[coseto6125]

Summary

• rtk git diff --no-index a b printed nothing when the two files differed. --no-index implies --exit-code, so git exits 1 and puts the diff on stdout. The compact path in run_diff read every non-zero exit as a failure, printed only stderr and returned. On two small differing files, plain git diff --no-index printed 106 bytes; rtk git diff --no-index printed 0 bytes and exited 1. An agent behind the hook saw a failed command and no diff.
• Exit 1 with non-empty stdout now goes through the normal compact path (stat header plus compacted diff) and returns git's exit code. Exit 1 with empty stdout (--no-index on a missing file) and every other non-zero exit keep the old error path. git's stderr is forwarded in both cases, so warnings such as core.autocrlf still reach the caller.
• Exit codes are unchanged for every input: the error path already returned git's code, and the success path returned 0. Only stdout changes, for the exit-1-with-output case. run_diff has two callers, git_cmd::run (rtk git diff) and gt_cmd::run_other (gt diff), and both pass the code through. A git revert of this commit restores the old behaviour.

Related: #3257 shows the same "prints nothing" symptom with a different trigger (diff size). #1981 introduced the raw passthrough for --exit-code, which is why rtk git diff --exit-code already keeps its output.

Test plan

• cargo fmt --all && cargo clippy --all-targets && cargo test: fmt and clippy are clean. 4534 passed, 1 failed: git_log_malformed_digit_run_propagates_real_git_error, which fails the same way on develop without this change. It expects newer git's not an integer wording, and local git 2.43.0 prints not a non-negative integer.
• Manual testing: rtk git diff --no-index x.txt y.txt output inspected (stat header plus the compacted hunk, exit 1).
• New tests in tests/guard_integration_test.rs: differing files keep the diff and exit 1; identical files exit 0; a missing file surfaces git's error with empty stdout and exit 1; a core.autocrlf warning reaches stderr alongside the diff. With the fix reverted, the differing-files and warning tests fail (the diff must survive git's exit 1: "").
• Two rows in tests/rewrite_exit_code_test.rs pin the exit codes of git diff --no-index (1 for differing files, 0 for identical) across the hook rewrite.

[rtk-wshm-sync-bot]

wshm · Automated triage by AI

📊 Automated PR Analysis

🐛 Type	bug-fix
🟢 Risk	low

Summary

Fixes rtk git diff --no-index silently dropping diff output when git exits 1 (since --no-index implies --exit-code). The compact diff path now treats exit 1 with non-empty stdout as a normal diff (stat header + compacted hunk, exit code forwarded), while exit 1 with empty stdout or any other non-zero exit still goes through the old error path; stderr is forwarded in both cases.

Review Checklist

• Tests present
• Breaking change
• Docs updated

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Analyzed automatically by wshm · This is an automated analysis, not a human review.

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