diff --git a/apps/cli/__tests__/helpers/acp-runtime.ts b/apps/cli/__tests__/helpers/acp-runtime.ts
new file mode 100644
index 00000000..d479d570
--- /dev/null
+++ b/apps/cli/__tests__/helpers/acp-runtime.ts
@@ -0,0 +1,26 @@
+import type { AgentEvent } from "@cyrus/schemas/rtc/chat";
+
+export type MockPromptOptions = {
+	message?: string;
+	messageId?: string;
+	failAfterToken?: boolean;
+};
+
+export function* createMockPromptStream(
+	options: MockPromptOptions = {}
+): Generator<AgentEvent> {
+	const messageId = options.messageId ?? "mock-message-1";
+	yield {
+		type: "token",
+		text: options.message ?? "mock response",
+		messageId,
+	};
+	if (options.failAfterToken) {
+		throw new Error("mock runtime failed");
+	}
+	yield {
+		type: "message_completed",
+		text: options.message ?? "mock response",
+		messageId,
+	};
+}
diff --git a/apps/cli/__tests__/integration/wiring.test.ts b/apps/cli/__tests__/integration/wiring.test.ts
new file mode 100644
index 00000000..79b5a801
--- /dev/null
+++ b/apps/cli/__tests__/integration/wiring.test.ts
@@ -0,0 +1,102 @@
+import { describe, expect, test } from "bun:test";
+import { mkdtemp, rm } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import type { AgentEvent } from "@cyrus/schemas/rtc/chat";
+import { runTurn } from "../../src/utils/run-turn";
+import { createMockPromptStream } from "../helpers/acp-runtime";
+
+describe("acp mock runtime", () => {
+	test("streams token and completion events", () => {
+		const events: AgentEvent[] = [];
+		for (const event of createMockPromptStream({ message: "hello" })) {
+			events.push(event);
+		}
+
+		expect(events).toEqual([
+			{ type: "token", text: "hello", messageId: "mock-message-1" },
+			{ type: "message_completed", text: "hello", messageId: "mock-message-1" },
+		]);
+	});
+
+	test("drives runTurn through a mock coordinator", async () => {
+		const emitted: Array<{ type: string }> = [];
+
+		const result = await runTurn({
+			agentName: "mock-agent",
+			threadId: "thread-1",
+			projectId: "project-1",
+			message: "ping",
+			emit: (event) => {
+				emitted.push({ type: event.type });
+				return Promise.resolve();
+			},
+			emitTerminal: () => Promise.resolve(),
+			runtime: {
+				threadCoordinator: {
+					prompt: () => createMockPromptStream({ message: "pong" }),
+				},
+			} as never,
+		});
+
+		expect(result.isOk()).toBe(true);
+		expect(emitted.map((event) => event.type)).toEqual([
+			"user_message",
+			"thread_started",
+			"token",
+			"message_completed",
+		]);
+	});
+
+	test("emits turn_interrupted when the mock stream fails", async () => {
+		const terminal: Array<{ type: string }> = [];
+
+		const result = await runTurn({
+			agentName: "mock-agent",
+			threadId: "thread-1",
+			projectId: "project-1",
+			message: "ping",
+			emit: () => Promise.resolve(),
+			emitTerminal: (event) => {
+				terminal.push({ type: event.type });
+				return Promise.resolve();
+			},
+			runtime: {
+				threadCoordinator: {
+					prompt: () =>
+						createMockPromptStream({
+							message: "pong",
+							failAfterToken: true,
+						}),
+				},
+			} as never,
+		});
+
+		expect(result.isErr()).toBe(true);
+		expect(terminal).toEqual([{ type: "turn_interrupted" }]);
+	});
+});
+
+describe("cli process integration", () => {
+	test("exits when start is invoked without a login token", async () => {
+		const home = await mkdtemp(join(tmpdir(), "cyrus-cli-test-"));
+
+		try {
+			const proc = Bun.spawn(["bun", "src/cli.ts", "start"], {
+				cwd: join(import.meta.dir, "../.."),
+				env: {
+					...process.env,
+					CYRUS_HOME: home,
+					CYRUS_DAEMON: "1",
+				},
+				stdout: "ignore",
+				stderr: "ignore",
+			});
+
+			const exitCode = await proc.exited;
+			expect(exitCode).toBe(1);
+		} finally {
+			await rm(home, { recursive: true, force: true });
+		}
+	});
+});
diff --git a/apps/cli/package.json b/apps/cli/package.json
index 5fd2d3da..d27b02d2 100644
--- a/apps/cli/package.json
+++ b/apps/cli/package.json
@@ -9,7 +9,8 @@
   "scripts": {
     "dev": "bun src/cli.ts",
     "check:types": "tsc --noEmit",
-    "test:unit": "bun test",
+    "test:unit": "bun test src",
+    "test:integration": "bun test __tests__/integration",
     "build": "bun build src/cli.ts --compile --env 'CLI_PUBLIC_*' --outfile dist/cyrusd"
   },
   "dependencies": {
diff --git a/bun.lock b/bun.lock
index 281ea729..ee4fe074 100644
--- a/bun.lock
+++ b/bun.lock
@@ -247,6 +247,7 @@
       },
       "devDependencies": {
         "@cyrus/typescript": "workspace:*",
+        "@types/bun": "catalog:",
         "@types/react": "^19.2.15",
         "react": "catalog:",
         "typescript": "catalog:",
diff --git a/docs/testing.md b/docs/testing.md
index df36ee0e..2b2bf191 100644
--- a/docs/testing.md
+++ b/docs/testing.md
@@ -41,7 +41,12 @@ package boundary they exercise. Cross-app tests live at the repo root.
 Phase 1 only adds the unit test foundation. Integration and E2E are introduced
 in later phases.
 
