The repo keeps binary assets as Git LFS objects, but the runner stage
installed plain git. Without git-lfs, checkout writes ~130-byte pointer files
in place of the real content and reports a clean tree, so an agent reads a
text stub where an image should be and any `git lfs` subcommand fails. That
is silent corruption of a working checkout, not a visibly missing tool, which
is why it goes in beside git rather than with the optional tooling.
Confirmed in the running container: screenshots/fn-061-medieval-desktop.png
was a `version https://git-lfs.github.com/spec/v1` stub — 129 tracked files
in that state — and became a valid 753KB PNG (signature and IEND intact)
after installing git-lfs and running `git lfs pull`.
The Dockerfile manifest guard now asserts the package so it cannot be dropped.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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