ADR-153 — Integrate @metaharness/darwin (Darwin Mode) into ruflo

Tracking issue for [ADR-153](https://github.com/ruvnet/ruflo/blob/main/v3/docs/adr/ADR-153-metaharness-darwin-mode-integration.md) — population-based harness self-improvement via [@metaharness/darwin@0.1.0](https://www.npmjs.com/package/@metaharness/darwin).

## Summary

`@metaharness/darwin` is the **write** layer of the metaharness ecosystem. Where [ADR-150](https://github.com/ruvnet/ruflo/blob/main/v3/docs/adr/ADR-150-metaharness-integration-surfaces.md) gave ruflo `score` / `genome` / `mcp-scan` / `threat-model` / `oia-audit` / `similarity` / `drift-from-history` (all read-only), Darwin Mode evolves a harness's 7 policy surfaces under a sandbox + safety inspector + promotion gate. **The model is frozen; the harness evolves.**

## Architectural constraints (per ADR-153, mirrors ADR-150)

1. **Removable** — `npm ls --without @metaharness/darwin` produces a working CLI
2. **Optional** — `@metaharness/darwin` lives in `optionalDependencies`, never `dependencies`
3. **Graceful degradation** — `MODULE_NOT_FOUND` emits `{degraded: true, reason: 'metaharness-darwin-not-installed', ...}` and exits 0
4. **CI gate** — `no-metaharness-smoke.yml` covers absence; `metaharness-ci.yml` adds a 5-min dry-run job

## Phase 1 MVP — checklist

- [ ] Add `@metaharness/darwin@~0.1.0` to `optionalDependencies` of:
- [ ] `package.json` (root umbrella)
- [ ] `ruflo/package.json`
- [ ] `v3/@claude-flow/cli/package.json`
- [ ] `plugins/ruflo-metaharness/scripts/evolve.mjs` — spawn wrapper, degraded payload on MODULE_NOT_FOUND, surfaces `winner.json` + top-N leaderboard
- [ ] Top-level CLI command `npx ruflo evolve ` (mirrors `ruflo eject`), or `metaharness evolve` subcommand — decide before implementation
- [ ] MCP tool `mcp__claude-flow__metaharness_evolve` with ADR-112 "Use when ..." guidance
- [ ] `npx ruflo doctor --component metaharness` extended to report `@metaharness/darwin` availability + `metaharness-darwin --version`
- [ ] New `darwin-dryrun` job in `.github/workflows/metaharness-ci.yml`:
- [ ] 5-min budget
- [ ] `metaharness-darwin evolve . --generations 1 --children 1 --concurrency 1 --seed 0` on a seed repo
- [ ] Asserts `archive.json` + `lineage.json` + `reports/winner.json` exist
- [ ] Smoke step 18 in `plugins/ruflo-metaharness/scripts/smoke.sh` — 5 grep checks + 1 runtime degraded-path check
- [ ] Extend `.github/workflows/no-metaharness-smoke.yml` graceful-degradation drill to cover darwin
- [ ] Update `CLAUDE.md` MetaHarness section with `ruflo evolve` + `metaharness_evolve`
- [ ] Add a "Darwin Mode" section to `docs/metaharness-user-guide.md`

## Explicit non-goals (Phase 1)

1. No model fine-tuning (model is frozen; harness evolves)
2. No auto-evolve in CI (user-initiated operation only)
3. No bypass of existing CVE / threat-model / mcp-scan checks
4. No cross-repo promotion (federation is Phase 3)
5. No in-place mutation of ruflo's own surfaces — variants land under `.metaharness/variants/`, promotion stays a manual PR through normal review

## Phases 2-4 (out of scope for this issue)

| Phase | Scope |
|---|---|
| 2 | Witness-sign winning archives (ADR-103) so promoted variants carry cryptographic provenance |
| 3 | Federated archives — share lineage trees across ruflo installations via the IPFS pattern from `hooks transfer` |
| 4 | Per-repo policy file `.metaharness/policy.json` — restrict which surfaces may mutate |

## Acceptance criteria

- All 4 ADR-153 architectural constraints verifiable via existing CI workflows
- Local validation: `bash plugins/ruflo-metaharness/scripts/smoke.sh` step 18 green
- Local validation: `npx ruflo evolve /tmp/seed-repo --generations 1 --children 1` produces archive/lineage/winner JSON
- Local validation: `npm uninstall @metaharness/darwin && npx ruflo evolve .` emits `{degraded: true, reason: 'metaharness-darwin-not-installed'}`, exits 0
- CI validation: new `darwin-dryrun` job in `metaharness-ci.yml` green
- Doctor validation: `npx ruflo doctor --component metaharness` includes a `darwin: { installed: true/false, version: '...' }` row

## Cross-references

- [ADR-153](https://github.com/ruvnet/ruflo/blob/main/v3/docs/adr/ADR-153-metaharness-darwin-mode-integration.md) — this integration design
- [ADR-150](https://github.com/ruvnet/ruflo/blob/main/v3/docs/adr/ADR-150-metaharness-integration-surfaces.md) — the original metaharness integration (read layer)
- [ADR-151](https://github.com/ruvnet/ruflo/blob/main/v3/docs/adr/ADR-151-harness-intelligence-layer.md) — the recommender that could consume Darwin archives (Phase 4 candidate)
- [ADR-152](https://github.com/ruvnet/ruflo/blob/main/v3/docs/adr/ADR-152-genome-similarity-search.md) — genome similarity (the metric Darwin's archive should ALSO be evaluated against)
- [@metaharness/darwin@0.1.0 on npm](https://www.npmjs.com/package/@metaharness/darwin)
- Upstream source: [`ruvnet/agent-harness-generator/packages/darwin-mode`](https://github.com/ruvnet/agent-harness-generator/tree/main/packages/darwin-mode)
- Upstream design ADRs: ADR-070…075 in the agent-harness-generator repo

## Target release

`ruflo@3.13.0` (MINOR — new CLI surface + MCP tool count, ADR-150 + ADR-153 are siblings).

🤖 Generated with [RuFlo](https://github.com/ruvnet/ruflo)

Start by reading ADR-153 and the existing ADR-150 integration, then inspect package.json files, plugins/ruflo-metaharness/scripts/evolve.mjs, smoke.sh, and the two metaharness workflows. Run the existing smoke script and review the current CLI and doctor entry points before choosing the evolve command shape. Done means the listed optional, degraded, CLI, MCP, doctor, smoke, CI, and documentation checks pass.

Written by the indexing model from the issue text.