# Repository Guidelines for Zero

These instructions apply to all work in this repository. For the user-facing
guide to extending Zero with specialists, hooks, plugins, MCP, and skills, see
[docs/EXTENDING.md](docs/EXTENDING.md).

## 1. Contribution and Pull Request Rules

- Before opening any pull request, **all contributors**—including maintainers,
  community contributors, and coding agents—must read and follow
  [CONTRIBUTING.md](CONTRIBUTING.md).
- Community pull requests require an existing parent issue with the
  `issue-approved` label. Team members may open pull requests through the
  internal development process described in `CONTRIBUTING.md`.
- Keep each change focused on the approved or assigned scope. Do not include
  unrelated fixes, refactors, formatting churn, generated output, or existing
  local changes in the same commit or pull request.
- Discuss new implementation languages, runtimes, major dependency changes,
  and broad architectural rewrites with maintainers before implementation.
- Pull request descriptions must explain what changed and why, link the parent
  issue when required, and list the tests or verification performed. Include
  screenshots or a short recording for user-visible UI changes when practical.

## 2. Repository and Implementation Conventions

- Use the Go version declared in `go.mod`. Do not hardcode a different local
  toolchain version in scripts or documentation.
- Use the repository build and release commands (`make` and
  `go run ./cmd/zero-release ...`) instead of inventing parallel build flows.
- Keep tests beside their source files (`foo_test.go` next to `foo.go`). Add a
  regression test for behavior changes and run affected concurrent code under
  the race detector.
- Never edit files under `third_party/`; they are vendored.
- Prefer one cross-platform function with small conditional checks over
  duplicated platform-specific helpers when the behavior can remain unified.
- Do not commit generated benchmark reports from
  `internal/perfbench/reports/*.json`; reports are configuration-specific
  evidence, not repository state.
- Preserve the user's working tree. Do not overwrite, delete, stage, or commit
  unrelated tracked or untracked files.

## 3. Required Validation

Run validation from the repository root before committing, opening a pull
request, or completing an implementation task:

1. **Formatting check**: `make fmt-check`. If it fails, format with
   `go fmt ./...` (or `make fmt`) and run the check again.
2. **Vet**: `go vet ./...` (or `make vet`).
3. **Tests**: `go test ./...`. Use `make test` for the full race-enabled suite,
   or run focused tests with `-race`, when concurrency is affected.
4. **Build**: `go run ./cmd/zero-release build`.
5. **Smoke test**: `go run ./cmd/zero-release smoke`.
6. **Advisory lint**: `make lint-static`.
7. **Security**: `make vulncheck`.
8. **Diff hygiene**: `git diff HEAD --check` (covers staged and unstaged
   tracked changes).

`make lint` currently runs the formatting check and `go vet`; it does **not**
run golangci-lint. The pinned golangci-lint job is advisory in CI while the
existing repository-wide backlog is cleaned up. Fix findings introduced by or
related to the current change. Unrelated pre-existing advisory findings do not
justify expanding a focused pull request; report them separately.

Formatting, vet, tests, build, smoke, diff hygiene, and govulncheck are hard
requirements. If a related check fails, fix it. If a required check cannot run
because of the environment or fails for an unrelated external reason, report
the exact failure and obtain maintainer direction rather than silently ignoring
it.

## 4. Common Review Blockers

These classes drive multi-round reviews. Fix them before requesting review:

- **Fresh base:** Rebase onto the current PR base (`main` or stacked target)
  before review. A stale head that rolls back mainline commits is a hard
  blocker, not a merge-time detail. Resolve conflicts by keeping upstream
  behavior unless the PR intentionally changes it.
- **Platform truth:** Code and tests must pass on Linux, macOS, and Windows.
  Compare paths after canonicalization (physical/`EvalSymlinks` form); never
  assert raw `t.TempDir()` spellings (`/var` vs `/private/var` on macOS, short
  paths on Windows). Prefer one cross-platform function with small `GOOS`
  checks over duplicated helpers that drift.
- **Security edges:** Keep secrets out of argv, env dumps, and logs. Redact
  success and error paths (including stderr). Fail closed on ownership, lease,
  and permission checks. Do not rely on pre-open path resolution
  (`EvalSymlinks` then open) for containment: that is a check-to-use race.
  Bind containment at open/use time with rooted or handle-relative,
  traversal-resistant APIs. If a no-follow API is used, apply it to every
  traversed component and enforce the platform's reparse-point protections;
  final-component-only no-follow is insufficient. On multi-step setup, roll back
  only what this run created; never destroy pre-existing resources you did
  not create; never report success when cleanup or unlock failed.
- **Atomic shared state:** Write a complete temporary file, then atomically
  replace the destination so concurrent readers never see a partial write.
  Exclusive create or a write lock alone is not enough for readers. Serialize
  the full read-modify-write sequence for lockfiles and shared stores.
- **Tests match the claim:** Every behavior or security-boundary change needs a
  regression test, including the failure path. Path-sensitive logic needs at
  least one non-Linux path case (or a hermetic fake that exercises the same
  normalization).
- **Honest scope:** PR description, help text, and comments must match what
  shipped. Wire advertised entry points or shrink the claim. Do not bundle
  unrelated fixes. Do not widen security allowlists by name alone; check
  classification and side effects too.