feat: adversarial prompt rewrite + README + example

- Rewrite all review prompts with XML-structured adversarial stance
  (role, operating_stance, attack_surface, finding_bar, calibration)
- Rename skill from codex-review to adversarial-review
- Add verbatim output rule for reviewer findings
- Improve resume prompt with adversarial re-review focus
- Add README with installation, usage, architecture, roadmap
- Add synthetic example of review output
- Inspired by openai/codex-plugin-cc (Apache-2.0) prompt structure

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

README.md

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+# Adversarial Review
+
+Claude Code skill for adversarial AI code and plan review.
+
+One AI writes the code. Another tears it apart. Iterate until approved.
+
+## What is this
+
+Most AI code review tools validate your changes — "looks good, maybe add tests."
+Adversarial review does the opposite: the reviewer **defaults to skepticism**
+and tries to break confidence in the change. It looks for what will fail
+in production, not what might be nice to improve.
+
+This is a [Claude Code skill](https://docs.anthropic.com/en/docs/claude-code)
+— a single `SKILL.md` file that teaches Claude how to run adversarial reviews
+through an external AI model (currently OpenAI Codex).
+
+## Key features
+
+**Two stages** — works on both planning and implementation:
+- **Plan review** — review the plan BEFORE writing code. Catch architecture
+  mistakes, missing steps, and risks early
+- **Code review** — review the implementation. Bugs, security, data loss
+- **Code-vs-plan** — verify the implementation matches the plan
+
+**Lightweight** — one file, no server, no broker, no dependencies beyond
+the reviewer CLI. Compare with [codex-plugin-cc](https://github.com/openai/codex-plugin-cc):
+~15 JS modules, App Server, JSON-RPC broker, lifecycle hooks.
+This skill is a text instruction that any AI agent can interpret.
+
+**Iterative** — Claude doesn't just show the review and stop.
+It actively fixes issues based on reviewer feedback and resubmits
+for re-review. Up to 5 rounds until approved.
+
+**Universal foundation** — the skill relies on basic agent capabilities:
+run a command, read a file, edit a file. The reviewer is a swappable
+component: today Codex, tomorrow Gemini CLI, next week a local model.
+Switching backends = changing one launch command; prompts and workflow stay the same.
+
+## How it works
+
+```
+┌─────────┐     ┌──────────┐     ┌─────────┐
+│  Claude  │────>│ Reviewer  │────>│  Claude  │
+│  (code)  │     │ (Codex)   │     │  (fix)   │
+└─────────┘     └──────────┘     └─────────┘
+     ^                                 │
+     │         ┌──────────┐            │
+     └─────────│ Reviewer  │<───────────┘
+               │(re-review)│
+               └──────────┘
+                    │
+              VERDICT: APPROVED
+```
+
+### Three modes
+
+| Mode | What it reviews | When to use |
+|------|----------------|-------------|
+| `plan` | Implementation plan | Before writing code |
+| `code` | Git diff (unstaged, staged, or branch) | After writing code |
+| `code-vs-plan` | Code changes against the plan | Verify implementation matches plan |
+
+Mode is auto-detected from context, or you can force it with an argument.
+
+## Installation
+
+### Requirements
+
+- [Claude Code](https://docs.anthropic.com/en/docs/claude-code)
+- [OpenAI Codex CLI](https://github.com/openai/codex): `npm install -g @openai/codex`
+- OpenAI API key (`OPENAI_API_KEY` environment variable)
+
+### Setup
+
+```bash
+# Clone the repository
+git clone https://github.com/<your-username>/adversarial-review.git
+
+# Symlink into Claude Code skills directory
+ln -s "$(pwd)/adversarial-review" ~/.agents/skills/adversarial-review
+```
+
+After symlinking, the skill is available as `/adversarial-review` in Claude Code.
+
+## Usage
+
+```
+# Auto-detect what to review
+/adversarial-review
+
+# Review a plan
+/adversarial-review plan
+
+# Review code changes
+/adversarial-review code
+
+# Review a specific file
+/adversarial-review path/to/plan.md
+
+# Use higher reasoning effort
+/adversarial-review xhigh
+
+# Use a different model
+/adversarial-review model:gpt-5.3-codex
+```
+
+## Prompt architecture
+
+The skill uses XML-structured prompts inspired by adversarial review methodology:
+
+- **`<role>`** — adversarial reviewer, defaults to skepticism
+- **`<operating_stance>`** — break confidence, not validate
+- **`<attack_surface>`** — concrete checklist: auth, data integrity,
+  race conditions, rollback safety, schema drift, error handling, observability
+- **`<finding_bar>`** — every finding must answer 4 questions:
+  what can go wrong, why this code is vulnerable, impact, recommendation
+- **`<scope_exclusions>`** — no style, naming, or speculative comments
+- **`<calibration>`** — one strong finding > five weak ones
+
+## Example output
+
+See [examples/review-output.md](examples/review-output.md) for a sample
+adversarial review output.
+
+## Roadmap
+
+- [ ] Gemini as alternative reviewer backend
+- [ ] Local model support (Ollama, llama.cpp)
+- [ ] CI integration (GitHub Actions)
+- [ ] Multi-reviewer mode (parallel review by multiple models)
+
+## Inspiration
+
+The adversarial prompt structure was developed after studying
+[openai/codex-plugin-cc](https://github.com/openai/codex-plugin-cc) (Apache-2.0)
+— the official OpenAI plugin for code review with Codex in Claude Code.
+
+What we borrowed as ideas:
+- XML-structured prompts (`<role>`, `<operating_stance>`, `<attack_surface>`, etc.)
+- Adversarial stance: "break confidence, not validate"
+- Attack surface checklist approach
+- Finding bar: 4 questions each finding must answer
+- Calibration rules: prefer strong findings over weak ones
+
+What we did differently:
+- **Iterative loop** — Claude actively fixes issues and resubmits (vs "stop and ask user")
+- **Plan review** — reviews plans before code, not just code
+- **Single file** — one SKILL.md vs 15+ JS modules with App Server
+- **Verbatim output** — reviewer findings shown as-is, not rephrased
+
+## License
+
+Apache-2.0 — see [LICENSE](LICENSE).