fix(llm): honor DeepSeek SSE keep-alives

examples/headless-agent/tests/fixtures/deepseek-defaults.cordis.yml

@@ -8,6 +8,7 @@
           apiKey: snapshot-key
           baseURL: !!js process.env.DSH_SNAPSHOT_BASE_URL
           thinking: disabled
+          streamIdleTimeoutMs: 100
       - id: cli-agent
         config:
           provider: deepseek-official

examples/headless-agent/tests/headless.snapshot.ts

@@ -66,12 +66,21 @@ async function deepseekDefaultsServer(): Promise<DeepSeekDefaultsServer> {
     request.on('end', () => {
       requests.push(JSON.parse(body) as JsonObject)
       response.writeHead(200, { 'content-type': 'text/event-stream' })
-      response.end([
-        'data: {"choices":[{"delta":{"content":"DEFAULTS_OK"}}]}',
-        'data: {"choices":[{"delta":{},"finish_reason":"stop"}],"usage":{"prompt_tokens":3,"completion_tokens":1}}',
-        'data: [DONE]',
-        '',
-      ].join('\n\n'))
+      let keepAlives = 3
+      const write = (): void => {
+        if (keepAlives-- > 0) {
+          response.write(': keep-alive\n\n')
+          setTimeout(write, 60)
+          return
+        }
+        response.end([
+          'data: {"choices":[{"delta":{"content":"DEFAULTS_OK"}}]}',
+          'data: {"choices":[{"delta":{},"finish_reason":"stop"}],"usage":{"prompt_tokens":3,"completion_tokens":1}}',
+          'data: [DONE]',
+          '',
+        ].join('\n\n'))
+      }
+      setTimeout(write, 60)
     })
   })
   await new Promise<void>(resolve => server.listen(0, '127.0.0.1', resolve))
@@ -297,7 +306,7 @@ describe('headless stream-json snapshots', () => {
     `)
   }, LOADER_SMOKE_TEST_TIMEOUT_MS)
 
-  it('logs and sends the DeepSeek adapter maxTokens default through the one-shot app', async () => {
+  it('keeps provider comments alive and sends DeepSeek defaults through the one-shot app', async () => {
     const server = await deepseekDefaultsServer()
     try {
       const result = await runLoaderSmoke({