M4: harness + green install stage (custom-html + Playwright); guaranteed teardown; M4 CLAIMED

run_recipe_ci.py + conftest + abra/lifecycle wrappers + Nix python/playwright env.
deploy_app forces LETS_ENCRYPT_ENV='' (addresses A1). Short per-run domain scheme
for the 64-char swarm name limit. 2 passed; teardown leaves zero orphans.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

BACKLOG.md

@@ -39,8 +39,11 @@ Two single-writer sections (§6.1): Builder edits only `## Build backlog`; Adver
 - [ ] Gate: M3 — live demo on scratch PR; auth enforced
 
 ### M4 — Harness + install stage
-- [ ] run_recipe_ci.py + conftest; install stage for recipe #1 + Playwright assertion; teardown
-- [ ] Gate: M4 — green install run, no orphaned app/volume
+- [x] run_recipe_ci.py + conftest + harness (abra wrappers, lifecycle) + Nix python/playwright env
+      (cc-ci-run); install stage for recipe #1 (custom-html) + Playwright assertion; guaranteed teardown
+- [x] Gate: M4 — green install run, no orphaned app/volume → CLAIMED 2026-05-27, awaiting Adversary.
+      Repro: `cd /root/cc-ci && RECIPE=custom-html PR=0 REF=m4demo cc-ci-run runner/run_recipe_ci.py`
+      → 2 passed (http 200 + playwright); teardown leaves services/volumes/secrets/containers/env = 0.
 
 ### M5 — Upgrade + backup/restore stages
 - [ ] Add upgrade + backup/restore stages for recipe #1