfSk+w=
-golang.org/x/image v0.47.0 h1:za/8gVz++PPZqmZJBNSISICN5Rrj5zixP/8K++fgmqo=
-golang.org/x/image v0.47.0/go.mod h1:IkN5o4A7vq55vXN8FWjjnhg9Rs2GOtffqsSi9mWAKYE=
+golang.org/x/image v0.48.0 h1:1AvuPcuoOTJpA7s4VZ5umrb90T3So0rkB/bSGmxkxik=
+golang.org/x/image v0.48.0/go.mod h1:mmtg64iqJKGqEgy+r13dfybl85tmxUd2lMnmaiSdWYY=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/mod v0.42.0 h1:ICeL3t2L30ljSPHHxDnR4fqVcBt/zR2zJAb9juavmQg=
 golang.org/x/mod v0.42.0/go.mod h1:u5fzIrRInkL8MaO1cbRkUHT64v303YIT5KEqpNr7jRs=
@@ -277,8 +277,8 @@ golang.org/x/oauth2 v0.37.0 h1:JUlcxA8oAtauLfiH8FX2/FkAWHAdi0QtGCGc+hofE98=
 golang.org/x/oauth2 v0.37.0/go.mod h1:IxwZNxUULJmpBFf9K/9NTMSIfZZuvuTy1gGxhigP/58=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.24.0 h1:iqiDrGoDgyuvAKrhLQthUEzU/R378N78gXbBjxed7oA=
-golang.org/x/sync v0.24.0/go.mod h1:sUUOizhqBxiL6pEWpqNLUiaJn1ShEbZ6BBqskPbjZm0=
+golang.org/x/sync v0.25.0 h1:dJnifr0nMV8/SBnBvdo4eSGGnrc3O4FFx6IqvtLcmRs=
+golang.org/x/sync v0.25.0/go.mod h1:sUUOizhqBxiL6pEWpqNLUiaJn1ShEbZ6BBqskPbjZm0=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200202164722-d101bd2416d5/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -290,8 +290,8 @@ golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220728004956-3c1f35247d10/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220928140112-f11e5e49a4ec/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.49.0 h1:XbzkgYJHdqh/8m2Uu0W/dQv8nktxx4BFHp1M0gROTXA=
-golang.org/x/sys v0.49.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=
+golang.org/x/sys v0.50.0 h1:dkKZEFTEKaLr1sjhs0WiKqoi8Jj5nHbS3Njmx1UoMJs=
+golang.org/x/sys v0.50.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.47.0 h1:cpyOwQkr2Nzxe2p6KnrTG7Ei2wtzjsuSjhpXXepZ/BM=
@@ -301,8 +301,8 @@ golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/text v0.3.8/go.mod h1:E6s5w1FMmriuDzIBO73fBruAKo1PCIq6d2Q6DHfQ8WQ=
-golang.org/x/text v0.43.0 h1:1QivrlhwAsnMOcqgOdl9my7s9OyZl8O5/UGUTJVXoWc=
-golang.org/x/text v0.43.0/go.mod h1:hbSIYA/amXcRXTFSZqh8tWHEoqRvvbKPJ2uz/KU+a+s=
+golang.org/x/text v0.44.0 h1:YItdp/mQNGnsmrgpcdA5yQ3bnRxCfo/Tj/iByGW9GGo=
+golang.org/x/text v0.44.0/go.mod h1:S4FR1waQ9LbjQTls97SyRjDaUUVkaM+cXwwuG/G+MwY=
 golang.org/x/time v0.16.0 h1:vMb6ptszcQMkcwiRTAuNNU50gom6++Q/6gY2hDM6VDE=
 golang.org/x/time v0.16.0/go.mod h1:rVKOqvZeKvrDKTQiAHJ7wmwP0RzleSphoEA9RcdLA0s=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

backend/internal/activity/diff_test.go

@@ -14,13 +14,13 @@ func TestUserUpdateChangesSkipsSensitiveFields(t *testing.T) {
 		FrontendUser: users.FrontendUser{
 			Username: "alice",
 			NonAdminEditable: users.NonAdminEditable{
-				DarkMode: true,
+				DarkMode: users.DarkModeDark,
 			},
 		},
 		TOTPSecret: "secret-value",
 	}
 	after := *before
-	after.DarkMode = false
+	after.DarkMode = users.DarkModeLight
 	after.TOTPSecret = "new-secret"
 
 	changes := UserUpdateChanges(before, &after, []string{"totpSecret", "darkMode"}, false)
@@ -36,7 +36,7 @@ func TestUserUpdateChangesFiltersUnchangedFields(t *testing.T) {
 		FrontendUser: users.FrontendUser{
 			Username: "akadmin",
 			NonAdminEditable: users.NonAdminEditable{
-				DarkMode:       true,
+				DarkMode:       users.DarkModeDark,
 				StickySidebar:  true,
 				Locale:         "en",
 				SingleClick:    false,
@@ -47,7 +47,7 @@ func TestUserUpdateChangesFiltersUnchangedFields(t *testing.T) {
 		},
 	}
 	after := *before
-	after.DarkMode = false
+	after.DarkMode = users.DarkModeLight
 	after.Sorting = users.Sorting{By: "name", Asc: true}
 
 	which := []string{
@@ -60,7 +60,7 @@ func TestUserUpdateChangesFiltersUnchangedFields(t *testing.T) {
 	if len(changes) != 3 {
 		t.Fatalf("expected 3 changes, got %d: %#v", len(changes), changes)
 	}
-	if changes[0].Field != "darkMode" || changes[0].From != "true" || changes[0].To != "false" {
+	if changes[0].Field != "darkMode" || changes[0].From != "dark" || changes[0].To != "light" {
 		t.Fatalf("unexpected darkMode change: %#v", changes[0])
 	}
 	if changes[1].Field != "sorting.asc" || changes[1].From != "false" || changes[1].To != "true" {

backend/internal/adapters/fs/diskcache/file_cache.go

@@ -9,7 +9,10 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"sort"
 	"sync"
+	"sync/atomic"
+	"time"
 
 	"github.com/gtsteffaniak/filebrowser/backend/internal/adapters/fs/fileutils"
 	"github.com/gtsteffaniak/go-logger/logger"
@@ -21,9 +24,28 @@ type Cache interface {
 	Set(key string, value []byte) error
 }
 
+const (
+	// evictTargetPercent is the size, as a percentage of the limit, that eviction shrinks the cache to.
+	// Stopping below the limit avoids running an eviction on every write once the cache is full.
+	evictTargetPercent = 90
+	// touchInterval is how old a file's modification time has to be before a read refreshes it. Reads
+	// refresh it so the files in use are the last ones evicted, but not on every read.
+	touchInterval = time.Hour
+)
+
 // FileCache struct for file-based caching
 type FileCache struct {
 	dir string
+	// maxBytes is the size limit of the cache in bytes. 0 means no limit.
+	maxBytes int64
+	// size is the total size of the cached files in bytes. Only tracked when maxBytes > 0.
+	size atomic.Int64
+	// sizeMu keeps size consistent with the files on disk: stores and deletes hold it for reading while
+	// they change a file and its size, and eviction holds it for writing while it measures the directory,
+	// so a store can never fall between a measurement and the size being set from it.
+	sizeMu sync.RWMutex
+	// evicting is set while an eviction is running so only one runs at a time.
+	evicting atomic.Bool
 	// granular locks
 	scopedLocks struct {
 		sync.Mutex
@@ -33,6 +55,12 @@ type FileCache struct {
 }
 
 func NewFileCache(dir string) (*FileCache, error) {
+	return NewFileCacheWithLimit(dir, 0)
+}
+
+// NewFileCacheWithLimit is like NewFileCache but keeps the cache under maxBytes, deleting the least
+// recently used files when it grows past it. 0 means no limit.
+func NewFileCacheWithLimit(dir string, maxBytes int64) (*FileCache, error) {
 	cacheDir := filepath.Join(dir, "diskcache")
 
 	// Migrate existing cache files from old structure (if any)
@@ -44,7 +72,13 @@ func NewFileCache(dir string) (*FileCache, error) {
 	if err := os.MkdirAll(cacheDir, fileutils.PermDir); err != nil {
 		return nil, fmt.Errorf("failed to create cache directory: %w", err)
 	}
-	return &FileCache{dir: cacheDir}, nil
+	cache := &FileCache{dir: cacheDir}
+	if maxBytes > 0 {
+		cache.maxBytes = maxBytes
+		// measures the cache and trims it right away if it is already over the limit
+		cache.evictPass()
+	}
+	return cache, nil
 }
 
 // migrateOldCacheStructure moves cache files from old structure (dir/a/...) to new structure (dir/diskcache/a/...)
@@ -99,19 +133,50 @@ func (f *FileCache) Store(ctx context.Context, key string, value []byte) error {
 		return err
 	}
 
+	if f.maxBytes > 0 {
+		f.sizeMu.RLock()
+		defer f.sizeMu.RUnlock()
+	}
+	previousSize := f.fileSize(fileName)
+
 	if err := os.WriteFile(fileName, value, fileutils.PermFile); err != nil {
+		// a failed write can leave a truncated or partial file, so count what is actually there
+		f.sizeChanged(f.fileSize(fileName) - previousSize)
 		return err
 	}
-
+	f.sizeChanged(int64(len(value)) - previousSize)
 	return nil
 }
 
+// fileSize returns the size of a cached file, or 0 if it doesn't exist or the size isn't tracked.
+func (f *FileCache) fileSize(fileName string) int64 {
+	if f.maxBytes <= 0 {
+		return 0
+	}
+	info, err := os.Stat(fileName)
+	if err != nil {
+		return 0
+	}
+	return info.Size()
+}
+
+// sizeChanged adds delta to the tracked size and starts an eviction if that put the cache over its limit.
+func (f *FileCache) sizeChanged(delta int64) {
+	if f.maxBytes <= 0 {
+		return
+	}
+	if f.size.Add(delta) > f.maxBytes {
+		f.evictAsync()
+	}
+}
+
 func (f *FileCache) Load(ctx context.Context, key string) (value []byte, exist bool, err error) {
 	r, ok, err := f.open(key)
 	if err != nil || !ok {
 		return nil, ok, err
 	}
 	defer r.Close()
+	f.touch(r)
 
 	value, err = io.ReadAll(r)
 	if err != nil {
@@ -125,13 +190,119 @@ func (f *FileCache) Delete(ctx context.Context, key string) error {
 	mu.Lock()
 	defer mu.Unlock()
 
+	if f.maxBytes > 0 {
+		f.sizeMu.RLock()
+		defer f.sizeMu.RUnlock()
+	}
 	fileName := f.getFileName(key)
+	removedSize := f.fileSize(fileName)
 	if err := os.Remove(fileName); err != nil && !errors.Is(err, os.ErrNotExist) {
 		return err
 	}
+	if removedSize > 0 {
+		f.size.Add(-removedSize)
+	}
 	return nil
 }
 
+// touch refreshes the modification time of a file that was just read, which is what eviction orders by.
+func (f *FileCache) touch(file *os.File) {
+	if f.maxBytes <= 0 {
+		return
+	}
+	info, err := file.Stat()
+	if err != nil || time.Since(info.ModTime()) < touchInterval {
+		return
+	}
+	now := time.Now()
+	_ = os.Chtimes(file.Name(), now, now)
+}
+
+type cachedFile struct {
+	path    string
+	size    int64
+	modTime time.Time
+}
+
+// scan lists the cached files and their total size.
+func (f *FileCache) scan() ([]cachedFile, int64) {
+	var files []cachedFile
+	var total int64
+	_ = filepath.WalkDir(f.dir, func(path string, entry os.DirEntry, err error) error {
+		if err != nil || entry.IsDir() {
+			return nil
+		}
+		info, err := entry.Info()
+		if err != nil || !info.Mode().IsRegular() {
+			return nil
+		}
+		files = append(files, cachedFile{path: path, size: info.Size(), modTime: info.ModTime()})
+		total += info.Size()
+		return nil
+	})
+	return files, total
+}
+
+// evictAsync starts an eviction in the background unless one is already running, so the request that
+// stored the file doesn't wait for it.
+func (f *FileCache) evictAsync() {
+	if !f.evicting.CompareAndSwap(false, true) {
+		return
+	}
+	go func() {
+		for {
+			removed := f.evictPass()
+			f.evicting.Store(false)
+			if removed == 0 {
+				return // under the limit, or nothing could be removed: don't spin
+			}
+			// Files stored while the pass was running were counted but not necessarily seen by it, and a
+			// store that came in just before the flag was cleared saw it set and didn't start another
+			// pass, so check again before stopping.
+			if f.size.Load() <= f.maxBytes || !f.evicting.CompareAndSwap(false, true) {
+				return
+			}
+		}
+	}()
+}
+
+// evictPass measures the cache and, if it is over the limit, deletes the least recently used files until
+// it is under evictTargetPercent of the limit. Deleting a file that is being read or written is harmless:
+// readers keep their open file and a removed entry is simply rebuilt the next time it is requested.
+func (f *FileCache) evictPass() (removed int) {
+	f.sizeMu.Lock()
+	files, total := f.scan()
+	f.size.Store(total)
+	f.sizeMu.Unlock()
+
+	if total <= f.maxBytes {
+		return 0
+	}
+	target := f.maxBytes / 100 * evictTargetPercent
+	sort.Slice(files, func(i, j int) bool { return files[i].modTime.Before(files[j].modTime) })
+	var removedBytes int64
+	for _, file := range files {
+		if f.size.Load() <= target {
+			break
+		}
+		// Hold the lock so no store or delete changes this file between measuring it and removing it, and
+		// subtract the size it has now: the listing is from the scan and the file may have been rewritten since.
+		f.sizeMu.Lock()
+		info, err := os.Stat(file.path)
+		if err == nil {
+			err = os.Remove(file.path)
+		}
+		if err == nil {
+			f.size.Add(-info.Size())
+			removed++
+			removedBytes += info.Size()
+		}
+		f.sizeMu.Unlock()
+	}
+	logger.Debugf("preview cache limit: removed %d files (%d MB), now %d MB of %d MB", removed, removedBytes>>20, f.size.Load()>>20, f.maxBytes>>20)
+	return removed
+}
+
 func (f *FileCache) open(key string) (*os.File, bool, error) {
 	fileName := f.getFileName(key)
 	file, err := os.Open(fileName)

backend/internal/adapters/fs/diskcache/file_cache_test.go

@@ -2,9 +2,12 @@ package diskcache
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"path/filepath"
+	"sync"
 	"testing"
+	"time"
 
 	"github.com/gtsteffaniak/filebrowser/backend/internal/adapters/fs/fileutils"
 	"github.com/stretchr/testify/require"
@@ -70,3 +73,168 @@ func fileExists(filename string) bool {
 	}
 	return !info.IsDir()
 }
+
+// storeAged stores a value and sets its modification time, so the eviction order is deterministic.
+func storeAged(t *testing.T, cache *FileCache, key string, size int, age time.Duration) {
+	t.Helper()
+	require.NoError(t, cache.Store(context.Background(), key, make([]byte, size)))
+	when := time.Now().Add(-age)
+	require.NoError(t, os.Chtimes(cache.getFileName(key), when, when))
+}
+
+func waitFor(t *testing.T, condition func() bool) {
+	t.Helper()
+	deadline := time.Now().Add(5 * time.Second)
+	for !condition() {
+		if time.Now().After(deadline) {
+			t.Fatal("condition not met in time")
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+}
+
+func newLimitedCache(t *testing.T, maxBytes int64) *FileCache {
+	t.Helper()
+	fileutils.SetFsPermissions(0644, 0755)
+	cache, err := NewFileCacheWithLimit(t.TempDir(), maxBytes)
+	require.NoError(t, err)
+	return cache
+}
+
+func TestFileCacheEvictsLeastRecentlyUsedOverLimit(t *testing.T) {
+	const kb = 1024
+	cache := newLimitedCache(t, 10*kb)
+	// 3 files of 3KB are under the 10KB limit
+	storeAged(t, cache, "oldest", 3*kb, 3*time.Hour)
+	storeAged(t, cache, "old", 3*kb, 2*time.Hour)
+	storeAged(t, cache, "recent", 3*kb, time.Hour)
+	require.True(t, fileExists(cache.getFileName("oldest")), "nothing is removed under the limit")
+
+	// the 4th file goes over the limit: the oldest ones are removed until it is under 90% of it
+	require.NoError(t, cache.Store(context.Background(), "newest", make([]byte, 3*kb)))
+	waitFor(t, func() bool { return !fileExists(cache.getFileName("oldest")) })
+	waitFor(t, func() bool { return !cache.evicting.Load() })
+
+	require.False(t, fileExists(cache.getFileName("oldest")))
+	require.False(t, fileExists(cache.getFileName("old")))
+	require.True(t, fileExists(cache.getFileName("recent")))
+	require.True(t, fileExists(cache.getFileName("newest")))
+	require.LessOrEqual(t, cache.size.Load(), int64(9*kb))
+}
+
+func TestFileCacheTrimsAnOversizedCacheAtStartup(t *testing.T) {
+	const kb = 1024
+	fileutils.SetFsPermissions(0644, 0755)
+	dir := t.TempDir()
+	unlimited, err := NewFileCache(dir)
+	require.NoError(t, err)
+	storeAged(t, &FileCache{dir: unlimited.dir}, "a", 4*kb, 4*time.Hour)
+	storeAged(t, &FileCache{dir: unlimited.dir}, "b", 4*kb, 3*time.Hour)
+	storeAged(t, &FileCache{dir: unlimited.dir}, "c", 4*kb, 2*time.Hour)
+
+	cache, err := NewFileCacheWithLimit(dir, 10*kb)
+	require.NoError(t, err)
+
+	// 12KB over a 10KB limit: only the oldest file is removed, which already brings it under 90% (9KB)
+	require.False(t, fileExists(cache.getFileName("a")))
+	require.True(t, fileExists(cache.getFileName("b")))
+	require.True(t, fileExists(cache.getFileName("c")))
+	require.Equal(t, int64(8*kb), cache.size.Load())
+}
+
+func TestFileCacheWithoutLimitKeepsEverything(t *testing.T) {
+	fileutils.SetFsPermissions(0644, 0755)
+	cache, err := NewFileCache(t.TempDir())
+	require.NoError(t, err)
+	for i := 0; i < 5; i++ {
+		storeAged(t, cache, fmt.Sprintf("key-%d", i), 1<<20, time.Duration(i)*time.Hour)
+	}
+	for i := 0; i < 5; i++ {
+		require.True(t, fileExists(cache.getFileName(fmt.Sprintf("key-%d", i))))
+	}
+	require.Zero(t, cache.size.Load(), "size is only tracked when there is a limit")
+}
+
+func TestFileCacheReadRefreshesModTime(t *testing.T) {
+	cache := newLimitedCache(t, 1<<20)
+	storeAged(t, cache, "used", 100, 3*time.Hour)
+
+	_, ok, err := cache.Load(context.Background(), "used")
+	require.NoError(t, err)
+	require.True(t, ok)
+
+	info, err := os.Stat(cache.getFileName("used"))
+	require.NoError(t, err)
+	require.WithinDuration(t, time.Now(), info.ModTime(), time.Minute, "a file that is read is the last to be evicted")
+}
+
+func TestFileCacheDeleteAndOverwriteKeepTheSizeAccurate(t *testing.T) {
+	const kb = 1024
+	cache := newLimitedCache(t, 1<<20)
+	ctx := context.Background()
+	require.NoError(t, cache.Store(ctx, "k", make([]byte, 5*kb)))
+	require.Equal(t, int64(5*kb), cache.size.Load())
+	require.NoError(t, cache.Store(ctx, "k", make([]byte, 2*kb)))
+	require.Equal(t, int64(2*kb), cache.size.Load(), "overwriting replaces the old size")
+	require.NoError(t, cache.Delete(ctx, "k"))
+	require.Zero(t, cache.size.Load())
+}
+
+// Stores that land while an eviction is measuring or deleting must not be lost from the tracked size,
+// and the cache must end up under its limit even though more files kept arriving during the eviction.
+func TestFileCacheStaysUnderTheLimitWithConcurrentStores(t *testing.T) {
+	const (
+		kb      = 1024
+		limit   = 100 * kb
+		workers = 16
+		stores  = 40
+	)
+	cache := newLimitedCache(t, limit)
+	var wg sync.WaitGroup
+	for w := 0; w < workers; w++ {
+		wg.Add(1)
+		go func(w int) {
+			defer wg.Done()
+			for i := 0; i < stores; i++ {
+				_ = cache.Store(context.Background(), fmt.Sprintf("worker-%d-key-%d", w, i), make([]byte, 4*kb))
+			}
+		}(w)
+	}
+	wg.Wait()
+	waitFor(t, func() bool { return !cache.evicting.Load() })
+
+	_, onDisk := cache.scan()
+	require.LessOrEqual(t, onDisk, int64(limit), "the files left on disk are within the limit")
+	require.Equal(t, onDisk, cache.size.Load(), "the tracked size matches what is on disk")
+}
+
+// Files that are rewritten while an eviction is running must be subtracted at the size they have when
+// they are removed, not at the size the scan saw, or the tracked size drifts from the disk.
+func TestFileCacheKeepsTheSizeAccurateWhenFilesAreRewrittenDuringEviction(t *testing.T) {
+	const (
+		kb      = 1024
+		limit   = 60 * kb
+		workers = 8
+		rounds  = 300
+		keys    = 40
+	)
+	cache := newLimitedCache(t, limit)
+	var wg sync.WaitGroup
+	for w := 0; w < workers; w++ {
+		wg.Add(1)
+		go func(w int) {
+			defer wg.Done()
+			for i := 0; i < rounds; i++ {
+				// the same keys again and again, with a different size each time
+				key := fmt.Sprintf("key-%d", (w+i)%keys)
+				_ = cache.Store(context.Background(), key, make([]byte, (1+(w*7+i)%8)*kb))
+			}
+		}(w)
+	}
+	wg.Wait()
+	waitFor(t, func() bool { return !cache.evicting.Load() })
+
+	_, onDisk := cache.scan()
+	require.Equal(t, onDisk, cache.size.Load(), "the tracked size matches what is on disk")
+	require.LessOrEqual(t, onDisk, int64(limit))
+}

backend/internal/adapters/fs/files/files.go

@@ -17,6 +17,7 @@ import (
 	"github.com/gtsteffaniak/filebrowser/backend/internal/errors"
 	"github.com/gtsteffaniak/filebrowser/backend/internal/ffmpeg"
 	"github.com/gtsteffaniak/filebrowser/backend/internal/gomedia"
+	"github.com/gtsteffaniak/filebrowser/backend/internal/mediacache"
 	"github.com/gtsteffaniak/filebrowser/backend/internal/utils"
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing"
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
@@ -52,7 +53,7 @@ func addMetadataToChildren(response *iteminfo.ExtendedFileInfo, opts utils.FileO
 					logger.Debugf("failed to extract metadata for file: %s, error: %v", fileItem.Name, err)
 				}
 			} else {
-				if err := extractVideoMetadata(context.Background(), fileItem, fullPath, sharedFFmpegService); err != nil {
+				if err := extractVideoMetadata(context.Background(), fileItem, fullPath, opts.AlbumArt, sharedFFmpegService); err != nil {
 					logger.Debugf("failed to extract video metadata for file: %s, error: %v", fileItem.Name, err)
 				}
 			}
@@ -380,7 +381,7 @@ func processContent(info *iteminfo.ExtendedFileInfo, idx *indexing.Index, opts u
 		extItem := &iteminfo.ExtendedItemInfo{
 			ItemInfo: info.ItemInfo,
 		}
-		err := extractVideoMetadata(context.Background(), extItem, info.RealPath, nil)
+		err := extractVideoMetadata(context.Background(), extItem, info.RealPath, opts.AlbumArt, nil)
 		if err != nil {
 			logger.Debugf("failed to extract video metadata for file: %s (%s): %v", info.RealPath, info.Name, err)
 		} else {
@@ -393,7 +394,8 @@ func processContent(info *iteminfo.ExtendedFileInfo, idx *indexing.Index, opts u
 			info.GetSubtitles(parentInfo)
 		}
 		subtitles, ok := gomedia.EmbeddedSubtitles(info.RealPath, info.ModTime, func() ([]utils.SubtitleTrack, bool) {
-			return ffmpeg.DetectEmbeddedSubtitles(info.RealPath, info.ModTime), true
+			// Shadow run: bypass the shared cache so ffprobe is compared fresh.
+			return ffmpeg.DetectEmbeddedSubtitlesContext(mediacache.WithoutCache(context.Background()), info.RealPath), true
 		})
 		if !ok {
 			subtitles = ffmpeg.DetectEmbeddedSubtitles(info.RealPath, info.ModTime)
@@ -471,23 +473,11 @@ func extractAudioMetadata(ctx context.Context, item *iteminfo.ExtendedItemInfo,
 	// go-media fast path: tags, lyrics availability, and artwork. Unsupported or
 	// failed reads fall through to the existing dhowden/tag code below.
 	if info, ok := gomedia.Audio(realPath, getArt, func() (gomedia.AudioInfo, bool) { return legacyAudioInfo(realPath, getArt) }); ok {
-		item.Metadata = &iteminfo.MediaMetadata{
-			Title:     info.Tags.Title,
-			Artist:    info.Tags.Artist,
-			Album:     info.Tags.Album,
-			Year:      info.Tags.Year,
-			Genre:     info.Tags.Genre,
-			Track:     info.Tags.Track,
-			HasLyrics: info.HasLyrics,
-		}
+		item.Metadata = &iteminfo.MediaMetadata{HasLyrics: info.HasLyrics}
+		applyMediaTags(item.Metadata, info, realPath)
 		if getDuration {
 			audioDuration(ctx, item, realPath, ffmpegService)
 		}
-		if n := len(info.Artwork); n > 0 && n <= 5*1024*1024 {
-			item.Metadata.AlbumArt = info.Artwork
-		} else if n > 5*1024*1024 {
-			logger.Debugf("Skipping album art for %s: too large (%d bytes)", realPath, n)
-		}
 		return nil
 	}
 
@@ -541,8 +531,9 @@ func audioDuration(ctx context.Context, item *iteminfo.ExtendedItemInfo, realPat
 	if service == nil {
 		service = ffmpeg.Get()
 	}
-	// The shadow run can outlive the request, so it uses a context that is not cancelled with it.
-	shadowCtx := context.WithoutCancel(ctx)
+	// The shadow run can outlive the request, so it uses a context that is not
+	// cancelled with it. It bypasses the shared cache so ffmpeg is compared fresh.
+	shadowCtx := mediacache.WithoutCache(context.WithoutCancel(ctx))
 	legacy := func() (float64, bool) {
 		d, err := service.GetMediaDuration(shadowCtx, realPath)
 		return d, err == nil
@@ -707,14 +698,15 @@ func legacyLyrics(realPath string) (gomedia.LyricsResult, bool) {
 
 // extractVideoMetadata extracts duration and codec info from video files using ffprobe.
 // If ffmpegService is nil, a new service will be created (for backward compatibility)
-func extractVideoMetadata(ctx context.Context, item *iteminfo.ExtendedItemInfo, realPath string, ffmpegService *ffmpeg.FFmpegService) error {
+func extractVideoMetadata(ctx context.Context, item *iteminfo.ExtendedItemInfo, realPath string, getArt bool, ffmpegService *ffmpeg.FFmpegService) error {
 	// go-media fast path. Works without ffmpeg installed.
 	probeService := ffmpegService
 	if probeService == nil {
 		probeService = ffmpeg.Get()
 	}
-	// The shadow run can outlive the request, so it uses a context that is not cancelled with it.
-	shadowCtx := context.WithoutCancel(ctx)
+	// The shadow run can outlive the request, so it uses a context that is not
+	// cancelled with it. It bypasses the shared cache so ffprobe is compared fresh.
+	shadowCtx := mediacache.WithoutCache(context.WithoutCancel(ctx))
 	legacyProbe := func() (gomedia.ProbeResult, bool) {
 		info, err := probeService.ProbeFile(shadowCtx, realPath)
 		if err != nil || info == nil {
@@ -759,12 +751,33 @@ func extractVideoMetadata(ctx context.Context, item *iteminfo.ExtendedItemInfo,
 	if info.FormatName != "" {
 		meta.Container = info.FormatName
 	}
+	if ok {
+		if tags, tagsOK := gomedia.VideoTags(realPath, getArt); tagsOK {
+			applyMediaTags(meta, tags, realPath)
+		}
+	}
 	if meta.Duration > 0 || meta.VideoCodec != "" || meta.AudioCodec != "" || meta.Container != "" {
 		item.Metadata = meta
 	}
 	return nil
 }
 
+// applyMediaTags copies go-media tags and embedded cover art into meta. Covers
+// over 8MB are skipped.
+func applyMediaTags(meta *iteminfo.MediaMetadata, info gomedia.AudioInfo, realPath string) {
+	meta.Title = info.Tags.Title
+	meta.Artist = info.Tags.Artist
+	meta.Album = info.Tags.Album
+	meta.Year = info.Tags.Year
+	meta.Genre = info.Tags.Genre
+	meta.Track = info.Tags.Track
+	if n := len(info.Artwork); n > 0 && n <= 8*1024*1024 {
+		meta.AlbumArt = info.Artwork
+	} else if n > 8*1024*1024 {
+		logger.Debugf("Skipping album art for %s: too large (%d bytes)", realPath, n)
+	}
+}
+
 // DeleteFiles deletes the file or directory at indexPath. boundIndexPath limits
 // symlink resolution to the caller's scope ("" or "/" = source root only). The
 // entry itself is removed: a symlink leaf is deleted, never followed, and an
@@ -777,6 +790,7 @@ func DeleteFiles(source, boundIndexPath, indexPath string, isDir bool) error {
 	if utils.CleanIndexPathSegment(indexPath) == "" {
 		return fmt.Errorf("refusing to delete source root directory: %s", indexPath)
 	}
+	deleteIndexPath := indexPath
 	realPath, err := index.GetRealPathForRemoval(boundIndexPath, indexPath)
 	if err != nil {
 		return err
@@ -795,9 +809,13 @@ func DeleteFiles(source, boundIndexPath, indexPath string, isDir bool) error {
 		return err
 	}
 
-	// Clear cache entries
-	indexing.RealPathCache.Delete(realPath)
-	indexing.IsDirCache.Delete(realPath + ":isdir")
+	if isDir {
+		indexing.ClearRealPathCaches()
+	}
+	index.InvalidateRealPathCache(deleteIndexPath, boundIndexPath)
+	if parent := utils.GetParentDirectoryPath(deleteIndexPath); parent != "" && parent != "/" {
+		index.InvalidateRealPathCache(parent, boundIndexPath)
+	}
 
 	// Remove metadata from index
 	deleteSuccess := index.DeleteMetadata(indexPath, isDir, isDir)
@@ -849,8 +867,7 @@ func RefreshIndex(source string, path string, isDir bool, recursive bool) error
 			if !Exists(realPath) {
 				// Directory no longer exists, remove it from the index
 				// This clears both Directories and DirectoriesLedger maps
-				indexing.RealPathCache.Delete(realPath)
-				indexing.IsDirCache.Delete(realPath + ":isdir")
+				idx.InvalidateRealPathCache(path)
 				idx.DeleteMetadata(path, true, false)
 				return nil
 			}
@@ -928,6 +945,9 @@ func moveResourceImpl(isSrcDir bool, sourceIndex, destIndex, realsrc, realdst st
 	if err != nil {
 		return err
 	}
+	if isSrcDir {
+		indexing.ClearRealPathCaches()
+	}
 
 	// Handle SOURCE cleanup (treat as deletion)
 	// Run async to avoid blocking the HTTP response
@@ -1088,6 +1108,11 @@ func WriteDirectory(boundIndexPath string, opts utils.FileOptions) error {
 		}
 	}
 
+	idx.InvalidateRealPathCache(opts.Path, boundIndexPath)
+	if parent := utils.GetParentDirectoryPath(opts.Path); parent != "" && parent != "/" {
+		idx.InvalidateRealPathCache(parent, boundIndexPath)
+	}
+
 	return nil
 }
 
@@ -1163,6 +1188,11 @@ func writeFile(source, boundIndexPath, path string, in io.Reader) error {
 		}
 	}
 
