> pi can help you use the SDK. Ask it to build an integration for your use case. # SDK The SDK provides programmatic access to pi's agent capabilities. Use it to embed pi in other applications, build custom interfaces, or integrate with automated workflows. **Example use cases:** - Build a custom UI (web, desktop, mobile) - Integrate agent capabilities into existing applications - Create automated pipelines with agent reasoning - Build custom tools that spawn sub-agents - Test agent behavior programmatically See [examples/sdk/](../examples/sdk/) for working examples from minimal to full control. ## Quick Start ```typescript import { createAgentSession, discoverAuthStorage, discoverModels, SessionManager } from "@mariozechner/pi-coding-agent"; // Set up credential storage and model registry const authStorage = discoverAuthStorage(); const modelRegistry = discoverModels(authStorage); const { session } = await createAgentSession({ sessionManager: SessionManager.inMemory(), authStorage, modelRegistry, }); session.subscribe((event) => { if (event.type === "message_update" && event.assistantMessageEvent.type === "text_delta") { process.stdout.write(event.assistantMessageEvent.delta); } }); await session.prompt("What files are in the current directory?"); ``` ## Installation ```bash npm install @mariozechner/pi-coding-agent ``` The SDK is included in the main package. No separate installation needed. ## Core Concepts ### createAgentSession() The main factory function. Creates an `AgentSession` with configurable options. **Philosophy:** "Omit to discover, provide to override." - Omit an option → pi discovers/loads from standard locations - Provide an option → your value is used, discovery skipped for that option ```typescript import { createAgentSession } from "@mariozechner/pi-coding-agent"; // Minimal: all defaults (discovers everything from cwd and ~/.pi/agent) const { session } = await createAgentSession(); // Custom: override specific options const { session } = await createAgentSession({ model: myModel, systemPrompt: "You are helpful.", tools: [readTool, bashTool], sessionManager: SessionManager.inMemory(), }); ``` ### AgentSession The session manages the agent lifecycle, message history, and event streaming. ```typescript interface AgentSession { // Send a prompt and wait for completion prompt(text: string, options?: PromptOptions): Promise; // Subscribe to events (returns unsubscribe function) subscribe(listener: (event: AgentSessionEvent) => void): () => void; // Session info sessionFile: string | undefined; // undefined for in-memory sessionId: string; // Model control setModel(model: Model): Promise; setThinkingLevel(level: ThinkingLevel): void; cycleModel(): Promise; cycleThinkingLevel(): ThinkingLevel | undefined; // State access agent: Agent; model: Model | undefined; thinkingLevel: ThinkingLevel; messages: AgentMessage[]; isStreaming: boolean; // Session management newSession(options?: { parentSession?: string }): Promise; // Returns false if cancelled by hook switchSession(sessionPath: string): Promise; // Branching branch(entryId: string): Promise<{ selectedText: string; cancelled: boolean }>; // Creates new session file navigateTree(targetId: string, options?: { summarize?: boolean }): Promise<{ editorText?: string; cancelled: boolean }>; // In-place navigation // Hook message injection sendHookMessage(message: HookMessage, triggerTurn?: boolean): Promise; // Compaction compact(customInstructions?: string): Promise; abortCompaction(): void; // Abort current operation abort(): Promise; // Cleanup dispose(): void; } ``` ### Agent and AgentState The `Agent` class (from `@mariozechner/pi-agent-core`) handles the core LLM interaction. Access it via `session.agent`. ```typescript // Access current state const state = session.agent.state; // state.messages: AgentMessage[] - conversation history // state.model: Model - current model // state.thinkingLevel: ThinkingLevel - current thinking level // state.systemPrompt: string - system prompt // state.tools: Tool[] - available tools // Replace messages (useful for branching, restoration) session.agent.replaceMessages(messages); // Wait for agent to finish processing await session.agent.waitForIdle(); ``` ### Events Subscribe to events to receive streaming