fix(hooks): guard-git.sh branch validation uses the real push target, not the hook's own cwd (#2386)

[carlos-alm]

Summary

guard-git.sh's branch-name validator fell back to the hook process's own ambient cwd whenever it couldn't parse a working directory out of the command string (git -C <dir> or cd <dir> &&). A bare git push that relies on the Bash tool's persistent cwd from an earlier, separate tool call matches neither shape, so work_dir was empty and the code substituted the hook's own cwd — the session project root, not the repo actually being pushed to. For a subagent pushing to a different repository, this validated an unrelated repo's branch and denied a perfectly valid push, showing the operator a branch name that appeared nowhere in the command they ran.

Root cause & fix

Every PreToolUse hook payload carries a top-level cwd field — the Bash tool's actual working directory for that specific call — completely independent of whatever cd/-C text happens to appear in the command string. guard-git.sh was never reading it.

• guard-git.sh now extracts this field as HOOK_CWD and uses it as validate_branch_name's fallback (after the existing -C/cd detection, which still takes precedence when present).
• When even HOOK_CWD isn't usable (missing or not a directory), the hook now declines to validate (allows) rather than guessing against its own ambient cwd — a false deny on valid work is worse than a missed check here, per the issue's own reasoning.
• The deny message now names the resolved working directory alongside the branch, so a wrong resolution is obvious immediately.
• The error text's pattern list now includes dependabot/, matching what the regex already permitted (a display-only inconsistency the issue flagged).
• Kept .claude/hooks/guard-git.sh and docs/examples/claude-code-hooks/guard-git.sh byte-identical, as enforced by the existing tests/unit/hook-guard-git-clean.test.ts sync check.

Verification

• bash -n / shellcheck: clean
• New test file tests/unit/hook-guard-git-branch-validation.test.ts (5 tests) reproduces the issue's exact scenario — two real temp git repos, one on an invalid-pattern branch (simulating the orchestrator's own worktree branch) and one on a valid branch (the subagent's actual target), with the hook's payload cwd and its actual process cwd set independently to prove the fix reads the right one. Verified these tests fail against the pre-fix hook (4/5 failed) before confirming they pass against the fix (5/5), and re-ran with the fix restored (5/5 pass) — not tautological.
• npx vitest run tests/unit/hook-guard-git-branch-validation.test.ts tests/unit/hook-guard-git-clean.test.ts: 47/47 pass (including the byte-identical docs-sync check)
• npm run lint: pass

Also filed

• chore(hooks): guard-git.sh's commit edit-log check has the same unresolved-cwd gap as #2386's branch validation #2526 — the commit-validation section (edit-log check) further down in the same file uses the identical detect_work_dir helper and has a milder version of the same gap (silently skips rather than falsely denies); split out as a separate, distinct fix rather than bundled here

Closes #2386

[greptile-apps]

Greptile Summary

The PR corrects branch validation for bare push and PR commands by resolving the repository from the PreToolUse payload’s cwd rather than the hook process’s ambient directory.

• Adds payload cwd extraction and uses it as the branch-resolution fallback.
• Declines validation when no repository can be resolved and improves denial diagnostics.
• Keeps the live and documented hooks synchronized and adds focused regression coverage.

Confidence Score: 5/5

The PR appears safe to merge with no actionable changed-code defects identified.

The updated fallback resolves bare commands against the payload cwd, preserves explicit target precedence, avoids consulting an unrelated ambient repository, and is covered by focused regression tests.

Important Files Changed

Filename	Overview
.claude/hooks/guard-git.sh	Reads the command’s payload cwd, uses it for branch resolution when no explicit target exists, and fails open when resolution is impossible.
docs/examples/claude-code-hooks/guard-git.sh	Mirrors the live hook changes to preserve the documented-hook synchronization contract.
tests/unit/hook-guard-git-branch-validation.test.ts	Adds regression tests separating the hook process cwd from the command payload cwd and covering precedence, denial diagnostics, and unresolved targets.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  Command["Bash PreToolUse command"] --> Explicit{"Explicit git -C or cd target?"}
  Explicit -->|Yes| Target["Use explicit target"]
  Explicit -->|No| Payload{"Usable payload cwd?"}
  Payload -->|Yes| Target
  Payload -->|No| Allow["Decline validation"]
  Target --> Branch["Resolve repository HEAD branch"]
  Branch --> Pattern{"Allowed branch pattern?"}
  Pattern -->|Yes| Allow
  Pattern -->|No| Deny["Deny with branch and resolved directory"]

Loading

_{Reviews (1): Last reviewed commit: "fix(hooks): guard-git.sh branch validati..." | Re-trigger Greptile}

[github-actions]

Codegraph Impact Analysis

1 functions changed → 1 callers affected across 1 files

• validate_branch_name in docs/examples/claude-code-hooks/guard-git.sh:233 (1 transitive callers)