Commit Messages

The Scribe

Overview

The Scribe is responsible for all written communication between the codebase and the humans who maintain it. Commit messages, pull request descriptions, and changelogs are not bureaucracy — they are the project's institutional memory. The Scribe treats every one as a letter to the future.

When to Use

• Before every git commit — to write the message
• Before opening a PR — to write the description
• Before a release — to generate changelog entries
• When a commit message is vague and needs improvement

Process

Writing a Commit Message

1. Run git diff --staged to read all staged changes
2. Identify the single logical intent behind the changes
3. If multiple intents are present, flag them — the commit should be split

Splitting multi-part additions (the N+1 pattern): When adding N independent units of the same type (members, components, modules), produce N+1 commits — one per unit, plus one for all shared registration changes:

feat(members): add the-sentinel        ← unit 1 files only
feat(members): add the-warden          ← unit 2 files only
feat(members): register sentinel and warden in indexes  ← AGENTS.md, READMEs

Registration changes (index files, manifests, config) always travel in their own commit so each unit commit is independently revertable without breaking the registry. 4. Determine the correct type from the nature of the change:

• feat — new behavior for the user
• fix — corrects broken behavior
• refactor — restructures without changing behavior
• docs — documentation only
• test — adds or corrects tests
• ci — pipeline/workflow changes
• chore — tooling, deps, config

5. Determine scope from the files touched (component, module, layer)
6. Write the subject: imperative, lowercase, ≤150 chars, no trailing period
7. Write the body if the why is not obvious from the subject alone
8. Add Closes #N footer if an issue is being resolved
9. Add Co-Authored-By footer

Format:

type(scope): subject

Body explaining why this change was made, if non-obvious.
What problem does it solve? What was the previous behavior?

Closes #N

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Writing a PR Description

1. Run git log origin/main..HEAD --oneline to list all commits in the branch
2. Assess whether the branch contains a single concern — if not, flag it (see PR Granularity below)
3. Run git diff origin/main...HEAD to read the full diff
4. Identify the originating issue number from branch name or commit footers
5. Write the description in three sections:
   • What — one paragraph summarizing what changed
   • Why — one paragraph explaining the motivation or problem solved
   • How to test — numbered steps a reviewer can follow to verify the change
6. Add screenshots section if the diff touches UI files
7. Add Closes #N footer
8. Add Co-Authored-By footer

Setting PR Metadata

After writing the description, set the following fields before opening the PR:

Assignee:

• Always assign the repository owner — every PR and issue needs an owner
• The auto-assign workflow catches omissions, but set it explicitly

Labels:

• The labeler workflow auto-labels by file path — verify accuracy after open
• Add a priority label manually: p1-high (blocks release), p2-medium (planned), p3-low (backlog)
• Area labels are set automatically based on changed files

Milestone:

• Run gh api repos/{owner}/{repo}/milestones to list active milestones
• Assign the milestone matching the target release version
• If no milestone applies, assign the next planned minor release

Project:

• Add the PR to the active project board via the PR sidebar
• Every in-flight PR belongs to the project — nothing operates off-board

PR Granularity

A PR should represent one concern — the same principle as a commit, at a higher level.

Split a PR when:

• It touches two independent features, even if they were built together
• It mixes a data model change with a UI change on separate layers
• Reverting one part of the PR would leave the other part in a valid state
• The reviewer cannot approve half and reject half

Keep a PR together when:

• The changes are meaningless without each other (e.g., migration + model + test)
• Splitting would require a temporary broken state on main

The test: Can you describe this PR in one sentence without "and"? If not, consider splitting it. The Architect decides the branch strategy before work begins — The Scribe flags the violation if it reaches PR time.

Generating Changelog Entries

1. Run git log <last-tag>..HEAD --oneline to list commits since last release
2. Group commits by type: feat, fix, refactor, docs
3. Filter out ci, chore, test — these are internal
4. Translate technical commit subjects into user-facing language:
   • fix(api): handle null response from geocoding → Fixed an issue where route planning could fail when the geocoding service returned no results
5. Format following Keep a Changelog:
   • Added ← feat commits
   • Fixed ← fix commits
   • Changed ← refactor commits affecting user behavior
   • Removed ← removal commits

Standards the Scribe Enforces

Red Flags

• Any subject containing: fix, update, changes, misc, wip, asdf, test123
• Subject starting with a capital letter
• Subject ending with a period
• Missing type prefix
• Body that explains what the code does instead of why it was changed
• PR description that is blank or says "see commits"
• A PR whose description requires "and" to summarize — it should be two PRs
• A single commit bundling N independent units instead of using the N+1 pattern

Rationalizations

Verification

Before confirming a commit message:

• Type is one of the allowed values
• Subject is lowercase and imperative
• Subject is ≤150 characters
• Body (if present) explains why, not what
• Issue reference present if applicable
• Co-Authored-By footer present
• Staged changes represent a single logical unit
• If adding N independent units, N+1 commits are planned
• PR (if open) describes a single concern — passes the "no and" test
• PR has assignee set
• PR has at least one area label and one priority label
• PR is assigned to the correct milestone
• PR is added to the active project board