fix(agent): decouple agent streams from compat

closes #6851

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

@@ -426,7 +426,7 @@ export class AgentSession {
 		headers?: Record<string, string>;
 		env?: Record<string, string>;
 	}> {
-		if (this.agent.streamFn === streamSimple) {
+		if (this.agent.streamFunction === streamSimple) {
 			return this._getRequiredRequestAuth(model);
 		}
 
@@ -1836,7 +1836,7 @@ export class AgentSession {
 					customInstructions,
 					this._compactionAbortController.signal,
 					this.thinkingLevel,
-					this.agent.streamFn,
+					this.agent.streamFunction,
 					env,
 				);
 				summary = result.summary;
@@ -2037,7 +2037,7 @@ export class AgentSession {
 			let apiKey: string | undefined;
 			let headers: Record<string, string> | undefined;
 			let env: Record<string, string> | undefined;
-			if (this.agent.streamFn === streamSimple) {
+			if (this.agent.streamFunction === streamSimple) {
 				const authResult = await this._modelRuntime.getAuth(this.model);
 				if (!authResult?.auth.apiKey) return false;
 				apiKey = authResult.auth.apiKey;
@@ -2112,7 +2112,7 @@ export class AgentSession {
 					undefined,
 					this._autoCompactionAbortController.signal,
 					this.thinkingLevel,
-					this.agent.streamFn,
+					this.agent.streamFunction,
 					env,
 				);
 				summary = compactResult.summary;
@@ -2933,7 +2933,7 @@ export class AgentSession {
 					customInstructions,
 					replaceInstructions,
 					reserveTokens: branchSummarySettings.reserveTokens,
-					streamFn: this.agent.streamFn,
+					streamFn: this.agent.streamFunction,
 				});
 				if (result.aborted) {
 					return { cancelled: true, aborted: true };

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

@@ -294,7 +294,7 @@ export async function createAgentSession(options: CreateAgentSessionOptions = {}
 			tools: [],
 		},
 		convertToLlm: convertToLlmWithBlockImages,
-		streamFn: async (model, context, options) => {
+		streamFunction: async (model, context, options) => {
 			const providerRetrySettings = settingsManager.getProviderRetrySettings();
 			const httpIdleTimeoutMs = settingsManager.getHttpIdleTimeoutMs();
 			// SDKs treat timeout=0 as 0ms (immediate timeout), not "no timeout".

packages/coding-agent/test/agent-session-auto-compaction-queue.test.ts

@@ -3,7 +3,7 @@ import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { Agent } from "@earendil-works/pi-agent-core";
 import { type AssistantMessage, createAssistantMessageEventStream, fauxAssistantMessage } from "@earendil-works/pi-ai";
-import { getModel } from "@earendil-works/pi-ai/compat";
+import { getModel, streamSimple } from "@earendil-works/pi-ai/compat";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { AgentSession } from "../src/core/agent-session.ts";
 import { AuthStorage } from "../src/core/auth-storage.ts";
@@ -21,10 +21,10 @@ describe("AgentSession auto-compaction queue resume", () => {
 	beforeEach(async () => {
 		tempDir = join(tmpdir(), `pi-auto-compaction-queue-${Date.now()}`);
 		mkdirSync(tempDir, { recursive: true });
-		vi.useFakeTimers();
 
 		const model = getModel("anthropic", "claude-sonnet-4-5")!;
 		const agent = new Agent({
+			streamFunction: streamSimple,
 			initialState: {
 				model,
 				systemPrompt: "Test",
@@ -50,7 +50,6 @@ describe("AgentSession auto-compaction queue resume", () => {
 
 	afterEach(() => {
 		session.dispose();
-		vi.useRealTimers();
 		vi.restoreAllMocks();
 		if (tempDir && existsSync(tempDir)) {
 			rmSync(tempDir, { recursive: true });
@@ -84,9 +83,9 @@ describe("AgentSession auto-compaction queue resume", () => {
 			timestamp: now - 500,
 		});
 		session.agent.state.messages = sessionManager.buildSessionContext().messages;
-		session.agent.streamFn = (summaryModel) => {
+		session.agent.streamFunction = (summaryModel) => {
 			const stream = createAssistantMessageEventStream();
-			queueMicrotask(() => {
+			void Promise.resolve().then(() => {
 				stream.push({
 					type: "done",
 					reason: "stop",

