fix(coding-agent): remove explicit tool choice from compaction calls

Fixes #8649\n\nFixes #8638

packages/ai/CHANGELOG.md

@@ -4,7 +4,7 @@
 
 ### Fixed
 
-- Fixed OpenAI-compatible Chat Completions requests sending `tool_choice` without tools, which gateways can reject during compaction ([#8607](https://github.com/earendil-works/pi/issues/8607)).
+- Fixed OpenAI-compatible Chat Completions ignoring an explicitly requested `toolChoice` when no tools are defined.
 
 ## [0.84.3] - 2026-08-24
 

packages/ai/src/api/openai-completions.ts

@@ -835,7 +835,7 @@ function buildParams(
 		applyAnthropicCacheControl(messages, params.tools, cacheControl);
 	}
 
-	if (options?.toolChoice && params.tools?.length) {
+	if (options?.toolChoice) {
 		params.tool_choice = options.toolChoice;
 	}
 

packages/ai/src/types.ts

@@ -312,7 +312,7 @@ export interface AnthropicAllowedFallbackModel {
 
 // Unified options with reasoning passed to streamSimple() and completeSimple()
 export interface SimpleStreamOptions extends StreamOptions {
-	/** Provider-neutral tool selection for simple requests. Default: "auto". */
+	/** Provider-neutral tool selection for simple requests. When omitted, adapters use provider-specific behavior. */
 	toolChoice?: ToolChoice;
 	reasoning?: ThinkingLevel;
 	/** Ask a capable provider to return a durable handle and continue the request asynchronously. */

packages/ai/test/openai-completions-tool-choice.test.ts

@@ -150,7 +150,7 @@ describe("openai-completions tool_choice", () => {
 		expect(params.tools?.length ?? 0).toBeGreaterThan(0);
 	});
 
-	it("omits toolChoice when no tools are provided", async () => {
+	it("includes toolChoice when no tools are provided", async () => {
 		const { compat: _compat, ...baseModel } = getModel("openai", "gpt-4o-mini")!;
 		const model = { ...baseModel, api: "openai-completions" } as const;
 		let payload: unknown;
@@ -170,7 +170,7 @@ describe("openai-completions tool_choice", () => {
 		).result();
 
 		const params = (payload ?? mockState.lastParams) as { tool_choice?: string; tools?: unknown[] };
-		expect(params).not.toHaveProperty("tool_choice");
+		expect(params.tool_choice).toBe("none");
 		expect(params).not.toHaveProperty("tools");
 	});
 

packages/coding-agent/CHANGELOG.md

@@ -10,6 +10,7 @@
 
 - Fixed Windows shell aborts crashing Pi when `taskkill.exe` is unavailable on `PATH` ([#6596](https://github.com/earendil-works/pi/issues/6596)).
 - Fixed extension messages sent with `triggerTurn: false` while the agent is running being inserted between a tool call and its result, which made providers that validate message order reject the replayed history. They are now appended once the turn's tool results are in ([#8537](https://github.com/earendil-works/pi/issues/8537)).
+- Fixed compaction and branch summaries forcing `toolChoice: "none"` ([#8649](https://github.com/earendil-works/pi/issues/8649), [#8638](https://github.com/earendil-works/pi/issues/8638)).
 
 ## [0.84.3] - 2026-08-24
 

packages/coding-agent/src/core/compaction/compaction.ts

@@ -590,7 +590,6 @@ export async function completeSummarization(
 		...options,
 		cacheRetention: "none",
 		sessionId: options.sessionId ?? uuidv7(),
-		toolChoice: "none",
 	};
 	const produce = async (): Promise<AssistantMessage> =>
 		streamFn

packages/coding-agent/test/branch-summarization.test.ts

@@ -44,7 +44,7 @@ function response(content: AssistantMessage["content"]): AssistantMessage {
 }
 
 describe("branch summarization", () => {
-	it("disables tools for branch summaries", async () => {
+	it("does not override tool choice for branch summaries", async () => {
 		let requestOptions: SimpleStreamOptions | undefined;
 		const streamFn: StreamFn = (_model, _context, options) => {
 			requestOptions = options;
@@ -61,7 +61,7 @@ describe("branch summarization", () => {
 			streamFn,
 		});
 
-		expect(requestOptions?.toolChoice).toBe("none");
+		expect(requestOptions?.toolChoice).toBeUndefined();
 	});
 
 	it("rejects tool calls from branch summaries", async () => {

packages/coding-agent/test/compaction-summary-reasoning.test.ts

@@ -109,13 +109,12 @@ describe("generateSummary reasoning options", () => {
 		const requestOptions = completeSimpleMock.mock.calls.map((call) => call[2]);
 		expect(requestOptions).toHaveLength(2);
 		expect(requestOptions.every((options) => options?.cacheRetention === "none")).toBe(true);
-		expect(requestOptions.every((options) => options?.toolChoice === "none")).toBe(true);
 
 		const sessionIds = requestOptions.map((options) => options?.sessionId);
 		expect(sessionIds[0]).not.toBe(sessionIds[1]);
 	});
 
-	it("honors a caller-supplied routing session without prompt caching", async () => {
+	it("honors caller-supplied routing session and tool choice without prompt caching", async () => {
 		await completeSummarization(
 			createModel(false),
 			{ systemPrompt: "Summarize", messages: [] },
@@ -125,7 +124,7 @@ describe("generateSummary reasoning options", () => {
 		expect(completeSimpleMock.mock.calls[0][2]).toMatchObject({
 			sessionId: "current-routing-session",
 			cacheRetention: "none",
-			toolChoice: "none",
+			toolChoice: "auto",
 		});
 	});