diff --git a/src/server/__tests__/conversation-service.test.ts b/src/server/__tests__/conversation-service.test.ts
index 87ba2ce7..aa438e22 100644
--- a/src/server/__tests__/conversation-service.test.ts
+++ b/src/server/__tests__/conversation-service.test.ts
@@ -549,6 +549,16 @@ describe('ConversationService', () => {
     expect(env.CC_HAHA_DESKTOP_AWAIT_MCP_TIMEOUT_MS).toBe('5000')
   })
 
+  test('buildChildEnv enables stream idle watchdog for desktop CLI sessions', async () => {
+    const service = new ConversationService() as any
+    const env = (await service.buildChildEnv(
+      '/tmp',
+      'ws://127.0.0.1:3456/sdk/test-session?token=test-token',
+    )) as Record<string, string>
+
+    expect(env.CLAUDE_ENABLE_STREAM_WATCHDOG).toBe('1')
+  })
+
   test('buildSessionCliArgs forwards the selected runtime model and effort to the CLI process', () => {
     const service = new ConversationService() as any
     const args = service.buildSessionCliArgs(
diff --git a/src/server/services/conversationService.ts b/src/server/services/conversationService.ts
index 7ce4b501..1bc74586 100644
--- a/src/server/services/conversationService.ts
+++ b/src/server/services/conversationService.ts
@@ -983,6 +983,8 @@ export class ConversationService {
       ...cleanEnv,
       CLAUDE_CODE_ENABLE_TASKS: '1',
       CLAUDE_CODE_ENABLE_SDK_FILE_CHECKPOINTING: '1',
+      // Desktop must fail stuck provider streams instead of leaving the UI running forever.
+      CLAUDE_ENABLE_STREAM_WATCHDOG: cleanEnv.CLAUDE_ENABLE_STREAM_WATCHDOG || '1',
       CLAUDE_CODE_DIAGNOSTICS_FILE: cliDiagnosticsPath,
       CLAUDE_COWORK_MEMORY_PATH_OVERRIDE: this.resolveDesktopAutoMemoryPath(workDir),
       CALLER_DIR: workDir,