diff --git a/BACKLOG-conc.md b/BACKLOG-conc.md
index 3e3acbc..e3efe0e 100644
--- a/BACKLOG-conc.md
+++ b/BACKLOG-conc.md
@@ -2,18 +2,18 @@
 
 ## Build backlog
 
-- [ ] P1 lock-lifetime hardening: prctl PDEATHSIG + ppid race check + SIGTERM handler →
+- [x] P1 lock-lifetime hardening: prctl PDEATHSIG + ppid race check + SIGTERM handler →
       teardown funnel + signal.alarm(3600) hard deadline; .drone.yml setsid/trap wrap;
       PEP 446 comment on lock open()
-- [ ] P2 flock-probe janitor: acquire_app_lock(domain) at register_run_app's call site;
+- [x] P2 flock-probe janitor: acquire_app_lock(domain) at register_run_app's call site;
       janitor probes per-domain lockfiles (acquired→reap under probe lock, held→leave,
       >120min mtime→warn); delete registry symbols
-- [ ] P3 per-run ABRA_DIR: /var/lib/cc-ci-runs/<build>/abra with servers+catalogue symlinks,
+- [x] P3 per-run ABRA_DIR: /var/lib/cc-ci-runs/<build>/abra with servers+catalogue symlinks,
       fresh recipes/; fetch_recipe = plain clone; delete acquire_recipe_lock; route harness
       recipe paths through ABRA_DIR
-- [ ] P4 config cleanup: remove concurrency.limit from .drone.yml; maxTests is the single knob
-- [ ] tests/concurrency suite (19 cases, real-kernel flock, explicit invocation only)
-- [ ] P5 docs/concurrency.md rewrite to the new model
+- [x] P4 config cleanup: remove concurrency.limit from .drone.yml; maxTests is the single knob
+- [x] tests/concurrency suite (19 cases, real-kernel flock, explicit invocation only)
+- [x] P5 docs/concurrency.md rewrite to the new model
 - [ ] M1 claim (branch complete, both suites + lint green)
 - [ ] M2: merge to main after M1 PASS, push build green, live verification a–d
 
diff --git a/STATUS-conc.md b/STATUS-conc.md
index 2e301d1..c8a2c3a 100644
--- a/STATUS-conc.md
+++ b/STATUS-conc.md
@@ -5,15 +5,46 @@ Plan: /srv/cc-ci/cc-ci-plan/concurrency-restructure-full-plan.md (SSOT for this
 ## Phase state
 
 - Phase: conc — concurrency restructure (P1–P5 + tests/concurrency)
-- Builder branch: `restructure/concurrency` (code lands there; main untouched until M2 merge)
-- Done on branch: P1 b492f99, P2 b302f3a, P3 17ebdf3, P4 91d3cc7
-- In flight: tests/concurrency suite (19 cases), then P5 spec rewrite
-- Gate: none claimed yet
+- Builder branch: `restructure/concurrency` — COMPLETE (P1–P5 + tests), tip `d3fe9e2`
+- Gate: **M1 — CLAIMED, awaiting Adversary**
+- M2 blocked on M1 PASS (no main merge yet; main untouched by this phase except state files)
 
-## Gates
+## Gate claim: M1 — implementation verified
 
-- M1 (implementation verified): NOT CLAIMED
-- M2 (merged + live-verified): NOT CLAIMED — blocked on M1 PASS
+**WHAT**: Branch `restructure/concurrency` implements the full phase plan: P1 lock-lifetime
+hardening, P2 flock-probe janitor (registry deleted), P3 per-run ABRA_DIR (recipe flock
+deleted), P4 single concurrency knob, P5 spec rewrite, + `tests/concurrency` (20 tests covering
+the 19 plan cases). One commit per phase.
+
+**WHERE**: origin/restructure/concurrency, commits (in order):
+- P1 `b492f99` — harness/lifetime.py guards + .drone.yml setsid/trap wrap
+- P2 `b302f3a` — acquire_app_lock + _probe_and_reap + janitor rewrite; registry symbols deleted
+- P3 `17ebdf3` — setup_run_abra_dir + per-run fetch_recipe + abra.abra_dir()/recipe_dir()
+  routing; acquire_recipe_lock/RECIPE_LOCK_DIR deleted; tests/{ghost,discourse}/install_steps.sh
+  one-line RECIPE_DIR resolution fix (justification: machine-docs/DECISIONS.md "conc P3" entry)
+- P4 `91d3cc7` — concurrency.limit removed from .drone.yml; maxTests comment updated
+- tests `84d90fb` — tests/concurrency/ (real-kernel; NOT in the default unit gate)
+- P5 `d3fe9e2` — docs/concurrency.md rewritten to the new model
+
+**HOW to verify (cold, from your clone)**:
+1. `git fetch && git checkout restructure/concurrency` (tip must be `d3fe9e2`)
+2. `cc-ci-run -m pytest tests/unit -q`
+3. `cc-ci-run -m pytest tests/concurrency -q`  (real flocks; uses tmp dirs, reaps its helpers)
+4. `nix develop .#lint --command bash scripts/lint.sh`
+5. dangling-reference grep (expect ZERO hits in code):
+   `grep -rn "register_run_app\|unregister_run_app\|_run_owner_state\|ACTIVE_RUN_DIR\|CCCI_JANITOR_MAX_AGE\|acquire_recipe_lock\|RECIPE_LOCK_DIR\|_stack_age_seconds" --include="*.py" --include="*.nix" --include="*.yml" --include="*.sh" .`
+6. adversarial diff review per phase plan (races, deleted-code fallout, gate integrity vs
+   RUN_APP_RE/warm apps/services_converged, test-suite blind spots vs the 19 cases)
+
+**EXPECTED**:
+- tests/unit: `138 passed`
+- tests/concurrency: `20 passed` (runtime ~10 s; spawns helper subprocesses, cleans them up)
+- lint: `lint: PASS`
+- grep: no hits outside docs/git-history references (docs/concurrency.md lists them as deleted)
+- `pytest tests/unit` does NOT collect tests/concurrency (separate dir, explicit invocation only)
+- gate-integrity notes: RUN_APP_RE, services_converged()/paused-is-settled, teardown_app order,
+  warm/canonical flows untouched; only non-assertion change under tests/<recipe>/ is the
+  RECIPE_DIR line in ghost+discourse install_steps.sh (DECISIONS.md "conc P3")
 
 ## Blockers