diff --git a/REVIEW-conc.md b/REVIEW-conc.md
index ae38453..340f876 100644
--- a/REVIEW-conc.md
+++ b/REVIEW-conc.md
@@ -30,3 +30,21 @@ Current-system facts I will hold the restructure against:
   same PR blocks visibly, one full green run. NEVER merge/push recipe mirror repos.
 
 No verdict yet — waiting for Builder bootstrap/claim.
+
+## 2026-06-10T04:05Z — cold-verify environment established (prep, no gate)
+
+Builder seeded STATUS/BACKLOG/JOURNAL-conc; STATUS says P1 in flight, no gate claimed. Mapped the
+test-execution environment I'll use for the M1 cold run so a time-sensitive gate isn't spent
+debugging tooling:
+- Local VM devshell (`nix develop`) has only lintTools (no pytest). So pytest does NOT run here.
+- pytest 8.3.3 + playwright live in the host `pyEnv` (nix/modules/harness.nix) exposed as
+  `cc-ci-run` on cc-ci. `cc-ci-run -m pytest <path> -q` works as the real harness interpreter
+  (verified: `cc-ci-run -c "import pytest" -> 8.3.3`).
+- `.drone.yml` lint stage runs `nix develop .#lint --command bash scripts/lint.sh`.
+- COLD M1 PLAN: fresh `git clone`/checkout of `restructure/concurrency` into a throwaway dir ON
+  cc-ci → `cc-ci-run -m pytest tests/unit -q` + `cc-ci-run -m pytest tests/concurrency -q` +
+  `nix develop .#lint --command bash scripts/lint.sh`, all from that clean checkout (not the
+  Builder's working tree). Then adversarial diff review per my baseline hit-list.
+- Baseline `.drone.yml` on main is still the pre-restructure version (concurrency.limit=2,
+  acquire_recipe_lock / /run/cc-ci-active registry referenced) — confirms P1/P4 edits are
+  branch-only so far. Good.