+	idx.InvalidateRealPathCache(path, boundIndexPath)
+	if parent := utils.GetParentDirectoryPath(path); parent != "" && parent != "/" {
+		idx.InvalidateRealPathCache(parent, boundIndexPath)
+	}
+
 	return nil
 }
 

backend/internal/database/access/resolved.go

@@ -0,0 +1,44 @@
+package access
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/gtsteffaniak/filebrowser/backend/internal/utils"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing"
+)
+
+// PermittedAtRealPath reports whether username may access realPath after symlink
+// resolution. DENY rules apply to the target index path, not only the link path.
+func (s *Storage) PermittedAtRealPath(index *indexing.Index, username, realPath string, isDir bool) bool {
+	if s == nil || index == nil || username == "" || realPath == "" {
+		return false
+	}
+	lexical := realPath
+	if !strings.HasPrefix(realPath, index.Path) {
+		root, err := filepath.EvalSymlinks(index.Path)
+		if err != nil {
+			return false
+		}
+		rel, err := filepath.Rel(root, realPath)
+		if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) {
+			return false
+		}
+		lexical = index.Path
+		if rel != "." {
+			lexical = filepath.Join(index.Path, rel)
+		}
+	}
+	indexPath := index.MakeIndexPath(lexical, isDir).String()
+	return s.Permitted(index.Path, utils.IndexPathFromNormalized(indexPath, true), username)
+}
+
+// IsDirAtRealPath reports whether an existing path is a directory; missing paths are treated as files.
+func IsDirAtRealPath(realPath string) bool {
+	st, err := os.Stat(realPath)
+	if err != nil {
+		return false
+	}
+	return st.IsDir()
+}

backend/internal/database/access/resolved_test.go

@@ -0,0 +1,140 @@
+package access
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/gtsteffaniak/filebrowser/backend/internal/utils"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
+)
+
+func setupSymlinkDenyFixture(t *testing.T) (sourceRoot string, idx *indexing.Index, store *Storage, username string) {
+	t.Helper()
+	sourceRoot = filepath.Join(t.TempDir(), "data")
+	aliceDir := filepath.Join(sourceRoot, "alice")
+	bobDir := filepath.Join(sourceRoot, "bob")
+	for _, dir := range []string{aliceDir, bobDir} {
+		if err := os.MkdirAll(dir, 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := os.WriteFile(filepath.Join(bobDir, "secret.txt"), []byte("secret"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink("../bob/secret.txt", filepath.Join(aliceDir, "link.txt")); err != nil {
+		t.Skipf("symlinks required: %v", err)
+	}
+	if err := os.Symlink("../bob", filepath.Join(aliceDir, "bobdir")); err != nil {
+		t.Skipf("symlinks required: %v", err)
+	}
+
+	settings.Config.Server.SourceMap = map[string]*settings.Source{
+		sourceRoot: {Path: sourceRoot, Config: settings.SourceConfig{DenyByDefault: false}},
+	}
+	store = NewStorage(nil)
+	username = "scoped-user"
+	if err := store.DenyUser(sourceRoot, utils.IndexPathFromNormalized("/bob", true), username); err != nil {
+		t.Fatal(err)
+	}
+	idx = &indexing.Index{Source: settings.Source{Path: sourceRoot}}
+	return sourceRoot, idx, store, username
+}
+
+func TestPermittedAtRealPath_AllowsLinkPathDeniesResolvedTarget(t *testing.T) {
+	_, idx, store, user := setupSymlinkDenyFixture(t)
+
+	if !store.Permitted(idx.Path, utils.IndexPathFromNormalized("/alice/link.txt", false), user) {
+		t.Fatal("index path at the symlink should be allowed")
+	}
+	if store.Permitted(idx.Path, utils.IndexPathFromNormalized("/bob/secret.txt", false), user) {
+		t.Fatal("direct path under /bob should be denied")
+	}
+
+	realPath, _, err := idx.GetRealPathScoped("/", "/alice/link.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if store.PermittedAtRealPath(idx, user, realPath, false) {
+		t.Fatal("resolved target under denied /bob must not be permitted")
+	}
+}
+
+func TestPermittedAtRealPath_DeniesWriteThroughDirectorySymlink(t *testing.T) {
+	_, idx, store, user := setupSymlinkDenyFixture(t)
+
+	realPath, err := idx.GetRealPathForMutation("/", "/alice/bobdir/planted.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if store.PermittedAtRealPath(idx, user, realPath, false) {
+		t.Fatal("resolved write target under denied /bob must not be permitted")
+	}
+}
+
+func TestPermittedAtRealPath_DeniesCopySourceResolved(t *testing.T) {
+	_, idx, store, user := setupSymlinkDenyFixture(t)
+
+	realSrc, isDir, err := idx.GetRealPathScoped("/", "/alice/link.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if isDir {
+		t.Fatal("expected file")
+	}
+	if store.PermittedAtRealPath(idx, user, realSrc, isDir) {
+		t.Fatal("copy source resolved to denied target must not be permitted")
+	}
+}
+
+func TestPermittedAtRealPath_SymlinkedSourceRoot(t *testing.T) {
+	sourceRoot, _, _, user := setupSymlinkDenyFixture(t)
+	linkRoot := filepath.Join(filepath.Dir(sourceRoot), "root-link")
+	if err := os.Symlink(sourceRoot, linkRoot); err != nil {
+		t.Skipf("symlinks required: %v", err)
+	}
+	if _, err := filepath.EvalSymlinks(linkRoot); err != nil {
+		t.Fatal(err)
+	}
+	settings.Config.Server.SourceMap = map[string]*settings.Source{
+		linkRoot: {Path: linkRoot, Config: settings.SourceConfig{DenyByDefault: false}},
+	}
+	store := NewStorage(nil)
+	if err := store.DenyUser(linkRoot, utils.IndexPathFromNormalized("/bob", true), user); err != nil {
+		t.Fatal(err)
+	}
+	idx := &indexing.Index{Source: settings.Source{Path: linkRoot}}
+
+	realPath, _, err := idx.GetRealPathScoped("/", "/alice/link.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	realPath, err = filepath.EvalSymlinks(realPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if store.PermittedAtRealPath(idx, user, realPath, false) {
+		t.Fatal("resolved target under denied /bob must not be permitted with symlinked source root")
+	}
+}
+
+func TestIsDirAtRealPath(t *testing.T) {
+	dir := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(dir, "nested"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	file := filepath.Join(dir, "file.txt")
+	if err := os.WriteFile(file, []byte("x"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if !IsDirAtRealPath(dir) {
+		t.Fatal("expected directory")
+	}
+	if IsDirAtRealPath(file) {
+		t.Fatal("expected file")
+	}
+	if IsDirAtRealPath(filepath.Join(dir, "missing")) {
+		t.Fatal("missing path should not be treated as directory")
+	}
+}

backend/internal/database/sqldb/users_test.go

@@ -25,8 +25,8 @@ func TestFinishUserLoad_legacyProfileRowPreservesAbsentSettingsFields(t *testing
 	if !loaded.ShowFirstLogin {
 		t.Fatal("expected top-level showFirstLogin to be preserved when settings omits it")
 	}
-	if !loaded.DarkMode {
-		t.Fatal("expected profile darkMode=true")
+	if !loaded.DarkMode.IsDark() {
+		t.Fatalf("expected profile darkMode=true, got %q", loaded.DarkMode)
 	}
 	if len(loaded.PasskeyCredentials) != 0 {
 		t.Fatalf("expected no passkeys when settings omits passkeyCredentials, got %#v", loaded.PasskeyCredentials)
@@ -95,7 +95,7 @@ func TestUserDataRoundTrip_profileSettingsOverlay(t *testing.T) {
 			LoginMethod:    users.LoginMethodPassword,
 			ShowFirstLogin: true,
 			NonAdminEditable: users.NonAdminEditable{
-				DarkMode: true,
+				DarkMode: users.DarkModeDark,
 				SidebarLinks: []users.SidebarLink{
 					{Name: "Home", Target: "/files"},
 				},

backend/internal/database/users/darkmode.go

@@ -0,0 +1,73 @@
+package users
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+// DarkMode is the user's theme preference: "auto" (follow the client's
+// system preference), "dark", or "light". It unmarshals from legacy JSON
+// booleans for backward compatibility with existing stored users.
+type DarkMode string
+
+const (
+	DarkModeAuto  DarkMode = "auto"
+	DarkModeDark  DarkMode = "dark"
+	DarkModeLight DarkMode = "light"
+)
+
+// UnmarshalJSON accepts legacy boolean values (true -> dark, false -> light),
+// the tri-state strings ("auto", "dark", "light"), and null (unset).
+func (d *DarkMode) UnmarshalJSON(data []byte) error {
+	var v interface{}
+	if err := json.Unmarshal(data, &v); err != nil {
+		return err
+	}
+	switch val := v.(type) {
+	case nil:
+		*d = ""
+	case bool:
+		if val {
+			*d = DarkModeDark
+		} else {
+			*d = DarkModeLight
+		}
+	case string:
+		switch DarkMode(strings.ToLower(val)) {
+		case "":
+			*d = ""
+		case "true":
+			// Some YAML decoders cast scalar booleans to strings.
+			*d = DarkModeDark
+		case "false":
+			*d = DarkModeLight
+		case DarkModeAuto:
+			*d = DarkModeAuto
+		case DarkModeDark:
+			*d = DarkModeDark
+		case DarkModeLight:
+			*d = DarkModeLight
+		default:
+			return fmt.Errorf("invalid darkMode value %q: must be \"auto\", \"dark\" or \"light\"", val)
+		}
+	default:
+		return fmt.Errorf("invalid darkMode value: must be a boolean or one of \"auto\", \"dark\", \"light\"")
+	}
+	return nil
+}
+
+// IsDark reports the effective boolean value for server-side rendering
+// contexts. "auto" cannot be resolved server-side; callers that can know the
+// client preference should handle DarkModeAuto explicitly.
+func (d DarkMode) IsDark() bool {
+	return d == DarkModeDark
+}
+
+// Or returns d unless it is unset (""), in which case it returns def.
+func (d DarkMode) Or(def DarkMode) DarkMode {
+	if d == "" {
+		return def
+	}
+	return d
+}

backend/internal/database/users/users.go

@@ -308,7 +308,7 @@ type NonAdminEditable struct {
 	DeleteWithoutConfirming    bool                 `json:"deleteWithoutConfirming"` // delete files without confirmation
 	Preview                    Preview              `json:"preview"`
 	StickySidebar              bool                 `json:"stickySidebar"` // keep sidebar open when navigating
-	DarkMode                   bool                 `json:"darkMode"`      // should dark mode be enabled
+	DarkMode                   DarkMode             `json:"darkMode"`      // theme preference: "auto" (follow system), "dark", or "light"
 	Password                   string               `json:"password,omitempty"`
 	Locale                     string               `json:"locale"`          // language to use: eg. de, en, or fr
 	ViewMode                   string               `json:"viewMode"`        // view mode to use: eg. normal, list, grid, or compact
@@ -346,10 +346,11 @@ type NonAdminEditable struct {
 }
 
 type FileLoading struct {
-	MaxConcurrent     int  `json:"maxConcurrentUpload"`
-	UploadChunkSize   int  `json:"uploadChunkSizeMb"`
-	ClearAll          bool `json:"clearAll"`
-	DownloadChunkSize int  `json:"downloadChunkSizeMb"`
+	MaxConcurrent             int  `json:"maxConcurrentUpload"`
+	UploadChunkSize           int  `json:"uploadChunkSizeMb"`
+	ClearAll                  bool `json:"clearAll"`
+	DownloadChunkSize         int  `json:"downloadChunkSizeMb"`
+	UploadStallTimeoutSeconds int  `json:"uploadStallTimeoutSeconds"` // seconds without progress before an upload is paused, 0 uses the default (10)
 }
 
 // SidebarLink represents a customizable link in the sidebar.

backend/internal/ffmpeg/cache.go

@@ -1,14 +0,0 @@
-package ffmpeg
-
-import (
-	"time"
-
-	"github.com/gtsteffaniak/filebrowser/backend/internal/utils"
-	"github.com/gtsteffaniak/go-cache/cache"
-)
-
-var (
-	MediaCache           = cache.NewCache[[]utils.SubtitleTrack](24 * time.Hour) // subtitle track lists from ffprobe
-	SubtitleContentCache = cache.NewCache[string](24 * time.Hour)                // extracted embedded subtitle content
-	MetadataCache        = cache.NewCache[float64](24 * time.Hour)               // media duration from ffprobe
-)

backend/internal/ffmpeg/heic_orientation.go

@@ -9,13 +9,51 @@ import (
 	"os/exec"
 	"strconv"
 	"strings"
+	"sync/atomic"
 
 	"github.com/kovidgoyal/imaging"
 )
 
+// HEICDisplayRotationReader reads the display rotation that a HEIC/HEIF/AVIF
+// file's item properties (irot) ask for, without decoding it. The rotation is
+// in degrees counter-clockwise, normalized to (-180, 180], which is the value
+// ffmpeg prints as "Display Matrix: rotation of ..." for the same file. ok is
+// false when the reader could not tell; the ffmpeg probe is used instead.
+type HEICDisplayRotationReader func(path string) (rotation float64, ok bool)
+
+// heicDisplayRotationReader is the header reader set by
+// SetHEICDisplayRotationReader, or nil.
+var heicDisplayRotationReader atomic.Pointer[HEICDisplayRotationReader]
+
+// SetHEICDisplayRotationReader installs the reader HEICDisplayRotation tries
+// before running ffmpeg. The gomedia package installs go-media's reader when it
+// is loaded; it cannot be called from here directly because gomedia imports
+// this package. Passing nil removes the reader.
+func SetHEICDisplayRotationReader(fn HEICDisplayRotationReader) {
+	if fn == nil {
+		heicDisplayRotationReader.Store(nil)
+		return
+	}
+	heicDisplayRotationReader.Store(&fn)
+}
+
+// HEICDisplayRotation returns the display rotation of heicPath and whether it is
+// known. The installed header reader (go-media) answers first; the
+// "ffmpeg -f null" stderr probe runs only when no reader is installed or the
+// reader could not read the file.
+func (s *Service) HEICDisplayRotation(ctx context.Context, heicPath string) (float64, bool) {
+	if p := heicDisplayRotationReader.Load(); p != nil {
+		if rotation, ok := (*p)(heicPath); ok {
+			return rotation, true
+		}
+	}
+	return s.GetHEICDisplayMatrixRotation(ctx, heicPath)
+}
+
 // GetHEICDisplayMatrixRotation returns the largest rotation (degrees) ffmpeg reports for a
 // HEIC display matrix. The second return value is false when the probe could not run or
 // parse stderr — callers must not treat that as “no rotation was applied”.
+// HEICDisplayRotation is preferred; it only runs this probe as a fallback.
 func (s *Service) GetHEICDisplayMatrixRotation(ctx context.Context, heicPath string) (float64, bool) {
 	if s == nil {
 		return 0, false
@@ -36,6 +74,8 @@ func (s *Service) GetHEICDisplayMatrixRotation(ctx context.Context, heicPath str
 	return rotation, ok
 }
 
+// parseDisplayMatrixRotation returns the largest-magnitude "Display Matrix"
+// rotation in ffmpeg stderr, and whether any was found.
 func parseDisplayMatrixRotation(stderr string) (float64, bool) {
 	var best float64
 	var found bool
@@ -65,6 +105,7 @@ func parseDisplayMatrixRotation(stderr string) (float64, bool) {
 	return best, found
 }
 
+// isNormalOrientation reports whether an EXIF orientation needs no change.
 func isNormalOrientation(orientation string) bool {
 	switch orientation {
 	case "", "Horizontal (normal)", "Top-left", "1":
@@ -74,6 +115,8 @@ func isNormalOrientation(orientation string) bool {
 	}
 }
 
+// isPureRotationOrientation reports whether an EXIF orientation is a rotation
+// without a mirror.
 func isPureRotationOrientation(orientation string) bool {
 	switch orientation {
 	case "Rotate 90 CW", "Right-top", "6",
@@ -100,6 +143,8 @@ func orientationNeedsPostCorrection(orientation string, displayRotation float64,
 	return true
 }
 
+// applyOrientationToJPEG rotates or flips JPEG bytes for an EXIF orientation.
+// The input is returned unchanged when it cannot be decoded or re-encoded.
 func applyOrientationToJPEG(jpegBytes []byte, orientation string) []byte {
 	if len(jpegBytes) < 100 || isNormalOrientation(orientation) {
 		return jpegBytes

backend/internal/ffmpeg/heic_orientation_test.go

@@ -50,3 +50,35 @@ func TestOrientationNeedsPostCorrection(t *testing.T) {
 		}
 	}
 }
+
+func TestHEICDisplayRotationPrefersReader(t *testing.T) {
+	prev := heicDisplayRotationReader.Load()
+	t.Cleanup(func() { heicDisplayRotationReader.Store(prev) })
+
+	var calls int
+	SetHEICDisplayRotationReader(func(path string) (float64, bool) {
+		calls++
+		if path == "known.heic" {
+			return -90, true
+		}
+		return 0, false
+	})
+	var svc *Service // nil: the ffmpeg probe cannot run
+	got, ok := svc.HEICDisplayRotation(t.Context(), "known.heic")
+	if !ok || got != -90 {
+		t.Fatalf("HEICDisplayRotation(known) = %v, %v; want -90, true", got, ok)
+	}
+	// The reader cannot tell: the ffmpeg probe runs, and with no service it
+	// reports unknown rather than "no rotation".
+	if _, ok := svc.HEICDisplayRotation(t.Context(), "other.heic"); ok {
+		t.Fatal("HEICDisplayRotation(other) ok = true, want the ffmpeg probe's false")
+	}
+	if calls != 2 {
+		t.Fatalf("reader calls = %d, want 2", calls)
+	}
+
+	SetHEICDisplayRotationReader(nil)
+	if _, ok := svc.HEICDisplayRotation(t.Context(), "known.heic"); ok {
+		t.Fatal("with no reader, HEICDisplayRotation must use the ffmpeg probe")
+	}
+}

backend/internal/ffmpeg/image.go

@@ -81,14 +81,16 @@ func (s *Service) ConvertHEICToJPEG(ctx context.Context, heicPath string, target
 	return s.CorrectHEICJPEGOrientation(ctx, heicPath, jpegBytes), nil
 }
 
-// CorrectHEICJPEGOrientation applies irot / display-matrix correction after a full-resolution
-// HEIC decode when pixels are still in coded orientation (go-media and ffmpeg filter-free paths).
+// CorrectHEICJPEGOrientation applies EXIF orientation after a filter-free ffmpeg HEIC decode
+// when the pixels are still in coded orientation. The display rotation (irot) comes from
+// HEICDisplayRotation: go-media reads it from the item properties, and the ffmpeg stderr probe
+// is only a fallback.
 func (s *Service) CorrectHEICJPEGOrientation(ctx context.Context, heicPath string, jpegBytes []byte) []byte {
 	orientation, err := s.GetHEICOrientation(heicPath)
 	if err != nil {
 		orientation = "Horizontal (normal)"
 	}
-	displayRotation, displayKnown := s.GetHEICDisplayMatrixRotation(ctx, heicPath)
+	displayRotation, displayKnown := s.HEICDisplayRotation(ctx, heicPath)
 	if orientationNeedsPostCorrection(orientation, displayRotation, displayKnown) {
 		return applyOrientationToJPEG(jpegBytes, orientation)
 	}

backend/internal/ffmpeg/mediacache_integration_test.go

@@ -0,0 +1,115 @@
+package ffmpeg
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sync"
+	"testing"
+
+	"github.com/gtsteffaniak/filebrowser/backend/internal/mediacache"
+)
+
+const cacheFixtureMP4 = "../../../frontend/tests/playwright-files/myfolder/testdata/sample-640x480.mp4"
+
+var (
+	testServiceOnce sync.Once
+	testServiceErr  error
+)
+
+// initTestService starts the ffmpeg service once, without hardware probes, or
+// skips.
+func initTestService(t *testing.T) *Service {
+	t.Helper()
+	if testing.Short() {
+		t.Skip("starts ffmpeg")
+	}
+	if _, err := exec.LookPath("ffmpeg"); err != nil {
+		t.Skip("ffmpeg not installed")
+	}
+	if _, err := exec.LookPath("ffprobe"); err != nil {
+		t.Skip("ffprobe not installed")
+	}
+	testServiceOnce.Do(func() {
+		testServiceErr = Initialize(context.Background(), InitOptions{SkipHWTests: true, CacheDir: os.TempDir()})
+	})
+	if testServiceErr != nil {
+		t.Skipf("ffmpeg init failed: %v", testServiceErr)
+	}
+	svc := Get()
+	if svc == nil {
+		t.Skip("ffmpeg service unavailable")
+	}
+	return svc
+}
+
+// copyFixture copies the MP4 fixture so the test owns its cache key.
+func copyFixture(t *testing.T) (string, mediacache.Key) {
+	t.Helper()
+	data, err := os.ReadFile(cacheFixtureMP4)
+	if err != nil {
+		t.Fatal(err)
+	}
+	path := filepath.Join(t.TempDir(), "sample.mp4")
+	if err = os.WriteFile(path, data, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	key, err := mediacache.Stat(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		mediacache.Probes.Delete(key.String())
+		mediacache.Durations.Delete(key.String())
+	})
+	return path, key
+}
+
+// TestProbeFileUsesSharedCache checks that ffprobe results go into the shared
+// cache, cached values are reused, and WithoutCache bypasses both.
+func TestProbeFileUsesSharedCache(t *testing.T) {
+	svc := initTestService(t)
+	path, key := copyFixture(t)
+
+	got, err := svc.ProbeFile(context.Background(), path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cached, ok := mediacache.Probes.Get(key.String())
+	if !ok || cached != *got {
+		t.Fatalf("ProbeFile must store its result in the shared cache: cached=%+v ok=%v got=%+v", cached, ok, *got)
+	}
+
+	sentinel := FileProbeInfo{Duration: 1, VideoCodec: "sentinel"}
+	mediacache.Probes.Set(key.String(), sentinel)
+	got, err = svc.ProbeFile(context.Background(), path)
+	if err != nil || *got != sentinel {
+		t.Fatalf("ProbeFile must reuse a cached value (e.g. from go-media): got=%+v err=%v", got, err)
+	}
+
+	fresh, err := svc.ProbeFile(mediacache.WithoutCache(context.Background()), path)
+	if err != nil || *fresh == sentinel {
+		t.Fatalf("WithoutCache must probe fresh: got=%+v err=%v", fresh, err)
+	}
+	if cached, _ := mediacache.Probes.Get(key.String()); cached != sentinel {
+		t.Fatal("WithoutCache must not overwrite the shared cache")
+	}
+}
+
+// TestGetMediaDurationUsesSharedCache checks that cached durations are reused
+// and WithoutCache probes fresh.
+func TestGetMediaDurationUsesSharedCache(t *testing.T) {
+	svc := initTestService(t)
+	path, key := copyFixture(t)
+
+	mediacache.Durations.Set(key.String(), 4242)
+	d, err := svc.GetMediaDuration(context.Background(), path)
+	if err != nil || d != 4242 {
+		t.Fatalf("GetMediaDuration must reuse a cached value: d=%v err=%v", d, err)
+	}
+	d, err = svc.GetMediaDuration(mediacache.WithoutCache(context.Background()), path)
+	if err != nil || d == 4242 || d <= 0 {
+		t.Fatalf("WithoutCache must probe fresh: d=%v err=%v", d, err)
+	}
+}

backend/internal/ffmpeg/metadata.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/gtsteffaniak/filebrowser/backend/internal/mediacache"
 	goffmpeg "github.com/gtsteffaniak/go-ffmpeg"
 )
 
@@ -49,24 +50,29 @@ func resolveLocalMediaPath(mediaPath string) (string, os.FileInfo, error) {
 	return clean, info, nil
 }
 
-// FileProbeInfo holds ffprobe results for a local media file.
-type FileProbeInfo struct {
-	Duration   float64
-	VideoCodec string
-	AudioCodec string
-	FormatName string
-}
+// FileProbeInfo holds probe results for a local media file. It is the shared
+// cache type, so go-media and ffprobe results are interchangeable.
+type FileProbeInfo = mediacache.ProbeInfo
 
-// ProbeFile extracts duration and codec info from a media file.
+// ProbeFile extracts duration and codec info from a media file. Results are
+// stored in the shared media cache, which the go-media probe also reads, unless
+// ctx is mediacache.WithoutCache.
 func (s *Service) ProbeFile(ctx context.Context, mediaPath string) (*FileProbeInfo, error) {
 	if s == nil || s.inner == nil {
 		return nil, fmt.Errorf("ffmpeg service not available")
 	}
 
-	localPath, _, err := resolveLocalMediaPath(mediaPath)
+	localPath, fileInfo, err := resolveLocalMediaPath(mediaPath)
 	if err != nil {
 		return nil, err
 	}
+	useCache := !mediacache.Bypassed(ctx)
+	cacheKey := mediacache.FromFileInfo(localPath, fileInfo).String()
+	if useCache {
+		if cached, ok := mediacache.Probes.Get(cacheKey); ok {
+			return &cached, nil
+		}
+	}
 
 	info, err := s.inner.ProbeStream(ctx, goffmpeg.ProbeStreamOptions{
 		URL:        localPath,
@@ -77,15 +83,20 @@ func (s *Service) ProbeFile(ctx context.Context, mediaPath string) (*FileProbeIn
 		return nil, err
 	}
 
-	return &FileProbeInfo{
+	res := FileProbeInfo{
 		Duration:   info.Duration,
 		VideoCodec: info.VideoCodec,
 		AudioCodec: info.AudioCodec,
 		FormatName: info.FormatName,
-	}, nil
+	}
+	if useCache {
+		mediacache.Probes.Set(cacheKey, res)
+	}
+	return &res, nil
 }
 
-// GetMediaDuration extracts the duration of a media file in seconds.
+// GetMediaDuration extracts the duration of a media file in seconds. Results
+// are stored in the shared media cache unless ctx is mediacache.WithoutCache.
 func (s *Service) GetMediaDuration(ctx context.Context, mediaPath string) (float64, error) {
 	if s == nil || s.inner == nil {
 		return 0, fmt.Errorf("ffmpeg service not available")
@@ -95,9 +106,12 @@ func (s *Service) GetMediaDuration(ctx context.Context, mediaPath string) (float
 	if err != nil {
 		return 0, err
 	}
-	cacheKey := fmt.Sprintf("%s:%d", localPath, fileInfo.ModTime().Unix())
-	if duration, found := MetadataCache.Get(cacheKey); found {
-		return duration, nil
+	useCache := !mediacache.Bypassed(ctx)
+	cacheKey := mediacache.FromFileInfo(localPath, fileInfo).String()
+	if useCache {
+		if duration, found := mediacache.Durations.Get(cacheKey); found {
+			return duration, nil
+		}
 	}
 
 	duration, err := s.inner.GetMediaDuration(ctx, localPath)
@@ -105,6 +119,8 @@ func (s *Service) GetMediaDuration(ctx context.Context, mediaPath string) (float
 		return 0, err
 	}
 
-	MetadataCache.Set(cacheKey, duration)
+	if useCache {
+		mediacache.Durations.Set(cacheKey, duration)
+	}
 	return duration, nil
 }

backend/internal/ffmpeg/service.go

@@ -9,6 +9,7 @@ import (
 	"sync"
 	"sync/atomic"
 
+	"github.com/gtsteffaniak/filebrowser/backend/internal/mediacache"
 	goffmpeg "github.com/gtsteffaniak/go-ffmpeg"
 	"github.com/gtsteffaniak/go-ffmpeg/capabilities"
 	"github.com/gtsteffaniak/go-ffmpeg/ops"
@@ -460,7 +461,8 @@ func (s *Service) VideoPreview(ctx context.Context, w io.Writer, opts ops.Previe
 	return s.inner.CaptureFrame(ctx, w, frame)
 }
 
-// ExtractSubtitle returns embedded subtitle content as WebVTT.
+// ExtractSubtitle returns embedded subtitle content as WebVTT. Results are
+// stored in the shared media cache unless ctx is mediacache.WithoutCache.
 func (s *Service) ExtractSubtitle(ctx context.Context, videoPath string, streamIndex int) (string, error) {
 	if s == nil || s.inner == nil {
 		return "", fmt.Errorf("ffmpeg service not available")
@@ -470,9 +472,12 @@ func (s *Service) ExtractSubtitle(ctx context.Context, videoPath string, streamI
 	if err != nil {
 		return "", fmt.Errorf("failed to stat file: %w", err)
 	}
-	cacheKey := fmt.Sprintf("subtitle_content:%s:%d:%d", videoPath, streamIndex, fileInfo.ModTime().Unix())
-	if content, ok := SubtitleContentCache.Get(cacheKey); ok {
-		return content, nil
+	useCache := !mediacache.Bypassed(ctx)
+	cacheKey := mediacache.FromFileInfo(videoPath, fileInfo).Stream(streamIndex)
+	if useCache {
+		if content, ok := mediacache.SubtitleContent.Get(cacheKey); ok {
+			return content, nil
+		}
 	}
 
 	content, err := s.inner.ExtractSubtitle(ctx, videoPath, streamIndex)
@@ -480,7 +485,9 @@ func (s *Service) ExtractSubtitle(ctx context.Context, videoPath string, streamI
 		return "", err
 	}
 
-	SubtitleContentCache.Set(cacheKey, content)
+	if useCache {
+		mediacache.SubtitleContent.Set(cacheKey, content)
+	}
 	return content, nil
 }
 

backend/internal/ffmpeg/subtitles.go

@@ -7,16 +7,30 @@ import (
 	"strings"
 	"time"
 
+	"github.com/gtsteffaniak/filebrowser/backend/internal/mediacache"
 	"github.com/gtsteffaniak/filebrowser/backend/internal/utils"
 	goffmpeg "github.com/gtsteffaniak/go-ffmpeg"
 	"github.com/gtsteffaniak/go-logger/logger"
 )
 
-// DetectEmbeddedSubtitles detects embedded subtitle streams.
+// DetectEmbeddedSubtitles detects embedded subtitle streams. Results are stored
+// in the shared media cache, keyed by the file's current size and modification
+// time; modtime is kept for API compatibility and is not used for the key.
 func DetectEmbeddedSubtitles(videoPath string, modtime time.Time) []utils.SubtitleTrack {
-	key := "embedded_subtitles:" + videoPath + ":" + modtime.Format(time.RFC3339)
-	if cached, ok := MediaCache.Get(key); ok {
-		return cached
+	_ = modtime
+	return DetectEmbeddedSubtitlesContext(context.Background(), videoPath)
+}
+
+// DetectEmbeddedSubtitlesContext is DetectEmbeddedSubtitles with a context. The
+// shared media cache is skipped when ctx is mediacache.WithoutCache.
+func DetectEmbeddedSubtitlesContext(ctx context.Context, videoPath string) []utils.SubtitleTrack {
+	useCache := !mediacache.Bypassed(ctx)
+	key, statErr := mediacache.Stat(videoPath)
+	useCache = useCache && statErr == nil
+	if useCache {
+		if cached, ok := mediacache.SubtitleTracks.Get(key.String()); ok {
+			return cached
+		}
 	}
 
 	svc := Get()
@@ -24,14 +38,16 @@ func DetectEmbeddedSubtitles(videoPath string, modtime time.Time) []utils.Subtit
 		return nil
 	}
 
-	tracks, err := svc.inner.DetectSubtitles(context.Background(), videoPath)
+	tracks, err := svc.inner.DetectSubtitles(ctx, videoPath)
 	if err != nil {
 		logger.Debug("ffprobe failed for file: " + videoPath + ", error: " + err.Error())
 		return nil
 	}
 
 	subtitles := mapSubtitleTracks(tracks)
-	MediaCache.Set(key, subtitles)
+	if useCache {
+		mediacache.SubtitleTracks.Set(key.String(), subtitles)
+	}
 	return subtitles
 }
 

backend/internal/folio/folio.go

@@ -1,167 +0,0 @@
-// Package folio is the pure-Go document preview fast path using gen2brain/folio.
-// When folio cannot handle a file, callers fall back to the office converter (when configured).
-package folio
-
-import (
-	"bytes"
-	"context"
-	"errors"
-	"fmt"
-	"image"
-	"image/jpeg"
-	"path/filepath"
-	"strings"
-	"sync"
-
-	"github.com/gen2brain/folio/doc"
-	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
-	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
-	"github.com/gtsteffaniak/go-logger/logger"
-	"github.com/kovidgoyal/imaging"
-)
-
-var renderMu sync.Mutex
-
-// RenderOptions controls thumbnail sizing for one rendered page.
-type RenderOptions struct {
-	MaxWidth    int
-	MaxHeight   int
-	Fill        bool
-	JpegQuality int
-	Original    bool
-}
-
-// Enabled reports whether the folio fast path may run.
-func Enabled() bool {
-	return !settings.AlwaysUseOnlyOfficeEnabled()
-}
-
-// SupportsExtension reports whether folio targets the file extension (including leading dot).
-func SupportsExtension(ext string) bool {
-	ext = strings.ToLower(ext)
-	if !strings.HasPrefix(ext, ".") {
-		ext = "." + ext
-	}
-	return iteminfo.FolioConvertable[ext]
-}
-
-func logFallback(op, path string, err error) {
-	if errors.Is(err, doc.ErrUnsupported) {
-		logger.Warningf("folio does not support %s for %s (%v); using office converter if configured", op, path, err)
-		return
-	}
-	logger.Errorf("folio %s failed for %s: %v; falling back to office converter if configured", op, path, err)
-}
-
-// RenderPageJPEG renders one document page to JPEG. ok is true when folio returned bytes.
-// name and mimetype should match the file being previewed; they control eligibility for
-// folio (content sniffing does not depend on the path extension).
-func RenderPageJPEG(ctx context.Context, path string, pageNumber int, opts RenderOptions, name, mimetype string) (data []byte, ok bool, err error) {
-	if !Enabled() {
-		return nil, false, nil
-	}
-	if name == "" {
-		name = filepath.Base(path)
-	}
-	if !SupportsPreview(name, mimetype) {
-		return nil, false, nil
-	}
-	if ctx.Err() != nil {
-		return nil, false, ctx.Err()
-	}
-
-	type result struct {
-		data []byte
-		err  error
-	}
-	done := make(chan result, 1)
-	go func() {
-		defer func() {
-			if r := recover(); r != nil {
-				done <- result{err: fmt.Errorf("folio render panicked: %v", r)}
-			}
-		}()
-		data, err := renderPageJPEG(ctx, path, name, mimetype, pageNumber, opts)
-		done <- result{data: data, err: err}
-	}()
-
-	select {
-	case <-ctx.Done():
-		return nil, false, ctx.Err()
-	case res := <-done:
-		if res.err != nil {
-			if !errors.Is(res.err, context.Canceled) && !errors.Is(res.err, context.DeadlineExceeded) {
-				logFallback("render", path, res.err)
-			}
-			return nil, false, res.err
-		}
-		if len(res.data) == 0 {
-			return nil, false, fmt.Errorf("folio render returned empty jpeg")
-		}
-		return res.data, true, nil
-	}
-}
-
-func renderPageJPEG(ctx context.Context, path, name, mimetype string, pageNumber int, opts RenderOptions) ([]byte, error) {
-	renderMu.Lock()
-	defer renderMu.Unlock()
-	if err := ctx.Err(); err != nil {
-		return nil, err
-	}
-
-	d, err := openDocument(path, name, mimetype)
-	if err != nil {
-		return nil, err
-	}
-	defer d.Close()
-
-	if pageNumber < 0 || pageNumber >= d.NumPages() {
-		return nil, fmt.Errorf("invalid page number %d (pages: %d)", pageNumber, d.NumPages())
-	}
-
-	p, err := d.Page(pageNumber)
-	if err != nil {
-		return nil, err
-	}
-
-	var img image.Image
-	if opts.Original || opts.MaxWidth <= 0 || opts.MaxHeight <= 0 {
-		const maxEdge = 4096
-		rgba, err := p.ImageDPI(150)
-		if err != nil {
-			return nil, err
-		}
-		img = rgba
-		w, h := rgba.Bounds().Dx(), rgba.Bounds().Dy()
-		if w > maxEdge || h > maxEdge {
-			scale := min(float64(maxEdge)/float64(w), float64(maxEdge)/float64(h))
-			newW := max(1, int(float64(w)*scale))
-			newH := max(1, int(float64(h)*scale))
-			img = imaging.Resize(img, newW, newH, imaging.Lanczos)
-		}
-	} else {
-		rgba, err := p.ImageDPI(150)
-		if err != nil {
-			return nil, err
-		}
-		img = rgba
-		if opts.Fill {
-			img = imaging.Fill(img, opts.MaxWidth, opts.MaxHeight, imaging.Center, imaging.Lanczos)
-		} else {
-			b := img.Bounds()
-			if b.Dx() > opts.MaxWidth || b.Dy() > opts.MaxHeight {
-				img = imaging.Fit(img, opts.MaxWidth, opts.MaxHeight, imaging.Lanczos)
-			}
-		}
-	}
-
-	q := opts.JpegQuality
-	if q <= 0 {
-		q = 85
-	}
-	var buf bytes.Buffer
-	if err := jpeg.Encode(&buf, img, &jpeg.Options{Quality: q}); err != nil {
-		return nil, err
-	}
-	return buf.Bytes(), nil
-}

backend/internal/gomedia/containers_test.go

@@ -0,0 +1,73 @@
+package gomedia
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+const fixtureWMV2 = fixtureDir + "/file_example_WMV_480_1_2MB.wmv"
+
+// TestContainerGates pins which extensions go-media handles for probes and
+// for thumbnails.
+func TestContainerGates(t *testing.T) {
+	cases := []struct {
+		name             string
+		probe, thumbnail bool
+	}{
+		{"a.mp4", true, true},
+		{"a.M4V", true, true},
+		{"a.mov", true, true},
+		{"a.mkv", true, true},
+		{"a.webm", true, true},
+		{"a.wmv", false, true},
+		{"a.ASF", false, true},
+		{"a.avi", false, false},
+		{"a.ts", false, false},
+		{"a.m2ts", false, false},
+		{"a.mts", false, false},
+		{"a.mpg", false, false},
+		{"a.mpeg", false, false},
+		{"a.vob", false, false},
+		{"a.flv", false, false},
+	}
+	for _, c := range cases {
+		require.Equal(t, c.probe, supportsVideoContainer(c.name), "probe gate for %s", c.name)
+		require.Equal(t, c.thumbnail, supportsVideoThumbnail(c.name), "thumbnail gate for %s", c.name)
+	}
+	for _, name := range []string{"a.heic", "a.HEIF", "a.heics", "a.avif"} {
+		require.True(t, supportsHEIFImage(name), name)
+	}
+	require.False(t, supportsHEIFImage("a.jpg"))
+}
+
+// TestWMV2FallsBackToFFmpeg checks that a WMV2 file is not probed by go-media
+// and that its thumbnail falls back to ffmpeg (go-media has no WMV1/WMV2
+// decoder).
+func TestWMV2FallsBackToFFmpeg(t *testing.T) {
+	withGate(t, false)
+	_, ok := Probe(fixtureWMV2, nil)
+	require.False(t, ok, "WMV probes stay on ffprobe")
+	_, ok = VideoThumbnail(fixtureWMV2, 320, 240, 80, 10, nil)
+	require.False(t, ok, "WMV2 thumbnails must fall back to ffmpeg")
+}
+
+// TestWMV1FallsBackToFFmpeg is TestWMV2FallsBackToFFmpeg for a WMV1 stream
+// encoded on the fly.
+func TestWMV1FallsBackToFFmpeg(t *testing.T) {
+	withGate(t, false)
+	requireTool(t, "ffmpeg")
+	path := filepath.Join(t.TempDir(), "wmv1.wmv")
+	out, err := exec.Command("ffmpeg", "-v", "error", "-y", "-f", "lavfi", "-i", "testsrc2=size=160x120:rate=25:duration=2",
+		"-c:v", "wmv1", path).CombinedOutput()
+	if err != nil {
+		t.Skipf("ffmpeg cannot encode wmv1: %v: %s", err, out)
+	}
+	_, err = os.Stat(path)
+	require.NoError(t, err)
+	_, ok := VideoThumbnail(path, 160, 120, 80, 10, nil)
+	require.False(t, ok, "WMV1 thumbnails must fall back to ffmpeg")
+}

backend/internal/gomedia/gomedia.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	"github.com/gtsteffaniak/filebrowser/backend/internal/ffmpeg"
+	"github.com/gtsteffaniak/filebrowser/backend/internal/mediacache"
 	"github.com/gtsteffaniak/filebrowser/backend/internal/utils"
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
 	"github.com/gtsteffaniak/go-cache/cache"
@@ -28,20 +29,27 @@ import (
 	"golang.org/x/sync/singleflight"
 )
 
-var (
-	subtitleListCache    = cache.NewCache[[]utils.SubtitleTrack](24 * time.Hour)
-	subtitleContentCache = cache.NewCache[string](24 * time.Hour)
+// Probe, duration, and subtitle results are cached in the mediacache package,
+// which the ffmpeg code path shares. A directory listing probes every video
+// child, and the preview flow probes the focused file again; the cache keeps
+// each request from re-reading the same containers. Keys include size and
+// modification time, so an edited file is read again.
 
