diff --git a/CHANGELOG.md b/CHANGELOG.md
index de4897e..f9a71bd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -34,7 +34,7 @@ All notable changes to this project will be documented here. Format: [Keep a Cha
 
 ### Validated end-to-end (M4 DoD)
 - `make clean && make up && make migrate && make seed-mitre` → 15 tactics / 222 techniques / 475 sub-techniques / 254 links / 0 orphans / ~1.1 s.
-- `make test-api` → **51 pytest pass** (1 health + 8 schema + 15 auth + 15 RBAC + 12 MITRE) in ~5 s.
+- `make test-api` → **53 pytest pass** (1 health + 8 schema + 15 auth + 15 RBAC + 14 MITRE) in ~5 s.
 - `make e2e` → **34 Playwright pass** (8 M0 + 4 M1 + 8 M2 + 8 M3 + 6 M4) in ~18 s.
 - Spec-reviewer PASS after fixes applied.
 
diff --git a/frontend/src/pages/MitrePage.tsx b/frontend/src/pages/MitrePage.tsx
index 411da1c..a674aad 100644
--- a/frontend/src/pages/MitrePage.tsx
+++ b/frontend/src/pages/MitrePage.tsx
@@ -118,7 +118,7 @@ export function MitrePage() {
 
       {selected.length === 0 && (
         <p className="mt-3 font-mono text-2xs text-text-dim">
-          Pick a tactic on the left, then a technique, then optionally a sub-technique. Selections accumulate.
+          Click any cell to toggle. Use <span className="text-purple">▸</span> to reveal sub-techniques inline. Hover a cell for its <code className="text-purple">external_id</code>. Selections accumulate.
         </p>
       )}
 
diff --git a/tasks/testing-m4.md b/tasks/testing-m4.md
index 7df8996..1de7211 100644
--- a/tasks/testing-m4.md
+++ b/tasks/testing-m4.md
@@ -21,7 +21,7 @@ make seed-mitre  # télécharge le bundle pinné v19.0 (~50 MB, ~1 s parse)
 ## 2. Tests automatisés
 
 ```bash
-make test-api    # 51 tests pytest dont 12 nouveaux MITRE (parser + endpoints)
+make test-api    # 53 tests pytest dont 14 nouveaux MITRE (parser + 5 read endpoints + matrix + status)
 make e2e         # 34 tests Playwright dont 6 M4
 ```