ci(deploy-cp): run STONITH verify last, after the agent relaunch

.github/workflows/deploy-cp.yml

@@ -275,41 +275,6 @@ jobs:
           echo "::error::dashboard / never returned 200 (last HTTP ${code})"
           exit 1
 
-      - name: Verify STONITH halted prior VM(s) in this env
-        env:
-          GCP_PROJECT_ID: ${{ secrets.GCP_PROJECT_ID }}
-        run: |
-          # dd-register STONITHs the old VM on startup by deleting its
-          # CF tunnel → old cloudflared exits → old dd-register poweroffs.
-          # Scoped to this env — per-PR previews are hostname-isolated,
-          # so this only reaps prior deploys of the same env.
-          NEW_VM=$(gcloud compute instances list \
-            --project="$GCP_PROJECT_ID" \
-            --filter="labels.devopsdefender=managed AND labels.dd_env=${DD_ENV}" \
-            --format="value(name)" --sort-by=~creationTimestamp | head -1)
-          echo "new VM: $NEW_VM"
-          SURVIVORS=""
-          for i in $(seq 1 24); do
-            SURVIVORS=$(gcloud compute instances list \
-              --project="$GCP_PROJECT_ID" \
-              --filter="labels.devopsdefender=managed AND labels.dd_env=${DD_ENV} AND status=RUNNING" \
-              --format="value(name)" \
-              | grep -vx "$NEW_VM" || true)
-            if [ -z "$SURVIVORS" ]; then
-              echo "STONITH verified — only $NEW_VM running in ${DD_ENV}"
-              exit 0
-            fi
-            echo "  still running besides $NEW_VM: $(echo "$SURVIVORS" | tr '\n' ' ')"
-            echo "  waiting for STONITH poweroff... (${i}/24)"
-            sleep 5
-          done
-          echo "::warning::STONITH-by-tunnel-delete timed out; force-deleting zombies:"
-          echo "$SURVIVORS"
-          # shellcheck disable=SC2086
-          gcloud compute instances delete $SURVIVORS \
-            --project="$GCP_PROJECT_ID" --zone="$GCP_ZONE" --quiet || true
-          echo "zombies reaped; $NEW_VM is the only ${DD_ENV} VM"
-
       - name: Comment preview URL on PR
         if: inputs.comment_on_pr && github.event_name == 'pull_request'
         uses: actions/github-script@v7
@@ -365,3 +330,45 @@ jobs:
           host: ${{ secrets.DD_LOCAL_HOST }}
           dd-pat: ${{ secrets.GITHUB_TOKEN }}
           ita-api-key: ${{ secrets.DD_ITA_API_KEY }}
+
+      # Runs last so the relaunch cascade's own STONITH wave (old agent
+      # re-registers → old CP's CF tunnel is deleted → old CP poweroffs)
+      # is captured by this verification, in addition to the kill that
+      # happens when the new CP first registers its own tunnel. Also
+      # keeps the slowest + flakiest verify (24×5s loop + fallback
+      # force-delete) behind the user-facing outputs (PR comment,
+      # relaunched local agent).
+      - name: Verify STONITH halted prior VM(s) in this env
+        env:
+          GCP_PROJECT_ID: ${{ secrets.GCP_PROJECT_ID }}
+        run: |
+          # dd-register STONITHs the old VM on startup by deleting its
+          # CF tunnel → old cloudflared exits → old dd-register poweroffs.
+          # Scoped to this env — per-PR previews are hostname-isolated,
+          # so this only reaps prior deploys of the same env.
+          NEW_VM=$(gcloud compute instances list \
+            --project="$GCP_PROJECT_ID" \
+            --filter="labels.devopsdefender=managed AND labels.dd_env=${DD_ENV}" \
+            --format="value(name)" --sort-by=~creationTimestamp | head -1)
+          echo "new VM: $NEW_VM"
+          SURVIVORS=""
+          for i in $(seq 1 24); do
+            SURVIVORS=$(gcloud compute instances list \
+              --project="$GCP_PROJECT_ID" \
+              --filter="labels.devopsdefender=managed AND labels.dd_env=${DD_ENV} AND status=RUNNING" \
+              --format="value(name)" \
+              | grep -vx "$NEW_VM" || true)
+            if [ -z "$SURVIVORS" ]; then
+              echo "STONITH verified — only $NEW_VM running in ${DD_ENV}"
+              exit 0
+            fi
+            echo "  still running besides $NEW_VM: $(echo "$SURVIVORS" | tr '\n' ' ')"
+            echo "  waiting for STONITH poweroff... (${i}/24)"
+            sleep 5
+          done
+          echo "::warning::STONITH-by-tunnel-delete timed out; force-deleting zombies:"
+          echo "$SURVIVORS"
+          # shellcheck disable=SC2086
+          gcloud compute instances delete $SURVIVORS \
+            --project="$GCP_PROJECT_ID" --zone="$GCP_ZONE" --quiet || true
+          echo "zombies reaped; $NEW_VM is the only ${DD_ENV} VM"