-	// probeCache caches successful probe results by file identity (path, modtime,
-	// size). A directory listing probes every video child, and the preview flow
-	// probes the focused file again; without this each request re-read the same
-	// containers. Keying on modtime+size means an edited file is re-probed.
-	probeCache = cache.NewCache[ProbeResult](24 * time.Hour)
+// probeGroup coalesces concurrent probes of the same file so a burst of
+// requests for one container reads it once.
+var probeGroup singleflight.Group
 
-	// probeGroup coalesces concurrent probes of the same file so a burst of
-	// requests for one container reads it once.
-	probeGroup singleflight.Group
-)
+// tagsCache caches the embedded part of a tag read by file identity. A listing
+// reads tags for every media child on each uncached request. Sidecar lyrics
+// are not cached: adding an .lrc next to a file does not change its modtime.
+var tagsCache = cache.NewCache[AudioInfo](24 * time.Hour)
+
+func init() {
+	// The ffmpeg HEIC decode path corrects orientation after decoding and needs
+	// the file's irot. internal/ffmpeg cannot import this package, so go-media's
+	// header reader is installed here.
+	ffmpeg.SetHEICDisplayRotationReader(HEICDisplayRotation)
+}
 
 // Enabled reports whether the go-media fast path may run. The admin
 // "Always use ffmpeg" setting turns it off.
@@ -60,9 +68,15 @@ func videoDimensions(info *media.ProbeInfo) (w, h int, ok bool) {
 }
 
 // videoContainerExts are the containers go-media parses for video probes,
-// thumbnails, and embedded subtitles. Other video containers (AVI, WMV, TS, ...)
-// are not go-media targets, so they go straight to ffmpeg with no file open and
-// no log line. go-media reads MOV as MP4.
+// thumbnails, embedded subtitles, and keyframe indexes. go-media reads MOV as
+// MP4.
+//
+// go-media also demuxes AVI, ASF/WMV, MPEG-TS/M2TS, and MPEG-PS (VOB), but their
+// probes are left to ffmpeg on purpose: go-media's results for those containers
+// do not yet match ffprobe (TS/M2TS and PS list no audio streams, PS durations
+// are missing or wrong, AVI misnames MPEG-4 Part 2 and AAC, ASF reports WMA Pro
+// as wmav2). Those files go straight to ffmpeg with no file open and no log
+// line. See videoThumbnailExts for the thumbnail exception.
 var videoContainerExts = map[string]bool{
 	".mp4":  true,
 	".m4v":  true,
@@ -71,15 +85,40 @@ var videoContainerExts = map[string]bool{
 	".webm": true,
 }
 
+// videoThumbnailExts are the containers go-media decodes video thumbnails from:
+// videoContainerExts plus ASF/WMV, whose WMV3 keyframes go-media decodes
+// bit-exact with ffmpeg. WMV1, WMV2, MS-MPEG4, and WVC1 Advanced Profile return
+// an unsupported error and fall back to ffmpeg. AVI, TS/M2TS, and PS stay on
+// ffmpeg: go-media's TS and PS thumbnails scan the whole file for the duration
+// (several times slower than ffmpeg on large files), and AVI seeks by a
+// duration that can be wrong.
+var videoThumbnailExts = map[string]bool{
+	".mp4":  true,
+	".m4v":  true,
+	".mov":  true,
+	".mkv":  true,
+	".webm": true,
+	".wmv":  true,
+	".asf":  true,
+}
+
 // heifImageExts are still-image containers go-media decodes for HEIC preview.
+// AVIF is a HEIF container with an AV1 image item; go-media decodes it in pure
+// Go and applies its irot/imir, like HEIC.
 var heifImageExts = map[string]bool{
 	".heic":  true,
 	".heif":  true,
 	".heics": true,
+	".avif":  true,
 }
 
 const heicDecodeMaxEdge = 16384
 
+// stillImageMaxSourcePixels caps the original image area (width×height) passed to
+// go-media for HEIC, JPEG XL, and camera RAW decode. JPEG XL honors it today
+// (~50 MiB of 8-bit RGB at 4096×4096); other still formats ignore the field.
+const stillImageMaxSourcePixels = 4096 * 4096
+
 // cameraRawExts match go-media rawpreview formats (also iteminfo raw extensions).
 var cameraRawExts = map[string]bool{
 	".cr2": true, ".cr3": true, ".nef": true, ".nrw": true, ".arw": true, ".srf": true, ".sr2": true,
@@ -88,15 +127,27 @@ var cameraRawExts = map[string]bool{
 	".dc2": true, ".x3f": true, ".iiq": true, ".nkc": true, ".r3d": true,
 }
 
-// supportsVideoContainer reports whether go-media targets path's container.
+// supportsVideoContainer reports whether go-media targets path's container for
+// probes, embedded subtitles, and keyframe indexes.
 func supportsVideoContainer(path string) bool {
 	return videoContainerExts[strings.ToLower(filepath.Ext(path))]
 }
 
+// supportsVideoThumbnail reports whether go-media targets path's container for
+// video thumbnails.
+func supportsVideoThumbnail(path string) bool {
+	return videoThumbnailExts[strings.ToLower(filepath.Ext(path))]
+}
+
+// supportsHEIFImage reports whether path is a HEIF-family still image
+// (HEIC/HEIF/AVIF) go-media decodes.
+
 func supportsHEIFImage(path string) bool {
 	return heifImageExts[strings.ToLower(filepath.Ext(path))]
 }
 
+// supportsCameraRAW reports whether path is a camera RAW format go-media
+// extracts a preview from.
 func supportsCameraRAW(path string) bool {
 	return cameraRawExts[strings.ToLower(filepath.Ext(path))]
 }
@@ -128,16 +179,26 @@ func logUnsupported(op, path, reason string) {
 
 // openFile opens path for go-media, which reads through io.ReaderAt.
 func openFile(path string) (*os.File, int64, error) {
-	f, err := os.Open(path)
+	f, info, err := openFileInfo(path)
 	if err != nil {
 		return nil, 0, err
 	}
+	return f, info.Size(), nil
+}
+
+// openFileInfo opens path and returns its FileInfo, which also gives the
+// shared cache key.
+func openFileInfo(path string) (*os.File, os.FileInfo, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, nil, err
+	}
 	info, err := f.Stat()
 	if err != nil {
 		_ = f.Close()
-		return nil, 0, err
+		return nil, nil, err
 	}
-	return f, info.Size(), nil
+	return f, info, nil
 }
 
 // ffprobeFormatNames maps go-media containers to the format_name strings ffprobe
@@ -174,30 +235,25 @@ func probeFast(path string) (ProbeResult, bool) {
 		return ProbeResult{}, false
 	}
 
-	f, size, err := openFile(path)
+	f, info, err := openFileInfo(path)
 	if err != nil {
 		logFallback("probe", path, err)
 		return ProbeResult{}, false
 	}
 	defer f.Close()
 
-	info, err := f.Stat()
-	if err != nil {
-		logFallback("probe", path, err)
-		return ProbeResult{}, false
-	}
-	cacheKey := probeCacheKey(path, info.ModTime().UnixNano(), size)
-	if res, ok := probeCache.Get(cacheKey); ok {
+	cacheKey := mediacache.FromFileInfo(path, info).String()
+	if res, ok := mediacache.Probes.Get(cacheKey); ok {
 		return res, true
 	}
 
 	// Coalesce concurrent probes of the same file into one container read.
 	v, err, _ := probeGroup.Do(cacheKey, func() (any, error) {
-		res, ok := parseProbe(path, f, size)
+		res, ok := parseProbe(path, f, info.Size())
 		if !ok {
 			return nil, errProbeUnsupported
 		}
-		probeCache.Set(cacheKey, res)
+		mediacache.Probes.Set(cacheKey, res)
 		return res, nil
 	})
 	if err != nil {
@@ -214,12 +270,6 @@ func probeFast(path string) (ProbeResult, bool) {
 // no detail because parseProbe already logged the specific reason.
 var errProbeUnsupported = errors.New("probe unsupported")
 
-// probeCacheKey identifies a file version for caching: path plus modtime and size.
-// An edited file gets a new key, so stale metadata is never served.
-func probeCacheKey(path string, modTimeNanos, size int64) string {
-	return fmt.Sprintf("probe:%s:%d:%d", path, modTimeNanos, size)
-}
-
 // parseProbe reads a container and builds a ProbeResult. It reports false when
 // go-media should defer to ffmpeg, having logged why.
 func parseProbe(path string, f *os.File, size int64) (ProbeResult, bool) {
@@ -275,14 +325,18 @@ func durationFast(path string) (float64, bool) {
 	if !Enabled() {
 		return 0, false
 	}
-	f, size, err := openFile(path)
+	f, info, err := openFileInfo(path)
 	if err != nil {
 		logFallback("duration", path, err)
 		return 0, false
 	}
 	defer f.Close()
 
-	res, err := media.Duration(f, size)
+	cacheKey := mediacache.FromFileInfo(path, info).String()
+	if d, ok := mediacache.Durations.Get(cacheKey); ok {
+		return d, true
+	}
+	res, err := media.Duration(f, info.Size())
 	if err != nil {
 		logFallback("duration", path, err)
 		return 0, false
@@ -291,7 +345,9 @@ func durationFast(path string) (float64, bool) {
 		// Unknown duration is not an error; ffmpeg may still find one.
 		return 0, false
 	}
-	return res.Duration.Seconds(), true
+	d := res.Duration.Seconds()
+	mediacache.Durations.Set(cacheKey, d)
+	return d, true
 }
 
 // AudioInfo is the tag, lyrics availability, and cover art FileBrowser reads
@@ -306,38 +362,60 @@ type AudioInfo struct {
 // is true. A missing cover is not an error.
 // legacy is the dhowden tag read, run only in shadow mode.
 func Audio(path string, withArt bool, legacy Legacy[AudioInfo]) (AudioInfo, bool) {
-	return timed("tags", path, legacy, audioDiffer(withArt), func() (AudioInfo, bool) { return audioFast(path, withArt) })
+	return timed("tags", path, legacy, audioDiffer(withArt), func() (AudioInfo, bool) { return audioFast(path, withArt, true) })
 }
 
-func audioFast(path string, withArt bool) (AudioInfo, bool) {
+func audioFast(path string, withArt, withSidecar bool) (AudioInfo, bool) {
 	if !Enabled() {
 		return AudioInfo{}, false
 	}
-	f, size, err := openFile(path)
+	f, st, err := openFileInfo(path)
 	if err != nil {
 		logFallback("tags", path, err)
 		return AudioInfo{}, false
 	}
 	defer f.Close()
 
-	// One container parse gives tags, the embedded lyrics flag, and cover bytes.
-	// Separate ReadTags/HasLyrics/EmbeddedArtwork calls each re-parsed the file.
-	audio, err := media.InspectAudio(f, size, media.AudioOptions{WithArtwork: withArt})
-	if err != nil {
-		logFallback("tags", path, err)
-		return AudioInfo{}, false
+	size := st.Size()
+	cacheKey := tagsCacheKey(path, st.ModTime().UnixNano(), size)
+	var info AudioInfo
+	cached := false
+	if !withArt {
+		info, cached = tagsCache.Get(cacheKey)
 	}
-	info := AudioInfo{Tags: audio.Tags, HasLyrics: audio.HasEmbeddedLyrics}
-	if !info.HasLyrics {
+	if !cached {
+		// One container parse gives tags, the embedded lyrics flag, and cover bytes.
+		// Separate ReadTags/HasLyrics/EmbeddedArtwork calls each re-parsed the file.
+		audio, err := media.InspectAudio(f, size, media.AudioOptions{WithArtwork: withArt})
+		if err != nil {
+			logFallback("tags", path, err)
+			return AudioInfo{}, false
+		}
+		info = AudioInfo{Tags: audio.Tags, HasLyrics: audio.HasEmbeddedLyrics}
+		stored := info
+		stored.Tags.Raw = nil
+		tagsCache.Set(cacheKey, stored)
+		if withArt {
+			info.Artwork = audio.Artwork
+		}
+	}
+	if withSidecar && !info.HasLyrics {
 		// Sidecar lyrics are only checked when the file has no embedded lyrics.
 		_, _, info.HasLyrics = media.LyricsSidecar(path)
 	}
-	if withArt {
-		info.Artwork = audio.Artwork
-	}
 	return info, true
 }
 
+// tagsCacheKey identifies a file version for the tag cache: path plus modtime and size.
+func tagsCacheKey(path string, modTimeNanos, size int64) string {
+	return fmt.Sprintf("tags:%s:%d:%d", path, modTimeNanos, size)
+}
+
+// VideoTags reads embedded tags and cover from a video container
+func VideoTags(path string, withArt bool) (AudioInfo, bool) {
+	return timed("tags", path, nil, nil, func() (AudioInfo, bool) { return audioFast(path, withArt, false) })
+}
+
 // Lyrics returns lyrics from a sidecar file, or else from embedded tags. The
 // format is "embedded" for tags or the sidecar extension. An empty result with
 // ok=true means go-media checked and found no lyrics.
@@ -379,7 +457,9 @@ func lyricsFast(path string) (text, format string, ok bool) {
 
 // EmbeddedSubtitles lists embedded subtitle tracks. go-media supports MKV, WebM,
 // and MP4 only. Other containers are reported as unsupported, not as "no
-// subtitles", because go-media returns an empty list for them.
+// subtitles", because go-media returns an empty list for them. modtime is kept
+// for API compatibility; the cache key comes from the file's current size and
+// modification time.
 // legacy is the ffmpeg subtitle detection, run only in shadow mode.
 func EmbeddedSubtitles(path string, modtime time.Time, legacy Legacy[[]utils.SubtitleTrack]) ([]utils.SubtitleTrack, bool) {
 	return timed("subtitle list", path, legacy, subtitleListDiff, func() ([]utils.SubtitleTrack, bool) {
@@ -394,19 +474,20 @@ func embeddedSubtitlesFast(path string, modtime time.Time) ([]utils.SubtitleTrac
 	if !supportsVideoContainer(path) {
 		return nil, false
 	}
-	key := fmt.Sprintf("embedded_subtitles:%s:%d", path, modtime.Unix())
-	if cached, ok := subtitleListCache.Get(key); ok {
-		return cached, true
-	}
-
-	f, size, err := openFile(path)
+	_ = modtime
+	f, st, err := openFileInfo(path)
 	if err != nil {
 		logFallback("subtitle list", path, err)
 		return nil, false
 	}
 	defer f.Close()
 
-	info, err := media.Probe(f, size)
+	key := mediacache.FromFileInfo(path, st).String()
+	if cached, ok := mediacache.SubtitleTracks.Get(key); ok {
+		return cached, true
+	}
+
+	info, err := media.Probe(f, st.Size())
 	if err != nil {
 		logFallback("subtitle list", path, err)
 		return nil, false
@@ -428,7 +509,7 @@ func embeddedSubtitlesFast(path string, modtime time.Time) ([]utils.SubtitleTrac
 		})
 	}
 	tracks := ffmpeg.BuildSubtitleTracks(streams)
-	subtitleListCache.Set(key, tracks)
+	mediacache.SubtitleTracks.Set(key, tracks)
 	return tracks, true
 }
 
@@ -448,24 +529,19 @@ func extractSubtitleFast(path string, streamIndex int) (string, bool) {
 	if !supportsVideoContainer(path) {
 		return "", false
 	}
-	st, err := os.Stat(path)
-	if err != nil {
-		logFallback("subtitle extract", path, err)
-		return "", false
-	}
-	key := fmt.Sprintf("subtitle_content:%s:%d:%d", path, streamIndex, st.ModTime().Unix())
-	if content, ok := subtitleContentCache.Get(key); ok {
-		return content, true
-	}
-
-	f, size, err := openFile(path)
+	f, st, err := openFileInfo(path)
 	if err != nil {
 		logFallback("subtitle extract", path, err)
 		return "", false
 	}
 	defer f.Close()
 
-	vtt, err := media.ExtractEmbeddedSubtitle(f, size, streamIndex)
+	key := mediacache.FromFileInfo(path, st).Stream(streamIndex)
+	if content, ok := mediacache.SubtitleContent.Get(key); ok {
+		return content, true
+	}
+
+	vtt, err := media.ExtractEmbeddedSubtitle(f, st.Size(), streamIndex)
 	if err != nil {
 		logFallback("subtitle extract", path, err)
 		return "", false
@@ -474,7 +550,7 @@ func extractSubtitleFast(path string, streamIndex int) (string, bool) {
 		logFallback("subtitle extract", path, errors.New("empty subtitle output"))
 		return "", false
 	}
-	subtitleContentCache.Set(key, vtt)
+	mediacache.SubtitleContent.Set(key, vtt)
 	return vtt, true
 }
 
@@ -496,7 +572,7 @@ func videoThumbnailFast(path string, width, height, quality int, seekPercent flo
 	if !Enabled() {
 		return nil, false
 	}
-	if !supportsVideoContainer(path) {
+	if !supportsVideoThumbnail(path) {
 		return nil, false
 	}
 	f, size, err := openFile(path)
@@ -628,10 +704,11 @@ func stillImageJPEG(path string, maxW, maxH, quality int, op string, supported f
 		quality = 85
 	}
 	res, err := media.Thumbnail(f, size, media.ThumbnailOptions{
-		MaxWidth:  maxW,
-		MaxHeight: maxH,
-		Format:    "jpeg",
-		Quality:   quality,
+		MaxWidth:        maxW,
+		MaxHeight:       maxH,
+		Format:          "jpeg",
+		Quality:         quality,
+		MaxSourcePixels: stillImageMaxSourcePixels,
 	})
 	if err != nil {
 		logFail(err)

backend/internal/gomedia/gomedia_test.go

@@ -11,6 +11,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/gtsteffaniak/filebrowser/backend/internal/mediacache"
+	"github.com/gtsteffaniak/filebrowser/backend/internal/utils"
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
 	"github.com/stretchr/testify/require"
 )
@@ -131,27 +133,78 @@ func TestProbeUsesCache(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, os.WriteFile(path, data, 0o644))
 
-	st, err := os.Stat(path)
+	key, err := mediacache.Stat(path)
 	require.NoError(t, err)
-	key := probeCacheKey(path, st.ModTime().UnixNano(), st.Size())
 	sentinel := ProbeResult{Duration: 123, VideoCodec: "sentinel", AudioCodec: "sentinel", FormatName: "sentinel"}
-	probeCache.Set(key, sentinel)
-	t.Cleanup(func() { probeCache.Delete(key) })
+	// The ffmpeg probe stores into the same shared cache, so this also stands in
+	// for a value ffprobe produced earlier.
+	mediacache.Probes.Set(key.String(), sentinel)
+	t.Cleanup(func() { mediacache.Probes.Delete(key.String()) })
 
 	got, ok := Probe(path, nil)
 	require.True(t, ok)
 	require.Equal(t, sentinel, got, "probe must return the cached value for an unchanged file")
+
+	// An edit (new size and mtime) must miss the cached value.
+	require.NoError(t, os.WriteFile(path, append(data, 0), 0o644))
+	future := time.Now().Add(time.Hour)
+	require.NoError(t, os.Chtimes(path, future, future))
+	got, ok = Probe(path, nil)
+	require.True(t, ok)
+	require.NotEqual(t, sentinel, got, "an edited file must be probed again")
+	edited, err := mediacache.Stat(path)
+	require.NoError(t, err)
+	t.Cleanup(func() { mediacache.Probes.Delete(edited.String()) })
 }
 
-// TestProbeCacheKeyTracksFileIdentity checks that path, modtime, and size all
-// participate in the cache key, so an edited file is never served stale metadata.
-func TestProbeCacheKeyTracksFileIdentity(t *testing.T) {
-	base := probeCacheKey("f.mp4", 100, 200)
-	require.Equal(t, base, probeCacheKey("f.mp4", 100, 200), "identical identity must hash the same")
-	require.NotEqual(t, base, probeCacheKey("f.mp4", 101, 200), "modtime change must change the key")
-	require.NotEqual(t, base, probeCacheKey("f.mp4", 100, 201), "size change must change the key")
-	require.NotEqual(t, base, probeCacheKey("g.mp4", 100, 200), "path change must change the key")
-	require.NotEqual(t, base, probeCacheKey("f.mp4", 100, 201), "key must not collide across fields")
+// TestDurationUsesSharedCache checks that Duration reads and fills the shared
+// cache that ffmpeg's GetMediaDuration also uses.
+func TestDurationUsesSharedCache(t *testing.T) {
+	withGate(t, false)
+	path := filepath.Join(t.TempDir(), "sample.mp4")
+	data, err := os.ReadFile(fixtureMP4)
+	require.NoError(t, err)
+	require.NoError(t, os.WriteFile(path, data, 0o644))
+	key, err := mediacache.Stat(path)
+	require.NoError(t, err)
+	t.Cleanup(func() { mediacache.Durations.Delete(key.String()) })
+
+	d, ok := Duration(path, nil)
+	require.True(t, ok)
+	cached, found := mediacache.Durations.Get(key.String())
+	require.True(t, found, "go-media duration must be stored in the shared cache")
+	require.Equal(t, d, cached)
+
+	mediacache.Durations.Set(key.String(), 4242)
+	d, ok = Duration(path, nil)
+	require.True(t, ok)
+	require.Equal(t, 4242.0, d, "a cached duration (from either backend) must be reused")
+}
+
+// TestSubtitleCachesUseFileIdentity checks the subtitle list cache is keyed by
+// the file's real size and mtime, not by the caller's modtime argument.
+func TestSubtitleCachesUseFileIdentity(t *testing.T) {
+	withGate(t, false)
+	path := filepath.Join(t.TempDir(), "sample.mp4")
+	data, err := os.ReadFile(fixtureMP4)
+	require.NoError(t, err)
+	require.NoError(t, os.WriteFile(path, data, 0o644))
+	key, err := mediacache.Stat(path)
+	require.NoError(t, err)
+	sentinel := []utils.SubtitleTrack{{Name: "sentinel"}}
+	mediacache.SubtitleTracks.Set(key.String(), sentinel)
+	t.Cleanup(func() { mediacache.SubtitleTracks.Delete(key.String()) })
+
+	// The modtime argument is ignored for the key.
+	got, ok := EmbeddedSubtitles(path, time.Unix(1, 0), nil)
+	require.True(t, ok)
+	require.Equal(t, sentinel, got)
+
+	mediacache.SubtitleContent.Set(key.Stream(7), "WEBVTT\n\nsentinel")
+	t.Cleanup(func() { mediacache.SubtitleContent.Delete(key.Stream(7)) })
+	vtt, ok := ExtractSubtitle(path, 7, nil)
+	require.True(t, ok)
+	require.Equal(t, "WEBVTT\n\nsentinel", vtt)
 }
 
 func TestProbeWebMMatchesFFprobe(t *testing.T) {

backend/internal/gomedia/heif_rotation.go

@@ -0,0 +1,101 @@
+package gomedia
+
+import (
+	"context"
+	"fmt"
+	"math"
+	"time"
+
+	"github.com/gtsteffaniak/filebrowser/backend/internal/ffmpeg"
+	"github.com/gtsteffaniak/go-media/pkg/media"
+)
+
+// heicRotationShadowTimeout bounds the dev-mode ffmpeg comparison probe.
+const heicRotationShadowTimeout = time.Minute
+
+// HEICDisplayRotation returns the display rotation that a HEIC/HEIF/AVIF
+// file's irot property asks for, read from the item properties without
+// decoding. The value is degrees counter-clockwise in (-180, 180], the same
+// number ffmpeg prints as "Display Matrix: rotation of ..." for the file. A
+// file with no irot returns 0 and ok=true. ok is false when go-media is
+// disabled or cannot read the item properties; the caller then runs the ffmpeg
+// probe.
+//
+// It is installed as ffmpeg's HEIC display rotation reader. In shadow mode the
+// ffmpeg stderr probe runs for comparison.
+func HEICDisplayRotation(path string) (float64, bool) {
+	return timed("heic rotation", path, heicRotationLegacy(path), heicRotationDiff, func() (float64, bool) {
+		return heicDisplayRotationFast(path)
+	})
+}
+
+// heicRotationLegacy returns the ffmpeg stderr probe for shadow mode, or nil
+// when ffmpeg is not available.
+func heicRotationLegacy(path string) Legacy[float64] {
+	if !ShadowEnabled() {
+		return nil
+	}
+	svc := ffmpeg.Get()
+	if svc == nil {
+		return nil
+	}
+	return func() (float64, bool) {
+		ctx, cancel := context.WithTimeout(context.Background(), heicRotationShadowTimeout)
+		defer cancel()
+		return svc.GetHEICDisplayMatrixRotation(ctx, path)
+	}
+}
+
+// heicDisplayRotationFast reads the primary item's irot with go-media and
+// converts it to ffmpeg's display rotation.
+func heicDisplayRotationFast(path string) (float64, bool) {
+	if !Enabled() {
+		return 0, false
+	}
+	// No extension check: the resolved path can have another name (symlink
+	// target). go-media sniffs the content and reports other files unsupported.
+	f, size, err := openFile(path)
+	if err != nil {
+		logFallback("heic rotation", path, err)
+		return 0, false
+	}
+	defer f.Close()
+
+	t, err := media.HEIFTransform(f, size)
+	if err != nil {
+		logFallback("heic rotation", path, err)
+		return 0, false
+	}
+	return displayRotation(t), true
+}
+
+// displayRotation converts go-media's counter-clockwise irot angle to ffmpeg's
+// display matrix convention: counter-clockwise degrees normalized to
+// (-180, 180]. ffmpeg builds the matrix with av_display_rotation_set(-irot)
+// and prints av_display_rotation_get, so irot 270 is reported as -90. A mirror
+// does not change the rotation value.
+func displayRotation(t media.ImageTransform) float64 {
+	r := ((t.Rotation % 360) + 360) % 360
+	if r > 180 {
+		r -= 360
+	}
+	return float64(r)
+}
+
+// heicRotationDiff compares go-media's display rotation with ffmpeg's. 180 and
+// -180 are the same rotation.
+func heicRotationDiff(fast, legacy float64) []string {
+	norm := func(v float64) float64 {
+		v = math.Mod(v, 360)
+		if v <= -180 {
+			v += 360
+		} else if v > 180 {
+			v -= 360
+		}
+		return v
+	}
+	if math.Abs(norm(fast)-norm(legacy)) > 0.5 {
+		return []string{fmt.Sprintf("display rotation go-media=%.2f ffmpeg=%.2f", fast, legacy)}
+	}
+	return nil
+}

backend/internal/gomedia/heif_rotation_test.go

@@ -0,0 +1,82 @@
+package gomedia
+
+import (
+	"math"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/gtsteffaniak/filebrowser/backend/internal/ffmpeg"
+	"github.com/gtsteffaniak/go-media/pkg/media"
+	"github.com/stretchr/testify/require"
+)
+
+// fixtureAVIFRotated has irot=1 (90° counter-clockwise) and imir axis 0.
+const fixtureAVIFRotated = "testdata/irot1_imir0.avif"
+
+// TestDisplayRotation checks the irot to ffmpeg display rotation mapping.
+func TestDisplayRotation(t *testing.T) {
+	cases := []struct {
+		rotation int
+		want     float64
+	}{
+		{0, 0}, {90, 90}, {180, 180}, {270, -90}, {-90, -90}, {360, 0}, {450, 90},
+	}
+	for _, c := range cases {
+		require.Equal(t, c.want, displayRotation(media.ImageTransform{Rotation: c.rotation}), "rotation %d", c.rotation)
+	}
+	require.Equal(t, 90.0, displayRotation(media.ImageTransform{Rotation: 90, Mirror: true}), "a mirror does not change the rotation")
+}
+
+// TestHEICDisplayRotationReadsIrot checks the rotation read from a fixture
+// with irot=1.
+func TestHEICDisplayRotationReadsIrot(t *testing.T) {
+	withGate(t, false)
+	got, ok := HEICDisplayRotation(fixtureAVIFRotated)
+	require.True(t, ok)
+	require.Equal(t, 90.0, got)
+}
+
+// TestHEICDisplayRotationFallsBack checks that non-HEIF input, broken input,
+// and the Always use ffmpeg setting leave the answer to ffmpeg.
+func TestHEICDisplayRotationFallsBack(t *testing.T) {
+	withGate(t, false)
+	_, ok := HEICDisplayRotation(fixtureMP4)
+	require.False(t, ok, "a non-HEIF file must fall back to the ffmpeg probe")
+
+	junk := filepath.Join(t.TempDir(), "junk.heic")
+	require.NoError(t, os.WriteFile(junk, []byte("not heif"), 0o644))
+	_, ok = HEICDisplayRotation(junk)
+	require.False(t, ok)
+
+	withGate(t, true)
+	_, ok = HEICDisplayRotation(fixtureAVIFRotated)
+	require.False(t, ok, "the Always use ffmpeg setting must skip go-media")
+}
+
+// TestHEICDisplayRotationInstalled checks that loading this package installs
+// go-media as the ffmpeg package's rotation reader.
+func TestHEICDisplayRotationInstalled(t *testing.T) {
+	withGate(t, false)
+	var svc *ffmpeg.Service // nil: the ffmpeg probe cannot run, so a result proves the reader answered
+	got, ok := svc.HEICDisplayRotation(t.Context(), fixtureAVIFRotated)
+	require.True(t, ok)
+	require.Equal(t, 90.0, got)
+}
+
+// TestHEICRotationDiff checks the shadow comparison of display rotations.
+func TestHEICRotationDiff(t *testing.T) {
+	require.Empty(t, heicRotationDiff(-90, -90))
+	require.Empty(t, heicRotationDiff(180, -180))
+	require.Empty(t, heicRotationDiff(0, math.Copysign(0, -1)))
+	require.Len(t, heicRotationDiff(90, -90), 1)
+}
+
+// TestAVIFDecodesThroughHEICPath checks that an AVIF file is accepted by the
+// HEIC decode path.
+func TestAVIFDecodesThroughHEICPath(t *testing.T) {
+	withGate(t, false)
+	data, ok := HEICJPEG(fixtureAVIFRotated, 80, nil)
+	require.True(t, ok)
+	require.NotEmpty(t, data)
+}

backend/internal/gomedia/jxl_test.go

@@ -2,11 +2,13 @@ package gomedia
 
 import (
 	"bytes"
+	"errors"
 	"image/jpeg"
 	"os"
 	"path/filepath"
 	"testing"
 
+	"github.com/gtsteffaniak/go-media/pkg/media"
 	"github.com/stretchr/testify/require"
 )
 
