Add README and plugin manifest for code-review-calibration

CI requires every skill directory to ship a README.md and a
.plugin/plugin.json with vendor symlinks so Codex and Claude Code can
load it.

Co-authored-by: openhands <openhands@all-hands.dev>

Author: rbren

skills/code-review-calibration/.claude-plugin

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+.plugin

skills/code-review-calibration/.codex-plugin

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+.plugin

skills/code-review-calibration/.plugin/plugin.json

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+{
+  "name": "code-review-calibration",
+  "version": "1.0.0",
+  "description": "Investigate a repository's commit history, bug fixes, reverts, house conventions, testing strategy, CI coverage, and past PR reviews, then write a calibrated code-review skill whose failure patterns, conventions, and hotspots are all cited from that repository.",
+  "author": {
+    "name": "OpenHands",
+    "email": "contact@all-hands.dev"
+  },
+  "homepage": "https://github.com/OpenHands/extensions",
+  "repository": "https://github.com/OpenHands/extensions",
+  "license": "MIT",
+  "keywords": [
+    "code-review",
+    "calibration",
+    "git-history",
+    "failure-patterns",
+    "conventions",
+    "hotspots"
+  ]
+}

skills/code-review-calibration/README.md

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+# Code Review Calibration
+
+Generate a code review skill that is calibrated to one specific repository, by investigating that repository's own history and conventions.
+
+## What It Does
+
+Most review guidance is generic, so the author has already heard it. This skill investigates a repo in two halves and writes what it learns to `.agents/skills/code-review.md`:
+
+- **How the codebase breaks** - fix-density hotspots, reverts, fix-inducing commits (SZZ), and temporal coupling between files.
+- **How the codebase works** - house conventions and idioms, testing strategy and regression-test discipline, what CI already enforces, and ownership/blast-radius signals.
+
+The result is a reviewer that can say "use `scopedQuery()`, the same omission caused `9f2a1bc`" instead of "consider filtering by tenant."
+
+## When to Use
+
+- "Write a code review skill for this repo"
+- "Recalibrate the reviewer to our codebase"
+- "Where do bugs cluster here?"
+- "What are our testing conventions?"
+- The current review skill is producing generic feedback
+- Onboarding to an unfamiliar codebase and needing to know its idioms and dangerous areas
+
+## Requirements
+
+- A git repository with real history. Very young or fully squash-merged repos yield weak patterns, and the skill is instructed to say so rather than pad the output.
+- Optional: GitHub CLI (`gh`), authenticated. Enables the PR review-comment phase, which shows what the team already knows is easy to get wrong.
+
+## Output
+
+Writes or updates `.agents/skills/code-review.md`. Generated sections are wrapped in `<!-- BEGIN GENERATED -->` / `<!-- END GENERATED -->` markers so later runs can refresh the evidence without discarding hand-written content.
+
+Ground rules the generated file must satisfy:
+
+- Every failure pattern cites two or more commit SHAs. Uncitable observations are nits and get dropped.
+- Six to twelve patterns. Beyond roughly fifteen the review loses focus.
+- Patterns that a design change made impossible move to a Retired section rather than being deleted.
+
+## Related Skills
+
+- `code-review` - perform a code review
+- `learn-from-code-review` - distill PR review feedback into guidelines
+- `agent-memory` - persist repository knowledge in AGENTS.md