Skill: Git Guardrails

Purpose

Protect repository history and user work by treating destructive git operations as high-risk.

When to use

Use before branch cleanup, rebases, resets, force pushes, or when an agent may run git commands.

Inputs

Current branch, status, user intent, remote policy, uncommitted changes, and risky command under consideration.

Workflow

1. Inspect git status before risky operations.
2. Never delete or overwrite user work without explicit instruction.
3. Prefer reversible commands and commits.
4. Document risks before destructive operations.
5. Run validation before commit/PR handoff.

Outputs

Guardrail checklist, safe command plan, commit readiness notes, and blocked-command rationale when needed.

Failure modes

Running reset/clean/force-push casually, committing unrelated changes, or ignoring untracked files.

Verification checklist

Status was inspected; destructive commands avoided or justified; commit only includes intended files; validation status is recorded.

Decision-context commit trailers (convention)

Preserve the reasoning behind a change inside the commit message itself, so future readers see why the code is shaped this way without re-running the investigation. This is a pure message convention: no tooling, no runtime, no enforcement engine.

Structure a non-trivial commit as a conventional subject line, an optional body, then structured trailers at the end:

• Constraint: an active constraint that shaped the decision.
• Rejected: an alternative considered, with | reason for why it was dropped.
• Directive: a warning or instruction for whoever modifies this code next.
• Confidence: high | medium | low — how sure you are the change is correct.
• Scope-risk: narrow | moderate | broad — blast radius if the change is wrong.
• Not-tested: an edge case or scenario the change does not cover.

Rules:

• Include a trailer only when it carries real signal. Skip all trailers for trivial commits (typos, formatting, comment tweaks).
• One fact per trailer line; repeat a key (e.g. two Constraint: lines) rather than packing several into one.
• Keep trailers at the very end of the message, after any prose body, so they parse cleanly.
• Trailers record decisions, not a changelog — describe constraints and trade-offs, not the diff.

Example:

fix(session): refresh tokens inline instead of dropping the session

Auth service returns inconsistent status codes on expiry, so the
interceptor now catches all 4xx and refreshes before retrying once.

Constraint: Auth service has no token-introspection endpoint
Rejected: Background timer refresh | races with concurrent requests
Confidence: high
Scope-risk: narrow
Directive: 4xx catch is intentionally broad — verify upstream before narrowing
Not-tested: cold-start latency above 500ms

Verification checklist (commit trailers)

Trailers are used only when they add signal; trivial commits skip them; each line holds one fact; Confidence/Scope-risk use the allowed values; trailers sit at the end of the message.

Provenance trailers (enforced by validate-provenance)

Distinct from the decision-context trailers above: those are optional, skipped on trivial commits, and carry no tooling. The provenance trailers below are required on every non-merge commit and are checked by scripts/validate-provenance.mjs (npm run validate:provenance), which fails the gate if any are missing or carry a value outside the allowed set.

Add all four to the end of every commit message:

• AI-Generated: yes | no | partial — was the diff written by an AI agent.
• Human-Edited: yes | no — did a human modify the AI output before committing.
• Tested-By: human | ai | ci | none — who/what exercised the change.
• Human-Reviewed: yes | no — did a human read the diff before it landed.

Keys match case-insensitively; values are compared lowercased; the last occurrence of a key wins.

Self-attested, not verified. The gate proves the declaration exists and is well-formed — it cannot tell whether AI actually wrote the code, whether a human truly reviewed it, or whether the named tests ran. A pass means "the author declared provenance", not "provenance is correct". The value is accountability hygiene: a deliberate, machine-checkable claim on every commit, not ground truth.

Scope. The gate checks commits on main..HEAD (override the base with PROVENANCE_BASE), so it matches a PR's commit range and runs cleanly in CI or a pre-commit hook. Merge commits are skipped; on the base branch the range is empty and the gate passes with nothing to check. A missing base ref (e.g. a shallow CI clone) is a skip, not a failure.

Example:

Add rate limiter to the public API

AI-Generated: partial
Human-Edited: yes
Tested-By: ci
Human-Reviewed: yes

Verification checklist (provenance trailers)

Every non-merge commit on the branch carries all four keys; each value is in its allowed set; the claim reflects what actually happened (the gate cannot check this — the author must be honest); npm run validate:provenance exits 0 before opening a PR.

Ghi chú tiếng Việt

Kỹ năng này bảo vệ git history và thay đổi của user. Dùng cho mọi thao tác nguy hiểm. Quy ước trailer commit (Constraint:/Rejected:/Directive:/Confidence:/Scope-risk:/Not-tested:) lưu lại lý do quyết định ngay trong commit message — chỉ là quy ước viết, không cần runtime; bỏ qua với commit nhỏ. File liên quan: commands/vibe-git-guardrails.md.

Ngoài ra, trailer provenance (AI-Generated:/Human-Edited:/Tested-By:/Human-Reviewed:) là bắt buộc trên mọi commit non-merge và được scripts/validate-provenance.mjs (npm run validate:provenance) kiểm: thiếu key hoặc value sai enum → fail. Gate chỉ chứng minh khai báo tồn tại và đúng định dạng, không xác minh AI có thật sự viết code, human có thật sự review, hay test có thật sự chạy — pass nghĩa là "tác giả đã khai báo provenance", không phải "provenance đúng". Phạm vi: commit trên main..HEAD (đổi base bằng PROVENANCE_BASE); merge commit được bỏ qua; base ref thiếu thì skip chứ không fail.

Nguồn cảm hứng / Inspiration

Convention adapted as original wording from yeachan-heo/oh-my-claudecode (MIT, Yeachan Heo) commit-protocol trailers. Inspiration only — no upstream text copied.