💭 I'm looking at a diff that changes how git numstat is handled—combining unstaged and staged changes into a single diff HEAD --numstat call. This is a behavioral shift, but it's not related to Effect service conventions, so the linter check shouldn't flag it. Let me verify the surrounding code to make sure no convention violations were introduced. Looking at the change discipline guidelines, this PR modifies backend behavior around numstat computation without adding corresponding tests, which seems like it could be a concrete violation. The instructions are pretty clear that behavioral changes should have focused tests, though I'm wondering how strictly to apply that convention here. Let me look for existing tests around statusDetails numstat to see if there's already coverage that might need updating. This is a behavior fix addressing double-counting when files are both staged and unstaged, but no test was added. The conventions require focused tests when backend behavior changes, which is a legitimate finding here since GitVcsDriverCore is an Effect service implementation being refactored. I'm weighing whether to fail the check—it defaults to failure unless there are no findings, so I need to decide if this missing test is significant enough to warrant that outcome. The instruction is explicit: "If backend behavior changes, require focused tests." The PR modifies backend behavior in statusDetails by merging numstat, yet there are no test changes in the diff at all. That's a defensible violation. Let me check the existing tests around that area to see if there's already a numstat-related test I could reference. I need to flag that the PR is missing a focused test for the behavior change—specifically, a case where a file is both staged and modified in the working tree, since the new approach using git diff HEAD will handle this differently than before. There's also a potential regression to watch for since git diff HEAD --numstat won't capture untracked files. So runGitStdout without allowNonZeroExit throws a GitCommandError when there's no commit history, which means git diff HEAD --numstat fails in an unborn HEAD state. This breaks statusDetails entirely, whereas the previous implementation handled both diff --numstat and diff --cached --numstat gracefully. That's a regression I need to flag under the requirement for focused tests when backend behavior changes. I'll add an inline review.

1. modify_pr — Effect service conventions review: one finding — a backend behavior change in GitVcsDriverCore.statusDetails lands without focused test coverage.