diff --git a/.github/workflows/e2e.yml b/.github/workflows/e2e.yml
index 266ce55..fc2f26a 100644
--- a/.github/workflows/e2e.yml
+++ b/.github/workflows/e2e.yml
@@ -23,6 +23,11 @@ on:
         description: "CLI version to test (e.g. 0.1.16). Empty = latest release."
         required: false
         default: ""
+      test_alert:
+        description: "Also fire the Slack alert on this manual run if e2e fails (for testing the notify job)."
+        type: boolean
+        required: false
+        default: false
   schedule:
     - cron: "0 6 * * *"
 
@@ -133,17 +138,18 @@ jobs:
           [ -n "$MARKERS" ] && args+=(-m "$MARKERS")
           uv run --project tests/e2e pytest tests/e2e "${args[@]}"
 
-  # Alert Slack when any e2e leg does not succeed. Runs only on the nightly
-  # schedule — manual dispatch is interactive, so the operator already sees the
-  # result. `result != 'success'` covers both failures and cancellations (the
-  # 30-min job timeout cancels rather than fails), so timed-out nightly runs
-  # still alert. Needs the SLACK_WEBHOOK_URL repo secret (a Slack Incoming
-  # Webhook URL; the target channel is fixed by the webhook). Self-skips if the
-  # secret is unset.
+  # Alert Slack when any e2e leg does not succeed. Fires on the nightly
+  # schedule (manual dispatch is interactive, so the operator already sees the
+  # result) — or on a manual run started with test_alert=true, to verify the
+  # notify path on demand without waiting for the cron. `result != 'success'`
+  # covers both failures and cancellations (the 30-min job timeout cancels
+  # rather than fails), so timed-out nightly runs still alert. Needs the
+  # SLACK_WEBHOOK_URL repo secret (a Slack Incoming Webhook URL; the target
+  # channel is fixed by the webhook). Self-skips if the secret is unset.
   notify:
     name: notify-slack-on-failure
     needs: e2e
-    if: ${{ always() && github.event_name == 'schedule' && needs.e2e.result != 'success' }}
+    if: ${{ always() && needs.e2e.result != 'success' && (github.event_name == 'schedule' || inputs.test_alert) }}
     runs-on: ubuntu-latest
     steps:
       - name: Post failure to Slack