perf: stop go-git walking ignored e2e/artifacts on every agent hook

[Soph]

https://entire.io/gh/entireio/cli/trails/984

Problem

The UserPromptSubmit hook took ~11.4s in this repo (9.8s of it system time), overshooting Claude Code's 30s hook timeout once the Go build cache was cold — e.g. right after 773db0d bumped Go to 1.26.5 and invalidated it.

Both seconds-scale costs were go-git's Worktree.Status(), measured here at 5.25s against 0.013s for git status --porcelain.

Root cause

go-git's gitignore.ReadPatterns does not thread a parent directory's patterns into its recursive walk. Each recursive call rebuilds its pattern set from that directory's own ignore files, so the prune check only ever matches patterns declared by the directory being scanned.

A rule prunes a subtree only when its target is a direct child of the .gitignore declaring it. Our root-level e2e/artifacts/ rule was one level too deep, so every Status() descended all ~15k artifact directories.

Verified against go-git main with the same 3,000-directory tree:

root .gitignore rule	result
big/	0ms — pruned
e2e/artifacts/	121ms — full descent

Reference git prunes both identically. A CPU profile of Status() shows 100% of samples inside collectIgnorePatterns → ReadPatterns; the diff walk contributes nothing, because it receives the full union of patterns and prunes correctly.

Changes

1. Move the ignore rule to e2e/.gitignore as artifacts/ so it is a direct child of its declaring .gitignore. Semantically identical to git, which reports the directory as ignored either way.

2. Add gitrepo.Status(ctx, repo) as the single entry point for reading worktree status, with gitrepo.WithStatusCache(ctx) memoizing the walk. handleLifecycleTurnStart installs a cache: it runs before the agent acts and writes only under .entire/ and .git/, so the status cannot change mid-hook. Previously CapturePrePromptState and the strategy's prompt attribution each paid for a full walk.

The cache is deliberately not installed on post-agent paths — DetectFileChanges on TurnEnd must observe the agent's edits. That constraint is documented on WithStatusCache.

3. Make the entry point real rather than aspirational: migrated the three remaining direct callers (DetectFileChanges, checkCanRewindWithWarning, checkResetSafety) and added a forbidigo rule alongside the existing Reset/Checkout ones. Behavior-preserving — without a cache in ctx, gitrepo.Status is exactly worktree.Status().

4. Documented both conventions in CLAUDE.md under Git Operations, including the .gitignore placement rule.

Results

	before	after
hook wall time	11.36s	0.91s
Status()	5.25s	0.045s
second Status() call	5.18s	0.015s (cache hit)

Artifacts were left in place and grew to 15,742 subdirectories during the test run with no regression.

Upstream

go-git#2284 (merged, unreleased — we are on v6.0.0-alpha.5, still the newest tag) cuts the blind ignore-file opens and would take Status() from 5.24s to 2.47s here, but does not address the pattern-inheritance gap. Its benchmark uses root-level ignore files, the placement that already prunes, so it cannot catch this.

The .gitignore placement in this PR is therefore a workaround pending a proper upstream fix to ReadPatterns. Once that lands and ships in a tag, the placement rule and possibly WithStatusCache become removable; gitrepo.Status and the forbidigo rule are worth keeping regardless.

Test plan

• mise run fmt && mise run lint clean
• mise run test — 8,534 tests pass
• mise run test:integration — 448 tests pass
• mise run test:e2e:canary — 59 + 4 tests pass
• forbidigo rule verified to fire: reintroducing a bare worktree.Status() is reported at the call site
• Hook re-timed at 0.76s after the cleanup commit

🤖 Generated with Claude Code

---

Note

Low Risk
Performance and routing changes with behavior-preserving status semantics when no cache is set; stale-cache misuse is documented but limited to the TurnStart window where the worktree is treated as stable.

Overview
Fixes TurnStart / UserPromptSubmit hooks spending ~5s+ per go-git Worktree.Status() by addressing how ignored e2e/artifacts is declared and by deduplicating status reads on the turn-start path.

The root .gitignore no longer lists e2e/artifacts/; e2e/.gitignore now ignores artifacts/ so go-git's ReadPatterns can prune that subtree (root-level nested patterns did not). gitrepo.Status(ctx, repo) is the only supported status API, with gitrepo.WithStatusCache(ctx) memoizing results per worktree root; handleLifecycleTurnStart installs the cache so pre-prompt capture and prompt attribution share one walk. Call sites in DetectFileChanges, rewind safety checks, and strategy rewind warnings now use gitrepo.Status. A forbidigo rule blocks new direct Worktree.Status() usage; CLAUDE.md documents the .gitignore placement rule and when caching is safe (TurnStart yes, TurnEnd no).

^{Reviewed by Cursor Bugbot for commit 45406d5. Configure here.}

[Copilot]

Pull request overview

This PR addresses a major performance bottleneck in agent lifecycle hooks caused by go-git’s Worktree.Status() traversing a large ignored subtree (e2e/artifacts) and by repeated status reads in the same hook. It does so by fixing .gitignore placement to enable go-git pruning and by introducing a single status entry point with an optional per-hook cache to deduplicate the expensive walk.

Changes:

• Moved the e2e/artifacts ignore rule into e2e/.gitignore as artifacts/ to allow go-git’s ignore walker to prune the subtree.
• Added gitrepo.Status(ctx, repo) as the canonical worktree-status API plus gitrepo.WithStatusCache(ctx) to memoize status reads when safe (TurnStart).
• Migrated remaining direct callers to gitrepo.Status and added a forbidigo rule to prevent reintroducing Worktree.Status() usage.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
e2e/.gitignore	Introduces artifacts/ ignore rule colocated with its parent dir for go-git pruning.
cmd/entire/cli/lifecycle.go	Installs a status cache on TurnStart to ensure status is walked at most once per hook.
cmd/entire/cli/gitrepo/status.go	Adds the canonical Status API and context-based memoization.
cmd/entire/cli/gitrepo/status_test.go	Adds tests validating cache reuse behavior and per-worktree cache keying.
cmd/entire/cli/strategy/manual_commit_hooks.go	Switches prompt-attribution status reads to gitrepo.Status to share the cached walk.
cmd/entire/cli/strategy/common.go	Migrates rewind warning status read to gitrepo.Status.
cmd/entire/cli/state.go	Migrates DetectFileChanges and untracked-file enumeration to gitrepo.Status.
cmd/entire/cli/rewind.go	Migrates reset-safety status read to gitrepo.Status.
CLAUDE.md	Documents the new “always use gitrepo.Status” convention and .gitignore placement rule.
.golangci.yaml	Adds a forbidigo rule preventing new Worktree.Status() call sites.
.gitignore	Removes nested e2e/artifacts/ ignore and documents why the rule lives under e2e/.gitignore.

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