Add tree navigation tests and shared test utilities

- Add test/utilities.ts with shared helpers (API_KEY, userMsg, assistantMsg, createTestSession)
- Add agent-session-tree-navigation.test.ts with e2e tests for tree navigation
- Add getChildren() method to SessionManager
- Add summaryEntry to navigateTree return type
- Update existing tests to use shared utilities

packages/coding-agent/test/utilities.ts

@@ -0,0 +1,158 @@
+/**
+ * Shared test utilities for coding-agent tests.
+ */
+
+import { existsSync, mkdirSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { Agent } from "@mariozechner/pi-agent-core";
+import { getModel } from "@mariozechner/pi-ai";
+import { AgentSession } from "../src/core/agent-session.js";
+import { AuthStorage } from "../src/core/auth-storage.js";
+import { ModelRegistry } from "../src/core/model-registry.js";
+import { SessionManager } from "../src/core/session-manager.js";
+import { SettingsManager } from "../src/core/settings-manager.js";
+import { codingTools } from "../src/core/tools/index.js";
+
+/**
+ * API key for authenticated tests. Tests using this should be wrapped in
+ * describe.skipIf(!API_KEY)
+ */
+export const API_KEY = process.env.ANTHROPIC_OAUTH_TOKEN || process.env.ANTHROPIC_API_KEY;
+
+/**
+ * Create a minimal user message for testing.
+ */
+export function userMsg(text: string) {
+	return { role: "user" as const, content: text, timestamp: Date.now() };
+}
+
+/**
+ * Create a minimal assistant message for testing.
+ */
+export function assistantMsg(text: string) {
+	return {
+		role: "assistant" as const,
+		content: [{ type: "text" as const, text }],
+		api: "anthropic-messages" as const,
+		provider: "anthropic",
+		model: "test",
+		usage: {
+			input: 1,
+			output: 1,
+			cacheRead: 0,
+			cacheWrite: 0,
+			totalTokens: 2,
+			cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+		},
+		stopReason: "stop" as const,
+		timestamp: Date.now(),
+	};
+}
+
+/**
+ * Options for creating a test session.
+ */
+export interface TestSessionOptions {
+	/** Use in-memory session (no file persistence) */
+	inMemory?: boolean;
+	/** Custom system prompt */
+	systemPrompt?: string;
+	/** Custom settings overrides */
+	settingsOverrides?: Record<string, unknown>;
+}
+
+/**
+ * Resources returned by createTestSession that need cleanup.
+ */
+export interface TestSessionContext {
+	session: AgentSession;
+	sessionManager: SessionManager;
+	tempDir: string;
+	cleanup: () => void;
+}
+
+/**
+ * Create an AgentSession for testing with proper setup and cleanup.
+ * Use this for e2e tests that need real LLM calls.
+ */
+export function createTestSession(options: TestSessionOptions = {}): TestSessionContext {
+	const tempDir = join(tmpdir(), `pi-test-${Date.now()}-${Math.random().toString(36).slice(2)}`);
+	mkdirSync(tempDir, { recursive: true });
+
+	const model = getModel("anthropic", "claude-sonnet-4-5")!;
+	const agent = new Agent({
+		getApiKey: () => API_KEY,
+		initialState: {
+			model,
+			systemPrompt: options.systemPrompt ?? "You are a helpful assistant. Be extremely concise.",
+			tools: codingTools,
+		},
+	});
+
+	const sessionManager = options.inMemory ? SessionManager.inMemory() : SessionManager.create(tempDir);
+	const settingsManager = SettingsManager.create(tempDir, tempDir);
+
+	if (options.settingsOverrides) {
+		settingsManager.applyOverrides(options.settingsOverrides);
+	}
+
+	const authStorage = new AuthStorage(join(tempDir, "auth.json"));
+	const modelRegistry = new ModelRegistry(authStorage, tempDir);
+
+	const session = new AgentSession({
+		agent,
+		sessionManager,
+		settingsManager,
+		modelRegistry,
+	});
+
+	// Must subscribe to enable session persistence
+	session.subscribe(() => {});
+
+	const cleanup = () => {
+		session.dispose();
+		if (tempDir && existsSync(tempDir)) {
+			rmSync(tempDir, { recursive: true });
+		}
+	};
+
+	return { session, sessionManager, tempDir, cleanup };
+}
+
+/**
+ * Build a session tree for testing using SessionManager.
+ * Returns the IDs of all created entries.
+ *
+ * Example tree structure:
+ * ```
+ * u1 -> a1 -> u2 -> a2
+ *          -> u3 -> a3  (branch from a1)
+ * u4 -> a4              (another root)
+ * ```
+ */
+export function buildTestTree(
+	session: SessionManager,
+	structure: {
+		messages: Array<{ role: "user" | "assistant"; text: string; branchFrom?: string }>;
+	},
+): Map<string, string> {
+	const ids = new Map<string, string>();
+
+	for (const msg of structure.messages) {
+		if (msg.branchFrom) {
+			const branchFromId = ids.get(msg.branchFrom);
+			if (!branchFromId) {
+				throw new Error(`Cannot branch from unknown entry: ${msg.branchFrom}`);
+			}
+			session.branch(branchFromId);
+		}
+
+		const id =
+			msg.role === "user" ? session.appendMessage(userMsg(msg.text)) : session.appendMessage(assistantMsg(msg.text));
+
+		ids.set(msg.text, id);
+	}
+
+	return ids;
+}