docs(doctrine): sync commit policy snapshot

Author: tinmanworks

templates/common/docs/doctrine/repo-management.md

@@ -17,8 +17,9 @@ This is policy and doctrine, not automation.
 ## Rule Order (enforce in this order)
 
 1. Commit signing policy
-2. Repo placement policy (Personal vs Organization)
-3. Visibility policy (Public vs Private vs Internal)
+2. Commit message policy
+3. Repo placement policy (Personal vs Organization)
+4. Visibility policy (Public vs Private vs Internal)
 
 ## Commit Signing Policy
 
@@ -70,6 +71,61 @@ For important repositories (templates, core libs, product repos), enable:
 
 If using an organization, prefer organization rulesets over per-repo configuration.
 
+## Commit Message Policy
+
+### Required outcome
+
+- Every non-merge commit message follows a structured format.
+- Commit subjects are short, specific, and searchable.
+- Breaking changes are explicit.
+
+### Required format
+
+Use this subject format:
+
+```text
+<type>(<scope>): <summary>
+```
+
+`(<scope>)` is optional. Use lowercase for `type` and `scope`.
+
+Allowed `type` values:
+
+- `feat` -> new behavior/capability
+- `fix` -> bug fix
+- `docs` -> documentation-only change
+- `chore` -> maintenance, tooling, housekeeping
+- `refactor` -> internal restructuring without behavior change
+- `test` -> tests added/updated
+- `ci` -> CI workflow/pipeline changes
+- `build` -> build/dependency/release tooling changes
+- `perf` -> performance-focused change
+- `revert` -> explicit revert commit
+
+Subject line rules:
+
+- Imperative mood (`add`, `fix`, `update`, not `added`, `fixes`).
+- Prefer <= 72 characters.
+- No trailing period.
+- Must describe what changed, not generic text (`update stuff`, `misc fixes`).
+
+Breaking change rule:
+
+- Use `!` in subject when applicable: `feat(api)!: remove v1 endpoints`
+- Include a `BREAKING CHANGE:` footer in the commit body explaining migration impact.
+
+### Exceptions
+
+- Merge commits generated by GitHub/Git are allowed.
+- Release merge commits can keep release-oriented phrasing.
+
+### Enforcement baseline
+
+For important repositories (templates, core libs, product repos), enforce both:
+
+- Signed commits
+- CI or hook-based commit message linting against this policy
+
 ## Repo Placement Policy (Personal vs Organization)
 
 ### Keep in personal account when