boatswain

A set of rules for the Shipshape Boatswain role, covering branch hygiene, reviewing changes, and making local commits.

In plain words
What is it for?
Use it before committing to inspect the branch and diff, make hygiene-only fixes, rerun affected checks, and record the related scenario or watch in the commit message.
Why use it?
It limits cleanup work to safe, relevant edits and helps ensure commits are based on passing checks and the correct task scope.

Cursor rule

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/dmytri/shipshape/boatswain
Clone the repo
git clone --depth 1 https://github.com/dmytri/shipshape
Per session 13 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 211 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00013 $0.00211
Opus 5 $0.00006 $0.00105
Sonnet 5 $0.00003 $0.00042
Haiku 4.5 $0.00001 $0.00021

Measured 2d ago against content hash 2c1aaca68037, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

boatswain scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

rules/boatswain.mdc · 15 lines

What it actually says

Boatswain, before committing:

  • The deck is the one retrieval: judge git status and the diff against the base commit, and sweep nothing beyond it, per the Boatswain skill.
  • Make hygiene edits and local commits only, and author no new behaviour, per the "Write scopes are strict" Article.
  • Commit only on green evidence for the staged executable state, rerunning what hygiene edits touched and labelling any cache-backed result, per the Boatswain skill.
  • Report stale planks and unreachable code for harbour; Boatswain deletes no production code, per the Boatswain skill.
  • Stage role-advanced hunks, in-flight durable artifacts, and own hygiene edits; leave unrelated operator work for Captain, per the Working tree policy.
  • Reference the advanced scenario or watch in the commit subject, per the Boatswain skill.

Doctrine lives in skills/boatswain/SKILL.md; when this rule and the skill disagree, the skill wins.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 15 lines · 13 tokens per session scan A 2c1aaca68037

Subscribe to this mod's changes

boatswain is a cursor rule published in the GitHub repository dmytri/shipshape (7 stars, last pushed 28d ago), licensed 0BSD. It adds 13 tokens to every session and 211 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.