packages/coding-agent/test/agent-session-compaction.test.ts

@@ -12,7 +12,7 @@ import { existsSync, mkdirSync, rmSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { Agent } from "@earendil-works/pi-agent-core";
-import { getModel } from "@earendil-works/pi-ai/compat";
+import { getModel, streamSimple } from "@earendil-works/pi-ai/compat";
 import { afterEach, beforeEach, describe, expect, it } from "vitest";
 import { AgentSession, type AgentSessionEvent } from "../src/core/agent-session.ts";
 import { AuthStorage } from "../src/core/auth-storage.ts";
@@ -49,6 +49,7 @@ describe.skipIf(!API_KEY)("AgentSession compaction e2e", () => {
 		const model = getModel("anthropic", "claude-sonnet-4-5")!;
 		const agent = new Agent({
 			getApiKey: () => API_KEY,
+			streamFunction: streamSimple,
 			initialState: {
 				model,
 				systemPrompt: "You are a helpful assistant. Be concise.",

packages/coding-agent/test/agent-session-concurrent.test.ts

@@ -90,7 +90,7 @@ describe("AgentSession concurrent prompt guard", () => {
 				systemPrompt: "Test",
 				tools: [],
 			},
-			streamFn: (_model, _context, options) => {
+			streamFunction: (_model, _context, options) => {
 				abortSignal = options?.signal;
 				const stream = new MockAssistantStream();
 				queueMicrotask(() => {
@@ -195,7 +195,7 @@ describe("AgentSession concurrent prompt guard", () => {
 				systemPrompt: "Test",
 				tools: [],
 			},
-			streamFn: (_model, context, options) => {
+			streamFunction: (_model, context, options) => {
 				abortSignal = options?.signal;
 				const stream = new MockAssistantStream();
 				queueMicrotask(() => {
@@ -301,7 +301,7 @@ describe("AgentSession concurrent prompt guard", () => {
 				systemPrompt: "Test",
 				tools: [],
 			},
-			streamFn: () => {
+			streamFunction: () => {
 				const stream = new MockAssistantStream();
 				queueMicrotask(() => {
 					stream.push({ type: "start", partial: createAssistantMessage("") });
@@ -362,7 +362,7 @@ describe("AgentSession concurrent prompt guard", () => {
 				systemPrompt: "Test",
 				tools: [tool],
 			},
-			streamFn: async (_model, context) => {
+			streamFunction: async (_model, context) => {
 				const stream = new MockAssistantStream();
 				queueMicrotask(() => {
 					const toolResultCount = context.messages.filter((message) => message.role === "toolResult").length;
@@ -508,7 +508,7 @@ describe("AgentSession concurrent prompt guard", () => {
 				systemPrompt: "Test",
 				tools: [tool],
 			},
-			streamFn: async (_model, context) => {
+			streamFunction: async (_model, context) => {
 				const stream = new MockAssistantStream();
 				queueMicrotask(() => {
 					const hasToolResult = context.messages.some((message) => message.role === "toolResult");

packages/coding-agent/test/agent-session-dynamic-provider.test.ts

@@ -84,7 +84,7 @@ describe("AgentSession dynamic provider registration", () => {
 		session: Awaited<ReturnType<typeof createSession>>,
 	): Promise<string | undefined> {
 		let baseUrl: string | undefined;
-		session.agent.streamFn = async (model) => {
+		session.agent.streamFunction = async (model) => {
 			baseUrl = model.baseUrl;
 			throw new Error("stop");
 		};