-## Phase 2 notes
+## Phase 3 notes
+
+- ACP prompt mocking lives in `apps/cli/__tests__/helpers/acp-runtime.ts`.
+- CLI integration tests use isolated `CYRUS_HOME` directories and subprocess checks.
+- Hooks tests currently cover the optimistic conversations cache contract used by
+  `use-controller-threads`.
 
 - `@cyrus/database` integration tests use isolated in-memory Turso databases via
   `shared/database/__tests__/helpers/turso.ts`.
diff --git a/shared/hooks/package.json b/shared/hooks/package.json
index 7eec27c5..475146f2 100644
--- a/shared/hooks/package.json
+++ b/shared/hooks/package.json
@@ -7,7 +7,8 @@
     "./*": "./src/*"
   },
   "scripts": {
-    "check:types": "tsc --noEmit"
+    "check:types": "tsc --noEmit",
+    "test:unit": "bun test"
   },
   "dependencies": {
     "@cyrus/connections": "workspace:*",
@@ -23,6 +24,7 @@
   },
   "devDependencies": {
     "@cyrus/typescript": "workspace:*",
+    "@types/bun": "catalog:",
     "@types/react": "^19.2.15",
     "react": "catalog:",
     "typescript": "catalog:"
diff --git a/shared/hooks/src/connection/use-controller-threads.test.ts b/shared/hooks/src/connection/use-controller-threads.test.ts
new file mode 100644
index 00000000..611e4a75
--- /dev/null
+++ b/shared/hooks/src/connection/use-controller-threads.test.ts
@@ -0,0 +1,26 @@
+import { describe, expect, test } from "bun:test";
+import { RTC_OPERATION_KEYS } from "@cyrus/constants/operation-keys";
+import { appendOptimisticUserMessage } from "@cyrus/utils/conversations/cache";
+import { QueryClient } from "@tanstack/react-query";
+
+describe("controller thread cache integration", () => {
+	test("appends an optimistic user message to the conversations cache", () => {
+		const queryClient = new QueryClient();
+		const threadId = "thread-1";
+		const turnId = "turn-1";
+
+		appendOptimisticUserMessage(queryClient, threadId, turnId, "hello");
+
+		const cached = queryClient.getQueryData<{
+			conversations: Array<{
+				chunk: { event: { type: string; content: string } };
+			}>;
+		}>(RTC_OPERATION_KEYS.getConversations(threadId));
+
+		expect(cached?.conversations).toHaveLength(1);
+		expect(cached?.conversations[0]?.chunk.event).toEqual({
+			type: "user_message",
+			content: "hello",
+		});
+	});
+});
diff --git a/shared/hooks/tsconfig.json b/shared/hooks/tsconfig.json
index 4fdc92aa..a5b66e8f 100644
--- a/shared/hooks/tsconfig.json
+++ b/shared/hooks/tsconfig.json
@@ -3,7 +3,7 @@
   "compilerOptions": {
     "jsx": "react-jsx",
     "lib": ["ESNext", "DOM", "DOM.Iterable"],
-    "types": [],
+    "types": ["bun"],
     "strictNullChecks": true,
     "paths": {
       "@cyrus/providers/*": ["../providers/src/*"]
diff --git a/tooling/test/mocks/README.md b/tooling/test/mocks/README.md
index bfb0352d..4184b3f7 100644
--- a/tooling/test/mocks/README.md
+++ b/tooling/test/mocks/README.md
@@ -2,7 +2,4 @@
 
 Shared mocks for cross-package tests live here.
 
-Planned Phase 3 additions:
-
-- ACP mock runtime based on `acp-kit/examples/mock-runtime`
-- Mock signaling and data-channel fixtures for PR CI
+- Mock data-channel fixtures for PR CI WebRTC paths (`data-channel.ts`)
diff --git a/tooling/test/mocks/data-channel.ts b/tooling/test/mocks/data-channel.ts
new file mode 100644
index 00000000..93f3a224
--- /dev/null
+++ b/tooling/test/mocks/data-channel.ts
@@ -0,0 +1,61 @@
+import { describe, expect, test } from "bun:test";
+
+type MockChannelState = "connecting" | "open" | "closing" | "closed";
+
+type MockChannel = {
+	readyState: MockChannelState;
+	listeners: Map<string, Set<() => void>>;
+};
+
+export function createMockDataChannel(
+	initialState: MockChannelState = "connecting"
+): MockChannel {
+	return {
+		readyState: initialState,
+		listeners: new Map(),
+	};
+}
+
+export function openMockDataChannel(channel: MockChannel): void {
+	channel.readyState = "open";
+	for (const listener of channel.listeners.get("open") ?? []) {
+		listener();
+	}
+}
+
+export function attachMockChannelListeners(
+	channel: MockChannel,
+	handlers: {
+		onOpen?: () => void;
+		onError?: () => void;
+		onClose?: () => void;
+	}
+): void {
+	const register = (type: string, handler?: () => void) => {
+		if (!handler) return;
+		const listeners = channel.listeners.get(type) ?? new Set();
+		listeners.add(handler);
+		channel.listeners.set(type, listeners);
+	};
+
+	register("open", handlers.onOpen);
+	register("error", handlers.onError);
+	register("close", handlers.onClose);
+}
+
+describe("mock data channel", () => {
+	test("opens and notifies listeners", () => {
+		const channel = createMockDataChannel();
+		let opened = false;
+
+		attachMockChannelListeners(channel, {
+			onOpen: () => {
+				opened = true;
+			},
+		});
+		openMockDataChannel(channel);
+
+		expect(channel.readyState).toBe("open");
+		expect(opened).toBe(true);
+	});
+});