D865 — The release changelog is grouped by area, in a post-processing step on the release PR

Decision. internal/changelog.Regroup rewrites the newest section of CHANGELOG.md and of the release PR body as one ### <Area> per area (Atlas, MCP tools, Lint & repair, Client & CLI, Server & KB, General), each with its Features and Bug Fixes, from the scope of every entry. The release-pr job of release-please.yml runs it after release-please on every push to main (make changelog-areas, plus gen -stdin on the body). dev, demo, deploy and ci entries are dropped; synonym scopes (webui, mcpserver, skills, gitx, …) map to their area; an unscoped entry or an unknown scope is General (an unknown scope keeps its **scope:** prefix there, since no heading says it). The pr-title check accepts only the canonical scopes and fails a PR whose body has a wrapped conventional line.

Why. release-please groups by commit type only, so a release was one list of 20+ Features and one of 30+ Bug Fixes, sorted by scope, with entries cut mid-sentence. The cut has one cause: release-please splits a squash message at every line that parses as a conventional header and keeps only its first physical line, and our bodies are hard-wrapped at about 72 columns. The grouping costs one small Go package and a step in the job that already edits the release PR; the truncation is stopped where it is written, in CI, because the rule had been implicit and was broken in at least three releases.

The GitHub release is created from the merged PR body: release-please (strategies/base.ts buildRelease) parses the body with PullRequestBody.parse, takes the content between its --- lines (single-release form: it must start with the ## [x.y.z] heading) and uses it verbatim as the release notes. So the body is regrouped too, and its header, footer and version heading are untouched.

Alternatives rejected. - One conventional-commit type per area (atlas:, mcp: …): changes the vocabulary every contributor and every tool reading types depends on. - changelog-sections in release-please-config.json: it maps types to headings, not scopes to headings. - A shell/awk step: the input is markdown with edge cases (multi-line entries, breaking changes, a Migration note) and make gate must cover it; hence Go with unit tests, as internal/webui/gen and internal/testkbs/gen. - The edited trigger in ci.yml: fixing a body must re-run pr-title, but in ci.yml it would re-run the whole suite on every gh pr edit and on every body rewrite release-please does to its PR, cancelling the run in flight. pr-title is its own workflow (pr-title.yml); the ruleset requires the job name pr-title, not a workflow, so the required check is unchanged.

Consequences. - Regroup never changes text it does not regroup (Migration note, version heading, PR boilerplate, breaking changes, any section other than Features and Bug Fixes), returns the input when it cannot parse an entry list, and is idempotent: the job runs after every push to main and feeds back what it wrote. A section with an area heading is returned as is. - The scope list is written three times: the area table in internal/changelog, the scopes of pr-title.yml and CONTRIBUTING.md. A test fails when the workflow or the contributor guide drift from CanonicalScopes(). - A scope in the table but not canonical (webui) groups correctly yet cannot be used in a new title; a scope in neither is General until it is added to the table and the list. docs(readme), test(git) and similar scoped titles are no longer accepted: those types do not reach the changelog, so they go unscoped. - A PR body edit by the job re-runs pr-title on the release PR; the job edits the body only when the grouping changes it.