gemini-cli - 💡(How to fix) Fix Bug: /executeCommand SSE stream omits blank-line event delimiters

What happened?

The A2A server streaming /executeCommand endpoint writes Server-Sent Events with a single trailing newline:

res.write(`data: ${JSON.stringify(jsonRpcResponse)}\n`);

A spec-compliant SSE/EventSource client requires a blank line (\n\n) to dispatch an event. Without that blank line, consecutive data: lines are folded into one record and the final event is never properly terminated, so clients cannot parse individual streaming updates.

What did you expect to happen?

Each JSON-RPC response emitted by the streaming endpoint should be a separate SSE event, delimited by a blank line:

data: {...}\n\n

Root cause

The handler emits \n instead of \n\n. The existing streaming test did not catch this because it used a Mocha-style done callback, which Vitest 3 does not honor, so the test returned before its asynchronous assertions ran.

Proposed fix

Append the missing blank line to each event and convert the streaming test to async/await so it genuinely validates emitted events.

Related PR: #27549