ci(experiment): add diagnostics to screenshot step; run as node

Author: kantord

.github/workflows/experiment-devcontainer-proof.yml

@@ -116,33 +116,49 @@ jobs:
           docker exec "$C" tail -200 /tmp/entrypoint.log || true
           exit 1
 
-      - name: Screenshot 1 — initial paint
+      - name: Display + tooling sanity check
         run: |
           C=${{ steps.container.outputs.id }}
-          docker exec "$C" bash -c 'DISPLAY=:99 import -window root /tmp/shot1.png'
-          docker cp "$C:/tmp/shot1.png" ./shot1.png
-          ls -la ./shot1.png
+          echo '--- which import / xdotool / xwininfo ---'
+          docker exec "$C" bash -c 'which import xdotool xwininfo xdpyinfo 2>&1 || true'
+          echo '--- xdpyinfo (X server reachable on :99?) ---'
+          docker exec -u node "$C" bash -c 'DISPLAY=:99 xdpyinfo 2>&1 | head -10' || echo "xdpyinfo failed exit=$?"
+          echo '--- xwininfo -root -tree ---'
+          docker exec -u node "$C" bash -c 'DISPLAY=:99 xwininfo -root -tree 2>&1' || true
+          echo '--- xdotool search --name ToolHive ---'
+          docker exec -u node "$C" bash -c 'DISPLAY=:99 xdotool search --name ToolHive 2>&1' || true
 
-      - name: Inspect window tree (sanity check)
+      - name: Screenshot 1 — initial paint
         run: |
+          set -x
           C=${{ steps.container.outputs.id }}
-          echo '--- xwininfo -root -tree ---'
-          docker exec "$C" bash -c 'DISPLAY=:99 xwininfo -root -tree' || true
-          echo '--- xdotool search --name ToolHive ---'
-          docker exec "$C" bash -c 'DISPLAY=:99 xdotool search --name ToolHive' || true
+          # Run as `node` to match the X server owner. Capture stderr explicitly
+          # so we can see *why* import fails if it does, instead of inferring.
+          docker exec -u node "$C" bash -c '
+            set -x
+            DISPLAY=:99 import -window root /tmp/shot1.png 2>&1
+            echo "import exit=$?"
+            ls -la /tmp/shot1.png 2>&1
+          '
+          docker cp "$C:/tmp/shot1.png" ./shot1.png
+          ls -la ./shot1.png
 
       - name: Drive xdotool — focus app and send Tab
         run: |
           C=${{ steps.container.outputs.id }}
-          docker exec "$C" bash -c 'DISPLAY=:99 xdotool search --name ToolHive windowactivate' || true
+          docker exec -u node "$C" bash -c 'DISPLAY=:99 xdotool search --name ToolHive windowactivate' || true
           sleep 2
-          docker exec "$C" bash -c 'DISPLAY=:99 xdotool key Tab' || true
+          docker exec -u node "$C" bash -c 'DISPLAY=:99 xdotool key Tab' || true
           sleep 1
 
       - name: Screenshot 2 — after input
         run: |
           C=${{ steps.container.outputs.id }}
-          docker exec "$C" bash -c 'DISPLAY=:99 import -window root /tmp/shot2.png'
+          docker exec -u node "$C" bash -c '
+            DISPLAY=:99 import -window root /tmp/shot2.png 2>&1
+            echo "import exit=$?"
+            ls -la /tmp/shot2.png 2>&1
+          '
           docker cp "$C:/tmp/shot2.png" ./shot2.png
           ls -la ./shot2.png