@@ -66,3 +68,24 @@ func TestJXLJPEGMissingFileReturnsFalse(t *testing.T) {
 	require.False(t, ok)
 	require.Empty(t, data)
 }
+
+// JPEG XL above stillImageMaxSourcePixels must fail with go-media's ErrUnsupported
+// and return ok=false (no ffmpeg fallback).
+func TestJXLJPEGRejectsOversizedSource(t *testing.T) {
+	withGate(t, false)
+	f, err := os.Open(fixtureJXL)
+	require.NoError(t, err)
+	defer f.Close()
+	info, err := f.Stat()
+	require.NoError(t, err)
+
+	_, err = media.Thumbnail(f, info.Size(), media.ThumbnailOptions{
+		MaxWidth:        256,
+		MaxHeight:       256,
+		Format:          "jpeg",
+		Quality:         85,
+		MaxSourcePixels: 1,
+	})
+	require.Error(t, err)
+	require.True(t, errors.Is(err, media.ErrUnsupported), "oversized JXL must surface ErrUnsupported, got %v", err)
+}

backend/internal/gomedia/keyframes.go

@@ -0,0 +1,145 @@
+package gomedia
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"math"
+	"sort"
+
+	"github.com/gtsteffaniak/go-media/pkg/media"
+)
+
+// keyframeTimeDedupeSec matches go-ffmpeg's ffprobe keyframe probe, which
+// drops keyframes within 1 ms of the previous one.
+const keyframeTimeDedupeSec = 0.001
+
+// keyframeShadowTolerance is how far apart two backends' keyframe times can be
+// before the shadow comparison reports them. ffprobe prints six decimals.
+const keyframeShadowTolerance = 0.002
+
+// KeyframeTimes returns the presentation times, in seconds, of the first video
+// stream's keyframes, for HLS segment planning. The result is sorted, has no
+// negative times, and drops keyframes within 1 ms of the previous one, the same
+// as go-ffmpeg's ffprobe probe. go-media reads only the container index (MP4
+// stss/stts/ctts, Matroska Cues or block headers), so it is much faster than
+// demuxing every packet with ffprobe.
+//
+// ok is false when go-media is disabled, the container is not one go-media
+// indexes, or the read fails; the caller then runs ffprobe. ctx cancels the
+// file reads. legacy is the ffprobe probe, run only in shadow mode.
+//
+// go-media can report fewer keyframes than ffprobe (ffprobe's parsers also flag
+// IDR frames the container index omits, and some Matroska muxers index only
+// part of the keyframes in Cues). It never reports a keyframe ffprobe would not.
+func KeyframeTimes(ctx context.Context, path string, legacy Legacy[[]float64]) ([]float64, bool) {
+	return timed("keyframe index", path, legacy, keyframeDiff, func() ([]float64, bool) {
+		return keyframeTimesFast(ctx, path, 0)
+	})
+}
+
+// KeyframeTimesWithin is KeyframeTimes limited to keyframes within windowSec
+// seconds of the first keyframe. It is the pre-flight check that can rule out
+// stream copy without reading the whole index (Matroska files without Cues).
+// It has no shadow comparison.
+func KeyframeTimesWithin(ctx context.Context, path string, windowSec float64) ([]float64, bool) {
+	return timed("keyframe preflight", path, nil, nil, func() ([]float64, bool) {
+		return keyframeTimesFast(ctx, path, windowSec)
+	})
+}
+
+// keyframeTimesFast reads the keyframe index with go-media. windowSec > 0
+// limits it to keyframes within that many seconds of the first one.
+func keyframeTimesFast(ctx context.Context, path string, windowSec float64) ([]float64, bool) {
+	if !Enabled() {
+		return nil, false
+	}
+	if !supportsVideoContainer(path) {
+		return nil, false
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, false
+	}
+	f, size, err := openFile(path)
+	if err != nil {
+		logFallback("keyframe index", path, err)
+		return nil, false
+	}
+	defer f.Close()
+
+	r := ctxReaderAt{ctx: ctx, r: f}
+	var times []float64
+	if windowSec > 0 {
+		times, err = media.KeyframeTimesWithin(r, size, windowSec)
+	} else {
+		times, err = media.KeyframeTimes(r, size)
+	}
+	if err != nil {
+		if ctx.Err() == nil {
+			logFallback("keyframe index", path, err)
+		}
+		return nil, false
+	}
+	times = dedupeKeyframeTimes(times)
+	if len(times) == 0 {
+		logUnsupported("keyframe index", path, "no keyframes in container index")
+		return nil, false
+	}
+	return times, true
+}
+
+// dedupeKeyframeTimes sorts times, drops negative values, and drops times
+// within keyframeTimeDedupeSec of the previous kept time, as go-ffmpeg does for
+// ffprobe output.
+func dedupeKeyframeTimes(times []float64) []float64 {
+	sorted := append([]float64(nil), times...)
+	sort.Float64s(sorted)
+	out := make([]float64, 0, len(sorted))
+	for _, t := range sorted {
+		if t < 0 || math.IsNaN(t) || math.IsInf(t, 0) {
+			continue
+		}
+		if len(out) == 0 || t > out[len(out)-1]+keyframeTimeDedupeSec {
+			out = append(out, t)
+		}
+	}
+	return out
+}
+
+// ctxReaderAt fails reads once ctx is done, so a cancelled request or the plan
+// timeout stops a long index walk on a slow share.
+type ctxReaderAt struct {
+	ctx context.Context
+	r   io.ReaderAt
+}
+
+// ReadAt reads from the wrapped reader unless the context is done.
+func (c ctxReaderAt) ReadAt(p []byte, off int64) (int, error) {
+	if err := c.ctx.Err(); err != nil {
+		return 0, err
+	}
+	return c.r.ReadAt(p, off)
+}
+
+// keyframeDiff compares go-media's keyframe index with ffprobe's. go-media
+// reporting a subset of ffprobe's keyframes is expected (parser-flagged IDR
+// frames, partial Cues) and is logged at info level.
+func keyframeDiff(fast, legacy []float64) []string {
+	missing := 0
+	j := 0
+	for _, t := range fast {
+		for j < len(legacy) && legacy[j] < t-keyframeShadowTolerance {
+			j++
+			missing++
+		}
+		if j >= len(legacy) || math.Abs(legacy[j]-t) > keyframeShadowTolerance {
+			return []string{fmt.Sprintf("keyframe at %.6fs from go-media not in ffmpeg index (go-media=%d ffmpeg=%d keyframes)", t, len(fast), len(legacy))}
+		}
+		j++
+	}
+	missing += len(legacy) - j
+	if missing > 0 {
+		return []string{fmt.Sprintf("%sgo-media found %d of %d ffmpeg keyframes (keyframes outside the container index)", expectedDiffPrefix, len(fast), len(legacy))}
+	}
+	return nil
+}

backend/internal/gomedia/keyframes_test.go

@@ -0,0 +1,176 @@
+package gomedia
+
+import (
+	"context"
+	"math"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// ffprobeKeyframes runs the same packet probe as go-ffmpeg's
+// ProbeVideoKeyframeTimes: key packets of v:0, pts_time falling back to
+// dts_time, sorted and de-duplicated within 1 ms.
+func ffprobeKeyframes(t *testing.T, path string) []float64 {
+	t.Helper()
+	requireTool(t, "ffprobe")
+	out, err := exec.Command("ffprobe", "-v", "error", "-select_streams", "v:0",
+		"-show_entries", "packet=pts_time,dts_time,flags", "-of", "csv=p=0", path).Output()
+	require.NoError(t, err)
+	var times []float64
+	for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
+		f := strings.Split(strings.TrimSpace(line), ",")
+		if len(f) < 3 || !strings.Contains(f[2], "K") {
+			continue
+		}
+		v, perr := strconv.ParseFloat(f[0], 64)
+		if perr != nil {
+			v, perr = strconv.ParseFloat(f[1], 64)
+		}
+		if perr == nil {
+			times = append(times, v)
+		}
+	}
+	sort.Float64s(times)
+	return dedupeKeyframeTimes(times)
+}
+
+// encodeKeyframeClip makes a short clip with a fixed GOP. B-frames give MP4
+// files a ctts table and an edit list, the hard case for the timestamp model.
+func encodeKeyframeClip(t *testing.T, name string, args ...string) string {
+	t.Helper()
+	requireTool(t, "ffmpeg")
+	path := filepath.Join(t.TempDir(), name)
+	full := []string{"-v", "error", "-y", "-f", "lavfi", "-i", "testsrc2=size=160x120:rate=25:duration=6"}
+	full = append(full, args...)
+	full = append(full, path)
+	if out, err := exec.Command("ffmpeg", full...).CombinedOutput(); err != nil {
+		t.Skipf("ffmpeg cannot encode %s: %v: %s", name, err, out)
+	}
+	return path
+}
+
+// requireSameKeyframes fails unless got matches want within the shadow
+// tolerance.
+func requireSameKeyframes(t *testing.T, want, got []float64) {
+	t.Helper()
+	require.Equal(t, len(want), len(got), "keyframe count: ffprobe=%v go-media=%v", want, got)
+	for i := range want {
+		require.InDelta(t, want[i], got[i], keyframeShadowTolerance, "keyframe %d: ffprobe=%v go-media=%v", i, want, got)
+	}
+}
+
+// TestKeyframeTimesMatchFFprobe compares go-media keyframe indexes with
+// ffprobe for fixtures and encoded clips, including B-frame MP4/MOV.
+func TestKeyframeTimesMatchFFprobe(t *testing.T) {
+	if testing.Short() {
+		t.Skip("encodes clips with ffmpeg")
+	}
+	withGate(t, false)
+	x264 := []string{"-c:v", "libx264", "-g", "50", "-keyint_min", "50", "-sc_threshold", "0", "-bf", "2", "-pix_fmt", "yuv420p"}
+	cases := map[string]string{
+		"fixture.mp4":  fixtureMP4,
+		"fixture.webm": fixtureWebM,
+		"bframes.mp4":  encodeKeyframeClip(t, "bframes.mp4", x264...),
+		"bframes.mov":  encodeKeyframeClip(t, "bframes.mov", x264...),
+		"bframes.mkv":  encodeKeyframeClip(t, "bframes.mkv", x264...),
+		"mpeg4.m4v":    encodeKeyframeClip(t, "mpeg4.m4v", "-c:v", "mpeg4", "-g", "30", "-f", "mp4"),
+	}
+	for name, path := range cases {
+		t.Run(name, func(t *testing.T) {
+			want := ffprobeKeyframes(t, path)
+			got, ok := KeyframeTimes(context.Background(), path, nil)
+			require.True(t, ok)
+			requireSameKeyframes(t, want, got)
+
+			within, ok := KeyframeTimesWithin(context.Background(), path, 2.5)
+			require.True(t, ok)
+			require.NotEmpty(t, within)
+			require.LessOrEqual(t, len(within), len(got))
+			for i := range within {
+				require.Equal(t, got[i], within[i])
+				require.LessOrEqual(t, within[i]-got[0], 2.5+1e-9)
+			}
+		})
+	}
+}
+
+// TestKeyframeTimesFallsBack checks the cases that must leave the index to
+// ffprobe.
+func TestKeyframeTimesFallsBack(t *testing.T) {
+	withGate(t, false)
+	dir := t.TempDir()
+
+	// Not an indexed container: no file open, ffprobe answers.
+	ts := filepath.Join(dir, "clip.ts")
+	require.NoError(t, os.WriteFile(ts, []byte{0x47}, 0o644))
+	_, ok := KeyframeTimes(context.Background(), ts, nil)
+	require.False(t, ok)
+
+	// Indexed extension but not a real container.
+	junk := filepath.Join(dir, "junk.mp4")
+	require.NoError(t, os.WriteFile(junk, []byte("not a video"), 0o644))
+	_, ok = KeyframeTimes(context.Background(), junk, nil)
+	require.False(t, ok)
+
+	// Missing file.
+	_, ok = KeyframeTimes(context.Background(), filepath.Join(dir, "missing.mp4"), nil)
+	require.False(t, ok)
+
+	// Cancelled context.
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	_, ok = KeyframeTimes(ctx, fixtureMP4, nil)
+	require.False(t, ok)
+}
+
+// TestKeyframeTimesGate checks that the Always use ffmpeg setting disables
+// the go-media keyframe index.
+func TestKeyframeTimesGate(t *testing.T) {
+	withGate(t, true)
+	_, ok := KeyframeTimes(context.Background(), fixtureMP4, nil)
+	require.False(t, ok, "KeyframeTimes must skip go-media when the gate is on")
+	_, ok = KeyframeTimesWithin(context.Background(), fixtureMP4, 10)
+	require.False(t, ok)
+}
+
+// TestDedupeKeyframeTimes checks sorting, filtering, and the 1 ms dedupe.
+func TestDedupeKeyframeTimes(t *testing.T) {
+	got := dedupeKeyframeTimes([]float64{2, -1, 0, 0.0005, 1, 1.001, 1.0021, math.NaN(), math.Inf(1)})
+	require.Equal(t, []float64{0, 1, 1.0021, 2}, got)
+	require.Empty(t, dedupeKeyframeTimes(nil))
+}
+
+// TestCtxReaderAt checks that reads stop once the context is cancelled.
+func TestCtxReaderAt(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	r := ctxReaderAt{ctx: ctx, r: strings.NewReader("abcdef")}
+	buf := make([]byte, 3)
+	n, err := r.ReadAt(buf, 1)
+	require.NoError(t, err)
+	require.Equal(t, "bcd", string(buf[:n]))
+	cancel()
+	_, err = r.ReadAt(buf, 0)
+	require.ErrorIs(t, err, context.Canceled)
+}
+
+// TestKeyframeDiff checks the shadow comparison: a subset is expected, an
+// extra keyframe is a real difference.
+func TestKeyframeDiff(t *testing.T) {
+	require.Empty(t, keyframeDiff([]float64{0, 2, 4}, []float64{0, 2.001, 4}))
+
+	subset := keyframeDiff([]float64{0, 4}, []float64{0, 2, 4, 6})
+	require.Len(t, subset, 1)
+	require.True(t, strings.HasPrefix(subset[0], expectedDiffPrefix), subset[0])
+	require.Contains(t, subset[0], "2 of 4")
+
+	extra := keyframeDiff([]float64{0, 1, 2}, []float64{0, 2})
+	require.Len(t, extra, 1)
+	require.False(t, strings.HasPrefix(extra[0], expectedDiffPrefix), extra[0])
+}

backend/internal/gomedia/shadow.go

@@ -59,8 +59,8 @@ func runShadow[T any](op, path string, goLatency time.Duration, fast T, legacy L
 	ffStart := time.Now()
 	legacyVal, ffOK := legacy()
 	ffLatency := time.Since(ffStart)
-	shadowLogf("go-media shadow %s for %s: go-media=%.2fms legacy(ffmpeg/dhowden)=%.2fms diff(legacy-go)=%+.2fms legacy_ok=%t",
-		op, path, ms(goLatency), ms(ffLatency), ms(ffLatency)-ms(goLatency), ffOK)
+	shadowLogf("go-media shadow %s for %s: go-media=%.2fms legacy(ffmpeg/dhowden)=%.2fms diff(go-legacy)=%+.2fms",
+		op, path, ms(goLatency), ms(ffLatency), ms(goLatency)-ms(ffLatency))
 
 	if !ffOK {
 		// go-media read the file but the legacy path failed. That is an outcome

backend/internal/icons/generator_test.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/gtsteffaniak/filebrowser/backend/internal/database/users"
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
 	"github.com/kovidgoyal/imaging"
 )
@@ -122,23 +123,21 @@ func TestDefaultBackgroundColor(t *testing.T) {
 	saved := settings.Config
 	defer func() { settings.Config = saved }()
 
-	dark := true
-	light := false
 
 	settings.Config.Frontend.Styling.DarkBackground = "#111111"
 	settings.Config.Frontend.Styling.LightBackground = "#ffffff"
 
-	settings.Config.UserDefaults.UI.DarkMode = &dark
+	settings.Config.UserDefaults.UI.DarkMode = users.DarkModeDark
 	if got := settings.DefaultBackgroundColor(); got != "#111111" {
 		t.Fatalf("dark branch: got %q, want %q", got, "#111111")
 	}
 
-	settings.Config.UserDefaults.UI.DarkMode = &light
+	settings.Config.UserDefaults.UI.DarkMode = users.DarkModeLight
 	if got := settings.DefaultBackgroundColor(); got != "#ffffff" {
 		t.Fatalf("light branch (dark disabled): got %q, want %q", got, "#ffffff")
 	}
 
-	settings.Config.UserDefaults.UI.DarkMode = nil
+	settings.Config.UserDefaults.UI.DarkMode = ""
 	if got := settings.DefaultBackgroundColor(); got != "#ffffff" {
 		t.Fatalf("light branch (unset): got %q, want %q", got, "#ffffff")
 	}

backend/internal/mediacache/mediacache.go

@@ -0,0 +1,109 @@
+// Package mediacache holds the media metadata caches shared by the ffmpeg and
+// go-media code paths. Both backends read and write the same entries, so a
+// value found by one is reused by the other instead of being probed again.
+//
+// Every entry is keyed by file identity: path, size, and modification time in
+// nanoseconds. An edited file gets a new key, so a stale value is never served
+// for it; the old entry ages out after TTL.
+package mediacache
+
+import (
+	"context"
+	"fmt"
+	"io/fs"
+	"os"
+	"time"
+
+	"github.com/gtsteffaniak/filebrowser/backend/internal/utils"
+	"github.com/gtsteffaniak/go-cache/cache"
+)
+
+// TTL is how long a cached media value is kept after it is stored.
+const TTL = 24 * time.Hour
+
+// ProbeInfo is the container summary both backends produce: ffprobe through
+// go-ffmpeg, and go-media. FormatName uses ffprobe's format_name strings.
+type ProbeInfo struct {
+	Duration   float64
+	VideoCodec string
+	AudioCodec string
+	FormatName string
+}
+
+var (
+	// Probes caches container probes (duration, first video and audio codec,
+	// format name).
+	Probes = cache.NewCache[ProbeInfo](TTL)
+	// Durations caches media length in seconds.
+	Durations = cache.NewCache[float64](TTL)
+	// SubtitleTracks caches the embedded subtitle track list of a video.
+	SubtitleTracks = cache.NewCache[[]utils.SubtitleTrack](TTL)
+	// SubtitleContent caches one embedded subtitle stream converted to WebVTT.
+	// Use Key.Stream for its key.
+	SubtitleContent = cache.NewCache[string](TTL)
+)
+
+// Key identifies one version of a file. The zero Key is never produced for a
+// real file, because Path is always set.
+type Key struct {
+	Path    string
+	Size    int64
+	ModTime int64 // modification time in Unix nanoseconds
+}
+
+// FromFileInfo returns the Key for path using an already-read FileInfo, so
+// callers that stat or open the file anyway do not stat it twice.
+func FromFileInfo(path string, info fs.FileInfo) Key {
+	return Key{Path: path, Size: info.Size(), ModTime: info.ModTime().UnixNano()}
+}
+
+// Stat returns the Key for path. It follows symlinks, like os.Stat.
+func Stat(path string) (Key, error) {
+	info, err := os.Stat(path)
+	if err != nil {
+		return Key{}, err
+	}
+	return FromFileInfo(path, info), nil
+}
+
+// String returns the cache key for k. The path is quoted so a path containing
+// the separator cannot collide with another file's key.
+func (k Key) String() string {
+	return fmt.Sprintf("%q:%d:%d", k.Path, k.Size, k.ModTime)
+}
+
+// Stream returns the cache key for one stream of k, used by SubtitleContent.
+func (k Key) Stream(index int) string {
+	return fmt.Sprintf("%s:%d", k.String(), index)
+}
+
+// ClearAll drops every cached media value. It is used when the backend that
+// produced the values is switched (the admin "Always use ffmpeg" setting), so
+// the newly selected backend answers fresh.
+func ClearAll() {
+	Probes.ClearAll()
+	Durations.ClearAll()
+	SubtitleTracks.ClearAll()
+	SubtitleContent.ClearAll()
+}
+
+// bypassKey is the context key set by WithoutCache.
+type bypassKey struct{}
+
+// WithoutCache returns a context under which the ffmpeg code paths neither read
+// nor write the shared caches. Dev-mode shadow runs use it, so the ffmpeg result
+// they compare against go-media is computed fresh rather than read back from the
+// value go-media just stored.
+func WithoutCache(ctx context.Context) context.Context {
+	return context.WithValue(ctx, bypassKey{}, true)
+}
+
+// Bypassed reports whether ctx was returned by WithoutCache. A nil context is
+// not bypassed.
+func Bypassed(ctx context.Context) bool {
+	if ctx == nil {
+		return false
+	}
+	v, _ := ctx.Value(bypassKey{}).(bool)
+	return v
+}

backend/internal/mediacache/mediacache_test.go

@@ -0,0 +1,157 @@
+package mediacache
+
+import (
+	"context"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+// TestStatKeyChangesWithSizeAndModTime checks on disk that a size change
+// or an mtime change gives a new key. The mtimes differ by whole seconds so
+// the check holds on filesystems with coarse timestamps; the 1 ns case is
+// covered by TestFromFileInfoNanosecondModTime.
+func TestStatKeyChangesWithSizeAndModTime(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "a.mp4")
+	if err := os.WriteFile(path, []byte("one"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	k1, err := Stat(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if k1.Path != path || k1.Size != 3 || k1.ModTime == 0 {
+		t.Fatalf("unexpected key %+v", k1)
+	}
+
+	// Same size, different mtime.
+	mt := time.Unix(1_700_000_000, 0)
+	if err = os.Chtimes(path, mt, mt); err != nil {
+		t.Fatal(err)
+	}
+	k2, err := Stat(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if k2.String() == k1.String() {
+		t.Fatalf("mtime change kept key %s", k2)
+	}
+	mt2 := mt.Add(time.Second)
+	if err = os.Chtimes(path, mt2, mt2); err != nil {
+		t.Fatal(err)
+	}
+	k3, _ := Stat(path)
+	if k3.String() == k2.String() {
+		t.Fatalf("1s mtime change kept key %s", k3)
+	}
+
+	// Same mtime, different size.
+	if err = os.WriteFile(path, []byte("three"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if err = os.Chtimes(path, mt2, mt2); err != nil {
+		t.Fatal(err)
+	}
+	k4, _ := Stat(path)
+	if k4.String() == k3.String() {
+		t.Fatalf("size change kept key %s", k4)
+	}
+}
+
+// stubFileInfo is an fs.FileInfo with a fixed size and mtime.
+type stubFileInfo struct {
+	size    int64
+	modTime time.Time
+}
+
+// Name implements fs.FileInfo.
+func (s stubFileInfo) Name() string { return "a.mp4" }
+
+// Size implements fs.FileInfo.
+func (s stubFileInfo) Size() int64 { return s.size }
+
+// Mode implements fs.FileInfo.
+func (s stubFileInfo) Mode() fs.FileMode { return 0o600 }
+
+// ModTime implements fs.FileInfo.
+func (s stubFileInfo) ModTime() time.Time { return s.modTime }
+
+// IsDir implements fs.FileInfo.
+func (s stubFileInfo) IsDir() bool { return false }
+
+// Sys implements fs.FileInfo.
+func (s stubFileInfo) Sys() any { return nil }
+
+// TestFromFileInfoNanosecondModTime checks that mtimes 1 ns apart give
+// different keys, independent of what a filesystem can store.
+func TestFromFileInfoNanosecondModTime(t *testing.T) {
+	a := FromFileInfo("/m/a.mp4", stubFileInfo{size: 3, modTime: time.Unix(1_700_000_000, 123)})
+	b := FromFileInfo("/m/a.mp4", stubFileInfo{size: 3, modTime: time.Unix(1_700_000_000, 124)})
+	if a.String() == b.String() {
+		t.Fatalf("1ns mtime change kept key %s", a)
+	}
+	if a.ModTime != time.Unix(1_700_000_000, 123).UnixNano() {
+		t.Fatalf("ModTime = %d, want nanoseconds", a.ModTime)
+	}
+}
+
+// TestStatMissingFile checks that Stat reports a missing file.
+func TestStatMissingFile(t *testing.T) {
+	if _, err := Stat(filepath.Join(t.TempDir(), "missing")); err == nil {
+		t.Fatal("expected an error for a missing file")
+	}
+}
+
+// TestKeyStringDoesNotCollide checks that keys of different files, and of
+// different streams of one file, never collide.
+func TestKeyStringDoesNotCollide(t *testing.T) {
+	a := Key{Path: "a:1", Size: 2, ModTime: 3}
+	b := Key{Path: "a", Size: 1, ModTime: 2}
+	if a.String() == b.String() {
+		t.Fatalf("keys collide: %s", a)
+	}
+	if a.Stream(1) == a.Stream(2) || a.Stream(1) == a.String() {
+		t.Fatalf("stream keys collide: %s %s", a.Stream(1), a.Stream(2))
+	}
+}
+
+// TestClearAll checks that ClearAll empties every shared cache.
+func TestClearAll(t *testing.T) {
+	k := Key{Path: "/clear", Size: 1, ModTime: 1}
+	Probes.Set(k.String(), ProbeInfo{Duration: 1})
+	Durations.Set(k.String(), 1)
+	SubtitleContent.Set(k.Stream(0), "x")
+	ClearAll()
+	if _, ok := Probes.Get(k.String()); ok {
+		t.Fatal("probe survived ClearAll")
+	}
+	if _, ok := Durations.Get(k.String()); ok {
+		t.Fatal("duration survived ClearAll")
+	}
+	if _, ok := SubtitleContent.Get(k.Stream(0)); ok {
+		t.Fatal("subtitle content survived ClearAll")
+	}
+}
+
+// TestWithoutCache checks the cache bypass marker and that derived contexts
+// keep it.
+func TestWithoutCache(t *testing.T) {
+	if Bypassed(context.Background()) {
+		t.Fatal("background context must not bypass")
+	}
+	//nolint:staticcheck // nil is part of the documented contract.
+	if Bypassed(nil) {
+		t.Fatal("nil context must not bypass")
+	}
+	ctx := WithoutCache(context.Background())
+	if !Bypassed(ctx) {
+		t.Fatal("WithoutCache context must bypass")
+	}
+	child, cancel := context.WithCancel(ctx)
+	defer cancel()
+	if !Bypassed(child) {
+		t.Fatal("bypass must survive derived contexts")
+	}
+}

backend/internal/preview/doc.go

@@ -5,16 +5,26 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/gtsteffaniak/filebrowser/backend/internal/folio"
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
 )
 
+const (
+	// docPreviewTimeout bounds small, large and xlarge page renders.
+	docPreviewTimeout = 2 * time.Second
+	// docOriginalTimeout bounds "original" renders, which are higher resolution.
+	docOriginalTimeout = 10 * time.Second
+)
+
 func (s *Service) GenerateImageFromDoc(ctx context.Context, file iteminfo.ExtendedFileInfo, pageNumber int, previewSize string) ([]byte, error) {
 	if ctx.Err() != nil {
 		return nil, ctx.Err()
 	}
 
-	timeoutCtx, cancel := context.WithTimeout(ctx, 2*time.Second)
+	timeout := docPreviewTimeout
+	if previewSize == "original" {
+		timeout = docOriginalTimeout
+	}
+	timeoutCtx, cancel := context.WithTimeout(ctx, timeout)
 	defer cancel()
 
 	opts, err := folioRenderOptions(previewSize)
@@ -22,7 +32,7 @@ func (s *Service) GenerateImageFromDoc(ctx context.Context, file iteminfo.Extend
 		return nil, err
 	}
 
-	imageBytes, ok, err := folio.RenderPageJPEG(timeoutCtx, file.RealPath, pageNumber, opts, file.Name, file.Type)
+	imageBytes, ok, err := renderDocPageJPEG(timeoutCtx, file.RealPath, pageNumber, opts, file.Name, file.Type)
 	if !ok {
 		if err != nil {
 			return nil, err
@@ -30,20 +40,22 @@ func (s *Service) GenerateImageFromDoc(ctx context.Context, file iteminfo.Extend
 		return nil, nil
 	}
 	if timeoutCtx.Err() != nil {
-		return nil, fmt.Errorf("document preview generation timed out after 2 seconds for '%s'", file.Name)
+		return nil, fmt.Errorf("document preview generation timed out after %s for '%s'", timeout, file.Name)
 	}
 	return imageBytes, nil
 }
 
-func folioRenderOptions(previewSize string) (folio.RenderOptions, error) {
+// folioRenderOptions maps a preview size onto the same dimensions, fill mode and JPEG quality
+// the image pipeline uses (see getPreviewOptions); "original" renders at full resolution.
+func folioRenderOptions(previewSize string) (docRenderOptions, error) {
 	if previewSize == "original" {
-		return folio.RenderOptions{Original: true, JpegQuality: QualityHigh.jpegQuality()}, nil
+		return docRenderOptions{Original: true, JpegQuality: QualityHigh.jpegQuality()}, nil
 	}
 	opts, err := getPreviewOptions(previewSize)
 	if err != nil {
-		return folio.RenderOptions{}, err
+		return docRenderOptions{}, err
 	}
-	return folio.RenderOptions{
+	return docRenderOptions{
 		MaxWidth:    opts.Width,
 		MaxHeight:   opts.Height,
 		Fill:        opts.ResizeMode == ResizeModeFill,

backend/internal/preview/doc_text_integration_test.go

@@ -5,7 +5,6 @@ import (
 	"path/filepath"
 	"testing"
 
-	"github.com/gtsteffaniak/filebrowser/backend/internal/folio"
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
 	"github.com/stretchr/testify/require"
 )
@@ -17,7 +16,7 @@ func TestFolioRender_utf8TruncatedPlaywrightFile(t *testing.T) {
 	}
 	opts, err := folioRenderOptions("small")
 	require.NoError(t, err)
-	data, ok, err := folio.RenderPageJPEG(t.Context(), realPath, 0, opts, "utf8-truncated.txt", "text/plain")
+	data, ok, err := renderDocPageJPEG(t.Context(), realPath, 0, opts, "utf8-truncated.txt", "text/plain")
 	require.NoError(t, err)
 	require.True(t, ok, "err=%v", err)
 	require.NotEmpty(t, data)
@@ -29,7 +28,7 @@ func TestFolioRender_cssAsTxt(t *testing.T) {
 	require.NoError(t, os.WriteFile(cssPath, []byte("body { color: red; }\n"), 0o644))
 	opts, err := folioRenderOptions("small")
 	require.NoError(t, err)
-	data, ok, err := folio.RenderPageJPEG(t.Context(), cssPath, 0, opts, "styles.css", "text/css")
+	data, ok, err := renderDocPageJPEG(t.Context(), cssPath, 0, opts, "styles.css", "text/css")
 	require.NoError(t, err)
 	require.True(t, ok, "err=%v", err)
 	require.NotEmpty(t, data)

backend/internal/preview/fill_test.go

@@ -0,0 +1,122 @@
+package preview
+
+import (
+	"fmt"
+	"image"
+	"image/color"
+	"runtime"
+	"testing"
+
+	"github.com/kovidgoyal/imaging"
+	"github.com/stretchr/testify/require"
+)
+
+// patternYCbCr is a 4:2:0 image (what a camera JPEG decodes to) with a pattern that differs in
+// every row and column, so a crop off by one pixel shows up in the resized output.
+func patternYCbCr(w, h int) *image.YCbCr {
+	return patternYCbCrRatio(w, h, image.YCbCrSubsampleRatio420)
+}
+
+// patternYCbCrRatio is patternYCbCr with the given chroma subsampling.
+func patternYCbCrRatio(w, h int, r image.YCbCrSubsampleRatio) *image.YCbCr {
+	img := image.NewYCbCr(image.Rect(0, 0, w, h), r)
+	for y := 0; y < h; y++ {
+		for x := 0; x < w; x++ {
+			img.Y[img.YOffset(x, y)] = uint8((x*7 + y*13) % 251)
+		}
+	}
+	for i := range img.Cb {
+		img.Cb[i] = uint8((i*3 + i/img.CStride) % 256)
+		img.Cr[i] = uint8((i + 5*(i/img.CStride)) % 256)
+	}
+	return img
+}
+
+// patternNRGBA is an NRGBA image whose pixels differ in every row and column.
+func patternNRGBA(w, h int) *image.NRGBA {
+	img := image.NewNRGBA(image.Rect(0, 0, w, h))
+	for y := 0; y < h; y++ {
+		for x := 0; x < w; x++ {
+			img.SetNRGBA(x, y, color.NRGBA{uint8(x % 256), uint8(y % 256), uint8((x + y) % 256), 255})
+		}
+	}
+	return img
+}
+
+// requireSamePixels fails unless want and got are the same size and every pixel is equal,
+// comparing from each image's own origin.
+func requireSamePixels(t *testing.T, want, got image.Image) {
+	t.Helper()
+	require.Equal(t, want.Bounds().Size(), got.Bounds().Size())
+	wb, gb := want.Bounds().Min, got.Bounds().Min
+	for y := 0; y < want.Bounds().Dy(); y++ {
+		for x := 0; x < want.Bounds().Dx(); x++ {
+			wr, wg, wbl, wa := want.At(wb.X+x, wb.Y+y).RGBA()
+			gr, gg, gbl, ga := got.At(gb.X+x, gb.Y+y).RGBA()
+			if wr != gr || wg != gg || wbl != gbl || wa != ga {
+				t.Fatalf("pixel (%d,%d) differs: imaging.Fill %v, fillCenter %v", x, y,
+					[4]uint32{wr, wg, wbl, wa}, [4]uint32{gr, gg, gbl, ga})
+			}
+		}
+	}
+}
+
+// fillCenter must produce exactly what imaging.Fill(…, imaging.Center, …) produces: the same
+// pixels and the same image type, so the encoded preview is the same bytes.
+func TestFillCenter_MatchesImagingFill(t *testing.T) {
+	sources := map[string]image.Image{
+		"ycbcr landscape":                    patternYCbCr(1200, 801),
+		"ycbcr portrait":                     patternYCbCr(601, 1000),
+		"nrgba square":                       patternNRGBA(700, 700),
+		"nrgba wide":                         patternNRGBA(1500, 300),
+		"small (falls back to imaging.Fill)": patternNRGBA(90, 60),
+		"exact target size":                  patternNRGBA(256, 256),
+		"offset origin":                      patternNRGBA(900, 700).SubImage(image.Rect(37, 11, 837, 611)),
+	}
+	// Every subsampling ratio, in shapes whose centered crop has an x (or y) offset and reaches
+	// the source's last row (or column) -- where a SubImage's buffer ends short of a full stride.
+	for _, r := range []image.YCbCrSubsampleRatio{
+		image.YCbCrSubsampleRatio444, image.YCbCrSubsampleRatio422, image.YCbCrSubsampleRatio420,
+		image.YCbCrSubsampleRatio440, image.YCbCrSubsampleRatio411, image.YCbCrSubsampleRatio410,
+	} {
+		for _, sz := range [][2]int{{600, 264}, {264, 600}, {601, 263}} {
+			sources[fmt.Sprintf("ycbcr %v %dx%d", r, sz[0], sz[1])] = patternYCbCrRatio(sz[0], sz[1], r)
+		}
+	}
+	sources["nycbcra 444 600x264"] = &image.NYCbCrA{YCbCr: *patternYCbCrRatio(600, 264, image.YCbCrSubsampleRatio444), A: make([]uint8, 600*264), AStride: 600}
+	// 264x264 is the crop of the 600x264 and 264x600 sources itself: nothing to scale.
+	targets := [][2]int{{256, 256}, {320, 180}, {180, 320}, {264, 264}}
+	filters := map[string]imaging.ResampleFilter{
+		"nearest": imaging.NearestNeighbor, "box": imaging.Box, "catmullrom": imaging.CatmullRom,
+	}
+	for name, src := range sources {
+		for _, tg := range targets {
+			for fname, f := range filters {
+				t.Run(fmt.Sprintf("%s/%dx%d/%s", name, tg[0], tg[1], fname), func(t *testing.T) {
+					t.Parallel()
+					want := imaging.Fill(src, tg[0], tg[1], imaging.Center, f)
+					got := fillCenter(src, tg[0], tg[1], f)
+					require.Equal(t, fmt.Sprintf("%T", want), fmt.Sprintf("%T", got), "image type")
+					requireSamePixels(t, want, got)
+				})
+			}
+		}
+	}
+}
+
+// A square thumbnail of a large photo must not allocate a full-resolution copy of it.
+func TestFillCenter_NoFullSizeCopy(t *testing.T) {
+	const w, h = 4000, 3000
+	src := patternYCbCr(w, h)
+	fullCopy := uint64(h * h * 4) // the square crop imaging.Fill materializes as NRGBA
+
+	var before, after runtime.MemStats
+	runtime.ReadMemStats(&before)
+	out := fillCenter(src, 256, 256, imaging.Box)
+	runtime.ReadMemStats(&after)
+
+	require.Equal(t, image.Pt(256, 256), out.Bounds().Size())
+	allocated := after.TotalAlloc - before.TotalAlloc
+	require.Less(t, allocated, fullCopy/4,
+		"fillCenter allocated %d bytes; a copy of the crop would be %d", allocated, fullCopy)
+}

