perf(router): trust fused request enhancement

Author: chrisbbreuer

storage/framework/core/router/src/stacks-router.ts

@@ -1601,7 +1601,11 @@ function createMiddlewareHandler(routeKey: string, handler: StacksHandler): Rout
         )
       }
     }
-    const enhancedReq = enhanceRequest(req)
+    // bun-router dispatches only after its enhancer has installed both its
+    // macros and the Stacks prototype. The fused enhancer also initializes the
+    // request id, so running the public fallback decorator again here only
+    // repeats params assignment and a marker lookup.
+    const enhancedReq = req
     const csrfHandledByOuter = (enhancedReq as unknown as Record<symbol, unknown>)[CSRF_SEEDED_BY_HANDLE_REQUEST] === true
 
     // Mint the CSRF token BEFORE the handler runs, not after.
@@ -3477,6 +3481,8 @@ function fuseRequestEnhancements(router: Router): void {
         enhanced.params = params
       }
       Object.setPrototypeOf(enhanced, combined)
+      if (!enhanced._requestId)
+        enhanced._requestId = incomingRequestId(enhanced) ?? crypto.randomUUID()
       return enhanced
     }
 

storage/framework/core/router/tests/hot-path.test.ts

@@ -65,6 +65,19 @@ describe('the request path keeps its defaults', () => {
     expect(answer.headers.get('set-cookie') ?? '').toContain('X-CSRF-Token=')
   })
 
+  it('initializes request ids on warm direct dispatches', async () => {
+    const { createStacksRouter } = await import('../src')
+    const direct = createStacksRouter()
+    direct.get('/_hot/direct-id', () => ({ ok: true }))
+
+    const first = await direct.bunRouter.handleRequest(new Request('http://localhost/_hot/direct-id'))
+    const second = await direct.bunRouter.handleRequest(new Request('http://localhost/_hot/direct-id'))
+
+    expect(first.headers.get('x-request-id')).toBeTruthy()
+    expect(second.headers.get('x-request-id')).toBeTruthy()
+    expect(second.headers.get('x-request-id')).not.toBe(first.headers.get('x-request-id'))
+  })
+
   it('still seeds a CSRF cookie on a cold GET', async () => {
     const answer = await get('/_hot/plain')