feat(editor): show composed webhook URL + Copy button on Webhook nodes

When the selected node is http.webhook, the config panel now shows the full
POST URL (${origin}/wh/${workflowId}/${path}) with a one-click Copy button
and an active-workflow reminder. Removes the guesswork of assembling the
URL by hand from the design spec.

frontend/src/editor/NodeConfigPanel.tsx

@@ -1,3 +1,5 @@
+import { useState } from "react";
+import { Copy, Check } from "lucide-react";
 import { useNodeTypes, useConnections } from "@/api/hooks";
 import { SchemaForm } from "@/forms/SchemaForm";
 import type { Node } from "@xyflow/react";
@@ -7,9 +9,11 @@ interface Props {
   selected: Node<VcNodeData> | null;
   onChange: (patch: Partial<VcNodeData>) => void;
   onDelete: () => void;
+  workflowId: string;
+  workflowActive: boolean;
 }
 
-export function NodeConfigPanel({ selected, onChange, onDelete }: Props) {
+export function NodeConfigPanel({ selected, onChange, onDelete, workflowId, workflowActive }: Props) {
   const nts = useNodeTypes();
   const cs = useConnections();
   if (!selected) {
@@ -56,6 +60,13 @@ export function NodeConfigPanel({ selected, onChange, onDelete }: Props) {
           onChange={(v) => onChange({ config: v })}
         />
       )}
+      {selected.data.typeId === "http.webhook" && (
+        <WebhookUrlHint
+          workflowId={workflowId}
+          workflowActive={workflowActive}
+          path={typeof selected.data.config.path === "string" ? selected.data.config.path : ""}
+        />
+      )}
       <button
         onClick={onDelete}
         className="mt-4 text-sm text-red-400 hover:text-red-300"
@@ -65,3 +76,47 @@ export function NodeConfigPanel({ selected, onChange, onDelete }: Props) {
     </aside>
   );
 }
+
+function WebhookUrlHint({
+  workflowId, workflowActive, path,
+}: { workflowId: string; workflowActive: boolean; path: string }) {
+  const [copied, setCopied] = useState(false);
+  const cleanPath = path.replace(/^\/+/, "");
+  const url = `${window.location.origin}/wh/${workflowId}/${cleanPath}`;
+
+  return (
+    <div className="bg-slate-950/60 border border-slate-800 rounded p-3 space-y-2">
+      <div className="flex items-center justify-between">
+        <span className="text-xs uppercase text-slate-500">Webhook URL</span>
+        <button
+          type="button"
+          onClick={async () => {
+            try {
+              await navigator.clipboard.writeText(url);
+              setCopied(true);
+              setTimeout(() => setCopied(false), 1500);
+            } catch {
+              // Clipboard blocked (insecure origin, no permission) — leave state alone.
+            }
+          }}
+          className="text-slate-400 hover:text-slate-200 flex items-center gap-1 text-xs"
+          aria-label="Copy webhook URL"
+        >
+          {copied ? <><Check size={12} /> Copied</> : <><Copy size={12} /> Copy</>}
+        </button>
+      </div>
+      <code className="block break-all text-xs text-slate-200 font-mono">
+        POST {url}
+      </code>
+      {!path && (
+        <p className="text-xs text-amber-400">Set a URL path above to complete the endpoint.</p>
+      )}
+      {!workflowActive && (
+        <p className="text-xs text-slate-500">
+          The webhook only responds when the workflow is <strong>active</strong> — activate it
+          from the toolbar to receive requests.
+        </p>
+      )}
+    </div>
+  );
+}

frontend/src/pages/EditorPage.tsx

@@ -158,6 +158,8 @@ export default function EditorPage() {
           selected={selected}
           onChange={patchSelected}
           onDelete={deleteSelected}
+          workflowId={id ?? ""}
+          workflowActive={wf.data.active}
         />
       </div>
     </div>