no-co-author-trailers

A Git commit and pull-request writing rule that keeps AI and tool attribution lines out of the text.

In plain words
What is it for?
It guides agents when creating or amending commits and pull requests, including use of Conventional Commits: a standard format such as feat(scope): description.
Why use it?
It prevents unwanted Co-authored-by, Signed-off-by, or similar trailer lines from being added to project history.

Cursor rule for Cursor

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/pymodel/pythinker-cli/no-co-author-trailers
Clone the repo
git clone --depth 1 https://github.com/PyModel/pythinker-cli

Made for: Cursor.

Per session 220 This file is loaded in full into every session.
When invoked 220 The same file — it is already loaded in full.
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 $0.00220 $0.00220
Opus 5 $0.00110 $0.00110
Sonnet 5 $0.00044 $0.00044
Haiku 4.5 $0.00022 $0.00022

Measured yesterday against content hash 5b7eca462506, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

no-co-author-trailers 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 yesterday.

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.

.cursor/rules/no-co-author-trailers.mdc · 32 lines

What it actually says

No co-author or AI trailers on commits

Never add Co-authored-by, Signed-off-by for an AI tool, or any Cursor/Claude/Copilot footer to commit messages or PR descriptions.

This matches AGENTS.md: commits use Conventional Commits subject (+ optional body) only.

When creating commits

  • Pass the message via HEREDoc or -m with only the intended subject/body.
  • Do not append Co-authored-by: Cursor <[email protected]> or similar.
  • If a hook or tool adds a co-author trailer, amend it out before pushing (only when amend rules allow).

Examples

feat(soul): emit TodoListUpdated wire event

Not:

feat(soul): emit TodoListUpdated wire event

Co-authored-by: Cursor <[email protected]>
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. yesterday First seen · 32 lines · 220 tokens per session scan A 5b7eca462506

Subscribe to this mod's changes

no-co-author-trailers is a cursor rule published in the GitHub repository PyModel/pythinker-cli (20 stars, last pushed 4d ago), licensed Apache-2.0. It adds 220 tokens to every session, about $0.0011 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 2026-08-30.