fix(editor): NodeEditorDialog — correct bracket-form path wrapping + focus trap on open

frontend/src/editor/NodeEditorDialog.test.tsx

@@ -192,6 +192,37 @@ describe("NodeEditorDialog", () => {
     expect(props.onClose).toHaveBeenCalled();
   });
 
+  it("focuses the first form field on open", async () => {
+    renderDialog();
+    // jsdom autofocuses via .focus(); label textarea should be active.
+    const label = screen.getByLabelText(/node label/i);
+    expect(document.activeElement).toBe(label);
+  });
+
+  it("bracket-form top-level keys wrap without a stray dot separator", async () => {
+    server.use(
+      http.get("/api/workflows/:id/executions", () =>
+        HttpResponse.json([
+          { id: "e1", workflowId: "wf1", trigger: "manual", status: "completed",
+            startedAt: "", endedAt: "", error: null } satisfies ExecutionSummary,
+        ])),
+      http.get("/api/executions/e1", () =>
+        HttpResponse.json({
+          id: "e1", workflowId: "wf1", trigger: "manual", status: "completed",
+          startedAt: "", endedAt: "", error: null,
+          nodes: [
+            { nodeId: "n1", status: "completed", startedAt: "", endedAt: "", error: null,
+              inputs: [[{ json: { "weird.key": "v" } }]], outputs: [] },
+          ],
+        } satisfies ExecutionDetail)),
+    );
+    renderControlledDialog();
+    const body = await screen.findByLabelText(/^body/i) as HTMLTextAreaElement;
+    body.focus();
+    await userEvent.click(await screen.findByText("weird.key"));
+    expect(body.value).toBe(`{input["weird.key"]}`);
+  });
+
   it("clicking a leaf in the Input tree inserts {input.<path>} at the focused parameter", async () => {
     // Seed an execution so the input tree has a leaf.
     server.use(

frontend/src/editor/NodeEditorDialog.tsx

@@ -39,6 +39,41 @@ export function NodeEditorDialog({
     return () => document.removeEventListener("keydown", onKey);
   }, [onClose]);
 
+  // Initial focus on mount — the first field inside the dialog body.
+  useEffect(() => {
+    const first = dialogRef.current?.querySelector<HTMLElement>(
+      "textarea, input, select"
+    );
+    first?.focus();
+  }, []);
+
+  // Focus trap: Tab / Shift+Tab cycle within the dialog. jsdom doesn't
+  // simulate real browser tab-order, so this behavior is intentionally
+  // exercised only in-browser — no unit test covers the wrap-around.
+  useEffect(() => {
+    function onKey(e: KeyboardEvent) {
+      if (e.key !== "Tab" || !dialogRef.current) return;
+      const focusables = Array.from(
+        dialogRef.current.querySelectorAll<HTMLElement>(
+          'textarea, input, select, button, [tabindex]:not([tabindex="-1"])'
+        ),
+      ).filter((el) => !el.hasAttribute("disabled"));
+      if (focusables.length === 0) return;
+      const first = focusables[0];
+      const last = focusables[focusables.length - 1];
+      const active = document.activeElement as HTMLElement | null;
+      if (e.shiftKey && active === first) {
+        e.preventDefault();
+        last.focus();
+      } else if (!e.shiftKey && active === last) {
+        e.preventDefault();
+        first.focus();
+      }
+    }
+    document.addEventListener("keydown", onKey);
+    return () => document.removeEventListener("keydown", onKey);
+  }, []);
+
   const executions = useExecutions(workflowId);
   const [pinnedExecutionId, setPinnedExecutionId] = useState<string | null>(null);
   const eid = pinnedExecutionId ?? executions.data?.[0]?.id;
@@ -78,7 +113,12 @@ export function NodeEditorDialog({
     focusedFieldRef.current = h;
   }, []);
   const insertPath = useCallback((path: string) => {
-    focusedFieldRef.current?.insertAtCaret(`{input.${path}}`);
+    // JsonTree emits identifier-rooted paths (`body.email`, `tags[1]`) or
+    // bracket-rooted paths (`["weird.key"]`, `[0].a`). Backend TemplateEngine
+    // grammar requires no separator before a leading `[` (i.e., `{input[0]}`,
+    // not `{input.[0]}`). Insert `.` only for identifier roots.
+    const sep = path.startsWith("[") ? "" : ".";
+    focusedFieldRef.current?.insertAtCaret(`{input${sep}${path}}`);
   }, []);
 
   const filteredConnections = connections.filter((c) => c.providerId === nt?.connectionProviderId);