docs: the one-sentence rule was written down but nothing enforced it

.changie.yaml

@@ -16,6 +16,11 @@ kinds:
   - label: Fixed
   - label: Security
   - label: Documentation
+body:
+  # A ceiling, not a target: one sentence is the rule (see RELEASE.md), and a
+  # body this long is a paragraph that belongs in the linked issue. Enforced by
+  # `changie new` only — a hand-written fragment is not checked.
+  maxLength: 400
 custom:
   - key: Issue
     label: Issue Number

.github/pull_request_template.md

@@ -26,4 +26,4 @@ Fixes #
 - [ ] Added/updated tests
 - [ ] Lint/format passes (`golangci-lint run`)
 - [ ] Updated documentation (if applicable)
-- [ ] Added a Changie changelog fragment for user-facing changes (`changie new`, see [RELEASE.md](../RELEASE.md)) — or N/A (docs/tests/chore only)
+- [ ] Added a Changie changelog fragment for user-facing changes (`changie new`, one sentence and two at most, see [RELEASE.md](../RELEASE.md#one-sentence-two-at-most)) — or N/A (docs/tests/chore only)

CONTRIBUTING.md

@@ -28,7 +28,7 @@ Thanks for your interest in contributing! This file is a short pointer — the f
 
 Conventional prefixes are preferred: `feat:`, `fix:`, `chore:`, `docs:`, `test:`, `refactor:`.
 
-Release notes are **not** generated from commits — they come from [Changie](https://changie.dev) fragments. Add one for any user-facing change with `changie new` (see [RELEASE.md](RELEASE.md)).
+Release notes are **not** generated from commits — they come from [Changie](https://changie.dev) fragments. Add one for any user-facing change with `changie new` — one sentence, two at most (see [RELEASE.md](RELEASE.md#one-sentence-two-at-most)).
 
 ## License of Contributions
 

RELEASE.md

@@ -29,7 +29,8 @@ You are prompted for a **kind** (`Added`, `Changed`, `Deprecated`, `Removed`,
 `Fixed`, `Security`, `Documentation`), a **body**, and the **issue number**. It
 writes a small YAML file under `changes/unreleased/` — commit it alongside your
 code. Prefer `changie new` over hand-writing the YAML: it enforces the issue
-number, and a fragment without one renders as a dead link.
+number — a fragment without one renders as a dead link — and refuses a body over
+400 characters.
 
 ### One sentence. Two at most.
 
@@ -44,6 +45,10 @@ already points at.
 - **Never a third.** If it needs one, it is either two changes (write two
   fragments) or a story that belongs in the issue.
 
+`changie new` refuses a body over 400 characters (`body.maxLength` in
+[`.changie.yaml`](.changie.yaml)). That is a ceiling for the two-sentence case,
+not a target, and it does not see a fragment you hand-write.
+
 ```yaml
 # too long — the root cause, the mechanism and the evidence all belong in #142
 body: 'S3 Control requests were served by S3. `s3control` signs with S3''s own

changes/unreleased/Documentation-20260906-185423.yaml

@@ -1,5 +1,5 @@
 kind: Documentation
-body: Changelog fragments are capped at one sentence, two at most, with the rule and a worked example in RELEASE.md and a line for it in the pre-flight checklist. Every entry already in the changelog is rewritten to that limit, and the v1.1.0 and v1.0.0 release notes are republished from their fragment files
+body: Changelog fragments are capped at one sentence, two at most — stated with a worked example in RELEASE.md, in the pre-flight checklist, in CONTRIBUTING.md and the PR checklist, and enforced by a 400-character body limit `changie new` refuses to exceed. Every entry already in the changelog is rewritten to that limit, and the v1.1.0 and v1.0.0 release notes are republished from their fragment files
 time: 2026-09-06T18:54:23.073014+09:00
 custom:
     Issue: "152"

changes/unreleased/Documentation-20260906-234500.yaml

@@ -1,5 +1,5 @@
 kind: Documentation
-body: 'The documentation no longer publishes the same figure at five different values: six numbers were restated across pages with no two agreeing, so docs/coverage.md now owns them and every other page links to it. Three statements that did not match the code are corrected — a GET /devcloud/api/health route that is not registered, a failed Lambda invoke blamed on Docker when the runtime is a stub, and codegen output files no template emits — and eighteen files are 1,063 lines shorter'
+body: 'The documentation no longer publishes the same figure at five different values: six numbers restated across pages now live in docs/coverage.md, which every other page links to. Three claims the code does not back are corrected — an unregistered `GET /devcloud/api/health`, a Lambda invoke failure blamed on Docker, and codegen outputs no template emits — and eighteen files are 1,063 lines shorter'
 time: 2026-09-06T23:45:00.000000+09:00
 custom:
     Issue: "151"