fix: lastResult should reflect resolved value

packages/pacer/src/async-debouncer.ts

@@ -29,7 +29,7 @@ export interface AsyncDebouncerState<TFn extends AnyAsyncFunction> {
   /**
    * The result from the most recent successful function execution
    */
-  lastResult: ReturnType<TFn> | undefined
+  lastResult: Awaited<ReturnType<TFn>> | undefined
   /**
    * Number of times maybeExecute has been called (for reduction calculations)
    */

packages/pacer/src/async-rate-limiter.ts

@@ -25,7 +25,7 @@ export interface AsyncRateLimiterState<TFn extends AnyAsyncFunction> {
   /**
    * The result from the most recent successful function execution
    */
-  lastResult: ReturnType<TFn> | undefined
+  lastResult: Awaited<ReturnType<TFn>> | undefined
   /**
    * Number of function executions that have been rejected due to rate limiting
    */

packages/pacer/src/async-throttler.ts

@@ -29,7 +29,7 @@ export interface AsyncThrottlerState<TFn extends AnyAsyncFunction> {
   /**
    * The result from the most recent successful function execution
    */
-  lastResult: ReturnType<TFn> | undefined
+  lastResult: Awaited<ReturnType<TFn>> | undefined
   /**
    * Number of times maybeExecute has been called (for reduction calculations)
    */

packages/pacer/tests/async-debouncer.test.ts

@@ -1,4 +1,4 @@
-import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { afterEach, beforeEach, describe, expect, expectTypeOf, it, vi } from 'vitest'
 import { AsyncDebouncer, asyncDebounce } from '../src/async-debouncer'
 
 describe('AsyncDebouncer', () => {
@@ -1359,4 +1359,23 @@ describe('asyncDebounce helper function', () => {
       expect(debouncer.getAbortSignal()).toBeNull()
     })
   })
+
+  describe('Type Safety', () => {
+    it('should type lastResult as the awaited return type, not a Promise', () => {
+      const debouncer = new AsyncDebouncer(async () => 'hello', { wait: 100 })
+      expectTypeOf(debouncer.store.state.lastResult).toEqualTypeOf<
+        string | undefined
+      >()
+    })
+
+    it('should type lastResult correctly for non-primitive return types', () => {
+      const debouncer = new AsyncDebouncer(
+        async () => ({ id: 1, name: 'test' }),
+        { wait: 100 },
+      )
+      expectTypeOf(debouncer.store.state.lastResult).toEqualTypeOf<
+        { id: number; name: string } | undefined
+      >()
+    })
+  })
 })

packages/pacer/tests/async-rate-limiter.test.ts

@@ -1,4 +1,4 @@
-import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { afterEach, beforeEach, describe, expect, expectTypeOf, it, vi } from 'vitest'
 import { AsyncRateLimiter, asyncRateLimit } from '../src/async-rate-limiter'
 
 describe('AsyncRateLimiter', () => {
@@ -775,4 +775,26 @@ describe('asyncRateLimit', () => {
       expect(rateLimiter.getAbortSignal()).toBeNull()
     })
   })
+
+  describe('Type Safety', () => {
+    it('should type lastResult as the awaited return type, not a Promise', () => {
+      const rateLimiter = new AsyncRateLimiter(async () => 'hello', {
+        limit: 5,
+        window: 1000,
+      })
+      expectTypeOf(rateLimiter.store.state.lastResult).toEqualTypeOf<
+        string | undefined
+      >()
+    })
+
+    it('should type lastResult correctly for non-primitive return types', () => {
+      const rateLimiter = new AsyncRateLimiter(
+        async () => ({ id: 1, name: 'test' }),
+        { limit: 5, window: 1000 },
+      )
+      expectTypeOf(rateLimiter.store.state.lastResult).toEqualTypeOf<
+        { id: number; name: string } | undefined
+      >()
+    })
+  })
 })

packages/pacer/tests/async-throttler.test.ts

@@ -1,4 +1,4 @@
-import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { beforeEach, describe, expect, expectTypeOf, it, vi } from 'vitest'
 import { AsyncThrottler } from '../src/async-throttler'
 
 describe('AsyncThrottler', () => {
@@ -998,4 +998,23 @@ describe('AsyncThrottler', () => {
       expect(throttler.getAbortSignal()).toBeNull()
     })
   })
+
+  describe('Type Safety', () => {
+    it('should type lastResult as the awaited return type, not a Promise', () => {
+      const throttler = new AsyncThrottler(async () => 'hello', { wait: 100 })
+      expectTypeOf(throttler.store.state.lastResult).toEqualTypeOf<
+        string | undefined
+      >()
+    })
+
+    it('should type lastResult correctly for non-primitive return types', () => {
+      const throttler = new AsyncThrottler(
+        async () => ({ id: 1, name: 'test' }),
+        { wait: 100 },
+      )
+      expectTypeOf(throttler.store.state.lastResult).toEqualTypeOf<
+        { id: number; name: string } | undefined
+      >()
+    })
+  })
 })