[aduffeck]

Improve and harden the new push-based thumbnail generator.

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 5 complexity

Metric	Results
Complexity	5

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🟢 Coverage 88.64% diff coverage

Metric	Results
Coverage variation	Report missing for 38845621
Diff coverage	✅ 88.64% diff coverage

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Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (3884562)	Report Missing	Report Missing	Report Missing
Head commit (9c15a7e)	92415	24921	26.97%

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#3793)	44	39	88.64%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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[butonic]

nice!

[dschmidt]

Two things I'd like changed, the rest looks good to me:

1. 0x0 still escapes the new guard. freeAxis only checks the limits when resize is true. For 0x0, autoAxis returns the source size with resize == false, so the check is skipped and the image comes back at its own size, up to the 7680x7680 input limit, well past the 2048 output bound. Both axes free is still a free axis. One check in freeAxis regardless of resize covers all three paths.

2. One sentence in MIGRATION.md for the files/ mount. With the root mounted it doesn't matter whether the subfolder is files or cache, so the change itself is fine. But someone who mounted exactly <root>/files, or copied cache_dir: .../thumbnails/files from the previous migration example, now silently writes the cache next to the mount. Telling them to point WEBDAV_THUMBNAILS_CACHE_DIR at the mount covers it.

Optional: in the gif path (push.go, serveAnimation) every error from resizeGIF is mapped to 422, while the still image path uses errors.Is(err, errBoxTooLarge). Same check in both would keep a future error from resizeGIF from turning into a silent 422.