fix: disable external diff drivers in workspace patch generation

[ischolten]

Summary

Workspace patches generated by depot ci run could silently contain non-diff content when a user has an external diff driver configured, causing all local actions to be invisible at compile and runtime.

What was happening

git diff --binary does not disable external diff drivers (GIT_EXTERNAL_DIFF env var or diff.external in gitconfig). If a user has one configured (e.g. difft, delta, or a custom viewer), the diff output is in whatever format that tool produces instead of unified diff. This non-diff content gets uploaded to the cache, and then git apply --allow-empty silently succeeds with zero hunks applied — so .depot/ files are never materialized on disk.

What happens now

Added --no-ext-diff to the git diff command in detectPatch(), which forces git's internal diff engine regardless of user configuration.

	Released CLI	Patched CLI
GIT_EXTERNAL_DIFF set	549 bytes (rendered, not a diff)	820 bytes (valid unified diff)
Job result	FAILED — action manifest not found	PASSED

Made with Cursor

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Note

Low Risk
Single flag change to patch generation; low blast radius and primarily improves determinism of git diff output.

Overview
Fixes workspace patch generation for depot ci run by forcing Git’s built-in diff output: detectPatch() now runs git diff --binary --no-ext-diff so user-configured external diff drivers can’t replace the unified diff content that gets uploaded/applied.

^{Reviewed by Cursor Bugbot for commit a55ff39. Bugbot is set up for automated code reviews on this repo. Configure here.}