Strip metadata from VHS-generated images for deterministic builds#42
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[WIP] Enhance determinism of image generation in vhs-build.sh
Strip metadata from VHS-generated images for deterministic builds
Oct 31, 2025
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Pull Request Overview
This PR introduces a metadata stripping utility to make VHS-generated PNG and GIF images deterministic. The implementation removes timestamps and other variable metadata from images, ensuring that regenerating images with unchanged content produces identical files, avoiding unnecessary git commits.
Key changes:
- Added
vhs-strip-metadata.shscript with ImageMagick support for both v6 and v7 - Integrated metadata stripping into the VHS build workflow
- Updated documentation to explain the determinism benefits
Reviewed Changes
Copilot reviewed 5 out of 67 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| docs/screencasts/bin/vhs-strip-metadata.sh | New script that strips metadata from PNG/GIF files using ImageMagick |
| docs/screencasts/README.md | Documents the new metadata stripping functionality and its purpose |
| docs/img/practical-workflows/wip-workflow.png | Binary image file (regenerated with metadata stripped) |
| docs/img/practical-workflows/branch-create.png | Binary image file (regenerated with metadata stripped) |
| SCREENSHOT_GENERATION.md | Updated documentation to include metadata stripping step |
| Makefile | Integrated metadata stripping into VHS build targets |
| .github/workflows/regenerate-vhs-images.yml | Added ImageMagick to CI dependencies |
Co-authored-by: elifarley <519940+elifarley@users.noreply.github.com>
- Created vhs-strip-metadata.sh to strip metadata from all PNG/GIF images - Added vhs-strip-metadata Makefile target - Updated vhs, vhs-build-one, and vhs-regenerate targets to call metadata stripping - Updated GitHub workflow files to install ImageMagick - Verified end-to-end: regenerated images now produce identical checksums Co-authored-by: elifarley <519940+elifarley@users.noreply.github.com> # Conflicts: # docs/commands/img/hug-COMMAND.gif # docs/commands/img/hug-branch-demo.gif # docs/commands/img/hug-commit-demo.gif # docs/commands/img/hug-h-back.png # docs/commands/img/hug-head-demo.gif # docs/commands/img/hug-la.png # docs/commands/img/hug-lc.png # docs/commands/img/hug-lla.png # docs/commands/img/hug-sl-staged.png # docs/commands/img/hug-sl-unstaged.png # docs/commands/img/hug-status-changes.gif # docs/commands/img/hug-t.png # docs/commands/img/hug-twc.png # docs/commands/img/hug-working-dir-demo.gif # docs/img/hug-for-beginners/hug-aa.png # docs/img/hug-for-beginners/hug-b-switch.png # docs/img/hug-for-beginners/hug-bc.png # docs/img/hug-for-beginners/hug-c.png # docs/img/hug-for-beginners/hug-h-back.png # docs/img/hug-for-beginners/hug-m.png # docs/img/hug-for-beginners/hug-wip.png
- Updated screencasts/README.md with vhs-strip-metadata information - Updated SCREENSHOT_GENERATION.md with metadata stripping workflow - Documented why deterministic images matter for version control Co-authored-by: elifarley <519940+elifarley@users.noreply.github.com>
- Support both ImageMagick v6 (convert) and v7 (magick) commands - Optimize find command to use single invocation with path pattern - Add CONVERT_CMD variable to dynamically select the right command - Verified end-to-end: deterministic output still works correctly Co-authored-by: elifarley <519940+elifarley@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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VHS embeds timestamps in PNG/GIF files, causing identical content to generate different hashes on each build. This creates spurious git diffs when regenerating documentation images.
Changes
New script:
docs/screencasts/bin/vhs-strip-metadata.shdocs/**/img/*.{png,gif}using ImageMagickconvert -stripconvert) and v7 (magick) commandsfind "$DOCS_DIR" -path "*/img/*" -type f \( -name "*.png" -o -name "*.gif" \)Makefile integration
vhs-strip-metadatavhs,vhs-build-one, andvhs-regenerateafter image generationCI/CD updates
imagemagickto workflow dependency installationsVerification
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