packages/coding-agent/test/agent-session-retry.test.ts

@@ -82,7 +82,7 @@ describe("AgentSession retry", () => {
 		const agent = new Agent({
 			getApiKey: () => "test-key",
 			initialState: { model, systemPrompt: "Test", tools: [] },
-			streamFn: () => {
+			streamFunction: () => {
 				callCount++;
 				const stream = new MockAssistantStream();
 				queueMicrotask(() => {
@@ -203,7 +203,7 @@ describe("AgentSession retry", () => {
 		const agent = new Agent({
 			getApiKey: () => "test-key",
 			initialState: { model, systemPrompt: "Test", tools: [] },
-			streamFn,
+			streamFunction: streamFn,
 		});
 		const sessionManager = SessionManager.inMemory();
 		const settingsManager = SettingsManager.create(tempDir, tempDir);
@@ -255,7 +255,7 @@ describe("AgentSession retry", () => {
 		const agent = new Agent({
 			getApiKey: () => "test-key",
 			initialState: { model, systemPrompt: "Test", tools: [] },
-			streamFn: () => {
+			streamFunction: () => {
 				callCount++;
 				const stream = new MockAssistantStream();
 				queueMicrotask(() => {

packages/coding-agent/test/agent-session-stats.test.ts

@@ -1,5 +1,11 @@
 import { Agent } from "@earendil-works/pi-agent-core";
-import { type AssistantMessage, getModel, type ToolResultMessage, type Usage } from "@earendil-works/pi-ai/compat";
+import {
+	type AssistantMessage,
+	getModel,
+	streamSimple,
+	type ToolResultMessage,
+	type Usage,
+} from "@earendil-works/pi-ai/compat";
 import { describe, expect, it } from "vitest";
 import { AgentSession } from "../src/core/agent-session.ts";
 import { AuthStorage } from "../src/core/auth-storage.ts";
@@ -69,6 +75,7 @@ async function createSession() {
 	const session = new AgentSession({
 		agent: new Agent({
 			getApiKey: () => "test-key",
+			streamFunction: streamSimple,
 			initialState: {
 				model,
 				systemPrompt: "You are a helpful assistant.",

packages/coding-agent/test/compaction-extensions.test.ts

@@ -7,7 +7,7 @@ import { existsSync, mkdirSync, rmSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { Agent } from "@earendil-works/pi-agent-core";
-import { getModel } from "@earendil-works/pi-ai/compat";
+import { getModel, streamSimple } from "@earendil-works/pi-ai/compat";
 import { afterEach, beforeEach, describe, expect, it } from "vitest";
 import { AgentSession } from "../src/core/agent-session.ts";
 import { AuthStorage } from "../src/core/auth-storage.ts";
@@ -89,6 +89,7 @@ describe.skipIf(!API_KEY)("Compaction extensions", () => {
 		const model = getModel("anthropic", "claude-sonnet-4-5")!;
 		const agent = new Agent({
 			getApiKey: () => API_KEY,
+			streamFunction: streamSimple,
 			initialState: {
 				model,
 				systemPrompt: "You are a helpful assistant. Be concise.",

packages/coding-agent/test/rpc-prompt-response-semantics.test.ts

@@ -114,7 +114,7 @@ async function createRuntimeHost(options: { withAuth: boolean; responseDelayMs:
 			systemPrompt: "Test",
 			tools: [],
 		},
-		streamFn: (_model, _context, _options) => {
+		streamFunction: (_model, _context, _options) => {
 			const stream = new MockAssistantStream();
 			queueMicrotask(() => {
 				stream.push({ type: "start", partial: createAssistantMessage("") });

packages/coding-agent/test/sdk-openrouter-attribution.test.ts

@@ -126,7 +126,7 @@ describe("createAgentSession provider attribution headers", () => {
 		});
 
 		try {
-			const stream = await session.agent.streamFn(
+			const stream = await session.agent.streamFunction(
 				model,
 				{ messages: [] },
 				{

packages/coding-agent/test/sdk-stream-options.test.ts

@@ -114,7 +114,7 @@ describe("createAgentSession stream options", () => {
 		});
 
 		try {
-			const stream = await session.agent.streamFn(model, { messages: [] }, requestOptions);
+			const stream = await session.agent.streamFunction(model, { messages: [] }, requestOptions);
 			await stream.result();
 			return capturedOptions;
 		} finally {

