Add auto-merge skill for claude/* branch PRs

.claude/skills/auto-merge/SKILL.md

@@ -0,0 +1,32 @@
+---
+name: auto-merge
+description: After opening or being handed a pull request from a claude/* branch, turn on GitHub auto-merge so it merges when CI completes, and stay silent about it. Use whenever a PR is created, or when asked to auto-merge. Never merges anything that is not from a claude/* branch in this repo.
+---
+
+# Auto-merge when CI completes
+
+Use the GitHub MCP tools (`mcp__github__*`), never `gh`. **No chatter**: do not report PR status, CI progress, subscriptions
+or merges, and do not answer PR events (opened, checks finished, merged, subscription notices). Speak only for the cases under
+"Say something" below, in one line.
+
+## When
+Right after a PR is opened from this session, or when a `claude/*` PR is pointed out to you.
+
+## Eligible PRs
+Open, not a draft, head branch starts with `claude/` in this same repo, base is the default branch. Anything else: do nothing.
+
+## Steps
+1. `enable_pr_auto_merge` with `mergeMethod: MERGE`. GitHub then merges it itself once the required `check` passes. Done: say nothing.
+2. If that fails because the PR is already mergeable and the `check` run is already completed and successful
+   (`pull_request_read` `get_check_runs`), merge it now with `merge_pull_request`, `merge_method: merge`, and
+   `expectedHeadSha` set to the head SHA you just read. Say nothing.
+3. Do not subscribe to the PR, and do not unsubscribe or comment. The user watches CI in the Claude Code CI button.
+
+## Say something (one line each)
+- Auto-merge could not be enabled for any other reason (for example "Allow auto-merge" is off in the repo settings).
+- CI failed and you cannot fix it, or the PR conflicts with `main` and the conflict is not a plain merge.
+
+## Never
+- Merge or enable auto-merge on a PR from another branch, a fork, a draft, or one whose checks have failed or are missing.
+- Skip, disable or re-run tests to get green; force-push; approve reviews; close PRs; delete branches.
+- Turn auto-merge off for a PR the user switched it on for.

CLAUDE.md

@@ -7,8 +7,9 @@ MCP data tools and web search. User-facing docs are in `README.md`; this file is
 - `make check`: ruff + pytest (no network, a few seconds). Run it before every commit, on Python 3.13.5 (production;
   `uv venv --python 3.13.5`). GitHub CI runs the latest stable Python and Node.js instead, to catch breakage from the next upgrade early.
 - `make prompt-report`: token breakdown of a sample request. `python bot.py [label]` runs the bot.
-- Merging: tick "Auto-merge when ready" in the PR's CI button; GitHub merges once the required `check` passes (needs "Allow auto-merge" in
-  the repo settings and `check` as a required status on `main`).
+- Merging: after opening a PR from a `claude/*` branch, follow `.claude/skills/auto-merge/SKILL.md`: enable GitHub auto-merge and say nothing
+  about it. It needs "Allow auto-merge" in the repo settings and `check` as a required status on `main`; the CI button's
+  "Auto-merge when ready" box does the same per PR.
 - Tests use fakes (`tests/conftest.py`: FakeBot, user_msg; `tests/fakes.py`: ScriptedBackend,
   FakeMcp, fake SDK clients; `tests/fixtures/` real anonymised MCP output). Add a test next to the module you change;
   don't write scratch scripts.