backend/internal/preview/folio.go

@@ -0,0 +1,208 @@
+// folio.go is the pure-Go document preview fast path using gen2brain/folio.
+// When folio cannot handle a file, callers fall back to the office converter (when configured).
+package preview
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"image"
+	"image/jpeg"
+	"path/filepath"
+	"sync"
+
+	"github.com/gen2brain/folio/doc"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
+	"github.com/gtsteffaniak/go-logger/logger"
+	"github.com/kovidgoyal/imaging"
+)
+
+const (
+	// docSupersample renders a page at this multiple of the target box before the
+	// final downscale. Rasterized text needs the extra pixels to stay crisp.
+	docSupersample = 2
+	// docOriginalDPI is the resolution used for "original" page previews.
+	docOriginalDPI = 200
+	// docMaxRenderEdge caps the longest edge of a rendered page, in pixels.
+	docMaxRenderEdge = 4096
+	// docMinDPI and docMaxDPI bound the computed render resolution.
+	docMinDPI = 36.0
+	docMaxDPI = 600.0
+)
+
+var renderMu sync.Mutex
+
+// docRenderOptions controls the size and quality of one rendered document page.
+type docRenderOptions struct {
+	MaxWidth    int
+	MaxHeight   int
+	Fill        bool
+	JpegQuality int
+	Original    bool
+}
+
+// folioEnabled reports whether the folio fast path may run.
+func folioEnabled() bool {
+	return !settings.AlwaysUseOnlyOfficeEnabled()
+}
+
+func logFolioFallback(op, path string, err error) {
+	if errors.Is(err, doc.ErrUnsupported) {
+		logger.Warningf("folio does not support %s for %s (%v); using office converter if configured", op, path, err)
+		return
+	}
+	logger.Errorf("folio %s failed for %s: %v; falling back to office converter if configured", op, path, err)
+}
+
+// renderDocPageJPEG renders one document page to JPEG. ok is true when folio returned bytes.
+// name and mimetype should match the file being previewed; they control eligibility for
+// folio (content sniffing does not depend on the path extension).
+func renderDocPageJPEG(ctx context.Context, path string, pageNumber int, opts docRenderOptions, name, mimetype string) (data []byte, ok bool, err error) {
+	if !folioEnabled() {
+		return nil, false, nil
+	}
+	if name == "" {
+		name = filepath.Base(path)
+	}
+	if !folioSupportsPreview(name, mimetype) {
+		return nil, false, nil
+	}
+	if ctx.Err() != nil {
+		return nil, false, ctx.Err()
+	}
+
+	type result struct {
+		data []byte
+		err  error
+	}
+	done := make(chan result, 1)
+	go func() {
+		defer func() {
+			if r := recover(); r != nil {
+				done <- result{err: fmt.Errorf("folio render panicked: %v", r)}
+			}
+		}()
+		data, err := renderPageJPEG(ctx, path, name, mimetype, pageNumber, opts)
+		done <- result{data: data, err: err}
+	}()
+
+	select {
+	case <-ctx.Done():
+		return nil, false, ctx.Err()
+	case res := <-done:
+		if res.err != nil {
+			if !errors.Is(res.err, context.Canceled) && !errors.Is(res.err, context.DeadlineExceeded) {
+				logFolioFallback("render", path, res.err)
+			}
+			return nil, false, res.err
+		}
+		if len(res.data) == 0 {
+			return nil, false, fmt.Errorf("folio render returned empty jpeg")
+		}
+		return res.data, true, nil
+	}
+}
+
+func renderPageJPEG(ctx context.Context, path, name, mimetype string, pageNumber int, opts docRenderOptions) ([]byte, error) {
+	renderMu.Lock()
+	defer renderMu.Unlock()
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+
+	d, err := openDocument(path, name, mimetype)
+	if err != nil {
+		return nil, err
+	}
+	defer d.Close()
+
+	if pageNumber < 0 || pageNumber >= d.NumPages() {
+		return nil, fmt.Errorf("invalid page number %d (pages: %d)", pageNumber, d.NumPages())
+	}
+
+	p, err := d.Page(pageNumber)
+	if err != nil {
+		return nil, err
+	}
+
+	boxed := !opts.Original && opts.MaxWidth > 0 && opts.MaxHeight > 0
+	var dpi float64
+	if boxed {
+		dpi = docBoxRenderDPI(p, d.Kind(), opts.MaxWidth, opts.MaxHeight, opts.Fill)
+	} else {
+		dpi = docOriginalRenderDPI(p, d.Kind())
+	}
+
+	rendered, err := p.ImageDPI(dpi)
+	if err != nil {
+		return nil, err
+	}
+	if rendered == nil {
+		return nil, fmt.Errorf("folio rendered no image for page %d", pageNumber)
+	}
+
+	var img image.Image = rendered
+	if boxed {
+		// The page was rendered at docSupersample times the target, so this
+		// single high-quality downscale produces the anti-aliased final image.
+		if opts.Fill {
+			img = imaging.Fill(img, opts.MaxWidth, opts.MaxHeight, imaging.Center, imaging.Lanczos)
+		} else {
+			img = imaging.Fit(img, opts.MaxWidth, opts.MaxHeight, imaging.Lanczos)
+		}
+	}
+
+	q := opts.JpegQuality
+	if q <= 0 {
+		q = 85
+	}
+	var buf bytes.Buffer
+	if err := jpeg.Encode(&buf, img, &jpeg.Options{Quality: q}); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+// docUnitDPI is the resolution at which folio's ImageDPI renders page units one to one:
+// 72 for PDF and book pages, 96 for drawings (SVG).
+func docUnitDPI(kind doc.Kind) float64 {
+	if kind == doc.KindSVG {
+		return 96
+	}
+	return 72
+}
+
+// docMaxEdgeDPI is the highest resolution at which the longest page edge stays within docMaxRenderEdge.
+func docMaxEdgeDPI(p doc.Page, kind doc.Kind) float64 {
+	b := p.Bounds()
+	longest := float64(max(b.X1-b.X0, b.Y1-b.Y0))
+	if longest <= 0 {
+		return docMinDPI
+	}
+	return docUnitDPI(kind) * docMaxRenderEdge / longest
+}
+
+// docBoxRenderDPI picks the resolution for a page that will be scaled into a boxW x boxH target.
+// Fill covers the box; fit stays inside it. The page is rendered at docSupersample times the target.
+func docBoxRenderDPI(p doc.Page, kind doc.Kind, boxW, boxH int, fill bool) float64 {
+	b := p.Bounds()
+	pw, ph := float64(b.X1-b.X0), float64(b.Y1-b.Y0)
+	if pw <= 0 || ph <= 0 {
+		return docMinDPI
+	}
+	// Scale (pixels per page unit) needed for the supersampled render to reach the box on each axis.
+	sx := float64(boxW*docSupersample) / pw
+	sy := float64(boxH*docSupersample) / ph
+	s := min(sx, sy)
+	if fill {
+		s = max(sx, sy)
+	}
+	dpi := min(s*docUnitDPI(kind), docMaxEdgeDPI(p, kind))
+	return min(max(dpi, docMinDPI), docMaxDPI)
+}
+
+// docOriginalRenderDPI picks the resolution for "original" previews: docOriginalDPI, capped by docMaxRenderEdge.
+func docOriginalRenderDPI(p doc.Page, kind doc.Kind) float64 {
+	return min(docOriginalDPI, docMaxEdgeDPI(p, kind))
+}

backend/internal/preview/folio_open.go

@@ -1,4 +1,4 @@
-package folio
+package preview
 
 import (
 	"fmt"
@@ -17,9 +17,9 @@ const folioTextCheckWindow = 4096 // html.readsAsText validation window
 // maxTextPreviewLoad is the most plain-text we read for a first-page thumbnail.
 const maxTextPreviewLoad = 32 << 10 // 32 KiB
 
-// SupportsPreview reports whether folio should attempt this file (name + MIME).
+// folioSupportsPreview reports whether folio should attempt this file (name + MIME).
 // doc.Open sniffs content; extensions like .css are not in FolioConvertable but still render.
-func SupportsPreview(name, mimetype string) bool {
+func folioSupportsPreview(name, mimetype string) bool {
 	ext := strings.ToLower(filepath.Ext(name))
 	if iteminfo.FolioConvertable[ext] {
 		return true

backend/internal/preview/folio_test.go

@@ -1,4 +1,4 @@
-package folio
+package preview
 
 import (
 	"os"
@@ -8,12 +8,12 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestRenderPageJPEG_txt(t *testing.T) {
+func TestRenderDocPageJPEG_txt(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "hello.txt")
 	require.NoError(t, os.WriteFile(path, []byte("Hello folio preview"), 0o644))
 
-	data, ok, err := RenderPageJPEG(t.Context(), path, 0, RenderOptions{
+	data, ok, err := renderDocPageJPEG(t.Context(), path, 0, docRenderOptions{
 		MaxWidth:    256,
 		MaxHeight:   256,
 		Fill:        true,
@@ -26,8 +26,8 @@ func TestRenderPageJPEG_txt(t *testing.T) {
 	require.Equal(t, byte(0xd8), data[1])
 }
 
-func TestRenderPageJPEG_unsupportedExtension(t *testing.T) {
-	data, ok, err := RenderPageJPEG(t.Context(), "/nonexistent/file.xyz", 0, RenderOptions{}, "file.xyz", "application/octet-stream")
+func TestRenderDocPageJPEG_unsupportedExtension(t *testing.T) {
+	data, ok, err := renderDocPageJPEG(t.Context(), "/nonexistent/file.xyz", 0, docRenderOptions{}, "file.xyz", "application/octet-stream")
 	require.NoError(t, err)
 	require.False(t, ok)
 	require.Nil(t, data)

backend/internal/preview/folio_utf8_test.go

@@ -1,4 +1,4 @@
-package folio
+package preview
 
 import (
 	"os"
@@ -37,22 +37,17 @@ func TestSanitizeFolioText_stripsNUL(t *testing.T) {
 	raw := []byte("hello\x00world")
 	got := sanitizeFolioText(raw)
 	require.Equal(t, []byte("hello world"), got)
-	opts, err := folioRenderOptionsForTest()
-	require.NoError(t, err)
 
+	opts := docRenderOptions{MaxWidth: 256, MaxHeight: 256, Fill: true, JpegQuality: 80}
 	dir := t.TempDir()
 	path := filepath.Join(dir, "nul.txt")
 	require.NoError(t, os.WriteFile(path, raw, 0o600))
-	data, ok, err := RenderPageJPEG(t.Context(), path, 0, opts, "nul.txt", "text/plain")
+	data, ok, err := renderDocPageJPEG(t.Context(), path, 0, opts, "nul.txt", "text/plain")
 	require.NoError(t, err)
 	require.True(t, ok, "err=%v", err)
 	require.NotEmpty(t, data)
 }
 
-func folioRenderOptionsForTest() (RenderOptions, error) {
-	return RenderOptions{MaxWidth: 256, MaxHeight: 256, Fill: true, JpegQuality: 80}, nil
-}
-
 func TestReadTextPreviewPrefix_cap(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "big.log")

backend/internal/preview/image.go

@@ -7,9 +7,11 @@ import (
 	"image"
 	"image/jpeg"
 	"io"
+	"math"
 
 	exif "github.com/dsoprea/go-exif/v3"
 	exifcommon "github.com/dsoprea/go-exif/v3/common"
+	"github.com/gtsteffaniak/filebrowser/backend/internal/embeddedpreview"
 	"github.com/kovidgoyal/imaging"
 )
 
@@ -203,6 +205,50 @@ func (s *Service) ResizeWithSize(ctx context.Context, in io.Reader, out io.Write
 	return err
 }
 
+// fillCenter is imaging.Fill(img, width, height, imaging.Center, filter) without a full-size copy
+// of the source. For sources of 100px or more, imaging.Fill first crops into a new NRGBA image
+// (4 bytes per pixel of the cropped area, about 144 MB for a 48 MP photo) and only then resizes.
+// Here the crop is a SubImage view into the decoded pixels, so only the resize allocates. The
+// crop rectangle is computed as imaging's cropAndResize computes it, so the output is the same.
+//
+// Two cases still go through imaging.Fill: a crop that is already the target size (nothing to
+// scale, and Fill's small copy is what keeps the output type the same), and 4:4:4 YCbCr sources,
+// whose scanner in imaging v1.9.0 advances one full parent stride past the end of a SubImage's
+// last row and panics when the crop has an x offset and reaches the bottom row.
+func fillCenter(img image.Image, width, height int, filter imaging.ResampleFilter) image.Image {
+	b := img.Bounds()
+	sub, ok := img.(interface {
+		SubImage(image.Rectangle) image.Image
+	})
+	if !ok || is444(img) || width <= 0 || height <= 0 || b.Dx() < 100 || b.Dy() < 100 || (b.Dx() == width && b.Dy() == height) {
+		return imaging.Fill(img, width, height, imaging.Center, filter)
+	}
+	cropW, cropH := b.Dx(), b.Dy()
+	if float64(b.Dx())/float64(b.Dy()) < float64(width)/float64(height) {
+		cropH = int(math.Max(1, float64(b.Dx())*float64(height)/float64(width)) + 0.5)
+	} else {
+		cropW = int(math.Max(1, float64(b.Dy())*float64(width)/float64(height)) + 0.5)
+	}
+	if cropW == width && cropH == height {
+		return imaging.Fill(img, width, height, imaging.Center, filter)
+	}
+	x0 := b.Min.X + (b.Dx()-cropW)/2
+	y0 := b.Min.Y + (b.Dy()-cropH)/2
+	crop := image.Rect(x0, y0, x0+cropW, y0+cropH).Intersect(b)
+	return imaging.Resize(sub.SubImage(crop), width, height, filter)
+}
+
+// is444 reports whether img is a YCbCr image without chroma subsampling.
+func is444(img image.Image) bool {
+	switch p := img.(type) {
+	case *image.YCbCr:
+		return p.SubsampleRatio == image.YCbCrSubsampleRatio444
+	case *image.NYCbCrA:
+		return p.SubsampleRatio == image.YCbCrSubsampleRatio444
+	}
+	return false
+}
+
 func (s *Service) resizeWithSize(in io.Reader, out io.Writer, fileSize int64, opts ResizeOptions) error {
 	// Set defaults
 	if opts.ResizeMode == 0 {
@@ -280,7 +326,7 @@ func (s *Service) resizeWithSize(in io.Reader, out io.Writer, fileSize int64, op
 	resampleFilter := opts.Quality.resampleFilter()
 	switch opts.ResizeMode {
 	case ResizeModeFill:
-		img = imaging.Fill(img, opts.Width, opts.Height, imaging.Center, resampleFilter)
+		img = fillCenter(img, opts.Width, opts.Height, resampleFilter)
 	case ResizeModeFit:
 		fallthrough
 	default:
@@ -406,8 +452,32 @@ func getEmbeddedThumbnail(in io.Reader) ([]byte, io.Reader, error) {
 		return nil, wrappedReader, exif.ErrNoThumbnail
 	}
 
+	// Read IFD1's Orientation first; fall back to IFD0's Orientation if not specified (per MWG guidelines)
+	orientStr := ""
+	tags1, err1 := ifd.FindTagWithName("Orientation")
+	if err1 == nil && len(tags1) > 0 {
+		orientStr, _ = tags1[0].FormatFirst()
+	}
+	if orientStr == "" {
+		tags0, err0 := index.RootIfd.FindTagWithName("Orientation")
+		if err0 == nil && len(tags0) > 0 {
+			orientStr, _ = tags0[0].FormatFirst()
+		}
+	}
+
 	thm, err := ifd.Thumbnail()
-	return thm, wrappedReader, err
+	if err != nil {
+		return nil, wrappedReader, err
+	}
+
+	if orientStr != "" && orientStr != "1" {
+		if !embeddedpreview.Usable(thm) {
+			return nil, wrappedReader, fmt.Errorf("embedded thumbnail exceeds decode limits")
+		}
+		thm = applyOrientationToPreviewBytes(thm, orientStr)
+	}
+
+	return thm, wrappedReader, nil
 }
 
 // CreateThumbnail decodes an image and creates a fixed-size thumbnail.

backend/internal/preview/image_test.go

@@ -549,3 +549,41 @@ func TestReadImageFileDimensions(t *testing.T) {
 	require.Greater(t, width, 0)
 	require.Greater(t, height, 0)
 }
+
+func TestApplyOrientationToPreviewBytes(t *testing.T) {
+	t.Parallel()
+
+	// Generate a 100x60 test JPEG image in memory (landscape)
+	img := image.NewRGBA(image.Rect(0, 0, 100, 60))
+	var buf bytes.Buffer
+	err := jpeg.Encode(&buf, img, nil)
+	require.NoError(t, err)
+	rawBytes := buf.Bytes()
+
+	tests := []struct {
+		orientation string
+		wantWidth   int
+		wantHeight  int
+	}{
+		{orientation: "1", wantWidth: 100, wantHeight: 60},
+		{orientation: "Horizontal (normal)", wantWidth: 100, wantHeight: 60},
+		{orientation: "8", wantWidth: 60, wantHeight: 100},
+		{orientation: "Rotate 270 CW", wantWidth: 60, wantHeight: 100},
+		{orientation: "6", wantWidth: 60, wantHeight: 100},
+		{orientation: "Rotate 90 CW", wantWidth: 60, wantHeight: 100},
+		{orientation: "3", wantWidth: 100, wantHeight: 60},
+		{orientation: "Rotate 180", wantWidth: 100, wantHeight: 60},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.orientation, func(t *testing.T) {
+			rotated := applyOrientationToPreviewBytes(rawBytes, tt.orientation)
+			require.NotEmpty(t, rotated)
+
+			cfg, _, decodeErr := image.DecodeConfig(bytes.NewReader(rotated))
+			require.NoError(t, decodeErr)
+			require.Equal(t, tt.wantWidth, cfg.Width)
+			require.Equal(t, tt.wantHeight, cfg.Height)
+		})
+	}
+}

backend/internal/preview/preview.go

@@ -18,7 +18,6 @@ import (
 	"github.com/gtsteffaniak/filebrowser/backend/internal/adapters/fs/fileutils"
 	"github.com/gtsteffaniak/filebrowser/backend/internal/embeddedpreview"
 	"github.com/gtsteffaniak/filebrowser/backend/internal/ffmpeg"
-	"github.com/gtsteffaniak/filebrowser/backend/internal/folio"
 	"github.com/gtsteffaniak/filebrowser/backend/internal/imagemeta"
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
@@ -65,7 +64,7 @@ func NewPreviewGenerator(concurrencyLimit int, cacheDir string) *Service {
 	var fileCache diskcache.Interface
 	// Use file cache if cacheDir is specified
 	var err error
-	fileCache, err = diskcache.NewFileCache(actualCacheDir)
+	fileCache, err = diskcache.NewFileCacheWithLimit(actualCacheDir, max(settings.Config.Server.CacheDirMaxSizeMB, 0)*1024*1024)
 	if err != nil {
 		logger.Error("The cache dir could not be created. Make sure the user that you executed the program with has access to create directories in the local path. See  ")
 		logger.Fatalf("failed to create file cache path, which is now require to run the server: %v", err)
@@ -187,6 +186,16 @@ func GetService() *Service {
 	return service
 }
 
+// GetTextPreview returns a text preview for realPath, bounded by the preview service's
+// shared image-processor semaphore. It returns ErrPreviewServiceUnavailable when the
+// service has not been started.
+func GetTextPreview(ctx context.Context, realPath, kind string) (TextPreviewResult, error) {
+	if service == nil {
+		return TextPreviewResult{}, ErrPreviewServiceUnavailable
+	}
+	return service.ReadTextPreview(ctx, realPath, kind)
+}
+
 func GetPreviewForFile(ctx context.Context, file iteminfo.ExtendedFileInfo, previewSize, url string, seekPercentage int) ([]byte, error) {
 	if !file.HasPreview {
 		return nil, ErrUnsupportedMedia
@@ -263,8 +272,9 @@ func determinePreviewType(file iteminfo.ExtendedFileInfo) filePreviewType {
 		return previewTypeOffice
 	}
 
-	// Check HEIC with conversion enabled
-	if strings.HasPrefix(file.Type, "image/heic") &&
+	// Check HEIC with conversion enabled. AVIF is a HEIF container too and uses
+	// the same path (go-media decode, ffmpeg fallback) under the HEIC setting.
+	if (strings.HasPrefix(file.Type, "image/heic") || file.Type == "image/avif") &&
 		settings.CanConvertImage(string(settings.HEICImagePreview)) {
 		return previewTypeHEIC
 	}
@@ -471,7 +481,7 @@ func GeneratePreviewWithMD5(ctx context.Context, file iteminfo.ExtendedFileInfo,
 
 	// Folio document previews render at target size in-process; they skip imageSem.
 	previewTypeEarly := determinePreviewType(file)
-	skipImageSem := previewTypeEarly == previewTypeDocument && folio.Enabled() && iteminfo.HasDocConvertableExtension(file.Name, file.Type)
+	skipImageSem := previewTypeEarly == previewTypeDocument && folioEnabled() && iteminfo.HasDocConvertableExtension(file.Name, file.Type)
 	// True when the semaphore block below holds a permit for this whole function.
 	imagePermitHeld := !skipImageSem
 	if !skipImageSem {
@@ -494,7 +504,9 @@ func GeneratePreviewWithMD5(ctx context.Context, file iteminfo.ExtendedFileInfo,
 	}
 
 	// Enforce file size limit for image preview generation to prevent memory exhaustion
-	if strings.HasPrefix(file.Type, "image") && file.Size > iteminfo.LargeFileSizeThreshold {
+	// Camera RAW is exempt: its preview is the embedded JPEG and the RAW data is never decoded.
+	if strings.HasPrefix(file.Type, "image") && file.Size > iteminfo.LargeFileSizeThreshold &&
+		!iteminfo.IsRawImage(strings.ToLower(filepath.Ext(file.Name))) {
 		message := fmt.Sprintf("Image file too large for preview: %s (size: %d bytes, limit: %d bytes)",
 			file.Name, file.Size, iteminfo.LargeFileSizeThreshold)
 		logger.Warning(message)
@@ -566,7 +578,7 @@ func GeneratePreviewWithMD5(ctx context.Context, file iteminfo.ExtendedFileInfo,
 	// Video thumbnails come from go-media or ffmpeg already sized to the preview
 	// box, so they are final and need no ffmpeg gate here.
 	if !fromEmbeddedPreview && (previewType == previewTypeImage ||
-		(previewType == previewTypeDocument && folio.Enabled() && iteminfo.HasDocConvertableExtension(file.Name, file.Type)) ||
+		(previewType == previewTypeDocument && folioEnabled() && iteminfo.HasDocConvertableExtension(file.Name, file.Type)) ||
 		previewType == previewTypeVideo) {
 		if err := service.fileCache.Store(ctx, cacheKey, imageBytes); err != nil {
 			logger.Errorf("failed to cache image: %v", err)

backend/internal/preview/preview_type_test.go

@@ -0,0 +1,49 @@
+package preview
+
+import (
+	"testing"
+
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
+)
+
+// withHEICConversion sets ffmpeg availability and the HEIC preview setting for
+// one test.
+func withHEICConversion(t *testing.T, enabled bool) {
+	t.Helper()
+	prevAvail := settings.Env.FFmpegAvailable
+	prevPreview := settings.Config.Integrations.Media.Convert.ImagePreview
+	t.Cleanup(func() {
+		settings.Env.FFmpegAvailable = prevAvail
+		settings.Config.Integrations.Media.Convert.ImagePreview = prevPreview
+	})
+	settings.Env.FFmpegAvailable = true
+	settings.Config.Integrations.Media.Convert.ImagePreview = map[settings.ImagePreviewType]*bool{
+		settings.HEICImagePreview: &enabled,
+	}
+}
+
+// previewFile returns a file info with only a name and MIME type set.
+func previewFile(name, mimeType string) iteminfo.ExtendedFileInfo {
+	var f iteminfo.ExtendedFileInfo
+	f.Name = name
+	f.Type = mimeType
+	return f
+}
+
+// TestDeterminePreviewTypeAVIF checks that AVIF uses the HEIF decode path when
+// HEIC conversion is enabled, and the plain image path otherwise.
+func TestDeterminePreviewTypeAVIF(t *testing.T) {
+	withHEICConversion(t, true)
+	if got := determinePreviewType(previewFile("a.avif", "image/avif")); got != previewTypeHEIC {
+		t.Fatalf("avif with HEIC conversion = %v, want previewTypeHEIC", got)
+	}
+	if got := determinePreviewType(previewFile("a.heic", "image/heic")); got != previewTypeHEIC {
+		t.Fatalf("heic with HEIC conversion = %v, want previewTypeHEIC", got)
+	}
+
+	withHEICConversion(t, false)
+	if got := determinePreviewType(previewFile("a.avif", "image/avif")); got != previewTypeImage {
+		t.Fatalf("avif without HEIC conversion = %v, want previewTypeImage", got)
+	}
+}

backend/internal/preview/textpreview.go

@@ -0,0 +1,138 @@
+// Text preview: a size-capped prefix of a text-like file for the text preview API.
+//
+// Output is not sanitized; the frontend is responsible for sanitizing everything it
+// renders from these results. ReadTextPreview does not generate an image and is not
+// written to the disk cache, so it is separate from the image preview pipeline.
+package preview
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"os"
+	"strings"
+	"unicode/utf8"
+)
+
+// MaxTextPreviewBytes is the largest amount of a file that is read for a preview.
+const MaxTextPreviewBytes = 16 * 1024
+
+// ErrNotText is returned for files that look binary (contain NUL bytes).
+var ErrNotText = errors.New("file does not look like text")
+
+// ErrPreviewServiceUnavailable is returned by text preview entry points when the
+// preview service has not been started.
+var ErrPreviewServiceUnavailable = errors.New("preview service not initialized")
+
+// TextPreviewResult is the JSON payload returned by the text preview endpoint.
+type TextPreviewResult struct {
+	// Content is plain text, or an HTML fragment when Format is "html".
+	Content string `json:"content"`
+	// Kind is the renderer the frontend should use: plain, csv, markdown, html, css, code, or rtf.
+	Kind string `json:"kind"`
+	// Format is "text" or "html". RTF is converted to HTML; everything else is text.
+	Format string `json:"format"`
+	// Truncated is true when the file is larger than the returned content.
+	Truncated bool `json:"truncated"`
+	// Size is the full size of the file in bytes.
+	Size int64 `json:"size"`
+}
+
+// ReadTextPreview returns up to MaxTextPreviewBytes of the file at realPath, prepared
+// for the given renderer kind. It reads directly from disk and does not take an image
+// processor permit; callers that need to bound concurrent reads use the service's
+// shared semaphore (see Service.ReadTextPreview).
+func ReadTextPreview(realPath, kind string) (TextPreviewResult, error) {
+	f, err := os.Open(realPath)
+	if err != nil {
+		return TextPreviewResult{}, err
+	}
+	defer f.Close()
+
+	info, err := f.Stat()
+	if err != nil {
+		return TextPreviewResult{}, err
+	}
+
+	buf := make([]byte, MaxTextPreviewBytes)
+	n, err := io.ReadFull(f, buf)
+	if err != nil && !errors.Is(err, io.EOF) && !errors.Is(err, io.ErrUnexpectedEOF) {
+		return TextPreviewResult{}, err
+	}
+	buf = buf[:n]
+
+	if bytes.IndexByte(buf, 0) >= 0 {
+		return TextPreviewResult{}, ErrNotText
+	}
+
+	truncated := info.Size() > int64(n)
+	if truncated {
+		buf = trimIncompleteRune(buf)
+		buf = trimToLastLine(buf)
+	}
+
+	// Legacy encodings are not valid UTF-8. Replace the bad bytes so the preview still renders.
+	text := strings.ToValidUTF8(string(buf), "\uFFFD")
+
+	result := TextPreviewResult{Kind: kind, Format: "text", Truncated: truncated, Size: info.Size()}
+	if kind == "rtf" {
+		result.Content = RTFToHTML(text)
+		result.Format = "html"
+	} else {
+		result.Content = text
+	}
+	return result, nil
+}
+
+// ReadTextPreview reads a text preview while holding a shared image-processor permit,
+// so text reads and conversions count against the same budget as image work instead of
+// opening an unbounded number of file handles when a listing is full of text files.
+// It returns ErrPreviewServiceUnavailable when the service has not been started.
+func (s *Service) ReadTextPreview(ctx context.Context, realPath, kind string) (TextPreviewResult, error) {
+	if err := s.acquireImageSem(ctx); err != nil {
+		return TextPreviewResult{}, err
+	}
+	defer s.releaseImageSem()
+	// The acquire select can win the slot at the same moment the request is canceled
+	// (both cases ready), so re-check before doing any file I/O for a dead request.
+	if err := ctx.Err(); err != nil {
+		return TextPreviewResult{}, err
+	}
+	return ReadTextPreview(realPath, kind)
+}
+
+// trimIncompleteRune removes a trailing partial UTF-8 sequence left by the read limit.
+func trimIncompleteRune(b []byte) []byte {
+	for i := 1; i <= utf8.UTFMax && i <= len(b); i++ {
+		c := b[len(b)-i]
+		if c&0xC0 == 0x80 {
+			// Continuation byte: keep looking for the lead byte.
+			continue
+		}
+		need := 1
+		switch {
+		case c&0xE0 == 0xC0:
+			need = 2
+		case c&0xF0 == 0xE0:
+			need = 3
+		case c&0xF8 == 0xF0:
+			need = 4
+		}
+		if need > i {
+			return b[:len(b)-i]
+		}
+		return b
+	}
+	return b
+}
+
+// trimToLastLine cuts at the last newline when that keeps at least half of the buffer.
+// Files with very long lines keep their full prefix so the preview is not empty.
+func trimToLastLine(b []byte) []byte {
+	idx := bytes.LastIndexByte(b, '\n')
+	if idx > len(b)/2 {
+		return b[:idx]
+	}
+	return b
+}

backend/internal/preview/textpreview_rtf.go

@@ -1,4 +1,4 @@
-package textpreview
+package preview
 
 import (
 	"html"

backend/internal/preview/textpreview_test.go

@@ -1,6 +1,7 @@
-package textpreview
+package preview
 
 import (
+	"context"
 	"os"
 	"path/filepath"
 	"strings"
@@ -43,15 +44,15 @@ func TestReadTruncatesAndKeepsUTF8Valid(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "big.txt")
 	// Multibyte characters so the 16KB cut is likely to land inside one.
-	content := strings.Repeat("\u00e9\n", MaxBytes)
+	content := strings.Repeat("\u00e9\n", MaxTextPreviewBytes)
 	require.NoError(t, os.WriteFile(path, []byte(content), 0o600))
 
-	res, err := Read(path, "plain")
+	res, err := ReadTextPreview(path, "plain")
 	require.NoError(t, err)
 	require.True(t, res.Truncated)
 	require.Equal(t, "plain", res.Kind)
 	require.Equal(t, "text", res.Format)
-	require.LessOrEqual(t, len(res.Content), MaxBytes)
+	require.LessOrEqual(t, len(res.Content), MaxTextPreviewBytes)
 	require.True(t, strings.HasSuffix(res.Content, "\u00e9"), "cut must land on a whole line")
 	require.Equal(t, int64(len(content)), res.Size)
 }
@@ -60,7 +61,7 @@ func TestReadSmallFileNotTruncated(t *testing.T) {
 	path := filepath.Join(t.TempDir(), "small.md")
 	require.NoError(t, os.WriteFile(path, []byte("# Title\n"), 0o600))
 
-	res, err := Read(path, "markdown")
+	res, err := ReadTextPreview(path, "markdown")
 	require.NoError(t, err)
 	require.False(t, res.Truncated)
 	require.Equal(t, "# Title\n", res.Content)
@@ -70,7 +71,7 @@ func TestReadRTFReturnsHTML(t *testing.T) {
 	path := filepath.Join(t.TempDir(), "doc.rtf")
 	require.NoError(t, os.WriteFile(path, []byte(`{\rtf1 Hi\par There}`), 0o600))
 
-	res, err := Read(path, "rtf")
+	res, err := ReadTextPreview(path, "rtf")
 	require.NoError(t, err)
 	require.Equal(t, "html", res.Format)
 	require.Equal(t, "<p>Hi</p><p>There</p>", res.Content)
@@ -80,7 +81,7 @@ func TestReadRejectsBinary(t *testing.T) {
 	path := filepath.Join(t.TempDir(), "data.txt")
 	require.NoError(t, os.WriteFile(path, []byte("text\x00binary"), 0o600))
 
-	_, err := Read(path, "plain")
+	_, err := ReadTextPreview(path, "plain")
 	require.ErrorIs(t, err, ErrNotText)
 }
 
@@ -88,7 +89,44 @@ func TestReadReplacesInvalidUTF8(t *testing.T) {
 	path := filepath.Join(t.TempDir(), "latin1.txt")
 	require.NoError(t, os.WriteFile(path, []byte("caf\xe9"), 0o600))
 
-	res, err := Read(path, "plain")
+	res, err := ReadTextPreview(path, "plain")
 	require.NoError(t, err)
 	require.Equal(t, "caf\uFFFD", res.Content)
 }
+
+// A single-processor service has a one-slot imageSem, so text previews must serialize
+// behind it rather than racing ahead of image work.
+func TestServiceReadTextPreviewSharesImageSemaphore(t *testing.T) {
+	svc := NewPreviewGenerator(1, t.TempDir())
+	path := filepath.Join(t.TempDir(), "notes.md")
+	require.NoError(t, os.WriteFile(path, []byte("# Title\n"), 0o600))
+
+	res, err := svc.ReadTextPreview(t.Context(), path, "markdown")
+	require.NoError(t, err)
+	require.Equal(t, "# Title\n", res.Content)
+	require.Equal(t, 0, len(svc.imageSem), "permit must be released after the read")
+}
+
+func TestServiceReadTextPreviewHonoursCancellation(t *testing.T) {
+	svc := NewPreviewGenerator(1, t.TempDir())
+	path := filepath.Join(t.TempDir(), "notes.md")
+	require.NoError(t, os.WriteFile(path, []byte("# Title\n"), 0o600))
+
+	// Hold the only permit, then confirm a cancelled caller does not block forever.
+	require.NoError(t, svc.acquireImageSem(t.Context()))
+	defer svc.releaseImageSem()
+
+	ctx, cancel := context.WithCancel(t.Context())
+	cancel()
+	_, err := svc.ReadTextPreview(ctx, path, "markdown")
+	require.ErrorIs(t, err, context.Canceled)
+}
+
+func TestGetTextPreviewWithoutService(t *testing.T) {
+	original := service
+	service = nil
+	t.Cleanup(func() { service = original })
+
+	_, err := GetTextPreview(t.Context(), "ignored.md", "markdown")
+	require.ErrorIs(t, err, ErrPreviewServiceUnavailable)
+}

backend/internal/preview/video.go

@@ -28,8 +28,11 @@ func (s *Service) GenerateVideoPreview(ctx context.Context, videoPath, previewSi
 		return nil, err
 	}
 
-	// go-media fast path: fit within the box, no crop. Falls back to ffmpeg when
-	// unsupported (e.g. HEVC, VP9, AV1) or failed.
+	// go-media fast path: fit within the box, no crop. go-media decodes H.264,
+	// HEVC, VP8, VP9, AV1, MPEG-4 Part 2, and WMV3 keyframes in pure Go. It falls
+	// back to ffmpeg when the container is not a go-media target (AVI, MPEG-TS,
+	// MPEG-PS, ...), the codec or profile is unsupported (WMV1/WMV2, VC-1
+	// Advanced, AV1 above 4K, ...), or the decode fails.
 	// In shadow mode (dev only) the ffmpeg preview also runs, for comparison.
 	// The shadow run can outlive the request, so it uses a context that is not cancelled with it.
 	shadowCtx := context.WithoutCancel(ctx)

backend/internal/state/access.go

@@ -19,6 +19,15 @@ func AccessPermitted(sourcePath string, indexPath utils.IndexPath, username stri
 	return accessDb.Permitted(sourcePath, indexPath, username)
 }
 
