fix(agent): decouple agent streams from compat

closes #6851

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();