[Ayush7614]

Summary

Fixes #1164.

ConfigStore.Upsert / Remove / SetEnabled read the whole hooks document, modify it, and rewrite it. Serialization was a package-local sync.Mutex (lockForPath), which only excludes goroutines in one process. Two concurrent zero hooks processes could both read revision N and the second full-document rename silently dropped the first update. WriteConfig also used os.WriteFile(temp) + os.Rename with no file or directory fsync, so a crash could publish a truncated/empty file after the CLI reported success.

Changes

• Acquire <hooks.json>.lock through the existing lockutil.TryAcquireFileLock protocol across the complete List() -> mutate -> publish sequence, in addition to the in-process mutex. The lock is a stable sibling and is never renamed or removed; the kernel releases it on process exit.
• WriteConfig now owns the same lock, so direct callers cannot bypass it. ConfigStore calls the locked write helper directly.
• Publish through a 0600 os.CreateTemp file, Sync, close, atomic replace (fsutil.RenameWithRetry), then fsync the parent directory.
• Create missing config directories 0700 and fsync each new entry into its parent; roll back only directories this call created.
• Join lock-release failures into the result instead of reporting success while the lock may still be held.
• Keep the existing in-process mutex so goroutines do not depend on file-lock behavior for serialization.

Tests

• Deterministic same-process test: holds <config>.lock and requires Upsert to wait. Fails on the previous code.
• Two-process test: child announces itself, parent holds the lock, asserts the child's write cannot appear, then both write and both hooks must survive. Fails on the previous code.
• Sync-barrier test: file and directory sync are both called.
• Injected sync failure: the old config remains readable and no temp debris is left.
• Unlock failure: the write is committed but the release error is returned.
• First write into missing nested directories.

Validation on cd3e0b0a + this branch:

• make fmt-check passed
• go vet ./... passed
• go test ./... -count=1 passed
• go test -race ./internal/hooks ./internal/cli -count=1 passed
• go run ./cmd/zero-release build passed
• go run ./cmd/zero-release smoke passed
• make vulncheck passed
• git diff HEAD --check passed
• make lint-static reports only the four pre-existing advisory staticcheck findings (installtest, proxydial x2, web_fetch); no new findings.

Windows: directory fsync is best-effort skipped, matching the existing config and sessions stores; the replace uses fsutil.RenameWithRetry. The new tests are cross-platform and re-exec os.Args[0] for the helper process.

Summary by CodeRabbit

• Bug Fixes
  • Improved reliability when multiple processes update hook configurations simultaneously, preventing conflicting changes from being lost.
  • Hook configuration writes are now safer during interruptions or synchronization failures, preserving the previous valid configuration when an update cannot be completed.
  • Missing configuration directories are created automatically with secure permissions.
  • No-op changes no longer create unnecessary configuration or lock files.
  • Improved error reporting for lock and persistence failures.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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• Configuration used: Repository: Twigpine/zero/.coderabbit.yaml
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📥 Commits

Reviewing files that changed from the base of the PR and between 54a6df4 and cbb820e.

📒 Files selected for processing: 2

• internal/hooks/config_lock_test.go
• internal/hooks/hooks.go

🚧 Files skipped from review as they are similar to previous changes: 2

• internal/hooks/hooks.go
• internal/hooks/config_lock_test.go

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 1 remain after this review.

Walkthrough

Hooks configuration mutations now use a stable cross-process lock. Configuration writes synchronize temporary files and parent directories around atomic replacement. Tests cover locking, concurrent updates, synchronization failures, unlock errors, and missing directories.

Changes

Hooks configuration

Layer / File(s)	Summary
Acquire the shared configuration lock internal/hooks/lock.go, internal/hooks/hooks.go, internal/hooks/config_lock_test.go	Configuration access uses a stable sibling lock file. Lock acquisition retries contention and reports timeouts and other errors.
Publish configuration durably internal/hooks/hooks.go, internal/hooks/config_lock_test.go	Writes synchronize temporary files before atomic replacement and sync the parent directory. Directory creation uses mode 0700 and rolls back directories created by the operation after setup or synchronization failures.
Serialize config-store mutations internal/hooks/hooks.go, internal/hooks/config_lock_test.go	Upsert, Remove, and SetEnabled perform read-modify-write operations under the shared lock. No-op mutations avoid creating configuration state. Tests cover same-process and cross-process exclusion and update preservation.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Bug fix · Severity of issue fixed: Medium

Sequence Diagram(s)

sequenceDiagram
  participant ConfigStore
  participant lockConfigFile
  participant WriteConfig
  participant hooks.json
  ConfigStore->>lockConfigFile: Acquire sibling lock
  lockConfigFile-->>ConfigStore: Return lock releaser
  ConfigStore->>hooks.json: Read and modify configuration
  ConfigStore->>WriteConfig: Persist updated configuration
  WriteConfig->>hooks.json: Sync temporary file and atomically replace configuration
  WriteConfig->>hooks.json: Sync parent directory

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Suggested reviewers: gnanam1990

Merge Risk: ⚪ Minimal · up to cbb82

The locking and durability changes appear ready to merge after normal checks; no actionable current-head risk remains.

