diff --git a/package.json b/package.json
index ef10141c..103050e3 100644
--- a/package.json
+++ b/package.json
@@ -26,6 +26,7 @@
     "check:framing": "tsx scripts/check-section-framing.ts",
     "check:self-input": "tsx scripts/check-self-provisioned-input.ts",
     "check:self-composed-set": "tsx scripts/check-self-composed-set.ts",
+    "check:branch-as-step": "tsx scripts/check-branch-as-step.ts",
     "check:activity-tech": "tsx scripts/check-activity-technique-overlap.ts",
     "check:prism-lenses": "tsx scripts/check-prism-lens-reachability.ts",
     "check:anchors": "tsx scripts/check-resource-anchors.ts",
diff --git a/scripts/guards.ts b/scripts/guards.ts
index e0b1f577..7f7f233f 100644
--- a/scripts/guards.ts
+++ b/scripts/guards.ts
@@ -152,6 +152,14 @@ export const GUARDS: GuardSpec[] = [
     json: false,
     proves: 'no set action builds its value out of the variable it writes',
   },
+  {
+    id: 'branch-as-step',
+    script: 'scripts/check-branch-as-step.ts',
+    npmScript: 'check:branch-as-step',
+    scope: 'corpus',
+    json: true,
+    proves: 'no protocol phase encodes a conditional branch as a step',
+  },
   {
     id: 'activity-technique-overlap',
     script: 'scripts/check-activity-technique-overlap.ts',
diff --git a/tests/e2e/__snapshots__/corpus-sha.json b/tests/e2e/__snapshots__/corpus-sha.json
index c06a2511..a7b7e1bd 100644
--- a/tests/e2e/__snapshots__/corpus-sha.json
+++ b/tests/e2e/__snapshots__/corpus-sha.json
@@ -1,4 +1,4 @@
 {
-  "corpusSha": "5f17da01a33bec58f36891d5af402231dd6d3a83",
+  "corpusSha": "fbd6f53bc8054f97ad631320d0cbe8151dfdcde9",
   "note": "Corpus commit the committed walk snapshots were generated against. Update it in the same commit that bumps the workflows submodule and re-baselines the walk (npm run baseline:stamp)."
 }
diff --git a/workflows b/workflows
index 5f17da01..fbd6f53b 160000
--- a/workflows
+++ b/workflows
@@ -1 +1 @@
-Subproject commit 5f17da01a33bec58f36891d5af402231dd6d3a83
+Subproject commit fbd6f53bc8054f97ad631320d0cbe8151dfdcde9