feat(claude-code-review)!: default to a GitHub-hosted runner

.github/workflows/claude-code-review.yml

@@ -7,9 +7,21 @@
   workflow_call:
     inputs:
       runs-on:
-        description: "Runner label(s) as a JSON array string (parsed with fromJSON). Defaults to the self-hosted pool. Public/open-source repos opt out by passing '[\"ubuntu-latest\"]'."
+        description: "Runner label(s) as a JSON array string (parsed with fromJSON). Defaults to a GitHub-hosted image; pass '[\"self-hosted\", \"linux\", \"x64\"]' to use a self-hosted pool instead."
         type: string
-        default: '["self-hosted", "linux", "x64"]'
+        # GitHub-hosted by default. This job reads the PR diff and calls the
+        # Claude API -- it needs no private-network access, no local toolchain
+        # and no persistent state, so a self-hosted runner buys it nothing.
+        #
+        # It cost quite a lot, though: on a contended pool the review queued
+        # 40-77 minutes for 3-6 minutes of work, routinely finishing after the
+        # PR had already merged, and failed outright at runner assignment
+        # roughly one run in six. Both faults are queueing artefacts, not
+        # review problems.
+        #
+        # Pinned to a dated image rather than ubuntu-latest so a GitHub-side
+        # image bump is an intentional, reviewable change.
+        default: '["ubuntu-24.04"]'
       timeout-minutes:
         type: number
         default: 30
@@ -24,7 +36,7 @@
         type: boolean
         default: false
       plugin-marketplace:
         description: "Optional plugin marketplace. Empty by default — the code-review plugin is broken on current Claude Code (spawns a non-existent claude-haiku agent), so we use a direct review prompt instead."
         type: string
         default: ""
       plugins:
@@ -91,10 +103,10 @@
           # on Claude Code 2.1.x — it spawns a non-existent claude-haiku agent
           # and posts nothing). Single line so it survives format(); a caller
           # passing `prompt` overrides it.
           prompt: ${{ inputs.prompt != '' && inputs.prompt || format('Review pull request {0}#{1} for bugs, security issues, performance problems, and missing test coverage. Follow the repo''s CLAUDE.md conventions if present. Post each specific problem as an inline comment with the mcp__github_inline_comment__create_inline_comment tool, and leave one short top-level summary via `gh pr comment`. Only flag real issues; if there are none, say so briefly.', github.repository, github.event.pull_request.number) }}
           # Without an explicit --allowedTools the inline-comment MCP tool is
           # denied, so Claude runs but posts nothing ("No buffered inline
           # comments" + permission_denials). Default to Anthropic's documented
           # PR-review tool set (examples/pr-review-comprehensive.yml); a caller
           # passing claude-args overrides it entirely.
           claude_args: ${{ inputs.claude-args != '' && inputs.claude-args || '--allowedTools "mcp__github_inline_comment__create_inline_comment,Bash(gh pr comment:*),Bash(gh pr diff:*),Bash(gh pr view:*)"' }}

CHANGELOG.md

@@ -6,6 +6,27 @@ project uses [SemVer](https://semver.org/) for the `vMAJOR.MINOR.PATCH` tags.
 
 ## [Unreleased]
 
+### Changed
+
+- **`claude-code-review.yml` now defaults to a GitHub-hosted runner**
+  (`["ubuntu-24.04"]`) instead of `["self-hosted", "linux", "x64"]`. The job
+  reads a PR diff and calls the Claude API — it needs no private-network
+  access, no local toolchain and no persistent state, so a self-hosted runner
+  bought it nothing while costing a great deal on a contended pool: measured
+  queue times of 40–77 minutes for 3–6 minutes of work, reviews routinely
+  landing after the PR had already merged, and outright failure at runner
+  assignment in roughly one run in six. Both faults are queueing artefacts
+  rather than review problems.
+
+  **This changes behaviour for every consumer that does not pass `runs-on`
+  explicitly** — currently all but one. Consumers that want the old behaviour
+  pass `runs-on: '["self-hosted", "linux", "x64"]'`, which is what
+  `sproncy/monitoring_stack` already does and is therefore unaffected.
+
+  Hosted minutes are metered on private repos; a review is 3–6 minutes, so
+  budget accordingly. The image is pinned to a dated label rather than
+  `ubuntu-latest` so a GitHub-side bump is an intentional, reviewable change.
+
 ## [3.3.0] - 2026-09-10
 
 ### Added