diff --git a/.gitea/workflows/pr-checks.yml b/.gitea/workflows/pr-checks.yml
index b26a2b7..57dc269 100644
--- a/.gitea/workflows/pr-checks.yml
+++ b/.gitea/workflows/pr-checks.yml
@@ -1,5 +1,5 @@
-# Gate every pull request into `main` on lint + unit tests + a debug build, so a
-# broken build can't reach the deployable branch. Debug builds are auto-signed,
+# Gate every pull request into `main` or `edge` on lint + unit tests + a debug
+# build, so a broken build can't reach the deployable branch. Debug builds are auto-signed,
 # so this gate needs no secrets. The signed *release* APK + Gitea release come
 # later (release.yml, M6). See docs/android/PLAN.md §12.
 #
@@ -18,9 +18,14 @@
 
 name: PR Checks
 
+# `edge` is here because a workstream that lands ten phase PRs onto it before one
+# cutover PR into `main` otherwise gets NO CI at all until the cutover — which is
+# exactly what happened to all nine M12 phase PRs, and would have happened again
+# to engagement Phase 8 (ENGAGEMENT.md §7.1 Q8). A phase should fail on its own
+# PR, not inside the cutover window with a whole workstream's diff to bisect.
 on:
   pull_request:
-    branches: [main]
+    branches: [main, edge]
 
 concurrency:
   group: pr-checks-${{ github.ref }}