+// AccessPermittedAtRealPath reports whether username may access realPath after symlink
+// resolution on the given index. When accessDb is not initialized, access is allowed.
+func AccessPermittedAtRealPath(idx *indexing.Index, username, realPath string, isDir bool) bool {
+	if accessDb == nil {
+		return true
+	}
+	return accessDb.PermittedAtRealPath(idx, username, realPath, isDir)
+}
+
 func AllowUser(sourcePath string, indexPath utils.IndexPath, username string) error {
 	return accessDb.AllowUser(sourcePath, indexPath, username)
 }

backend/internal/state/media_settings.go

@@ -14,14 +14,21 @@ const (
 
 var (
 	mediaSettingsMu      sync.RWMutex
-	mediaSettingsDefault settings.MediaSettings
+	mediaSettingsDefault settings.FullAdminMedia
 )
 
+// saveMediaSettings is the only write path for media settings. It clears derived
+// fields (EnabledProfiles, ImagePreview) so read-time values are never persisted.
+func saveMediaSettings(key string, ms settings.FullAdminMedia) error {
+	settings.ClearMediaDerived(&ms)
+	return sqlDb.SaveSetting(key, ms)
+}
+
 // InitMediaSettings loads persisted runtime media settings from SQLite and seeds from config when missing.
 func InitMediaSettings() error {
 	if _, err := sqlDb.GetSetting(mediaSettingsDefaultKey); err != nil {
 		seed := settings.SanitizeMediaSettings(settings.CurrentMediaSettings())
-		if saveErr := sqlDb.SaveSetting(mediaSettingsDefaultKey, seed); saveErr != nil {
+		if saveErr := saveMediaSettings(mediaSettingsDefaultKey, seed); saveErr != nil {
 			return fmt.Errorf("seed media settings: %w", saveErr)
 		}
 	}
@@ -43,7 +50,7 @@ func InitMediaSettings() error {
 		// sanitize, so clamps (e.g. the readRate floor) must run again.
 		overlaid = settings.SanitizeMediaSettings(overlaid)
 		if !settings.MediaSettingsEqual(loaded, overlaid) {
-			if saveErr := sqlDb.SaveSetting(mediaSettingsDefaultKey, overlaid); saveErr != nil {
+			if saveErr := saveMediaSettings(mediaSettingsDefaultKey, overlaid); saveErr != nil {
 				return fmt.Errorf("save config-synced media settings: %w", saveErr)
 			}
 			loaded = overlaid
@@ -57,22 +64,22 @@ func InitMediaSettings() error {
 	return nil
 }
 
-func loadMediaSettingsSetting(key string) (settings.MediaSettings, error) {
+func loadMediaSettingsSetting(key string) (settings.FullAdminMedia, error) {
 	raw, err := sqlDb.GetSetting(key)
 	if err != nil {
-		return settings.MediaSettings{}, err
+		return settings.FullAdminMedia{}, err
 	}
-	var ms settings.MediaSettings
+	var ms settings.FullAdminMedia
 	if err := json.Unmarshal(raw, &ms); err != nil {
-		return settings.MediaSettings{}, fmt.Errorf("parse %s: %w", key, err)
+		return settings.FullAdminMedia{}, fmt.Errorf("parse %s: %w", key, err)
 	}
 	return ms, nil
 }
 
-// GetMediaSettings returns the runtime media settings. The value is deep-copied
+// GetMediaSettings returns the stored runtime media settings. The value is deep-copied
 // so callers cannot mutate the stored settings (or the live config they are
 // applied to) through the conversion maps.
-func GetMediaSettings() settings.MediaSettings {
+func GetMediaSettings() settings.FullAdminMedia {
 	mediaSettingsMu.RLock()
 	defer mediaSettingsMu.RUnlock()
 	return settings.CloneMediaSettings(mediaSettingsDefault)
@@ -90,8 +97,11 @@ func PatchMediaSettings(patchJSON []byte) error {
 		return mergeErr
 	}
 	merged = settings.SanitizeMediaSettings(merged)
+	// A patch may echo derived fields back (e.g. imagePreview from the admin UI).
+	// Clear them before the value reaches memory or the database.
+	settings.ClearMediaDerived(&merged)
 
-	if saveErr := sqlDb.SaveSetting(mediaSettingsDefaultKey, merged); saveErr != nil {
+	if saveErr := saveMediaSettings(mediaSettingsDefaultKey, merged); saveErr != nil {
 		mediaSettingsMu.Unlock()
 		return fmt.Errorf("save media settings: %w", saveErr)
 	}

backend/internal/state/media_settings_test.go

@@ -1,6 +1,7 @@
 package state
 
 import (
+	"encoding/json"
 	"testing"
 
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
@@ -34,6 +35,56 @@ func TestGetMediaSettingsReturnsIndependentCopy(t *testing.T) {
 	}
 }
 
+// Derived read-time values must never reach the database, even when a caller
+// passes a struct that has them populated.
+func TestSaveMediaSettingsNeverPersistsDerivedFields(t *testing.T) {
+	initSidebarLinkTestDB(t)
+
+	ms := GetMediaSettings()
+	ms.Transcode.EnabledProfiles = []string{"quality"}
+	ms.ImagePreview = map[settings.ImagePreviewType]bool{settings.JPEGImagePreview: true}
+	if err := saveMediaSettings(mediaSettingsDefaultKey, ms); err != nil {
+		t.Fatalf("saveMediaSettings: %v", err)
+	}
+
+	raw, err := sqlDb.GetSetting(mediaSettingsDefaultKey)
+	if err != nil {
+		t.Fatalf("GetSetting: %v", err)
+	}
+	var stored map[string]any
+	if err := json.Unmarshal(raw, &stored); err != nil {
+		t.Fatalf("decode stored settings: %v", err)
+	}
+	transcode, ok := stored["transcode"].(map[string]any)
+	if !ok {
+		t.Fatalf("stored transcode = %T, want object", stored["transcode"])
+	}
+	if _, ok := transcode["enabledProfiles"]; ok {
+		t.Fatal("enabledProfiles (derived) was persisted")
+	}
+	if _, ok := stored["imagePreview"]; ok {
+		t.Fatal("imagePreview (derived) was persisted")
+	}
+}
+
+// The admin UI echoes its whole payload back on PATCH, derived fields included.
+// Those must be dropped before the value reaches memory, not only before the database.
+func TestPatchMediaSettingsDropsEchoedDerivedFields(t *testing.T) {
+	initSidebarLinkTestDB(t)
+
+	patch := []byte(`{"imagePreview":{"jpeg":true},"transcode":{"enabledProfiles":["quality"]}}`)
+	if err := PatchMediaSettings(patch); err != nil {
+		t.Fatalf("PatchMediaSettings: %v", err)
+	}
+	got := GetMediaSettings()
+	if got.ImagePreview != nil {
+		t.Fatal("echoed imagePreview stayed in memory")
+	}
+	if got.Transcode.EnabledProfiles != nil {
+		t.Fatal("echoed enabledProfiles stayed in memory")
+	}
+}
+
 // A fresh install seeds the stored media settings from config.
 func TestMediaSettingsSeedFromConfigOnFirstInit(t *testing.T) {
 	initSidebarLinkTestDB(t)

backend/internal/state/user_defaults.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"reflect"
+	"slices"
 	"strings"
 	"sync"
 
@@ -297,6 +298,17 @@ func ApplyUserDefaults(u *users.User) {
 	applyToolAccessDefaults(u)
 }
 
+// PrefillUserProfileDefaults seeds u with the effective profile defaults so a JSON decode
+// overlays only the keys the request sent (encoding/json leaves absent keys untouched).
+// Permissions are left zero so omitted permissions stay distinguishable; CreateUser merges them.
+func PrefillUserProfileDefaults(u *users.User) {
+	settings.ApplyFullProfileFromDefaults(u, EffectiveUserDefaults())
+	// json.Unmarshal reuses an existing slice's backing array, so clone it or a request
+	// would overwrite the shared in-memory defaults.
+	u.NewFileTemplate = slices.Clone(u.NewFileTemplate)
+	u.Permissions = users.Permissions{}
+}
+
 func applyUserSettingsDefaults(u *users.User) {
 	settings.ApplyUserDefaultsFrom(u, EffectiveUserDefaults())
 }

backend/internal/state/user_defaults_yaml_integration_test.go

@@ -90,7 +90,7 @@ func TestStateInit_jwtYAML_organizedDefaultsOnNewUser(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if !loaded.DarkMode || !loaded.Preview.Image {
+	if !loaded.DarkMode.IsDark() || !loaded.Preview.Image {
 		t.Fatalf("profile fields: darkMode=%v preview.image=%v", loaded.DarkMode, loaded.Preview.Image)
 	}
 	if loaded.BackendScopes[0].Permissions.Modify != access.Modify {

backend/internal/state/users.go

@@ -202,6 +202,18 @@ func UserForShareOwner(link share.Share) (users.User, error) {
 // may apply default-enabled sources. In-memory/cache users always keep FrontendScopes nil; GET handlers use
 // PrepForFrontend to repopulate FrontendScopes from BackendScopes for responses.
 func CreateUser(user *users.User, plaintextPassword string) error {
+	return createUser(user, plaintextPassword, false)
+}
+
+// CreateUserKeepingProfile is CreateUser for callers whose user was seeded with
+// PrefillUserProfileDefaults before decoding the request: the profile fields already hold
+// defaults overlaid with the request, so they are not replaced by userDefaults again.
+// Enforced defaults still win.
+func CreateUserKeepingProfile(user *users.User, plaintextPassword string) error {
+	return createUser(user, plaintextPassword, true)
+}
+
+func createUser(user *users.User, plaintextPassword string, keepProfile bool) error {
 	if err := users.ValidateUsername(user.Username); err != nil {
 		return err
 	}
@@ -256,12 +268,19 @@ func CreateUser(user *users.User, plaintextPassword string) error {
 			requestedScopePermissions[backendScopeKeyFor(scope)] = scope.Permissions
 		}
 	}
+	var requestedProfile settings.UserProfile
+	if keepProfile {
+		requestedProfile = settings.ProfileFromUser(user)
+	}
 	// Apply profile/scope defaults using the final account permissions (admin flag drives scope defaults).
 	if permissionsRequested {
 		settings.ApplyUserDefaultsFromKeepingAccountPermissions(user, EffectiveUserDefaults())
 	} else {
 		applyUserSettingsDefaults(user)
 	}
+	if keepProfile {
+		settings.ExpandProfileIntoUser(user, requestedProfile)
+	}
 	if preserveRequirePasswordChange {
 		user.RequirePasswordChange = true
 	}

backend/internal/textpreview/textpreview.go

@@ -1,112 +0,0 @@
-// Package textpreview reads a size-capped prefix of a text-like file for the text preview API.
-//
-// It does not use the image preview pipeline and does not sanitize output. The frontend
-// is responsible for sanitizing everything it renders from this package.
-package textpreview
-
-import (
-	"bytes"
-	"errors"
-	"io"
-	"os"
-	"strings"
-	"unicode/utf8"
-)
-
-// MaxBytes is the largest amount of a file that is read for a preview.
-const MaxBytes = 16 * 1024
-
-// ErrNotText is returned for files that look binary (contain NUL bytes).
-var ErrNotText = errors.New("file does not look like text")
-
-// Result is the JSON payload returned by the text preview endpoint.
-type Result struct {
-	// Content is plain text, or an HTML fragment when Format is "html".
-	Content string `json:"content"`
-	// Kind is the renderer the frontend should use: plain, csv, markdown, html, css, code, or rtf.
-	Kind string `json:"kind"`
-	// Format is "text" or "html". RTF is converted to HTML; everything else is text.
-	Format string `json:"format"`
-	// Truncated is true when the file is larger than the returned content.
-	Truncated bool `json:"truncated"`
-	// Size is the full size of the file in bytes.
-	Size int64 `json:"size"`
-}
-
-// Read returns up to MaxBytes of the file at realPath, prepared for the given renderer kind.
-func Read(realPath, kind string) (Result, error) {
-	f, err := os.Open(realPath)
-	if err != nil {
-		return Result{}, err
-	}
-	defer f.Close()
-
-	info, err := f.Stat()
-	if err != nil {
-		return Result{}, err
-	}
-
-	buf := make([]byte, MaxBytes)
-	n, err := io.ReadFull(f, buf)
-	if err != nil && !errors.Is(err, io.EOF) && !errors.Is(err, io.ErrUnexpectedEOF) {
-		return Result{}, err
-	}
-	buf = buf[:n]
-
-	if bytes.IndexByte(buf, 0) >= 0 {
-		return Result{}, ErrNotText
-	}
-
-	truncated := info.Size() > int64(n)
-	if truncated {
-		buf = trimIncompleteRune(buf)
-		buf = trimToLastLine(buf)
-	}
-
-	// Legacy encodings are not valid UTF-8. Replace the bad bytes so the preview still renders.
-	text := strings.ToValidUTF8(string(buf), "\uFFFD")
-
-	result := Result{Kind: kind, Format: "text", Truncated: truncated, Size: info.Size()}
-	if kind == "rtf" {
-		result.Content = RTFToHTML(text)
-		result.Format = "html"
-	} else {
-		result.Content = text
-	}
-	return result, nil
-}
-
-// trimIncompleteRune removes a trailing partial UTF-8 sequence left by the read limit.
-func trimIncompleteRune(b []byte) []byte {
-	for i := 1; i <= utf8.UTFMax && i <= len(b); i++ {
-		c := b[len(b)-i]
-		if c&0xC0 == 0x80 {
-			// Continuation byte: keep looking for the lead byte.
-			continue
-		}
-		need := 1
-		switch {
-		case c&0xE0 == 0xC0:
-			need = 2
-		case c&0xF0 == 0xE0:
-			need = 3
-		case c&0xF8 == 0xF0:
-			need = 4
-		}
-		if need > i {
-			return b[:len(b)-i]
-		}
-		return b
-	}
-	return b
-}
-
-// trimToLastLine cuts at the last newline when that keeps at least half of the buffer.
-// Files with very long lines keep their full prefix so the preview is not empty.
-func trimToLastLine(b []byte) []byte {
-	idx := bytes.LastIndexByte(b, '\n')
-	if idx > len(b)/2 {
-		return b[:idx]
-	}
-	return b
-}

backend/internal/transcoding/engine.go

@@ -133,7 +133,7 @@ func (e *MediaEngine) BuildPlan(ctx context.Context, realPath string, profile Pr
 	copyImpossible := false
 	plan.segmentSec = defaults.SegmentDurationSec
 	if plan.remux || plan.videoCopy {
-		rawKeyframes, kfErr := probeKeyframesCached(ctx, svc, realPath, stat.Size(), stat.ModTime().UnixNano(), plan.segmentSec, true)
+		rawKeyframes, kfErr := probeKeyframesCached(ctx, svc, realPath, stat.Size(), stat.ModTime().UnixNano(), plan.segmentSec, mediaSpan{durationSec: info.Duration, startTimeSec: info.StartTime}, true)
 		if kfErr != nil {
 			copyImpossible = true
 			logger.Warningf("transcode: keyframe probe failed on %s (%v) — forcing video transcode for HLS", realPath, kfErr)

backend/internal/transcoding/keyframe_cache.go

@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/gtsteffaniak/filebrowser/backend/internal/ffmpeg"
+	"github.com/gtsteffaniak/filebrowser/backend/internal/gomedia"
 	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
 	"github.com/gtsteffaniak/go-logger/logger"
 )
@@ -55,6 +56,9 @@ type keyframeCache struct {
 
 var defaultKeyframeCache = &keyframeCache{entries: map[keyframeKey]*keyframeEntry{}}
 
+// get returns the keyframe timeline for key from memory, then disk, then
+// probe. Concurrent callers for one key wait on a single probe; failures are
+// not cached.
 func (c *keyframeCache) get(ctx context.Context, key keyframeKey, probe func(context.Context) ([]float64, error)) ([]float64, error) {
 	c.mu.Lock()
 	e := c.entries[key]
@@ -105,12 +109,15 @@ func keyframeDiskCacheEnabled() bool {
 	return settings.Config.Server.CacheDir != ""
 }
 
+// keyframeDiskPath returns the disk cache file for key's path.
 func keyframeDiskPath(key keyframeKey) string {
 	sum := sha256.Sum256([]byte(key.path))
 	name := hex.EncodeToString(sum[:])[:32] + ".json"
 	return filepath.Join(settings.TranscodeKeyframeCacheDir(), name)
 }
 
+// readKeyframeDiskCache returns the persisted timeline for key when it exists
+// and matches the file's size, mtime, and the cache version.
 func readKeyframeDiskCache(key keyframeKey) ([]float64, bool) {
 	if !keyframeDiskCacheEnabled() {
 		return nil, false
@@ -132,6 +139,8 @@ func readKeyframeDiskCache(key keyframeKey) ([]float64, bool) {
 	return stamp.Times, true
 }
 
+// writeKeyframeDiskCache persists a timeline for key atomically. Errors are
+// ignored; the cache is an optimization.
 func writeKeyframeDiskCache(key keyframeKey, times []float64) {
 	if len(times) == 0 || !keyframeDiskCacheEnabled() {
 		return
@@ -219,19 +228,88 @@ func probeKeyframesWithPreflight(ctx context.Context, svc *ffmpeg.Service, realP
 	)
 }
 
+// mediaSpan is the ffprobe format duration and start time of a file, the
+// values the HLS planner turns into its media timeline. The zero value means
+// unknown.
+type mediaSpan struct {
+	durationSec  float64
+	startTimeSec float64
+}
+
+// trailingGapExceedsCopyCap reports whether the stretch from the last
+// keyframe to the end of the media is longer than the copy cap, measured on
+// the same normalized timeline the planner builds: the final segment runs
+// from the last keyframe to the media end, so such a gap forces a transcode
+// just like a gap between two keyframes. An unknown span reports false.
+func trailingGapExceedsCopyCap(keyframes []float64, span mediaSpan, segmentSec float64) bool {
+	if len(keyframes) == 0 || span.durationSec <= 0 {
+		return false
+	}
+	kf, mediaDur := ffmpeg.PrepareHLSMediaTimeline(keyframes, span.durationSec, span.startTimeSec)
+	if len(kf) == 0 || mediaDur <= 0 {
+		return false
+	}
+	return mediaDur-kf[len(kf)-1] > maxCopySegmentDurationSec(segmentSec)
+}
+
 // keyframeProbeTimeout bounds a single full-file keyframe probe. The default
 // demux has no deadline of its own, so a slow network share would otherwise
 // stall plan building (and the client's session POST) indefinitely.
 const keyframeProbeTimeout = 2 * time.Minute
 
-func probeKeyframesCached(ctx context.Context, svc *ffmpeg.Service, realPath string, size, modTime int64, segmentSec float64, preflight bool) ([]float64, error) {
+// probeKeyframesCached returns the keyframe timeline of a file version from
+// the memory or disk cache, or probes it: go-media reads the container index
+// first, and ffprobe runs only when go-media cannot answer or reports a gap
+// that would rule out stream copy. span is the file's duration and start
+// time, used to check the gap after the last keyframe; the zero value skips
+// that check.
+func probeKeyframesCached(ctx context.Context, svc *ffmpeg.Service, realPath string, size, modTime int64, segmentSec float64, span mediaSpan, preflight bool) ([]float64, error) {
 	key := keyframeKey{path: realPath, size: size, modTime: modTime}
 	return defaultKeyframeCache.get(ctx, key, func(ctx context.Context) ([]float64, error) {
 		probeCtx, cancel := context.WithTimeout(ctx, keyframeProbeTimeout)
 		defer cancel()
+		if times, ok := gomediaKeyframes(probeCtx, svc, realPath, segmentSec, span, preflight); ok {
+			return times, nil
+		}
 		if preflight {
 			return probeKeyframesWithPreflight(probeCtx, svc, realPath, segmentSec)
 		}
 		return svc.ProbeVideoKeyframeTimes(probeCtx, realPath)
 	})
 }
+
+// gomediaKeyframes reads the keyframe timeline from the container index with
+// go-media. It reports ok=false when go-media cannot answer, and also when
+// preflight is set and the timeline has a gap past the copy cap, including
+// the gap from the last keyframe to the end of span: go-media can miss
+// keyframes that ffprobe's parsers flag (IDR frames not in the index,
+// partial Matroska Cues) but never adds one, so only ffprobe may decide that
+// stream copy is impossible. A bounded go-media read runs first, so a file
+// whose head already shows such a gap does not pay for a full index walk.
+func gomediaKeyframes(ctx context.Context, svc *ffmpeg.Service, realPath string, segmentSec float64, span mediaSpan, preflight bool) ([]float64, bool) {
+	if preflight {
+		if head, ok := gomedia.KeyframeTimesWithin(ctx, realPath, keyframeBoundedPreflightWindowSec); ok && keyframesExceedCopyCap(head, segmentSec) {
+			logger.Debugf("transcode: go-media keyframe pre-flight shows a gap past the copy cap on %s; confirming with ffprobe", realPath)
+			return nil, false
+		}
+	}
+	legacy := func() ([]float64, bool) {
+		shadowCtx, cancel := context.WithTimeout(context.WithoutCancel(ctx), keyframeProbeTimeout)
+		defer cancel()
+		times, err := svc.ProbeVideoKeyframeTimes(shadowCtx, realPath)
+		return times, err == nil
+	}
+	times, ok := gomedia.KeyframeTimes(ctx, realPath, legacy)
+	if !ok {
+		return nil, false
+	}
+	if preflight && keyframesExceedCopyCap(times, segmentSec) {
+		logger.Debugf("transcode: go-media keyframe index shows a gap past the copy cap on %s; confirming with ffprobe", realPath)
+		return nil, false
+	}
+	if preflight && trailingGapExceedsCopyCap(times, span, segmentSec) {
+		logger.Debugf("transcode: go-media keyframe index ends more than the copy cap before the end of %s; confirming with ffprobe", realPath)
+		return nil, false
+	}
+	return times, true
+}

backend/internal/transcoding/keyframe_cache_test.go

@@ -177,3 +177,33 @@ func TestKeyframeCacheDoesNotCacheFailures(t *testing.T) {
 		t.Fatalf("retry after failure: %v, %v", got, err)
 	}
 }
+
+// TestTrailingGapExceedsCopyCap checks the gap from the last keyframe to the
+// end of the media, on the planner's start-time-normalized timeline.
+func TestTrailingGapExceedsCopyCap(t *testing.T) {
+	every2 := func(from, to float64) []float64 {
+		var out []float64
+		for v := from; v < to; v += 2 {
+			out = append(out, v)
+		}
+		return out
+	}
+	cases := []struct {
+		name string
+		kf   []float64
+		span mediaSpan
+		want bool
+	}{
+		{"partial index", []float64{0, 2}, mediaSpan{durationSec: 60}, true},
+		{"full index", every2(0, 60), mediaSpan{durationSec: 60}, false},
+		{"unknown span", []float64{0, 2}, mediaSpan{}, false},
+		{"start time, partial", []float64{10, 12}, mediaSpan{durationSec: 70, startTimeSec: 10}, true},
+		{"start time, full", every2(10, 70), mediaSpan{durationSec: 70, startTimeSec: 10}, false},
+		{"no keyframes", nil, mediaSpan{durationSec: 60}, false},
+	}
+	for _, c := range cases {
+		if got := trailingGapExceedsCopyCap(c.kf, c.span, 4); got != c.want {
+			t.Errorf("%s: got %v, want %v", c.name, got, c.want)
+		}
+	}
+}

backend/internal/transcoding/keyframe_gomedia_test.go

@@ -0,0 +1,111 @@
+package transcoding
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
+)
+
+const keyframeFixtureMP4 = "../../../frontend/tests/playwright-files/myfolder/testdata/sample-640x480.mp4"
+
+// TestProbeKeyframesCachedUsesGoMedia checks that an MP4 keyframe timeline is
+// built without ffprobe: with no ffmpeg service, only go-media can answer.
+func TestProbeKeyframesCachedUsesGoMedia(t *testing.T) {
+	if settings.AlwaysUseFfmpegEnabled() {
+		t.Skip("go-media disabled by settings")
+	}
+	prevCacheDir := settings.Config.Server.CacheDir
+	settings.Config.Server.CacheDir = "" // keep the disk cache out of the test
+	t.Cleanup(func() { settings.Config.Server.CacheDir = prevCacheDir })
+
+	path := filepath.Join(t.TempDir(), "sample.mp4")
+	data, err := os.ReadFile(keyframeFixtureMP4)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = os.WriteFile(path, data, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	st, err := os.Stat(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	times, err := probeKeyframesCached(context.Background(), nil, path, st.Size(), st.ModTime().UnixNano(), 4, mediaSpan{}, true)
+	if err != nil {
+		t.Fatalf("probeKeyframesCached: %v", err)
+	}
+	if len(times) == 0 || times[0] < 0 {
+		t.Fatalf("unexpected keyframes %v", times)
+	}
+	for i := 1; i < len(times); i++ {
+		if times[i] <= times[i-1] {
+			t.Fatalf("keyframes not strictly increasing: %v", times)
+		}
+	}
+}
+
+// TestGomediaKeyframesDefersCopyDecision checks that a go-media timeline with a
+// gap past the copy cap is not used for the pre-flight decision (ffprobe must
+// confirm it), while a plain probe still returns it.
+func TestGomediaKeyframesDefersCopyDecision(t *testing.T) {
+	if testing.Short() {
+		t.Skip("encodes a clip with ffmpeg")
+	}
+	if settings.AlwaysUseFfmpegEnabled() {
+		t.Skip("go-media disabled by settings")
+	}
+	if _, err := exec.LookPath("ffmpeg"); err != nil {
+		t.Skip("ffmpeg not installed")
+	}
+	path := filepath.Join(t.TempDir(), "longgop.mp4")
+	out, err := exec.Command("ffmpeg", "-v", "error", "-y", "-f", "lavfi", "-i", "testsrc2=size=128x96:rate=25:duration=40",
+		"-c:v", "libx264", "-g", "750", "-keyint_min", "750", "-sc_threshold", "0", "-pix_fmt", "yuv420p", path).CombinedOutput()
+	if err != nil {
+		t.Skipf("ffmpeg cannot encode libx264: %v: %s", err, out)
+	}
+
+	if times, ok := gomediaKeyframes(context.Background(), nil, path, 4, mediaSpan{}, true); ok {
+		t.Fatalf("pre-flight must defer a 30s GOP to ffprobe, got %v", times)
+	}
+	times, ok := gomediaKeyframes(context.Background(), nil, path, 4, mediaSpan{}, false)
+	if !ok {
+		t.Fatal("a plain probe must return the go-media timeline")
+	}
+	if len(times) != 2 || times[0] != 0 || times[1] < 29.9 || times[1] > 30.1 {
+		t.Fatalf("unexpected keyframes %v, want [0 30]", times)
+	}
+}
+
+// TestGomediaKeyframesDefersTrailingGap checks that a go-media index whose
+// last keyframe is more than the copy cap before the end of the media is not
+// used for the pre-flight decision, so ffprobe can confirm it, while the
+// same index is used when it reaches the end.
+func TestGomediaKeyframesDefersTrailingGap(t *testing.T) {
+	if testing.Short() {
+		t.Skip("encodes a clip with ffmpeg")
+	}
+	if settings.AlwaysUseFfmpegEnabled() {
+		t.Skip("go-media disabled by settings")
+	}
+	if _, err := exec.LookPath("ffmpeg"); err != nil {
+		t.Skip("ffmpeg not installed")
+	}
+	path := filepath.Join(t.TempDir(), "short.mp4")
+	out, err := exec.Command("ffmpeg", "-v", "error", "-y", "-f", "lavfi", "-i", "testsrc2=size=128x96:rate=25:duration=4",
+		"-c:v", "libx264", "-g", "50", "-keyint_min", "50", "-sc_threshold", "0", "-pix_fmt", "yuv420p", path).CombinedOutput()
+	if err != nil {
+		t.Skipf("ffmpeg cannot encode libx264: %v: %s", err, out)
+	}
+	// The index ends at 2 s; a 60 s span leaves a 58 s final segment.
+	if times, ok := gomediaKeyframes(context.Background(), nil, path, 4, mediaSpan{durationSec: 60}, true); ok {
+		t.Fatalf("pre-flight must defer a 58s trailing gap to ffprobe, got %v", times)
+	}
+	times, ok := gomediaKeyframes(context.Background(), nil, path, 4, mediaSpan{durationSec: 4}, true)
+	if !ok || len(times) != 2 {
+		t.Fatalf("index reaching the end must be used, got %v, %v", times, ok)
+	}
+}

backend/internal/transcoding/manager_test.go

@@ -1098,14 +1098,14 @@ func TestManagerSuspendsProducerWhenAllClientsPaused(t *testing.T) {
 	in := testInput(t, "pauser", "/v.mp4")
 	sess := mustStart(t, mgr, in)
 	waitForStarts(t, engine, 1)
-	job := engine.LastJob()
 
 	if err := mgr.Heartbeat(in.Username, sess.ID, HeartbeatRequest{ClientID: "c1", Paused: true}); err != nil {
 		t.Fatal(err)
 	}
+	waitForProducerVODJobAttached(t, mgr, sess.ID)
 	suspendPausedProducers(t, mgr, time.Now().Add(time.Hour))
 
-	pollUntil(t, 2*time.Second, func() bool { return !job.Running() }, "suspended job to stop")
+	waitForProducerParked(t, mgr, sess.ID)
 	if snap := snapshotProducer(t, mgr, sess.ID); !snap.exists || !snap.suspended {
 		t.Fatal("a suspended producer must stay registered and marked suspended")
 	}
@@ -1185,13 +1185,13 @@ func TestManagerResumesProducerOnUnpauseHeartbeat(t *testing.T) {
 	pollUntil(t, 2*time.Second, func() bool {
 		return snapshotProducer(t, mgr, sess.ID).encodeHead >= 1
 	}, "encode head to advance past segment 0")
-	job := engine.LastJob()
 
 	if err := mgr.Heartbeat(in.Username, sess.ID, HeartbeatRequest{ClientID: "c1", Paused: true}); err != nil {
 		t.Fatal(err)
 	}
+	waitForProducerVODJobAttached(t, mgr, sess.ID)
 	suspendPausedProducers(t, mgr, time.Now().Add(time.Hour))
-	pollUntil(t, 2*time.Second, func() bool { return !job.Running() }, "suspended job to stop")
+	waitForProducerParked(t, mgr, sess.ID)
 
 	if err := mgr.Heartbeat(in.Username, sess.ID, HeartbeatRequest{ClientID: "c1", Paused: false}); err != nil {
 		t.Fatal(err)
@@ -1216,13 +1216,13 @@ func TestManagerResumesProducerOnSegmentRequest(t *testing.T) {
 	in := testInput(t, "pauser", "/v.mp4")
 	sess := mustStart(t, mgr, in)
 	waitForStarts(t, engine, 1)
-	job := engine.LastJob()
 
 	if err := mgr.Heartbeat(in.Username, sess.ID, HeartbeatRequest{ClientID: "c1", Paused: true}); err != nil {
 		t.Fatal(err)
 	}
+	waitForProducerVODJobAttached(t, mgr, sess.ID)
 	suspendPausedProducers(t, mgr, time.Now().Add(time.Hour))
-	pollUntil(t, 2*time.Second, func() bool { return !job.Running() }, "suspended job to stop")
+	waitForProducerParked(t, mgr, sess.ID)
 
 	// The suspended job reads as !Running, so a request beyond its head takes
 	// the restart path: the relaunched job produces the requested segment.
@@ -1246,13 +1246,13 @@ func TestManagerStopReleasesSuspendedProducer(t *testing.T) {
 	in := testInput(t, "pauser", "/v.mp4")
 	sess := mustStart(t, mgr, in)
 	waitForStarts(t, engine, 1)
-	job := engine.LastJob()
 
 	if err := mgr.Heartbeat(in.Username, sess.ID, HeartbeatRequest{ClientID: "c1", Paused: true}); err != nil {
 		t.Fatal(err)
 	}
+	waitForProducerVODJobAttached(t, mgr, sess.ID)
 	suspendPausedProducers(t, mgr, time.Now().Add(time.Hour))
-	pollUntil(t, 2*time.Second, func() bool { return !job.Running() }, "suspended job to stop")
+	waitForProducerParked(t, mgr, sess.ID)
 
 	if err := mgr.Stop(in.Username, sess.ID); err != nil {
 		t.Fatal(err)
@@ -1308,6 +1308,29 @@ func mustStart(t *testing.T, mgr *Manager, in StartInput) SessionInfo {
 	return info
 }
 
+// waitForProducerVODJobAttached waits until the session's producer has the VOD
+// job wired up. StartCount can advance before runProducerJob assigns p.job.
+func waitForProducerVODJobAttached(t *testing.T, mgr *Manager, sessionID string) {
+	t.Helper()
+	pollUntil(t, 5*time.Second, func() bool {
+		mgr.mu.Lock()
+		p := mgr.producers[sessionID]
+		ok := p != nil && p.job != nil
+		mgr.mu.Unlock()
+		return ok
+	}, "producer VOD job attached")
+}
+
+// waitForProducerParked waits until suspendPausedProducers has parked the
+// producer (suspended flag), instead of polling a stale *fakeJob snapshot.
+func waitForProducerParked(t *testing.T, mgr *Manager, sessionID string) {
+	t.Helper()
+	pollUntil(t, 5*time.Second, func() bool {
+		snap := snapshotProducer(t, mgr, sessionID)
+		return snap.exists && snap.suspended
+	}, "suspended producer to park")
+}
+
 // pollUntil fails the test when cond is not met within timeout.
 func pollUntil(t *testing.T, timeout time.Duration, cond func() bool, msg string) {
 	t.Helper()

backend/internal/utils/media.go

@@ -15,12 +15,18 @@ type SubtitleTrack struct {
 	Embedded bool   `json:"embedded"`        // true for embedded subtitles, false for external files
 }
 
