feat(hooks): Hook Session Lifecycle & Compression Integration (#14151)

packages/core/src/services/chatCompressionService.test.ts

@@ -157,6 +157,8 @@ describe('ChatCompressionService', () => {
       getContentGenerator: vi.fn().mockReturnValue({
         countTokens: vi.fn().mockResolvedValue({ totalTokens: 100 }),
       }),
+      getEnableHooks: vi.fn().mockReturnValue(false),
+      getMessageBus: vi.fn().mockReturnValue(undefined),
     } as unknown as Config;
 
     vi.mocked(tokenLimit).mockReturnValue(1000);

packages/core/src/services/chatCompressionService.ts

@@ -21,6 +21,8 @@ import {
   DEFAULT_GEMINI_MODEL,
   PREVIEW_GEMINI_MODEL,
 } from '../config/models.js';
+import { firePreCompressHook } from '../core/sessionHookTriggers.js';
+import { PreCompressTrigger } from '../hooks/types.js';
 
 /**
  * Default threshold for compression token count as a fraction of the model's
@@ -123,6 +125,17 @@ export class ChatCompressionService {
       };
     }
 
+    // Fire PreCompress hook before compression (only if hooks are enabled)
+    // This fires for both manual and auto compression attempts
+    const hooksEnabled = config.getEnableHooks();
+    const messageBus = config.getMessageBus();
+    if (hooksEnabled && messageBus) {
+      const trigger = force
+        ? PreCompressTrigger.Manual
+        : PreCompressTrigger.Auto;
+      await firePreCompressHook(messageBus, trigger);
+    }
+
     const originalTokenCount = chat.getLastPromptTokenCount();
 
     // Don't compress if not forced and we are under the limit.