feat(api): abort signal core plumbing (#615)

- Add abortSignal?: AbortSignal to ApiHandlerCreateMessageMetadata interface
- Update SingleCompletionHandler.completePrompt to accept metadata parameter
- Move AbortController creation before metadata construction in Task.ts
- Include abortSignal directly in metadata object literal (not post-mutation)
- Forward metadata through single-completion-handler.ts
- Add tests for signal identity and fresh controller per request

Author: easonliang28

src/api/index.ts

@@ -41,7 +41,7 @@ import {
 import { NativeOllamaHandler } from "./providers/native-ollama"
 
 export interface SingleCompletionHandler {
-	completePrompt(prompt: string): Promise<string>
+	completePrompt(prompt: string, metadata?: ApiHandlerCreateMessageMetadata): Promise<string>
 }
 
 export interface ApiHandlerCreateMessageMetadata {
@@ -90,6 +90,11 @@ export interface ApiHandlerCreateMessageMetadata {
 	 * Only applies to providers that support function calling restrictions (e.g., Gemini).
 	 */
 	allowedFunctionNames?: string[]
+	/**
+	 * Abort signal from the Task's AbortController, used by providers to cancel
+	 * in-flight HTTP requests when the user presses Stop.
+	 */
+	abortSignal?: AbortSignal
 }
 
 export interface ApiHandler {

src/core/__tests__/task-abort-signal-passing.spec.ts

@@ -0,0 +1,38 @@
+import { describe, it, expect } from "vitest"
+
+import type { ApiHandlerCreateMessageMetadata } from "../../api"
+
+describe("abort signal passing", () => {
+	it("should pass the same AbortController signal instance to metadata.abortSignal", async () => {
+		// Arrange: create an AbortController
+		const controller = new AbortController()
+
+		// Act: simulate what Task.ts does - construct metadata with abortSignal
+		const metadata: ApiHandlerCreateMessageMetadata = {
+			taskId: "test-task-id",
+			abortSignal: controller.signal,
+		}
+
+		// Assert: signal identity (toBe, not just toBeInstanceOf)
+		expect(metadata.abortSignal).toBe(controller.signal)
+	})
+
+	it("should create a fresh AbortController for each request", async () => {
+		// Arrange: simulate two sequential requests
+		const controller1 = new AbortController()
+		const metadata1: ApiHandlerCreateMessageMetadata = {
+			taskId: "task-1",
+			abortSignal: controller1.signal,
+		}
+
+		const controller2 = new AbortController()
+		const metadata2: ApiHandlerCreateMessageMetadata = {
+			taskId: "task-2",
+			abortSignal: controller2.signal,
+		}
+
+		// Assert: different instances
+		expect(metadata1.abortSignal).not.toBe(metadata2.abortSignal)
+		expect(controller1.signal).not.toBe(controller2.signal)
+	})
+})

src/core/task/Task.ts

@@ -4144,10 +4144,15 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 
 		const shouldIncludeTools = allTools.length > 0
 
+		// Create an AbortController FIRST so we can include its signal in metadata
+		this.currentRequestAbortController = new AbortController()
+		const abortSignal = this.currentRequestAbortController.signal
+
 		const metadata: ApiHandlerCreateMessageMetadata = {
 			mode: mode,
 			taskId: this.taskId,
 			suppressPreviousResponseId: this.skipPrevResponseIdOnce,
+			abortSignal: abortSignal,
 			// Include tools whenever they are present.
 			...(shouldIncludeTools
 				? {
@@ -4160,11 +4165,6 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 					}
 				: {}),
 		}
-
-		// Create an AbortController to allow cancelling the request mid-stream
-		this.currentRequestAbortController = new AbortController()
-		const abortSignal = this.currentRequestAbortController.signal
-		// Reset the flag after using it
 		this.skipPrevResponseIdOnce = false
 
 		// The provider accepts reasoning items alongside standard messages; cast to the expected parameter type.

src/utils/__tests__/enhance-prompt.spec.ts

@@ -42,7 +42,7 @@ describe("enhancePrompt", () => {
 
 		expect(result).toBe("Enhanced prompt")
 		const handler = buildApiHandler(mockApiConfig)
-		expect((handler as any).completePrompt).toHaveBeenCalledWith(`Test prompt`)
+		expect((handler as any).completePrompt).toHaveBeenCalledWith(`Test prompt`, undefined)
 	})
 
 	it("enhances prompt using custom enhancement prompt when provided", async () => {
@@ -64,7 +64,7 @@ describe("enhancePrompt", () => {
 
 		expect(result).toBe("Enhanced prompt")
 		const handler = buildApiHandler(mockApiConfig)
-		expect((handler as any).completePrompt).toHaveBeenCalledWith(`${customEnhancePrompt}\n\nTest prompt`)
+		expect((handler as any).completePrompt).toHaveBeenCalledWith(`${customEnhancePrompt}\n\nTest prompt`, undefined)
 	})
 
 	it("throws error for empty prompt input", async () => {

src/utils/single-completion-handler.ts

@@ -1,12 +1,16 @@
 import type { ProviderSettings } from "@roo-code/types"
 
-import { buildApiHandler, SingleCompletionHandler } from "../api"
+import { buildApiHandler, SingleCompletionHandler, type ApiHandlerCreateMessageMetadata } from "../api"
 
 /**
  * Enhances a prompt using the configured API without creating a full Cline instance or task history.
  * This is a lightweight alternative that only uses the API's completion functionality.
  */
-export async function singleCompletionHandler(apiConfiguration: ProviderSettings, promptText: string): Promise<string> {
+export async function singleCompletionHandler(
+	apiConfiguration: ProviderSettings,
+	promptText: string,
+	metadata?: ApiHandlerCreateMessageMetadata,
+): Promise<string> {
 	if (!promptText) {
 		throw new Error("No prompt text provided")
 	}
@@ -21,5 +25,5 @@ export async function singleCompletionHandler(apiConfiguration: ProviderSettings
 		throw new Error("The selected API provider does not support prompt enhancement")
 	}
 
-	return (handler as SingleCompletionHandler).completePrompt(promptText)
+	return (handler as SingleCompletionHandler).completePrompt(promptText, metadata)
 }