feat: Add post-hook support for start and checkout commands

[sotarok]

Summary

• Add configurable post_start_hook and post_checkout_hook options to .gwrc
• Hook commands are executed via sh -c with environment variables (GW_WORKTREE_PATH, GW_BRANCH_NAME, GW_REPO_NAME, GW_COMMAND)
• Enables integration with tmux, iTerm2, or any custom workflow without hardcoding terminal-specific behavior
• Include example hook scripts in examples/hooks/ for tmux and iTerm2

Inspired by #20 (thanks @pnikonowicz).

Closes #20

Test plan

• make check passes (lint + all tests)
• Manual test: post_start_hook = echo ... fires after gw start
• Manual test: tmux new-window hook works
• Manual test: iTerm2 new-tab hook works
• Hook failure does not block command execution
• Backward compatible: no hooks configured = existing behavior unchanged

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.68%. Comparing base (f4d53dc) to head (d3c718e).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #22      +/-   ##
==========================================
+ Coverage   88.37%   88.68%   +0.30%     
==========================================
  Files          29       30       +1     
  Lines        1832     1882      +50     
==========================================
+ Hits         1619     1669      +50     
  Misses        173      173              
  Partials       40       40              

Flag	Coverage Δ
unittests	88.68% <100.00%> (+0.30%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
cmd/command_checkout.go	82.07% <100.00%> (+1.46%)	⬆️
cmd/command_start.go	76.66% <100.00%> (+4.66%)	⬆️
internal/config/config.go	91.93% <100.00%> (+1.19%)	⬆️
internal/hook/hook.go	100.00% <100.00%> (ø)

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[claude]

PR Review: feat/post-hooks

This is a clean, well-structured addition. The hook abstraction is minimal and correct, test coverage is solid, and the failure-as-warning behaviour is exactly right. A few issues worth addressing before merging.

Bug: Stale comment implies end hook support

In internal/hook/hook.go line 15, the comment says // "start", "checkout", or "end" but no end hook is wired up in this PR. This will confuse users. Either remove "or end" from the comment, or add a TODO clarifying it is planned.

Inconsistency: worktreePath vs absolutePath for GW_WORKTREE_PATH

command_checkout.go explicitly resolves to an absolute path before passing it to the hook (absolutePath, err := filepath.Abs(worktreePath)), but command_start.go passes worktreePath directly. In practice this works because git.CreateWorktree() builds the path from git rev-parse --show-toplevel (which is absolute), but it relies on an undocumented implementation detail. The README promises an absolute path, so enforce it explicitly with filepath.Abs the same way checkout does.

Nit: Unnecessary intermediate variable

command_start.go line 115: repoNameForHook := repoName is redundant. Use repoName directly.

Gap: Hooks can't be configured via the interactive editor

The test comment acknowledges this: // Test setting post_start_hook (not supported via SetConfigItem, it's bool-only). Since SetConfigItem only handles booleans, the interactive config editor cannot set hook values. The docs should explicitly note that users must edit ~/.gwrc by hand for these fields.

No execution timeout

A misbehaving hook that blocks on input will hang gw indefinitely. Consider exec.CommandContext with a 30-second timeout so users get a clear error instead of a silent hang.

Security note: example script path injection

In examples/hooks/iterm2-new-tab.sh, GW_WORKTREE_PATH is embedded inside single quotes in AppleScript: write text "cd '${GW_WORKTREE_PATH}' && clear". A path containing a single quote will break the script. The tmux example is safe. Consider documenting this limitation in the example.

What is working well

• The internal/hook package is clean and well-tested (7 tests covering empty command, all env vars, failure, stderr, and parent env inheritance)
• Hook failures printing as warnings without blocking is the correct design
• append(os.Environ(), envToSlice(env)...) correctly inherits the parent environment
• Config load/save round-trip handles values containing = signs correctly
• CHANGELOG and README are both updated

The core feature is solid. The absolutePath inconsistency and stale end comment are the most important fixes before merging.

[claude]

Code Review: feat: Add post-hook support for start and checkout commands

Overall this is a clean, well-scoped feature with solid test coverage. The design is backward-compatible and the hook-failure-as-warning behavior is the right call. A few issues worth addressing before merging:

---

Bug: Inconsistent WorktreePath between start and checkout

command_checkout.go explicitly resolves to an absolute path before passing it to the hook:

// command_checkout.go
absolutePath, err := filepath.Abs(worktreePath)
...
hookEnv := hook.Env{
    WorktreePath: absolutePath,   // ✅ absolute

But command_start.go passes worktreePath directly without resolution:

// command_start.go
hookEnv := hook.Env{
    WorktreePath: worktreePath,   // ⚠️ potentially relative

If git.CreateWorktree returns a relative path, GW_WORKTREE_PATH will be relative in the start hook, breaking integrations like tmux new-window -c "$GW_WORKTREE_PATH". Should use filepath.Abs(worktreePath) here for consistency.

---

Minor: Unnecessary variable alias

In command_start.go:

repoNameForHook := repoName
hookEnv := hook.Env{
    RepoName: repoNameForHook,

repoNameForHook is an alias that adds no clarity. Use repoName directly.

---

Misleading comment in hook.go

// Env holds environment variables passed to hook commands
type Env struct {
    ...
    Command string // "start", "checkout", or "end"
}

end hooks are not implemented — this comment will confuse future readers. Change to // "start" or "checkout" or remove the value examples.

---

Potential issue: Hook values with = in config parsing

The .gwrc parser appears to split on the first =. The test case "hook with equals sign in value" validates this works for env GW_EXTRA=1 my-script. However, the Save() method formats hook values without quoting:

hookLines += fmt.Sprintf("post_start_hook = %s\n", c.PostStartHook)

If a user sets a hook with leading/trailing whitespace or a value that starts with =, it could round-trip incorrectly. This may be an acceptable limitation but worth a comment or a note in the README.

---

Security note: paths with special characters in example scripts

The iTerm2 example hook script uses single-quoted paths in AppleScript:

write text "cd '${GW_WORKTREE_PATH}' && clear"

If GW_WORKTREE_PATH contains a single quote (e.g., /Users/it's-me/work/repo-123), the AppleScript will break. The tmux example is fine since tmux handles this via -c. Worth adding a comment in iterm2-new-tab.sh about this limitation.

---

No hook timeout

Hooks run synchronously with no timeout. A misbehaving hook (e.g., a script waiting for input) will block gw indefinitely. Not a blocker, but worth a note in the README warning users, or a future post_hook_timeout config option.

---

Test coverage: Good

The test suite is comprehensive:

• internal/hook/hook_test.go covers empty command, env vars, failure, stderr, and env inheritance
• cmd/command_test.go covers success and failure cases for both start and checkout
• internal/config/config_test.go covers load, save, round-trip, and default values

The comment // Test setting post_start_hook (not supported via SetConfigItem, it's bool-only) at line ~546 of config_test.go documents a gap worth a follow-up — it may be useful to support SetConfigItem for string fields so users can configure hooks via gw config set.

---

Summary

Issue	Severity
worktreePath not resolved to absolute in start hook	Bug
Misleading // "end" comment in hook.go	Minor
repoNameForHook unnecessary alias	Nit
iTerm2 script breaks on paths with single quotes	Minor
No hook timeout	Design consideration

The path inconsistency is the one concrete bug — everything else is polish. Great feature overall.

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