Security architecture risk: 🔵 Low · up to 54a6d

The change strengthens concurrent updates and crash recovery without changing hook execution authority or configuration scope. Remaining limitations concern cooperating writers, platform-dependent durability, and errors reported after a replacement is already visible. No introduced security concern was established in the inspected paths.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The affected persistent authority remains project-scoped or user-scoped hook configuration. User-level edits can affect sessions loading that user's configuration, while project edits feed the existing workspace-trust-controlled loading path. The inspected change does not introduce a new remote entrypoint or execution privilege.

Trust Boundaries and Controls

• observed — The existing CLI dispatcher excludes project hooks when the trust root is empty, untrusted, or cannot be checked. That gate and the command execution implementation are unchanged by this PR; persisting configuration does not itself grant workspace trust.
• observed — On non-Windows platforms, the reused lock opener uses handle-relative, no-follow access and rejects non-regular or multiply-linked lock files before diagnostic metadata is written. Its root is the configuration parent directory; these checks do not establish confinement against replacement of that trusted parent.

Resilience and Maintainability Implications

• observed — The stable lock file is retained, and kernel-held locking avoids a stale-lock reclamation protocol after process exit. Durability remains best effort on Windows and when a directory cannot be opened because of permissions; these are limits of the stronger publication guarantee, not evidence of a newly introduced attack path.

Pre-merge checks: 5

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the primary changes: cross-process serialization of hooks configuration mutations and durable configuration publication.
Linked Issues check		The changes satisfy the coding requirements in #1164. ConfigStore mutations hold the stable <hooks.json>.lock across read, mutation, and publication. WriteConfig locks direct callers. Publ…
Out of Scope Changes check		The changes are limited to internal/hooks/hooks.go, internal/hooks/lock.go, and focused tests in internal/hooks/config_lock_test.go. These changes directly implement #1164. No unrelated CLI API …
Docstring Coverage		Docstring coverage is 89.47% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 19 functions across 3 files.

Full details: Linked Issues check

Explanation

The changes satisfy the coding requirements in #1164. ConfigStore mutations hold the stable <hooks.json>.lock across read, mutation, and publication. WriteConfig locks direct callers. Publication uses a 0600 temporary file, file sync, close, atomic replacement, and parent-directory sync. Failure handling preserves the previous file and removes call-created temporary files. Lock-release errors are returned. Focused tests cover process locking, lost-update prevention, sync barriers, failure preservation, unlock errors, and missing directories.

Full details: Out of Scope Changes check

Explanation

The changes are limited to internal/hooks/hooks.go, internal/hooks/lock.go, and focused tests in internal/hooks/config_lock_test.go. These changes directly implement #1164. No unrelated CLI API or product behavior changes are identified.

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[coderabbitai]

Actionable comments posted: 1

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• 🪄 Fix comments: Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at @internal/hooks/hooks.go:
- Around line 494-536: Short-circuit ConfigStore.Remove and
ConfigStore.SetEnabled when store.configPath does not exist by checking it with
os.Lstat and returning false, nil before calling withConfigLock. Preserve other
filesystem errors for normal handling, and leave existing lock-and-update
behavior unchanged when the configuration file exists.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: Repository: Twigpine/zero/.coderabbit.yaml
• Review profile: CHILL
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📥 Commits

Reviewing files that changed from the base of the PR and between cd3e0b0 and 54a6df4.

📒 Files selected for processing: 3

• internal/hooks/config_lock_test.go
• internal/hooks/hooks.go
• internal/hooks/lock.go

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 3 remain after this review.

[Ayush7614]

Follow-up cbb820e addresses the no-op tree mutation: Remove/SetEnabled now return false, nil without creating .zero/ or the lock when the config does not exist, with TestNoOpMutationsDoNotCreateConfigState.

Re-ran after the follow-up: make fmt-check, go vet ./..., go test ./... -count=1, go test -race ./internal/hooks ./internal/cli -count=1, release build, smoke, make vulncheck, and git diff HEAD --check all pass.

[Vasanthdev2004]

Thanks. The exclusion and the durable publish both hold. With the file lock taken out, Upsert completes while hooks.json.lock is held elsewhere, and dropping the fsync before the rename fails TestWriteConfigSyncsFileAndDirectory. internal/hooks passes under -race on Windows.

One thing to change before this lands: the lock file stays behind in the user's repository. zero hooks add without --user edits the project's .zero/hooks.json, and the stable sibling it now locks is never removed, by design. After a project mutation on main, .zero/ holds only hooks.json; on this head it also holds hooks.json.lock, for good. EXTENDING.md suggests committing .zero/hooks.json, so the lock would show up in git status in every repository where the command ever ran, and anyone who adds .zero/ would commit it. Keeping the lock for the project file outside the repository would avoid that, for example under the user state directory, keyed by the config's canonical path. The user config can keep its sibling.

CI is 10/10, and vet is clean for windows, linux and darwin.