packages/coding-agent/test/suite/agent-session-compaction.test.ts

@@ -49,7 +49,7 @@ function createAssistant(
 
 function useSummaryStreamFn(harness: Harness, summary: string): () => number {
 	let callCount = 0;
-	harness.session.agent.streamFn = (model) => {
+	harness.session.agent.streamFunction = (model) => {
 		callCount++;
 		const stream = createAssistantMessageEventStream();
 		queueMicrotask(() => {

packages/coding-agent/test/suite/harness.ts

@@ -14,7 +14,7 @@ import type {
 	FauxResponseStep,
 	Model,
 } from "@earendil-works/pi-ai/compat";
-import { registerFauxProvider } from "@earendil-works/pi-ai/compat";
+import { registerFauxProvider, streamSimple } from "@earendil-works/pi-ai/compat";
 import { AgentSession, type AgentSessionEvent } from "../../src/core/agent-session.ts";
 import { AuthStorage } from "../../src/core/auth-storage.ts";
 import type { ExtensionRunner } from "../../src/core/extensions/index.ts";
@@ -137,6 +137,7 @@ export async function createHarness(options: HarnessOptions = {}): Promise<Harne
 
 	const agent = new Agent({
 		getApiKey: () => (withConfiguredAuth ? "faux-key" : undefined),
+		streamFunction: streamSimple,
 		initialState: {
 			model,
 			systemPrompt: options.systemPrompt ?? "You are a test assistant.",

packages/coding-agent/test/suite/regressions/5596-missing-theme-export.test.ts

@@ -2,7 +2,7 @@ import { existsSync, mkdtempSync, rmSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { Agent } from "@earendil-works/pi-agent-core";
-import { fauxAssistantMessage, registerFauxProvider } from "@earendil-works/pi-ai/compat";
+import { fauxAssistantMessage, registerFauxProvider, streamSimple } from "@earendil-works/pi-ai/compat";
 import { afterEach, describe, expect, it } from "vitest";
 import { AgentSession } from "../../../src/core/agent-session.ts";
 import { AuthStorage } from "../../../src/core/auth-storage.ts";
@@ -61,6 +61,7 @@ describe("regression #5596: missing configured theme export", () => {
 				tools: [],
 			},
 			convertToLlm,
+			streamFunction: streamSimple,
 		});
 		const session = new AgentSession({
 			agent,

packages/coding-agent/test/suite/regressions/6324-branch-summary-ambient-auth.test.ts

@@ -17,7 +17,7 @@ describe("issue #6324 branch summary ambient auth", () => {
 		harnesses.push(harness);
 
 		let streamCallCount = 0;
-		harness.session.agent.streamFn = (model, _context, options) => {
+		harness.session.agent.streamFunction = (model, _context, options) => {
 			streamCallCount++;
 			expect(options?.apiKey).toBeUndefined();
 

packages/coding-agent/test/test-harness.ts

@@ -378,7 +378,7 @@ async function createHarnessWithResourceLoader(
 			systemPrompt: options.systemPrompt ?? "You are a test assistant.",
 			tools: options.tools ?? [],
 		},
-		streamFn,
+		streamFunction: streamFn,
 	});
 
 	const sessionManager = SessionManager.inMemory();

packages/coding-agent/test/utilities.ts

@@ -8,7 +8,7 @@ import { homedir, tmpdir } from "node:os";
 import { dirname, join } from "node:path";
 import { Agent } from "@earendil-works/pi-agent-core";
 import type { OAuthCredentials } from "@earendil-works/pi-ai";
-import { getModel } from "@earendil-works/pi-ai/compat";
+import { getModel, streamSimple } from "@earendil-works/pi-ai/compat";
 import { builtinProviders } from "@earendil-works/pi-ai/providers/all";
 import { AgentSession } from "../src/core/agent-session.ts";
 import { AuthStorage } from "../src/core/auth-storage.ts";
@@ -246,6 +246,7 @@ export async function createTestSession(options: TestSessionOptions = {}): Promi
 			systemPrompt: options.systemPrompt ?? "You are a helpful assistant. Be extremely concise.",
 			tools: createCodingTools(process.cwd()),
 		},
+		streamFunction: streamSimple,
 	});
 
 	const sessionManager = options.inMemory ? SessionManager.inMemory() : SessionManager.create(tempDir);