+// ErrSubtitleSidecarNotRegular is returned when an external subtitle path is not a regular file (e.g. symlink).
+var ErrSubtitleSidecarNotRegular = errors.New("subtitle sidecar is not a regular file")
+
 func GetSubtitleSidecarContent(subtitlePath string) (string, error) {
-	// validate the size is not too large
-	info, err := os.Stat(subtitlePath)
+	// Sidecars sit beside the media file; do not follow symlink leaves (see lyricsSidecar).
+	info, err := os.Lstat(subtitlePath)
 	if err != nil {
 		return "", err
 	}
+	if !info.Mode().IsRegular() {
+		return "", ErrSubtitleSidecarNotRegular
+	}
 	if info.Size() > 1024*1024*50 { // 50MB
 		return "", errors.New("subtitle file is too large")
 	}

backend/internal/web/access_test.go

@@ -22,6 +22,7 @@ import (
 
 func setupAccessHTTPTest(t *testing.T) {
 	t.Helper()
+	lockWebGlobals(t)
 	dbPath := filepath.Join(t.TempDir(), "access-http-test.sqlite")
 	if _, err := state.Initialize(dbPath); err != nil {
 		t.Fatal(err)

backend/internal/web/archive.go

@@ -279,19 +279,21 @@ func archiveCreateHandler(w http.ResponseWriter, r *http.Request, d *Context) (i
 	if fullDestParent != fullDestFile && !state.AccessPermitted(idxTo.Path, utils.IndexPathFromNormalized(fullDestParent, true), d.User.Username) {
 		return http.StatusForbidden, fmt.Errorf("access denied to destination parent of %s", req.Destination)
 	}
-	parentReal, err := idxTo.GetRealPathForMutation(userScopeTo, fullDestParent)
-	if err != nil {
-		return http.StatusBadRequest, fmt.Errorf("destination parent path invalid: %v", err)
-	}
-	if err = os.MkdirAll(parentReal, fileutils.EffectiveDirPerm()); err != nil {
-		return http.StatusInternalServerError, fmt.Errorf("cannot create destination parent directory: %v", err)
-	}
 	destRel := strings.TrimLeft(filepath.ToSlash(req.Destination), "/")
 	fileName := path.Base(destRel)
 	if fileName == "." || fileName == "/" {
 		return http.StatusBadRequest, fmt.Errorf("invalid destination file name")
 	}
-	destFileReal := filepath.Join(parentReal, fileName)
+	destFileReal, err := idxTo.GetRealPathForMutation(userScopeTo, fullDestFile)
+	if err != nil {
+		return http.StatusBadRequest, fmt.Errorf("destination path invalid: %v", err)
+	}
+	if !state.AccessPermittedAtRealPath(idxTo, d.User.Username, destFileReal, false) {
+		return http.StatusForbidden, fmt.Errorf("access denied to destination %s", req.Destination)
+	}
+	if err = os.MkdirAll(filepath.Dir(destFileReal), fileutils.EffectiveDirPerm()); err != nil {
+		return http.StatusInternalServerError, fmt.Errorf("cannot create destination parent directory: %v", err)
+	}
 
 	format := strings.ToLower(strings.TrimSpace(req.Format))
 	if format == "" {
@@ -1270,6 +1272,7 @@ func extractArchivedSymlink(destRoot, destPath, target string, modTime time.Time
 		logger.Debugf("unarchive: symlink: %v", err)
 		return fmt.Errorf("failed to create symlink from archive entry")
 	}
+	indexing.ClearRealPathCaches()
 	return applyArchivedTimesAndPerm(destPath, fs.ModeSymlink, modTime)
 }
 

backend/internal/web/archive_create_access_test.go

@@ -0,0 +1,86 @@
+package web
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/gtsteffaniak/filebrowser/backend/internal/state"
+	"github.com/gtsteffaniak/filebrowser/backend/internal/utils"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
+)
+
+func TestArchiveCreate_DeniesResolvedSymlinkDestination(t *testing.T) {
+	_, sourceRoot, sourceName, username := setupExtractAccessPolicyTest(t)
+	if err := state.DenyUser(sourceRoot, utils.IndexPathFromNormalized("/denied", true), username); err != nil {
+		t.Fatal(err)
+	}
+	allowedDir := filepath.Join(sourceRoot, "allowed")
+	deniedDir := filepath.Join(sourceRoot, "denied")
+	for _, dir := range []string{allowedDir, deniedDir} {
+		if err := os.MkdirAll(dir, 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	victim := filepath.Join(deniedDir, "victim")
+	if err := os.WriteFile(victim, []byte("keep"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(sourceRoot, "a.txt"), []byte("payload"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	link := filepath.Join(allowedDir, "report.zip")
+	if err := os.Symlink(filepath.Join("..", "denied", "victim"), link); err != nil {
+		t.Fatal(err)
+	}
+
+	user, err := state.GetUserByUsername(username)
+	if err != nil {
+		t.Fatal(err)
+	}
+	settings.Config.Server.SourceMap[sourceRoot].Config.DenyByDefault = false
+
+	body := `{"fromSource":"` + sourceName + `","paths":["/a.txt"],"destination":"/allowed/report.zip","format":"zip"}`
+	req := httptest.NewRequest(http.MethodPost, "/api/resources/archive", strings.NewReader(body))
+	rec := httptest.NewRecorder()
+	status, handlerErr := archiveCreateHandler(rec, req, &Context{User: &user})
+	if status != http.StatusForbidden || handlerErr == nil {
+		t.Fatalf("status=%d err=%v", status, handlerErr)
+	}
+	got, err := os.ReadFile(victim)
+	if err != nil || string(got) != "keep" {
+		t.Fatalf("victim content=%q err=%v", got, err)
+	}
+}
+
+func TestArchiveCreate_AllowsNonSymlinkDestination(t *testing.T) {
+	_, sourceRoot, sourceName, username := setupExtractAccessPolicyTest(t)
+	dest := filepath.Join(sourceRoot, "out.zip")
+	if err := os.WriteFile(filepath.Join(sourceRoot, "a.txt"), []byte("payload"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	user, err := state.GetUserByUsername(username)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	body := `{"fromSource":"` + sourceName + `","paths":["/a.txt"],"destination":"/out.zip","format":"zip"}`
+	req := httptest.NewRequest(http.MethodPost, "/api/resources/archive", strings.NewReader(body))
+	rec := httptest.NewRecorder()
+	status, handlerErr := archiveCreateHandler(rec, req, &Context{User: &user})
+	if status != http.StatusOK || handlerErr != nil {
+		t.Fatalf("status=%d err=%v body=%s", status, handlerErr, rec.Body.String())
+	}
+	var resp map[string]string
+	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(dest); err != nil {
+		t.Fatalf("expected archive at %s: %v", dest, err)
+	}
+}

backend/internal/web/archive_extract_access_test.go

@@ -23,6 +23,7 @@ import (
 
 func setupExtractAccessPolicyTest(t *testing.T) (destDir, sourceRoot, sourceName, username string) {
 	t.Helper()
+	lockWebGlobals(t)
 	tempDir := t.TempDir()
 	dbPath := filepath.Join(tempDir, "access.sqlite")
 	if _, err := state.Initialize(dbPath); err != nil {

backend/internal/web/archive_test.go

@@ -3,11 +3,16 @@ package web
 import (
 	"archive/tar"
 	"archive/zip"
+	"errors"
 	"io"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
+
+	commonerrors "github.com/gtsteffaniak/filebrowser/backend/internal/errors"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/settings"
 )
 
 func TestNormalizeArchiveEntryName(t *testing.T) {
@@ -557,3 +562,19 @@ func TestExtractZip_symlinkDestination(t *testing.T) {
 		t.Fatalf("victim.txt should be unchanged: %q, %v", victimData, err)
 	}
 }
+
+func TestArchiveCreateDestination_RejectsEscapingSymlinkLeaf(t *testing.T) {
+	t.Parallel()
+	root := t.TempDir()
+	outside := filepath.Join(filepath.Dir(root), "outside-archive")
+	if err := os.MkdirAll(outside, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink(outside, filepath.Join(root, "report.zip")); err != nil {
+		t.Fatal(err)
+	}
+	idx := &indexing.Index{Source: settings.Source{Path: root}}
+	if _, err := idx.GetRealPathForMutation("", "/report.zip"); !errors.Is(err, commonerrors.ErrPathEscapesScope) {
+		t.Fatalf("expected ErrPathEscapesScope, got %v", err)
+	}
+}

backend/internal/web/download_share_test.go

@@ -25,6 +25,7 @@ import (
 
 func setupShareArchiveDownloadTest(t *testing.T) (sourceRoot string, sourceName string, owner *users.User) {
 	t.Helper()
+	lockWebGlobals(t)
 	dbPath := filepath.Join(t.TempDir(), "share-dl-test.sqlite")
 	if _, err := state.Initialize(dbPath); err != nil {
 		t.Fatal(err)

backend/internal/web/duplicates.go

@@ -1,16 +1,13 @@
 package web
 
 import (
-	"crypto/md5"
+	"context"
 	"fmt"
-	"io"
 	"net/http"
-	"os"
 	"path/filepath"
 	"strings"
 	"sync"
 	"time"
-	"unicode"
 
 	"github.com/gtsteffaniak/filebrowser/backend/internal/activity"
 	activitydb "github.com/gtsteffaniak/filebrowser/backend/internal/database/activity"
@@ -39,9 +36,6 @@ const (
 // duplicateResultsCache caches duplicate search results for 15 seconds
 var duplicateResultsCache = cache.NewCache[duplicateResponse](15 * time.Second)
 
-// checksumCache caches file checksums for 1 hour, keyed by source/path/modtime
-var checksumCache = cache.NewCache[string](1 * time.Hour)
-
 type duplicateGroup struct {
 	Size  int64                    `json:"size"`
 	Count int                      `json:"count"`
@@ -127,10 +121,12 @@ func (s *duplicateProcessingStats) shouldStop() (bool, string) {
 //     identical content but different filenames)
 //
 // Performance Optimizations:
-// - Checksums are cached for 1 hour (keyed by path/size/modtime) to speed up subsequent requests
-// - Files are processed in batches to balance memory usage vs SQL query count
-// - Resource limits prevent timeouts: max 2 minutes, max 10K checksum operations
-// - Large fuzzy groups are skipped to avoid expensive checksum operations on false positives
+//   - Checksums are cached for 1 hour (keyed by path/size/modtime) to speed up subsequent requests
+//     The checksum budget counts only cache misses (real disk I/O); cached digests are free,
+//     so a re-run proceeds past the previously-examined files instead of stalling at the limit.
+//   - Files are processed in batches to balance memory usage vs SQL query count
+//   - Resource limits prevent timeouts: max 2 minutes, max 10K checksum operations
+//   - Large fuzzy groups are skipped to avoid expensive checksum operations on false positives
 //
 // Response includes incomplete flag if processing was stopped early due to resource limits.
 //
@@ -170,7 +166,10 @@ func duplicatesHandler(w http.ResponseWriter, r *http.Request, d *Context) (int,
 
 	// Safety check: Reject duplicate search during active indexing to prevent resource contention
 	// This protects against CPU/memory spikes and ensures indexing performance is not degraded
-	if string(index.Status) == "indexing" {
+	// Use GetStatus() (computed from active scanners and persisted lastScanned) rather than
+	// the raw Status field, which is only set to "ready" by PostScan and would otherwise
+	// block searches indefinitely after a restart until the first scheduled scan runs.
+	if index.GetStatus() == indexing.INDEXING {
 		return http.StatusServiceUnavailable, fmt.Errorf("duplicate search is not available while indexing is in progress - please try again when indexing completes")
 	}
 
@@ -238,7 +237,13 @@ func duplicatesHandler(w http.ResponseWriter, r *http.Request, d *Context) (int,
 		startTime:       time.Now(),
 		uniqueChecksums: make(map[string]bool),
 	}
-	duplicateGroups := findDuplicatesInIndex(index, opts, stats)
+	duplicateGroups := findDuplicatesInIndex(r.Context(), index, opts, stats)
+
+	// The client went away — do not cache or record a truncated result. A cached
+	// partial response would poison the 15s duplicateResultsCache for the next user.
+	if err := r.Context().Err(); err != nil {
+		return http.StatusRequestTimeout, err
+	}
 
 	// Log resource usage for monitoring
 	uniqueChecksumCount := len(stats.uniqueChecksums)
@@ -254,8 +259,7 @@ func duplicatesHandler(w http.ResponseWriter, r *http.Request, d *Context) (int,
 		Reason:     stats.stopReason,
 	}
 
-	// Cache the results before returning (even partial results)
-	duplicateResultsCache.Set(cacheKey, response)
+	cacheDuplicateResponse(r.Context(), cacheKey, response)
 
 	if stats.stopped {
 		w.Header().Set("X-Search-Incomplete", "true")
@@ -267,7 +271,7 @@ func duplicatesHandler(w http.ResponseWriter, r *http.Request, d *Context) (int,
 }
 
 // findDuplicatesInIndex finds duplicates using the shared IndexDB with resource limits
-func findDuplicatesInIndex(index *indexing.Index, opts *duplicatesOptions, stats *duplicateProcessingStats) []duplicateGroup {
+func findDuplicatesInIndex(ctx context.Context, index *indexing.Index, opts *duplicatesOptions, stats *duplicateProcessingStats) []duplicateGroup {
 	// Get the shared IndexDB
 	indexDB := indexing.GetIndexDB()
 
@@ -290,6 +294,11 @@ func findDuplicatesInIndex(index *indexing.Index, opts *duplicatesOptions, stats
 
 	// Process sizes in batches
 	for batchStart := 0; batchStart < len(sizes); batchStart += bulkSizeQueryLimit {
+		if ctx.Err() != nil {
+			stats.stopped = true
+			stats.stopReason = ctx.Err().Error()
+			break
+		}
 		// Check resource limits before processing each batch
 		if shouldStop, reason := stats.shouldStop(); shouldStop {
 			stats.stopped = true
@@ -327,6 +336,11 @@ func findDuplicatesInIndex(index *indexing.Index, opts *duplicatesOptions, stats
 		// Memory optimization: Delete entries from filesBySize immediately after processing
 		// to allow GC to reclaim memory as we go, rather than holding all data until batch completes
 		for _, size := range sizeBatch {
+			if ctx.Err() != nil {
+				stats.stopped = true
+				stats.stopReason = ctx.Err().Error()
+				break
+			}
 			files, ok := filesBySize[size]
 			if !ok || len(files) < 2 {
 				// Clear entry even if not processing to free memory
@@ -345,8 +359,8 @@ func findDuplicatesInIndex(index *indexing.Index, opts *duplicatesOptions, stats
 				continue
 			}
 
-			// Group files by MIME type in memory (already ordered by type from SQL)
-			filesByType := groupFilesByType(files)
+			// Group files by MIME (+ extension when MIME is ambiguous) within this size bucket.
+			filesByType := groupFilesByTypeBucket(files)
 
 			// Process each MIME type group
 			for _, typeFiles := range filesByType {
@@ -364,29 +378,13 @@ func findDuplicatesInIndex(index *indexing.Index, opts *duplicatesOptions, stats
 
 				// Use fuzzy filename matching to group files within this MIME type
 				// This reduces checksum operations by grouping similar filenames
-				filenameGroups := groupFilesByFilename(typeFiles, size)
+				filenameGroups := groupFilesByFilename(ctx, typeFiles, size, stats)
 
-				totalFilesInGroups := 0
-				for _, g := range filenameGroups {
-					if len(g) >= 2 {
-						totalFilesInGroups += len(g)
-					}
-				}
-
-				// Process each fuzzy filename group
 				for _, fileGroup := range filenameGroups {
 					if len(fileGroup) < 2 {
 						continue
 					}
 
-					// Skip checksumming if fuzzy group is too large - groups with many files
-					// are unlikely to be true duplicates (fuzzy matching is too permissive)
-					// This optimization prevents expensive checksum operations on false positives
-					if len(fileGroup) > maxFuzzyGroupSize {
-						logger.Debugf("[Duplicates] Skipping checksum for fuzzy group with %d files (exceeds limit of %d)", len(fileGroup), maxFuzzyGroupSize)
-						continue
-					}
-
 					// Stop if we've hit the group limit
 					if len(groupsWithChecksums) >= maxGroups {
 						break
@@ -403,7 +401,7 @@ func findDuplicatesInIndex(index *indexing.Index, opts *duplicatesOptions, stats
 					// Verify with checksums using 3-pass progressive verification
 					// At this point, files match on: size + MIME type + fuzzy filename similarity (50%+)
 					// Large fuzzy groups (>10 files) are skipped above to avoid expensive false positives
-					verifiedGroups := groupFilesByChecksum(fileGroup, index, size, stats)
+					verifiedGroups := groupFilesByChecksum(ctx, fileGroup, index, size, stats)
 
 					// Create SearchResult objects and track checksums for merging
 					for _, checksumGroup := range verifiedGroups {
@@ -483,100 +481,15 @@ func findDuplicatesInIndex(index *indexing.Index, opts *duplicatesOptions, stats
 		})
 	}
 
-	// Groups are already sorted by size (largest to smallest) from SQL query
 	return duplicateGroups
 }
 
-// mergeGroupsByChecksum merges groups that share any checksum values
-// This catches cases where files have identical content but were grouped separately
-func mergeGroupsByChecksum(groups []duplicateGroupWithChecksums) []duplicateGroupWithChecksums {
-	if len(groups) <= 1 {
-		return groups
+// cacheDuplicateResponse stores a duplicate search response when the client context is still active.
+func cacheDuplicateResponse(ctx context.Context, cacheKey string, response duplicateResponse) {
+	if ctx.Err() != nil {
+		return
 	}
-
-	// Build a map: checksum -> list of group indices that contain this checksum
-	checksumToGroups := make(map[string][]int)
-	for i, group := range groups {
-		if group.Checksum != "" {
-			checksumToGroups[group.Checksum] = append(checksumToGroups[group.Checksum], i)
-		}
-	}
-
-	// Use union-find to merge groups that share checksums
-	parent := make([]int, len(groups))
-	for i := range parent {
-		parent[i] = i
-	}
-
-	var find func(int) int
-	find = func(x int) int {
-		if parent[x] != x {
-			parent[x] = find(parent[x]) // Path compression
-		}
-		return parent[x]
-	}
-
-	union := func(x, y int) {
-		px, py := find(x), find(y)
-		if px != py {
-			parent[px] = py
-		}
-	}
-
-	// Merge groups that share any checksum
-	for _, groupIndices := range checksumToGroups {
-		if len(groupIndices) < 2 {
-			continue
-		}
-		// Merge all groups that share this checksum
-		for i := 1; i < len(groupIndices); i++ {
-			union(groupIndices[0], groupIndices[i])
-		}
-	}
-
-	// Group indices by their root parent
-	groupsByRoot := make(map[int][]int)
-	for i := range groups {
-		root := find(i)
-		groupsByRoot[root] = append(groupsByRoot[root], i)
-	}
-
-	// Merge groups that belong to the same root
-	merged := make([]duplicateGroupWithChecksums, 0, len(groupsByRoot))
-	for _, indices := range groupsByRoot {
-		if len(indices) == 1 {
-			// No merging needed, just add the group
-			merged = append(merged, groups[indices[0]])
-			continue
-		}
-
-		// Merge multiple groups
-		combinedFiles := make([]*indexing.SearchResult, 0)
-		var combinedSize int64
-		var combinedChecksum string
-
-		for _, idx := range indices {
-			group := groups[idx]
-			combinedFiles = append(combinedFiles, group.Files...)
-			if combinedChecksum == "" {
-				combinedChecksum = group.Checksum
-			}
-			if combinedSize == 0 {
-				combinedSize = group.Size
-			}
-		}
-
-		// Only include merged groups with 2+ files
-		if len(combinedFiles) >= 2 {
-			merged = append(merged, duplicateGroupWithChecksums{
-				Size:     combinedSize,
-				Files:    combinedFiles,
-				Checksum: combinedChecksum,
-			})
-		}
-	}
-
-	return merged
+	duplicateResultsCache.Set(cacheKey, response)
 }
 
 func prepDuplicatesOptions(r *http.Request, d *Context) (*duplicatesOptions, error) {
@@ -624,349 +537,6 @@ func prepDuplicatesOptions(r *http.Request, d *Context) (*duplicatesOptions, err
 	}, nil
 }
 
-// groupFilesByChecksum groups files by partial checksum and returns groups with their checksums
-func groupFilesByChecksum(files []*iteminfo.FileInfo, index *indexing.Index, fileSize int64, stats *duplicateProcessingStats) []checksumGroup {
-	if len(files) < 2 {
-		return nil
-	}
-
-	// PASS 1: Header checksums only (first 8KB)
-	// This is the fastest way to eliminate files that are definitely different
-	// ONLY checksum files that already matched on filename+size
-	headerGroups := make(map[string][]*iteminfo.FileInfo)
-
-	for _, file := range files {
-		// Check if we've hit the checksum operation limit
-		if stats.checksumOperations >= maxChecksumOperations {
-			logger.Warningf("[Duplicates] Reached checksum operation limit (%d) in header pass", maxChecksumOperations)
-			break
-		}
-
-		// Verify size matches expected size (should match as we queried by size)
-		if file.Size != fileSize {
-			continue
-		}
-
-		// Construct filesystem path for checksum computation
-		// index.Path is the absolute filesystem root, file.Path is index-relative
-		filePath := filepath.Join(index.Path, file.Path)
-		headerChecksum, err := computeHeaderChecksum(index.Path, filePath, fileSize, file.ModTime)
-		if err != nil {
-			continue
-		}
-		stats.checksumOperations++
-		stats.uniqueChecksums[headerChecksum] = true
-		headerGroups[headerChecksum] = append(headerGroups[headerChecksum], file)
-	}
-
-	// Filter to only groups with 2+ files (candidates for duplicates)
-	headerCandidates := make([][]*iteminfo.FileInfo, 0)
-	filesAfterHeaderPass := 0
-	for _, group := range headerGroups {
-		if len(group) >= 2 {
-			headerCandidates = append(headerCandidates, group)
-			filesAfterHeaderPass += len(group)
-		}
-	}
-
-	if len(headerCandidates) == 0 {
-		return nil
-	}
-
-	// PASS 2: Middle checksums (header + middle) for header-matched groups
-	// Only process files that matched on header to save disk I/O
-	middleGroups := make(map[string][]*iteminfo.FileInfo)
-
-	for _, headerGroup := range headerCandidates {
-		if len(headerGroup) < 2 {
-			continue
-		}
-
-		for _, file := range headerGroup {
-			// Check if we've hit the checksum operation limit
-			if stats.checksumOperations >= maxChecksumOperations {
-				logger.Warningf("[Duplicates] Reached checksum operation limit (%d) in middle pass", maxChecksumOperations)
-				break
-			}
-
-			filePath := filepath.Join(index.Path, file.Path)
-			middleChecksum, err := computeMiddleChecksum(index.Path, filePath, fileSize, file.ModTime)
-			if err != nil {
-				continue
-			}
-			stats.checksumOperations++
-			stats.uniqueChecksums[middleChecksum] = true
-			middleGroups[middleChecksum] = append(middleGroups[middleChecksum], file)
-		}
-	}
-
-	// Final verification: Use middle checksum as final (header + middle is sufficient)
-	// Files that match on header + middle but differ at end are extremely rare
-	// This 2-pass system catches 99.9%+ of differences while being faster
-	groups := make([]checksumGroup, 0, len(middleGroups))
-	for checksum, group := range middleGroups {
-		if len(group) >= 2 {
-			groups = append(groups, checksumGroup{
-				Files:    group,
-				Checksum: checksum,
-			})
-		}
-	}
-
-	return groups
-}
-
-// computeHeaderChecksum calculates MD5 hash of only the first 8KB of a file
-// This is the fastest initial pass to eliminate non-matching files
-func computeHeaderChecksum(sourcePath, filePath string, size int64, modTime time.Time) (string, error) {
-	// Generate cache key for header-only checksum
-	cacheKey := fmt.Sprintf("%s:%s:%d:%d:header", sourcePath, filePath, size, modTime.Unix())
-
-	// Check cache first
-	if cachedChecksum, ok := checksumCache.Get(cacheKey); ok {
-		return cachedChecksum, nil
-	}
-
-	file, err := os.Open(filePath)
-	if err != nil {
-		return "", err
-	}
-	defer file.Close()
-
-	hash := md5.New()
-	buf := make([]byte, 8192) // 8KB buffer
-
-	// Read only first 8KB (or entire file if smaller)
-	n, err := io.ReadFull(file, buf)
-	if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
-		return "", err
-	}
-	hash.Write(buf[:n])
-
-	checksum := fmt.Sprintf("%x", hash.Sum(nil))
-
-	// Cache the result
-	checksumCache.Set(cacheKey, checksum)
-
-	return checksum, nil
-}
-
-// computeMiddleChecksum calculates MD5 hash of header + middle portion
-// Only called when header checksums match (progressive verification)
-func computeMiddleChecksum(sourcePath, filePath string, size int64, modTime time.Time) (string, error) {
-	// Generate cache key for header+middle checksum
-	cacheKey := fmt.Sprintf("%s:%s:%d:%d:middle", sourcePath, filePath, size, modTime.Unix())
-
-	// Check cache first
-	if cachedChecksum, ok := checksumCache.Get(cacheKey); ok {
-		return cachedChecksum, nil
-	}
-
-	file, err := os.Open(filePath)
-	if err != nil {
-		return "", err
-	}
-	defer file.Close()
-
-	hash := md5.New()
-	buf := make([]byte, 8192) // 8KB buffer
-
-	// Read first 8KB
-	n, err := io.ReadFull(file, buf)
-	if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
-		return "", err
-	}
-	hash.Write(buf[:n])
-
-	// For larger files, also read middle 8KB
-	if size > 16384 { // 16KB
-		middleOffset := size / 2
-		if _, err := file.Seek(middleOffset, 0); err == nil {
-			n, err := io.ReadFull(file, buf)
-			if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
-				return "", err
-			}
-			hash.Write(buf[:n])
-		}
-	}
-
-	checksum := fmt.Sprintf("%x", hash.Sum(nil))
-
-	// Cache the result
-	checksumCache.Set(cacheKey, checksum)
-
-	return checksum, nil
-}
-
-// groupFilesByFilename groups files by fuzzy filename matching
-// Works with iteminfo.FileInfo from the main IndexDB
-// Normalizes filenames on-the-fly for comparison
-// NOTE: Files passed in should already be filtered by MIME type at the SQL level,
-// so no need to check extensions here (extension checking is redundant with MIME type filtering)
-func groupFilesByFilename(files []*iteminfo.FileInfo, expectedSize int64) [][]*iteminfo.FileInfo {
-	if len(files) == 0 {
-		return nil
-	}
-
-	groups := [][]*iteminfo.FileInfo{}
-	used := make(map[int]bool)
-
-	for i := 0; i < len(files); i++ {
-		if used[i] || files[i].Name == "" {
-			continue
-		}
-
-		group := []*iteminfo.FileInfo{files[i]}
-		used[i] = true
-
-		// Normalize filename for fuzzy matching
-		filename1 := normalizeFilename(files[i].Name)
-
-		for j := i + 1; j < len(files); j++ {
-			if used[j] || files[j].Name == "" {
-				continue
-			}
-
-			// Check size (should match, but safe to check)
-			if files[j].Size != expectedSize {
-				continue
-			}
-
-			filename2 := normalizeFilename(files[j].Name)
-
-			// Check if filenames are similar enough using levenshtein distance
-			if filenamesSimilar(filename1, filename2) {
-				group = append(group, files[j])
-				used[j] = true
-			}
-		}
-
-		if len(group) >= 2 {
-			groups = append(groups, group)
-		}
-	}
-
-	return groups
-}
-
-// normalizeFilename converts filename to lowercase and removes special characters
-// to make fuzzy matching more effective
-func normalizeFilename(filename string) string {
-	// Convert to lowercase
-	filename = strings.ToLower(filename)
-
-	// Remove file extension for comparison
-	if idx := strings.LastIndex(filename, "."); idx > 0 {
-		filename = filename[:idx]
-	}
-
-	// Remove non-alphanumeric characters except spaces and hyphens
-	var result strings.Builder
-	for _, r := range filename {
-		if unicode.IsLetter(r) || unicode.IsDigit(r) || r == ' ' || r == '-' {
-			result.WriteRune(r)
-		}
-	}
-
-	return strings.TrimSpace(result.String())
-}
-
-// filenamesSimilar checks if two normalized filenames are similar enough to be considered duplicates
-func filenamesSimilar(name1, name2 string) bool {
-	// Exact match
-	if name1 == name2 {
-		return true
-	}
-
-	// Empty names don't match
-	if len(name1) == 0 || len(name2) == 0 {
-		return false
-	}
-
-	// Calculate Levenshtein distance
-	distance := levenshteinDistance(name1, name2)
-	maxLen := max(len(name1), len(name2))
-
-	// Require at least 50% similarity (lowered to catch more duplicates with username prefixes)
-	// Examples: "video.mp4" vs "username_video.mp4" should match
-	similarity := 1.0 - float64(distance)/float64(maxLen)
-	return similarity >= 0.5
-}
-
-// levenshteinDistance calculates the edit distance between two strings
-func levenshteinDistance(s1, s2 string) int {
-	if len(s1) == 0 {
-		return len(s2)
-	}
-	if len(s2) == 0 {
-		return len(s1)
-	}
-
-	// Create matrix
-	matrix := make([][]int, len(s1)+1)
-	for i := range matrix {
-		matrix[i] = make([]int, len(s2)+1)
-	}
-
-	// Initialize first row and column
-	for i := 0; i <= len(s1); i++ {
-		matrix[i][0] = i
-	}
-	for j := 0; j <= len(s2); j++ {
-		matrix[0][j] = j
-	}
-
-	// Fill matrix
-	for i := 1; i <= len(s1); i++ {
-		for j := 1; j <= len(s2); j++ {
-			cost := 0
-			if s1[i-1] != s2[j-1] {
-				cost = 1
-			}
-
-			matrix[i][j] = min(
-				matrix[i-1][j]+1,      // deletion
-				matrix[i][j-1]+1,      // insertion
-				matrix[i-1][j-1]+cost, // substitution
-			)
-		}
-	}
-
-	return matrix[len(s1)][len(s2)]
-}
-
-// min returns the minimum of three integers
-func min(a, b, c int) int {
-	if a < b {
-		if a < c {
-			return a
-		}
-		return c
-	}
-	if b < c {
-		return b
-	}
-	return c
-}
-
-// max returns the maximum of two integers
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}
-
-// groupFilesByType groups files by MIME type
-// Assumes files are already sorted by type (from SQL ORDER BY)
-func groupFilesByType(files []*iteminfo.FileInfo) map[string][]*iteminfo.FileInfo {
-	grouped := make(map[string][]*iteminfo.FileInfo)
-	for _, file := range files {
-		grouped[file.Type] = append(grouped[file.Type], file)
-	}
-	return grouped
-}
-
 // filterFilesByPermission filters files to only include those the user is permitted to access
 // This is called early in the duplicate search process to avoid processing files the user can't see
 func filterFilesByPermission(files []*iteminfo.FileInfo, index *indexing.Index, username string) []*iteminfo.FileInfo {

backend/internal/web/duplicates_bench_test.go

@@ -0,0 +1,157 @@
+package web
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
+)
+
+type duplicateCorpus struct {
+	dir   string
+	files []*iteminfo.FileInfo
+}
+
+func buildDuplicateCorpus(b *testing.B) *duplicateCorpus {
+	b.Helper()
+	dir := b.TempDir()
+	now := time.Now()
+
+	write := func(name string, payload []byte, mutateTail bool) {
+		if mutateTail && len(payload) > 32 {
+			dup := append([]byte(nil), payload...)
+			dup[len(dup)-1] ^= 0xff
+			payload = dup
+		}
+		if err := os.WriteFile(filepath.Join(dir, name), payload, 0o600); err != nil {
+			b.Fatal(err)
+		}
+	}
+
+	jpegHeader := []byte{0xff, 0xd8, 0xff, 0xe0}
+	pngHeader := []byte{0x89, 0x50, 0x4e, 0x47}
+	pdfHeader := []byte("%PDF-1.4\n")
+	mp4Header := []byte{0x00, 0x00, 0x00, 0x18, 'f', 't', 'y', 'p'}
+
+	mkPayload := func(header []byte, size int) []byte {
+		out := make([]byte, size)
+		copy(out, header)
+		for i := len(header); i < len(out); i++ {
+			out[i] = byte(i)
+		}
+		return out
+	}
+
+	baseJPEG := mkPayload(jpegHeader, 65536)
+	basePNG := mkPayload(pngHeader, 65536)
+	basePDF := mkPayload(pdfHeader, 65536)
+	baseMP4 := mkPayload(mp4Header, 65536)
+
+	entries := []struct {
+		name string
+		typ  string
+		data []byte
+	}{
+		{"exact-a.jpg", "image/jpeg", baseJPEG},
+		{"exact-b.jpg", "image/jpeg", baseJPEG},
+		{"renamed-copy.jpeg", "image/jpeg", baseJPEG},
+		{"user_exact-a.jpg", "image/jpeg", baseJPEG},
+		{"png-a.png", "image/png", basePNG},
+		{"png-b.png", "image/png", basePNG},
+		{"doc-a.pdf", "application/pdf", basePDF},
+		{"doc-b.pdf", "application/pdf", basePDF},
+		{"clip-a.mp4", "video/mp4", baseMP4},
+		{"clip-b.mp4", "video/mp4", baseMP4},
+		{"sized-a.bin", "application/octet-stream", baseJPEG},
+		{"sized-b.bin", "application/octet-stream", mkPayload(jpegHeader, 65536)},
+	}
+
+	files := make([]*iteminfo.FileInfo, 0, len(entries)+50)
+	for _, e := range entries {
+		write(e.name, e.data, false)
+		files = append(files, &iteminfo.FileInfo{
+			ItemInfo: iteminfo.ItemInfo{Name: e.name, Size: int64(len(e.data)), ModTime: now, Type: e.typ},
+			Path:     "/" + e.name,
+		})
+	}
+	write("tail-b.jpg", baseJPEG, true)
+
+	for i := 0; i < 12; i++ {
+		name := fmt.Sprintf("fuzzy_photo_%d.jpg", i)
+		write(name, baseJPEG, false)
+		files = append(files, &iteminfo.FileInfo{
+			ItemInfo: iteminfo.ItemInfo{Name: name, Size: int64(len(baseJPEG)), ModTime: now, Type: "image/jpeg"},
+			Path:     "/" + name,
+		})
+	}
+
+	for i := 0; i < 30; i++ {
+		name := fmt.Sprintf("bucket_%04d.jpg", i)
+		write(name, mkPayload(jpegHeader, 65536), i%7 == 0)
+		files = append(files, &iteminfo.FileInfo{
+			ItemInfo: iteminfo.ItemInfo{Name: name, Size: 65536, ModTime: now, Type: "image/jpeg"},
+			Path:     "/" + name,
+		})
+	}
+
+	return &duplicateCorpus{dir: dir, files: files}
+}
+
+func BenchmarkDuplicateTypeBuckets(b *testing.B) {
+	corpus := buildDuplicateCorpus(b)
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = groupFilesByTypeBucket(corpus.files)
+	}
+}
+
+func BenchmarkDuplicateFilenameGroups(b *testing.B) {
+	corpus := buildDuplicateCorpus(b)
+	subset := corpus.files[len(corpus.files)-30:]
+	ctx := context.Background()
+	stats := &duplicateProcessingStats{startTime: time.Now()}
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = groupFilesByFilename(ctx, subset, 65536, stats)
+	}
+}
+
+func BenchmarkDuplicateChecksumGrouping(b *testing.B) {
+	corpus := buildDuplicateCorpus(b)
+	pair := []*iteminfo.FileInfo{corpus.files[0], corpus.files[1]}
+	idx := &indexing.Index{Path: corpus.dir}
+	ctx := context.Background()
+	stats := &duplicateProcessingStats{startTime: time.Now(), uniqueChecksums: map[string]bool{}}
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = groupFilesByChecksum(ctx, pair, idx, pair[0].Size, stats)
+	}
+}
+
+func BenchmarkDuplicateMerge(b *testing.B) {
+	mkFiles := func(n int, prefix string) []*indexing.SearchResult {
+		out := make([]*indexing.SearchResult, n)
+		for i := range out {
+			out[i] = &indexing.SearchResult{Path: fmt.Sprintf("/%s/%d", prefix, i)}
+		}
+		return out
+	}
+	groups := []duplicateGroupWithChecksums{
+		{Size: 100, Checksum: "d1", Files: mkFiles(4, "a")},
+		{Size: 100, Checksum: "d1", Files: mkFiles(3, "b")},
+		{Size: 200, Checksum: "d2", Files: mkFiles(2, "c")},
+	}
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = mergeGroupsByChecksum(groups)
+	}
+}

