diff --git a/docker-compose.yml b/docker-compose.yml
index 4eb915848..e33ba70a8 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -131,6 +131,13 @@ services:
       dockerfile: Dockerfile-migrate
     environment:
       - MONGODB_ADDRESS=mongodb
+      # Required by the notification-topic migrations; they throw without it.
+      # Absent here, `make test-migrate` never got past 20260317125624 — and
+      # because the entrypoint swallowed the failure, CI reported the clean
+      # migration run as green anyway. Same defect that let prod go five
+      # months unmigrated (ENG-565). Values are placeholders: this is a
+      # throwaway database, so only the shape matters.
+      - NOTIFICATION_TOPICS=EMERGENCY,ATTENTION
   mongodb:
     image: mongo:${MONGODB_VERSION:-6.0.5}
     ports: []
diff --git a/scripts/mongodb-migrate.sh b/scripts/mongodb-migrate.sh
index 31938604e..3f6cbbdc4 100755
--- a/scripts/mongodb-migrate.sh
+++ b/scripts/mongodb-migrate.sh
@@ -1,5 +1,41 @@
 #!/bin/sh
+#
+# Runs on every helm release, and EVERY Mongo-touching workload waits on it via
+# the `wait-for-mongodb-migrate` initContainer. That gate is only worth
+# anything if this script can fail — so it does.
+#
+# It did not, until 2026-08-26. `migrate-mongo up` aborts the whole run on the
+# first migration that throws, and with no `set -e` and a trailing `status`
+# (which always succeeds) the Job exited 0 regardless. Prod applied no
+# migration for five months while every deploy reported success, and the
+# breakage only surfaced when an api pod crash-looped building a unique index
+# whose dedupe migration had never run. See ENG-565.
+set -eu
 
-node_modules/.bin/migrate-mongo status -f src/migrations/migrate-mongo-config.js
-node_modules/.bin/migrate-mongo up -f src/migrations/migrate-mongo-config.js
-node_modules/.bin/migrate-mongo status -f src/migrations/migrate-mongo-config.js
+CONFIG=src/migrations/migrate-mongo-config.js
+MIGRATE=node_modules/.bin/migrate-mongo
+
+echo "=== migrations before ==="
+"$MIGRATE" status -f "$CONFIG"
+
+echo "=== applying ==="
+# `set -e` already aborts here on a non-zero exit, which is the common failure
+# (a migration throwing). Belt and braces below for the case where migrate-mongo
+# reports success while leaving work undone.
+"$MIGRATE" up -f "$CONFIG"
+
+echo "=== migrations after ==="
+STATUS_AFTER=$("$MIGRATE" status -f "$CONFIG")
+echo "$STATUS_AFTER"
+
+# A green run that applied nothing is indistinguishable from a real one unless
+# we look. Anything still PENDING here means the DB is not at the schema this
+# release expects, and admitting pods against it is how the index-build
+# crash-loop happened.
+if echo "$STATUS_AFTER" | grep -q "PENDING"; then
+  echo "ERROR: migrations still PENDING after 'up' — refusing to report success." >&2
+  echo "Pods gate on this Job; letting it pass would start them against an unmigrated database." >&2
+  exit 1
+fi
+
+echo "All migrations applied."
diff --git a/src/migrations/20260423000000-bridge-virtual-account-unique-accountid.ts b/src/migrations/20260423000000-bridge-virtual-account-unique-accountid.ts
index 3b6d676b4..cb67027dc 100644
--- a/src/migrations/20260423000000-bridge-virtual-account-unique-accountid.ts
+++ b/src/migrations/20260423000000-bridge-virtual-account-unique-accountid.ts
@@ -70,7 +70,12 @@ module.exports = {
     }
 
     // ── Step 2: drop stale plain index if it exists ──────────────────────────
-    const existingIndexes = await col.indexes()
+    // `.indexes()` throws "ns does not exist" on a collection the app has not
+    // created yet — which is every fresh database, including the clean run in
+    // `make test-migrate`. `createIndex` below creates the collection
+    // implicitly, so treating "no namespace" as "no indexes" is correct rather
+    // than merely tolerant.
+    const existingIndexes = await col.indexes().catch(() => [])
     const hasPlainIndex = existingIndexes.some(
       (idx) => idx.name === INDEX_NAME && !idx.unique,
     )
@@ -88,7 +93,7 @@ module.exports = {
     const col = db.collection(COLLECTION)
 
     // Drop the unique index
-    const existingIndexes = await col.indexes()
+    const existingIndexes = await col.indexes().catch(() => [])
     const hasUniqueIndex = existingIndexes.some(
       (idx) => idx.name === INDEX_NAME && idx.unique,
     )