fix(coding-agent): preserve run prompt during tool refresh

closes #6162

packages/agent/CHANGELOG.md

@@ -2,6 +2,14 @@
 
 ## [Unreleased]
 
+### Added
+
+- Added `prepareNextTurnWithContext` for `Agent` users that need the next-turn loop context.
+
+### Fixed
+
+- Fixed `Agent.prepareNextTurn` to keep receiving the run abort signal instead of the next-turn context.
+
 ## [0.80.2] - 2026-06-23
 
 ### Changed

packages/agent/src/agent.ts

@@ -105,6 +105,9 @@ export interface AgentOptions {
 	beforeToolCall?: (context: BeforeToolCallContext, signal?: AbortSignal) => Promise<BeforeToolCallResult | undefined>;
 	afterToolCall?: (context: AfterToolCallContext, signal?: AbortSignal) => Promise<AfterToolCallResult | undefined>;
 	prepareNextTurn?: (
+		signal?: AbortSignal,
+	) => Promise<AgentLoopTurnUpdate | undefined> | AgentLoopTurnUpdate | undefined;
+	prepareNextTurnWithContext?: (
 		context: PrepareNextTurnContext,
 		signal?: AbortSignal,
 	) => Promise<AgentLoopTurnUpdate | undefined> | AgentLoopTurnUpdate | undefined;
@@ -186,6 +189,9 @@ export class Agent {
 		signal?: AbortSignal,
 	) => Promise<AfterToolCallResult | undefined>;
 	public prepareNextTurn?: (
+		signal?: AbortSignal,
+	) => Promise<AgentLoopTurnUpdate | undefined> | AgentLoopTurnUpdate | undefined;
+	public prepareNextTurnWithContext?: (
 		context: PrepareNextTurnContext,
 		signal?: AbortSignal,
 	) => Promise<AgentLoopTurnUpdate | undefined> | AgentLoopTurnUpdate | undefined;
@@ -212,6 +218,7 @@ export class Agent {
 		this.beforeToolCall = options.beforeToolCall;
 		this.afterToolCall = options.afterToolCall;
 		this.prepareNextTurn = options.prepareNextTurn;
+		this.prepareNextTurnWithContext = options.prepareNextTurnWithContext;
 		this.steeringQueue = new PendingMessageQueue(options.steeringMode ?? "one-at-a-time");
 		this.followUpQueue = new PendingMessageQueue(options.followUpMode ?? "one-at-a-time");
 		this.sessionId = options.sessionId;
@@ -436,9 +443,15 @@ export class Agent {
 			toolExecution: this.toolExecution,
 			beforeToolCall: this.beforeToolCall,
 			afterToolCall: this.afterToolCall,
-			prepareNextTurn: this.prepareNextTurn
-				? async (context) => await this.prepareNextTurn?.(context, this.signal)
-				: undefined,
+			prepareNextTurn:
+				this.prepareNextTurnWithContext || this.prepareNextTurn
+					? async (context) => {
+							if (this.prepareNextTurnWithContext) {
+								return await this.prepareNextTurnWithContext(context, this.signal);
+							}
+							return await this.prepareNextTurn?.(this.signal);
+						}
+					: undefined,
 			convertToLlm: this.convertToLlm,
 			transformContext: this.transformContext,
 			getApiKey: this.getApiKey,

packages/agent/test/agent.test.ts

@@ -630,6 +630,47 @@ describe("Agent", () => {
 		expect(responseCount).toBe(2);
 	});
 
+	it("keeps legacy prepareNextTurn signal callback behavior", async () => {
+		const schema = Type.Object({});
+		const tool: AgentTool<typeof schema> = {
+			name: "noop",
+			label: "Noop",
+			description: "Noop tool",
+			parameters: schema,
+			execute: async () => ({ content: [{ type: "text", text: "ok" }], details: {} }),
+		};
+		let requestCount = 0;
+		let sawAbortSignal = false;
+		const agent = new Agent({
+			initialState: { tools: [tool] },
+			prepareNextTurn: async (signal) => {
+				sawAbortSignal = signal instanceof AbortSignal;
+				return undefined;
+			},
+			streamFn: () => {
+				requestCount++;
+				const stream = new MockAssistantStream();
+				queueMicrotask(() => {
+					if (requestCount === 1) {
+						const message = createAssistantToolUseMessage([
+							{ type: "toolCall", id: "tool-1", name: "noop", arguments: {} },
+						]);
+						stream.push({ type: "done", reason: "toolUse", message });
+						return;
+					}
+					const message = createAssistantMessage("done");
+					stream.push({ type: "done", reason: "stop", message });
+				});
+				return stream;
+			},
+		});
+
+		await agent.prompt("start");
+
+		expect(requestCount).toBe(2);
+		expect(sawAbortSignal).toBe(true);
+	});
+
 	it("forwards sessionId to streamFn options", async () => {
 		let receivedSessionId: string | undefined;
 		const agent = new Agent({