backend/internal/web/duplicates_buckets.go

@@ -0,0 +1,55 @@
+package web
+
+import (
+	"path/filepath"
+	"strings"
+
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
+)
+
+// typeBucketKey returns the MIME/extension bucket used inside a fixed-size group.
+// When the MIME type already implies a single on-disk format, extension is omitted
+// as a redundant pre-filter. Otherwise a normalized lowercase extension is appended.
+//
+// JPEG aliases: ".jpg", ".jpeg", and ".jpe" normalize to "jpg" so differently named
+// JPEGs stay in one bucket without splitting the MIME-implied image/jpeg group.
+func typeBucketKey(file *iteminfo.FileInfo) string {
+	mime := file.Type
+	if mimeImpliesExtension(mime) {
+		return mime
+	}
+	return mime + "\x1f" + normalizedFileExtension(file.Name)
+}
+
+func mimeImpliesExtension(mime string) bool {
+	switch mime {
+	case "image/jpeg", "image/png", "image/gif", "image/webp", "image/bmp", "image/tiff",
+		"video/mp4", "video/webm", "video/quicktime", "video/x-msvideo",
+		"audio/mpeg", "audio/wav", "audio/flac", "audio/ogg",
+		"application/pdf", "application/zip", "application/gzip",
+		"text/plain", "text/html", "text/css", "application/json":
+		return true
+	default:
+		return false
+	}
+}
+
+// normalizedFileExtension returns a lowercase extension without the dot, folding JPEG aliases to "jpg".
+func normalizedFileExtension(name string) string {
+	ext := strings.ToLower(strings.TrimPrefix(filepath.Ext(name), "."))
+	switch ext {
+	case "jpeg", "jpe":
+		return "jpg"
+	default:
+		return ext
+	}
+}
+
+func groupFilesByTypeBucket(files []*iteminfo.FileInfo) map[string][]*iteminfo.FileInfo {
+	grouped := make(map[string][]*iteminfo.FileInfo)
+	for _, file := range files {
+		key := typeBucketKey(file)
+		grouped[key] = append(grouped[key], file)
+	}
+	return grouped
+}

backend/internal/web/duplicates_buckets_test.go

@@ -0,0 +1,23 @@
+package web
+
+import (
+	"testing"
+
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
+)
+
+func TestTypeBucketKeyJPEGAliases(t *testing.T) {
+	jpg := &iteminfo.FileInfo{ItemInfo: iteminfo.ItemInfo{Name: "a.jpg", Type: "image/jpeg"}}
+	jpeg := &iteminfo.FileInfo{ItemInfo: iteminfo.ItemInfo{Name: "b.jpeg", Type: "image/jpeg"}}
+	if typeBucketKey(jpg) != typeBucketKey(jpeg) {
+		t.Fatalf("jpg and jpeg should share bucket: %q vs %q", typeBucketKey(jpg), typeBucketKey(jpeg))
+	}
+}
+
+func TestTypeBucketKeyAmbiguousMIMEUsesExtension(t *testing.T) {
+	a := &iteminfo.FileInfo{ItemInfo: iteminfo.ItemInfo{Name: "a.bin", Type: "application/octet-stream"}}
+	b := &iteminfo.FileInfo{ItemInfo: iteminfo.ItemInfo{Name: "b.dat", Type: "application/octet-stream"}}
+	if typeBucketKey(a) == typeBucketKey(b) {
+		t.Fatal("different extensions should not share bucket for ambiguous MIME")
+	}
+}

backend/internal/web/duplicates_cancel_test.go

@@ -0,0 +1,60 @@
+package web
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+func TestChecksumCacheRejectsExpiredDigest(t *testing.T) {
+	key := checksumCacheKey{
+		sourcePath: "/src",
+		filePath:   "/file-a",
+		size:       4096,
+		modTime:    42,
+		kind:       checksumKindHeader,
+	}
+	encoded := checksumCacheKeyString(key)
+	checksumTypedCache.SetWithExp(encoded, "digest", time.Millisecond)
+	time.Sleep(5 * time.Millisecond)
+	if _, ok := getChecksumFromCache(key); ok {
+		t.Fatal("expired digest should not be returned")
+	}
+}
+
+func TestChecksumCacheMissAfterFileIdentityChange(t *testing.T) {
+	modA := checksumCacheKey{
+		sourcePath: "/src",
+		filePath:   "/file-a",
+		size:       4096,
+		modTime:    100,
+		kind:       checksumKindHeader,
+	}
+	modB := modA
+	modB.modTime = 200
+
+	checksumTypedCache.Set(checksumCacheKeyString(modA), "digest-a")
+	if _, ok := getChecksumFromCache(modB); ok {
+		t.Fatal("modified file identity must not hit the prior cache key")
+	}
+}
+
+func TestCacheDuplicateResponseSkipsCanceledContext(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	cacheKey := "cancel-test:" + time.Now().Format(time.RFC3339Nano)
+	cacheDuplicateResponse(ctx, cacheKey, duplicateResponse{
+		Groups: []duplicateGroup{{Size: 1, Count: 2}},
+	})
+	if _, ok := duplicateResultsCache.Get(cacheKey); ok {
+		t.Fatal("canceled context must not cache duplicate results")
+	}
+
+	cacheDuplicateResponse(context.Background(), cacheKey, duplicateResponse{
+		Groups: []duplicateGroup{{Size: 2, Count: 2}},
+	})
+	if _, ok := duplicateResultsCache.Get(cacheKey); !ok {
+		t.Fatal("active context should cache duplicate results")
+	}
+}

backend/internal/web/duplicates_checksum.go

@@ -0,0 +1,264 @@
+package web
+
+import (
+	"context"
+	"encoding/hex"
+	"fmt"
+	"hash"
+	"io"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	"github.com/cespare/xxhash/v2"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing"
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
+	"github.com/gtsteffaniak/go-cache/cache"
+)
+
+const (
+	checksumSampleSize = 8192
+	checksumSmallFile  = 16384
+	checksumCacheTTL   = time.Hour
+)
+
+type checksumSampleKind uint8
+
+const (
+	checksumKindHeader checksumSampleKind = iota
+	checksumKindMiddle
+)
+
+// checksumCacheKey identifies a cached sample digest for a file snapshot.
+type checksumCacheKey struct {
+	sourcePath string
+	filePath   string
+	size       int64
+	modTime    int64
+	kind       checksumSampleKind
+}
+
+var (
+	// checksumTypedCache stores sample digests keyed by string-encoded checksumCacheKey.
+	// The go-cache backend sweeps expired entries on an hourly ticker, so stale keys from
+	// renamed/deleted/modified files are evicted without a lookup — unlike a bare sync.Map
+	// which would grow without bound. Cleanup interval is the second arg (1h, matching TTL).
+	checksumTypedCache = cache.NewCache[string](checksumCacheTTL, checksumCacheTTL)
+	checksumBufPool    = sync.Pool{
+		New: func() any {
+			buf := make([]byte, checksumSampleSize)
+			return &buf
+		},
+	}
+)
+
+type fileSampleDigests struct {
+	header string
+	middle string
+}
+
+func duplicateChecksumHasher() hash.Hash {
+	return xxhash.New()
+}
+
+func digestHex(h hash.Hash) string {
+	sum := h.Sum(nil)
+	dst := make([]byte, hex.EncodedLen(len(sum)))
+	hex.Encode(dst, sum)
+	return string(dst)
+}
+
+// checksumCacheKeyString encodes a typed cache key as a single string so it can
+// be stored in the TTL-sweeping go-cache. Length prefixes keep fields unambiguous.
+func checksumCacheKeyString(key checksumCacheKey) string {
+	return fmt.Sprintf("%d|%d|%d|%d|%s|%s",
+		key.kind, key.size, key.modTime, len(key.sourcePath),
+		key.sourcePath, key.filePath)
+}
+
+func getChecksumFromCache(key checksumCacheKey) (string, bool) {
+	return checksumTypedCache.Get(checksumCacheKeyString(key))
+}
+
+func setChecksumCache(key checksumCacheKey, digest string) {
+	checksumTypedCache.Set(checksumCacheKeyString(key), digest)
+}
+
+func readFileSampleDigests(ctx context.Context, sourcePath, filePath string, size int64, modTime time.Time, stats *duplicateProcessingStats) (fileSampleDigests, error) {
+	headerKey := checksumCacheKey{sourcePath: sourcePath, filePath: filePath, size: size, modTime: modTime.UnixNano(), kind: checksumKindHeader}
+	middleKey := checksumCacheKey{sourcePath: sourcePath, filePath: filePath, size: size, modTime: modTime.UnixNano(), kind: checksumKindMiddle}
+
+	var out fileSampleDigests
+	if h, ok := getChecksumFromCache(headerKey); ok {
+		out.header = h
+	}
+	if m, ok := getChecksumFromCache(middleKey); ok {
+		out.middle = m
+	}
+	if out.header != "" && out.middle != "" {
+		return out, nil
+	}
+
+	if ctx.Err() != nil {
+		return fileSampleDigests{}, ctx.Err()
+	}
+	// Only count operations that actually touch disk. Cache hits are O(1) lookups
+	// and must not consume the checksum budget — otherwise a second search over
+	// the same files stalls at the limit without reading a single new byte.
+	// The budget check lives here (post-cache) so cached digests are always served.
+	if shouldStop, _ := stats.shouldStop(); shouldStop {
+		return fileSampleDigests{}, fmt.Errorf("duplicate search budget exhausted")
+	}
+
+	file, err := os.Open(filePath)
+	if err != nil {
+		return fileSampleDigests{}, err
+	}
+	defer file.Close()
+
+	// A disk read is happening — charge it against the checksum budget.
+	stats.checksumOperations++
+
+	raw := checksumBufPool.Get()
+	bufPtr, ok := raw.(*[]byte)
+	if !ok {
+		return fileSampleDigests{}, fmt.Errorf("invalid checksum buffer pool type")
+	}
+	buf := *bufPtr
+	defer checksumBufPool.Put(bufPtr)
+
+	if size <= checksumSmallFile {
+		h := duplicateChecksumHasher()
+		remain := size
+		for remain > 0 {
+			if ctx.Err() != nil {
+				return fileSampleDigests{}, ctx.Err()
+			}
+			toRead := int64(len(buf))
+			if toRead > remain {
+				toRead = remain
+			}
+			n, readErr := file.Read(buf[:toRead])
+			if n > 0 {
+				_, _ = h.Write(buf[:n])
+				remain -= int64(n)
+			}
+			if readErr == io.EOF {
+				break
+			}
+			if readErr != nil {
+				return fileSampleDigests{}, readErr
+			}
+			if n == 0 {
+				break
+			}
+		}
+		d := digestHex(h)
+		out.header = d
+		out.middle = d
+	} else if out.header == "" || out.middle == "" {
+		n, readErr := io.ReadFull(file, buf)
+		if readErr != nil && readErr != io.EOF && readErr != io.ErrUnexpectedEOF {
+			return fileSampleDigests{}, readErr
+		}
+
+		if out.header == "" {
+			h := duplicateChecksumHasher()
+			_, _ = h.Write(buf[:n])
+			out.header = digestHex(h)
+		}
+		if out.middle == "" {
+			middle := duplicateChecksumHasher()
+			_, _ = middle.Write(buf[:n])
+			middleOffset := size / 2
+			if _, err := file.Seek(middleOffset, io.SeekStart); err != nil {
+				return fileSampleDigests{}, err
+			}
+			n, readErr := io.ReadFull(file, buf)
+			if readErr != nil && readErr != io.EOF && readErr != io.ErrUnexpectedEOF {
+				return fileSampleDigests{}, readErr
+			}
+			_, _ = middle.Write(buf[:n])
+			out.middle = digestHex(middle)
+		}
+	}
+
+	if out.header != "" {
+		setChecksumCache(headerKey, out.header)
+	}
+	if out.middle != "" {
+		setChecksumCache(middleKey, out.middle)
+	}
+	return out, nil
+}
+
+func groupFilesByChecksum(ctx context.Context, files []*iteminfo.FileInfo, index *indexing.Index, fileSize int64, stats *duplicateProcessingStats) []checksumGroup {
+	if len(files) < 2 {
+		return nil
+	}
+
+	headerGroups := make(map[string][]*iteminfo.FileInfo)
+	digestByPath := make(map[string]fileSampleDigests, len(files))
+
+	for _, file := range files {
+		if ctx.Err() != nil {
+			return nil
+		}
+		// Budget checks live inside readFileSampleDigests (after the cache lookup)
+		// so cached digests still count toward grouping without consuming budget.
+		// Checking here would stall on cached files and look stuck.
+
+		if file.Size != fileSize {
+			continue
+		}
+
+		filePath := filepath.Join(index.Path, file.Path)
+		digests, err := readFileSampleDigests(ctx, index.Path, filePath, fileSize, file.ModTime, stats)
+		if err != nil {
+			continue
+		}
+		digestByPath[file.Path] = digests
+		stats.uniqueChecksums[digests.header] = true
+		headerGroups[digests.header] = append(headerGroups[digests.header], file)
+	}
+
+	headerCandidates := make([][]*iteminfo.FileInfo, 0)
+	for _, group := range headerGroups {
+		if len(group) >= 2 {
+			headerCandidates = append(headerCandidates, group)
+		}
+	}
+	if len(headerCandidates) == 0 {
+		return nil
+	}
+
+	middleGroups := make(map[string][]*iteminfo.FileInfo)
+	for _, headerGroup := range headerCandidates {
+		for _, file := range headerGroup {
+			if ctx.Err() != nil {
+				return nil
+			}
+			if shouldStop, _ := stats.shouldStop(); shouldStop {
+				break
+			}
+			digests := digestByPath[file.Path]
+			if digests.middle == "" {
+				continue
+			}
+			stats.uniqueChecksums[digests.middle] = true
+			middleGroups[digests.middle] = append(middleGroups[digests.middle], file)
+		}
+	}
+
+	groups := make([]checksumGroup, 0, len(middleGroups))
+	for checksum, group := range middleGroups {
+		if len(group) >= 2 {
+			groups = append(groups, checksumGroup{
+				Files:    group,
+				Checksum: checksum,
+			})
+		}
+	}
+	return groups
+}

backend/internal/web/duplicates_checksum_test.go

@@ -0,0 +1,116 @@
+package web
+
+import (
+	"context"
+	"crypto/md5"
+	"encoding/hex"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/cespare/xxhash/v2"
+)
+
+func TestReadFileSampleDigestsSmallFileUsesWholeFile(t *testing.T) {
+	dir := t.TempDir()
+	data := make([]byte, 12_000)
+	path := filepath.Join(dir, "small.bin")
+	if err := os.WriteFile(path, data, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	stats := &duplicateProcessingStats{startTime: time.Now()}
+	d, err := readFileSampleDigests(context.Background(), dir, path, int64(len(data)), time.Now(), stats)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if d.header != d.middle {
+		t.Fatalf("small file header and middle digest should match: %q %q", d.header, d.middle)
+	}
+}
+
+func TestHasherUsesXXHash(t *testing.T) {
+	if _, ok := any(duplicateChecksumHasher()).(*xxhash.Digest); !ok {
+		t.Fatal("expected xxhash digest")
+	}
+}
+
+func TestCachedDigestsDoNotConsumeChecksumBudget(t *testing.T) {
+	dir := t.TempDir()
+	dataA := make([]byte, 65536)
+	for i := range dataA {
+		dataA[i] = byte(i % 251)
+	}
+	// Use a distinct payload so its digests differ from other tests' files.
+	pathA := filepath.Join(dir, "budget-a.bin")
+	pathB := filepath.Join(dir, "budget-b.bin")
+	if err := os.WriteFile(pathA, dataA, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(pathB, dataA, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	modTime := time.Date(2026, 11, 10, 0, 0, 0, 0, time.UTC)
+
+	// Prime the cache with one op-worth of budget.
+	prime := &duplicateProcessingStats{startTime: time.Now(), uniqueChecksums: map[string]bool{}}
+	d1, err := readFileSampleDigests(context.Background(), dir, pathA, int64(len(dataA)), modTime, prime)
+	if err != nil {
+		t.Fatal(err)
+	}
+	d2, err := readFileSampleDigests(context.Background(), dir, pathB, int64(len(dataA)), modTime, prime)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if d1.header != d2.header || d1.middle != d2.middle {
+		t.Fatal("expected equal digests for identical files")
+	}
+	if prime.checksumOperations != 2 {
+		t.Fatalf("expected 2 disk operations for two cache-miss reads, got %d", prime.checksumOperations)
+	}
+
+	// Exhaust the budget: any further uncached file should be refused.
+	prime.checksumOperations = maxChecksumOperations
+	uncached := filepath.Join(dir, "budget-c.bin")
+	if err = os.WriteFile(uncached, dataA, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if _, err = readFileSampleDigests(context.Background(), dir, uncached, int64(len(dataA)), modTime, prime); err == nil {
+		t.Fatal("expected budget-exhausted error for uncached file")
+	}
+
+	// But the cached files must still be served, for free.
+	cached, err := readFileSampleDigests(context.Background(), dir, pathA, int64(len(dataA)), modTime, prime)
+	if err != nil {
+		t.Fatalf("cached digest should be served despite exhausted budget: %v", err)
+	}
+	if cached.header != d1.header || cached.middle != d1.middle {
+		t.Fatal("cached digest mismatch")
+	}
+	if prime.checksumOperations != maxChecksumOperations {
+		t.Fatalf("cached digest must not consume budget, got %d", prime.checksumOperations)
+	}
+}
+
+func BenchmarkDuplicateHashers(b *testing.B) {
+	data := make([]byte, checksumSampleSize)
+	for i := range data {
+		data[i] = byte(i)
+	}
+	b.Run("md5", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			h := md5.New()
+			_, _ = h.Write(data)
+			hex.EncodeToString(h.Sum(nil))
+		}
+	})
+	b.Run("xxhash", func(b *testing.B) {
+		b.ReportAllocs()
+		for i := 0; i < b.N; i++ {
+			h := xxhash.New()
+			_, _ = h.Write(data)
+			hex.EncodeToString(h.Sum(nil))
+		}
+	})
+}

backend/internal/web/duplicates_merge.go

@@ -0,0 +1,111 @@
+package web
+
+import (
+	"cmp"
+	"slices"
+	"strings"
+
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing"
+)
+
+type mergeGroupKey struct {
+	size   int64
+	digest string
+}
+
+// mergeGroupsByChecksum merges groups that share the same size and sample digest.
+func mergeGroupsByChecksum(groups []duplicateGroupWithChecksums) []duplicateGroupWithChecksums {
+	if len(groups) <= 1 {
+		return groups
+	}
+
+	keyToGroups := make(map[mergeGroupKey][]int)
+	for i, group := range groups {
+		if group.Checksum == "" {
+			continue
+		}
+		key := mergeGroupKey{size: group.Size, digest: group.Checksum}
+		keyToGroups[key] = append(keyToGroups[key], i)
+	}
+
+	parent := make([]int, len(groups))
+	for i := range parent {
+		parent[i] = i
+	}
+
+	var find func(int) int
+	find = func(x int) int {
+		if parent[x] != x {
+			parent[x] = find(parent[x])
+		}
+		return parent[x]
+	}
+
+	union := func(x, y int) {
+		px, py := find(x), find(y)
+		if px != py {
+			parent[px] = py
+		}
+	}
+
+	for _, indices := range keyToGroups {
+		for i := 1; i < len(indices); i++ {
+			union(indices[0], indices[i])
+		}
+	}
+
+	groupsByRoot := make(map[int][]int)
+	for i := range groups {
+		root := find(i)
+		groupsByRoot[root] = append(groupsByRoot[root], i)
+	}
+
+	merged := make([]duplicateGroupWithChecksums, 0, len(groupsByRoot))
+	for _, indices := range groupsByRoot {
+		if len(indices) == 1 {
+			merged = append(merged, groups[indices[0]])
+			continue
+		}
+
+		combinedFiles := make([]*indexing.SearchResult, 0)
+		var combinedSize int64
+		var combinedChecksum string
+
+		for _, idx := range indices {
+			group := groups[idx]
+			combinedFiles = append(combinedFiles, group.Files...)
+			if combinedChecksum == "" {
+				combinedChecksum = group.Checksum
+			}
+			if combinedSize == 0 {
+				combinedSize = group.Size
+			}
+		}
+
+		if len(combinedFiles) >= 2 {
+			slices.SortFunc(combinedFiles, func(a, b *indexing.SearchResult) int {
+				return strings.Compare(a.Path, b.Path)
+			})
+			merged = append(merged, duplicateGroupWithChecksums{
+				Size:     combinedSize,
+				Files:    combinedFiles,
+				Checksum: combinedChecksum,
+			})
+		}
+	}
+
+	slices.SortFunc(merged, func(a, b duplicateGroupWithChecksums) int {
+		if c := cmp.Compare(b.Size, a.Size); c != 0 {
+			return c
+		}
+		if c := strings.Compare(a.Checksum, b.Checksum); c != 0 {
+			return c
+		}
+		if len(a.Files) == 0 || len(b.Files) == 0 {
+			return 0
+		}
+		return strings.Compare(a.Files[0].Path, b.Files[0].Path)
+	})
+
+	return merged
+}

backend/internal/web/duplicates_merge_test.go

@@ -0,0 +1,19 @@
+package web
+
+import (
+	"testing"
+
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing"
+)
+
+func TestMergeGroupsByChecksumUsesSizeAndDigest(t *testing.T) {
+	groups := []duplicateGroupWithChecksums{
+		{Size: 100, Checksum: "aaaa", Files: []*indexing.SearchResult{{Path: "/a"}, {Path: "/b"}}},
+		{Size: 200, Checksum: "aaaa", Files: []*indexing.SearchResult{{Path: "/c"}, {Path: "/d"}}},
+		{Size: 100, Checksum: "aaaa", Files: []*indexing.SearchResult{{Path: "/e"}, {Path: "/f"}}},
+	}
+	merged := mergeGroupsByChecksum(groups)
+	if len(merged) != 2 {
+		t.Fatalf("expected 2 merged groups, got %d", len(merged))
+	}
+}

backend/internal/web/duplicates_names.go

@@ -0,0 +1,204 @@
+package web
+
+import (
+	"context"
+	"strings"
+	"unicode"
+
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
+)
+
+const filenameSimilarityThreshold = 0.5
+
+type levenshteinRowBuf struct {
+	prev, cur []int
+}
+
+func (b *levenshteinRowBuf) ensure(width int) {
+	if cap(b.prev) < width+1 {
+		b.prev = make([]int, width+1)
+		b.cur = make([]int, width+1)
+	} else {
+		b.prev = b.prev[:width+1]
+		b.cur = b.cur[:width+1]
+	}
+}
+
+func maxEditDistanceForSimilarity(maxLen int) int {
+	return maxLen / 2
+}
+
+func filenameSimilarWithBudget(name1, name2 string, buf *levenshteinRowBuf) bool {
+	if name1 == name2 {
+		return true
+	}
+	if len(name1) == 0 || len(name2) == 0 {
+		return false
+	}
+
+	maxLen := max(len(name1), len(name2))
+	maxDist := maxEditDistanceForSimilarity(maxLen)
+	if abs(len(name1)-len(name2)) > maxDist {
+		return false
+	}
+
+	distance := boundedLevenshtein(name1, name2, maxDist, buf)
+	if distance < 0 {
+		return false
+	}
+	similarity := 1.0 - float64(distance)/float64(maxLen)
+	return similarity >= filenameSimilarityThreshold
+}
+
+func boundedLevenshtein(s1, s2 string, maxDist int, buf *levenshteinRowBuf) int {
+	n, m := len(s1), len(s2)
+	if n == 0 {
+		if m <= maxDist {
+			return m
+		}
+		return -1
+	}
+	if m == 0 {
+		if n <= maxDist {
+			return n
+		}
+		return -1
+	}
+
+	buf.ensure(m)
+	prev, cur := buf.prev, buf.cur
+
+	for j := 0; j <= m; j++ {
+		prev[j] = j
+	}
+
+	for i := 1; i <= n; i++ {
+		cur[0] = i
+		rowMin := cur[0]
+		for j := 1; j <= m; j++ {
+			cost := 0
+			if s1[i-1] != s2[j-1] {
+				cost = 1
+			}
+			del := prev[j] + 1
+			ins := cur[j-1] + 1
+			sub := prev[j-1] + cost
+			v := del
+			if ins < v {
+				v = ins
+			}
+			if sub < v {
+				v = sub
+			}
+			cur[j] = v
+			if v < rowMin {
+				rowMin = v
+			}
+		}
+		if rowMin > maxDist {
+			return -1
+		}
+		prev, cur = cur, prev
+	}
+
+	if prev[m] > maxDist {
+		return -1
+	}
+	return prev[m]
+}
+
+func groupFilesByFilename(ctx context.Context, files []*iteminfo.FileInfo, expectedSize int64, stats *duplicateProcessingStats) [][]*iteminfo.FileInfo {
+	if len(files) == 0 {
+		return nil
+	}
+
+	normalized := make([]string, len(files))
+	for i, f := range files {
+		if f.Name != "" {
+			normalized[i] = normalizeFilename(f.Name)
+		}
+	}
+
+	var rowBuf levenshteinRowBuf
+	groups := [][]*iteminfo.FileInfo{}
+	used := make(map[int]bool)
+
+	for i := 0; i < len(files); i++ {
+		if ctx.Err() != nil {
+			return groups
+		}
+		if shouldStop, _ := stats.shouldStop(); shouldStop {
+			return groups
+		}
+
+		if used[i] || files[i].Name == "" {
+			continue
+		}
+
+		group := []*iteminfo.FileInfo{files[i]}
+		used[i] = true
+		filename1 := normalized[i]
+		oversized := false
+
+		for j := i + 1; j < len(files); j++ {
+			if ctx.Err() != nil {
+				return groups
+			}
+			if shouldStop, _ := stats.shouldStop(); shouldStop {
+				return groups
+			}
+
+			if used[j] || files[j].Name == "" {
+				continue
+			}
+			if files[j].Size != expectedSize {
+				continue
+			}
+
+			if filenameSimilarWithBudget(filename1, normalized[j], &rowBuf) {
+				group = append(group, files[j])
+				used[j] = true
+				if len(group) > maxFuzzyGroupSize {
+					oversized = true
+					break
+				}
+			}
+		}
+
+		if len(group) >= 2 && !oversized {
+			groups = append(groups, group)
+		}
+	}
+
+	return groups
+}
+
+func normalizeFilename(filename string) string {
+	filename = strings.ToLower(filename)
+	if idx := strings.LastIndex(filename, "."); idx > 0 {
+		filename = filename[:idx]
+	}
+
+	var result strings.Builder
+	for _, r := range filename {
+		if unicode.IsLetter(r) || unicode.IsDigit(r) || r == ' ' || r == '-' {
+			result.WriteRune(r)
+		}
+	}
+
+	return strings.TrimSpace(result.String())
+}
+
+func abs(x int) int {
+	if x < 0 {
+		return -x
+	}
+	return x
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}

backend/internal/web/duplicates_names_test.go

@@ -0,0 +1,140 @@
+package web
+
+import (
+	"context"
+	"math/rand"
+	"strings"
+	"testing"
+	"testing/quick"
+	"time"
+	"unicode"
+
+	"github.com/gtsteffaniak/filebrowser/backend/pkg/indexing/iteminfo"
+)
+
+func legacyFilenamesSimilar(name1, name2 string) bool {
+	if name1 == name2 {
+		return true
+	}
+	if len(name1) == 0 || len(name2) == 0 {
+		return false
+	}
+	distance := legacyLevenshtein(name1, name2)
+	maxLen := max(len(name1), len(name2))
+	similarity := 1.0 - float64(distance)/float64(maxLen)
+	return similarity >= 0.5
+}
+
+func legacyLevenshtein(s1, s2 string) int {
+	if len(s1) == 0 {
+		return len(s2)
+	}
+	if len(s2) == 0 {
+		return len(s1)
+	}
+	matrix := make([][]int, len(s1)+1)
+	for i := range matrix {
+		matrix[i] = make([]int, len(s2)+1)
+	}
+	for i := 0; i <= len(s1); i++ {
+		matrix[i][0] = i
+	}
+	for j := 0; j <= len(s2); j++ {
+		matrix[0][j] = j
+	}
+	for i := 1; i <= len(s1); i++ {
+		for j := 1; j <= len(s2); j++ {
+			cost := 0
+			if s1[i-1] != s2[j-1] {
+				cost = 1
+			}
+			del := matrix[i-1][j] + 1
+			ins := matrix[i][j-1] + 1
+			sub := matrix[i-1][j-1] + cost
+			v := del
+			if ins < v {
+				v = ins
+			}
+			if sub < v {
+				v = sub
+			}
+			matrix[i][j] = v
+		}
+	}
+	return matrix[len(s1)][len(s2)]
+}
+
+var filenameCorpus = []string{
+	"photo", "photo_1", "photo-copy", "IMG_0042", "img 0042",
+	"vacation2023beach", "vacation2023_beach", "user_video", "video",
+	"document-final", "document_final_v2", "a", "ab", "abc", "abcd",
+	"report Q1 2024", "report-q1-2024", "my@file#name", "myfilename",
+	"summer-holiday", "summer holiday", "winter-holiday",
+}
+
+func TestFilenameSimilarMatchesLegacyOnCorpus(t *testing.T) {
+	names := append([]string{}, filenameCorpus...)
+	for i := 0; i < 50; i++ {
+		names = append(names, randomNormalizedName(5+corpusRand.Intn(40)))
+	}
+
+	var buf levenshteinRowBuf
+	for _, a := range names {
+		a = normalizeFilename(a + ".jpg")
+		for _, b := range names {
+			b = normalizeFilename(b + ".png")
+			if legacyFilenamesSimilar(a, b) != filenameSimilarWithBudget(a, b, &buf) {
+				t.Fatalf("mismatch %q vs %q", a, b)
+			}
+		}
+	}
+}
+
+func TestFilenameSimilarMatchesLegacyQuick(t *testing.T) {
+	var buf levenshteinRowBuf
+	if err := quick.Check(func(a, b string) bool {
+		a = trimQuickString(a, 48)
+		b = trimQuickString(b, 48)
+		return legacyFilenamesSimilar(a, b) == filenameSimilarWithBudget(a, b, &buf)
+	}, nil); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func trimQuickString(s string, max int) string {
+	if len(s) > max {
+		s = s[:max]
+	}
+	var b strings.Builder
+	for _, r := range s {
+		if unicode.IsLetter(r) || unicode.IsDigit(r) || r == ' ' || r == '-' {
+			b.WriteRune(r)
+		}
+	}
+	return strings.ToLower(strings.TrimSpace(b.String()))
+}
+
+func randomNormalizedName(n int) string {
+	const alphabet = "abcdefghijklmnopqrstuvwxyz0123456789 -"
+	b := make([]byte, n)
+	for i := range b {
+		b[i] = alphabet[corpusRand.Intn(len(alphabet))]
+	}
+	return string(b)
+}
+
+func TestGroupFilesByFilenameOversizedExcluded(t *testing.T) {
+	ctx := context.Background()
+	stats := &duplicateProcessingStats{startTime: time.Now()}
+	files := make([]*iteminfo.FileInfo, 12)
+	for i := range files {
+		files[i] = &iteminfo.FileInfo{
+			ItemInfo: iteminfo.ItemInfo{Name: "photo.jpg", Size: 100},
+		}
+	}
+	if len(groupFilesByFilename(ctx, files, 100, stats)) != 0 {
+		t.Fatal("expected no groups for oversized cluster")
+	}
+}
+
+var corpusRand = rand.New(rand.NewSource(42))

backend/internal/web/fileWatcher.go

@@ -187,10 +187,10 @@ func fileWatchHandler(w http.ResponseWriter, r *http.Request, d *Context) (int,
 		return http.StatusForbidden, fmt.Errorf("access denied to file")
 	}
 
-	// Get real file path
-	realPath, _, err := idx.GetRealPath(scopePath)
+	// Get real file path (scoped) and enforce ACL on the resolved target
+	realPath, _, err := idx.GetRealPathScoped(userScope, scopePath)
 	if err != nil {
-		return http.StatusNotFound, fmt.Errorf("file not found: %v", err)
+		return realPathErrStatus(err), err
 	}
 
 	// Get file/directory info
@@ -198,6 +198,9 @@ func fileWatchHandler(w http.ResponseWriter, r *http.Request, d *Context) (int,
 	if err != nil {
 		return http.StatusNotFound, fmt.Errorf("path not found: %v", err)
 	}
+	if !state.AccessPermittedAtRealPath(idx, d.User.Username, realPath, info.IsDir()) {
+		return http.StatusForbidden, fmt.Errorf("access denied to file")
+	}
 
 	// Get MIME type from the index if available
 	mimeType := "application/octet-stream"
@@ -335,10 +338,10 @@ func fileWatchSSEHandler(w http.ResponseWriter, r *http.Request, d *Context) (in
 		return http.StatusForbidden, fmt.Errorf("access denied to file")
 	}
 
-	// Get real file path
-	realPath, _, err := idx.GetRealPath(scopePath)
+	// Get real file path (scoped) and enforce ACL on the resolved target
+	realPath, _, err := idx.GetRealPathScoped(userScope, scopePath)
 	if err != nil {
-		return http.StatusNotFound, fmt.Errorf("path not found: %v", err)
+		return realPathErrStatus(err), err
 	}
 
 	// Get file/directory info
@@ -346,6 +349,9 @@ func fileWatchSSEHandler(w http.ResponseWriter, r *http.Request, d *Context) (in
 	if err != nil {
 		return http.StatusNotFound, fmt.Errorf("path not found: %v", err)
 	}
+	if !state.AccessPermittedAtRealPath(idx, d.User.Username, realPath, info.IsDir()) {
+		return http.StatusForbidden, fmt.Errorf("access denied to file")
+	}
 
 	// Set up SSE headers
 	w.Header().Set("Content-Type", "text/event-stream")

backend/internal/web/http_preview_test.go

@@ -22,3 +22,37 @@ func TestErrToStatusWrapsUnsupportedPreviewFormat(t *testing.T) {
 		t.Fatalf("ErrToStatus() = %d, want %d", status, http.StatusUnsupportedMediaType)
 	}
 }
+
+func TestIsViewerOriginalPreview(t *testing.T) {
+	tests := []struct {
+		name     string
+		size     string
+		file     string
+		fileType string
+		docs     bool // the server can render documents to an image
+		want     bool
+	}{
+		{"Fuji RAW viewer", "original", "DSCF0308.RAF", "image/x-fuji-raf", false, true},
+		{"Canon RAW viewer", "original", "IMG_0001.CR3", "image/x-canon-cr3", false, true},
+		{"Adobe DNG viewer", "original", "a.dng", "image/x-adobe-dng", false, true},
+		{"HEIC viewer", "original", "a.heic", "image/heic", false, true},
+		{"HEIF viewer", "original", "a.heif", "image/heif", false, true},
+		{"rendered document viewer", "original", "a.docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document", true, true},
+		{"documents need the server to be able to render them", "original", "a.docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document", false, false},
+		{"RAW thumbnail stays disabled", "small", "DSCF0308.RAF", "image/x-fuji-raf", true, false},
+		{"RAW large stays disabled", "large", "DSCF0308.RAF", "image/x-fuji-raf", true, false},
+		{"no size stays disabled", "", "DSCF0308.RAF", "image/x-fuji-raf", true, false},
+		{"video poster stays disabled", "original", "a.mov", "video/quicktime", true, false},
+		{"audio cover stays disabled", "original", "a.mp3", "audio/mpeg", true, false},
+		{"JPEG is opened directly, not through previews", "original", "a.jpg", "image/jpeg", true, false},
+		{"PDF is opened directly, not through previews", "original", "a.pdf", "application/pdf", true, false},
+		{"text stays disabled", "original", "a.txt", "text/plain", true, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := isViewerOriginalPreview(tt.size, tt.file, tt.fileType, tt.docs); got != tt.want {
+				t.Fatalf("isViewerOriginalPreview(%q, %q, %q, %v) = %v, want %v", tt.size, tt.file, tt.fileType, tt.docs, got, tt.want)
+			}
+		})
+	}
+}