test(ui): expect the refusal of a binding no add-on serves

A binding needs a running add-on that serves its kind, so the real
server of the UI tests, which runs none, answers 400 instead of
storing an inactive binding. The spec now checks that answer and that
nothing leaks. Switching and listing stay covered by the add-on specs.

Assisted-by: Claude:claude-sonnet-5-5 playwright

core/http/react-ui/e2e/chats-crud-real.spec.js

@@ -115,33 +115,24 @@ test.describe('Skills, agents, triggers and connectors against the real server',
 })
 
 test.describe('Connector bindings against the real server', () => {
-  test('a binding made through the API is listed, waits for its add-on, is switched on and off; the token is never returned', async ({ page }) => {
+  // A binding is made for a kind that a running add-on serves. The test server
+  // runs none, so the server refuses the binding and says so; listing, switching
+  // and token handling of a binding are covered by the add-on specs.
+  test('a binding for a kind no add-on serves is refused, and nothing is stored or leaked', async ({ page }) => {
     const name = unique('bot')
-    // The add-on of a platform adds and edits bindings; the test server has none
-    // installed, so the binding is made through the API and kept as inactive.
     const made = await page.request.post('/api/chats/agents', { data: { name: `${name}-agent`, model: 'mock-model', instructions: 'x' } })
     expect(made.ok()).toBe(true)
     const agent = await made.json()
+    const before = await (await page.request.get('/api/chats/connectors')).json()
     const bound = await page.request.post('/api/chats/connectors', { data: { kind: 'telegram', name, token: '123456:SECRET-TOKEN-VALUE', agent_id: agent.id, enabled: false } })
-    expect(bound.status(), await bound.text()).toBe(201)
-    const saved = await bound.json()
-    expect(JSON.stringify(saved)).not.toContain('SECRET-TOKEN-VALUE')
-    expect(saved.has_token).toBe(true)
-
-    await page.goto('/app/chats/connectors')
-    await expect(page.getByTestId('connector-row').filter({ hasText: name })).toBeVisible()
-    await expect(page.getByTestId('connector-inactive').first()).toContainText('Not running')
-    // No form here: the page lists the bindings and switches them.
-    await expect(page.getByLabel('Bot token')).toHaveCount(0)
-
-    await page.getByRole('checkbox', { name: `${name} on` }).check()
-    await expect.poll(async () => (await json(page, `/api/chats/connectors/${saved.id}`)).enabled).toBe(true)
-    await page.getByRole('checkbox', { name: `${name} on` }).uncheck()
-    await expect.poll(async () => (await json(page, `/api/chats/connectors/${saved.id}`)).enabled).toBe(false)
+    expect(bound.status()).toBe(400)
+    const body = await bound.text()
+    expect(body).toContain('no installed add-on serves the kind')
+    expect(body).not.toContain('SECRET-TOKEN-VALUE')
     const text = await (await page.request.get('/api/chats/connectors')).text()
+    expect(text).not.toContain(name)
     expect(text).not.toContain('SECRET-TOKEN-VALUE')
-
-    expect((await page.request.delete(`/api/chats/connectors/${saved.id}`)).ok()).toBe(true)
+    expect(JSON.stringify(before)).not.toContain(name)
     await page.request.delete(`/api/chats/agents/${agent.id}`)
   })
 })