output and lifecycle notifications. ```typescript session.subscribe((event) => { switch (event.type) { // Streaming text from assistant case "message_update": if (event.assistantMessageEvent.type === "text_delta") { process.stdout.write(event.assistantMessageEvent.delta); } if (event.assistantMessageEvent.type === "thinking_delta") { // Thinking output (if thinking enabled) } break; // Tool execution case "tool_execution_start": console.log(`Tool: ${event.toolName}`); break; case "tool_execution_update": // Streaming tool output break; case "tool_execution_end": console.log(`Result: ${event.isError ? "error" : "success"}`); break; // Message lifecycle case "message_start": // New message starting break; case "message_end": // Message complete break; // Agent lifecycle case "agent_start": // Agent started processing prompt break; case "agent_end": // Agent finished (event.messages contains new messages) break; // Turn lifecycle (one LLM response + tool calls) case "turn_start": break; case "turn_end": // event.message: assistant response // event.toolResults: tool results from this turn break; // Session events (auto-compaction, retry) case "auto_compaction_start": case "auto_compaction_end": case "auto_retry_start": case "auto_retry_end": break; } }); ``` ## Options Reference ### Directories ```typescript const { session } = await createAgentSession({ // Working directory for project-local discovery cwd: process.cwd(), // default // Global config directory agentDir: "~/.pi/agent", // default (expands ~) }); ``` `cwd` is used for: - Project hooks (`.pi/hooks/`) - Project tools (`.pi/tools/`) - Project skills (`.pi/skills/`) - Project commands (`.pi/commands/`) - Context files (`AGENTS.md` walking up from cwd) - Session directory naming `agentDir` is used for: - Global hooks (`hooks/`) - Global tools (`tools/`) - Global skills (`skills/`) - Global commands (`commands/`) - Global context file (`AGENTS.md`) - Settings (`settings.json`) - Custom models (`models.json`) - Credentials (`auth.json`) - Sessions (`sessions/`) ### Model ```typescript import { getModel } from "@mariozechner/pi-ai"; import { discoverAuthStorage, discoverModels } from "@mariozechner/pi-coding-agent"; const authStorage = discoverAuthStorage(); const modelRegistry = discoverModels(authStorage); // Find specific built-in model (doesn't check if API key exists) const opus = getModel("anthropic", "claude-opus-4-5"); if (!opus) throw new Error("Model not found"); // Find any model by provider/id, including custom models from models.json // (doesn't check if API key exists) const customModel = modelRegistry.find("my-provider", "my-model"); // Get only models that have valid API keys configured const available = await modelRegistry.getAvailable(); const { session } = await createAgentSession({ model: opus, thinkingLevel: "medium", // off, minimal, low, medium, high, xhigh // Models for cycling (Ctrl+P in interactive mode) scopedModels: [ { model: opus, thinkingLevel: "high" }, { model: haiku, thinkingLevel: "off" }, ], authStorage, modelRegistry, }); ``` If no model is provided: 1. Tries to restore from session (if continuing) 2. Uses default from settings 3. Falls back to first available model > See [examples/sdk/02-custom-model.ts](../examples/sdk/02-custom-model.ts) ### API Keys and OAuth API key resolution priority (handled by AuthStorage): 1. Runtime overrides (via `setRuntimeApiKey`, not persisted) 2. Stored credentials in `auth.json` (API keys or OAuth tokens) 3. Environment variables (`ANTHROPIC_API_KEY`, `OPENAI_API_KEY`, etc.) 4. Fallback resolver (for custom provider keys from `models.json`) ```typescript import { AuthStorage, ModelRegistry, discoverAuthStorage, discoverModels } from "@mariozechner/pi-coding-agent"; // Default: uses ~/.pi/agent/auth.json and ~/.pi/agent/models.json const authStorage = discoverAuthStorage(); const modelRegistry = discoverModels(authStorage); const { session } = await createAgentSession({ sessionManager: SessionManager.inMemory(), authStorage, modelRegistry, }); // Runtime API key override (not persisted to disk) authStorage.setRuntimeApiKey("anthropic", "sk-my-temp-key"); // Custom auth storage location const customAuth = new AuthStorage("/my/app/auth.json"); const customRegistry = new ModelRegistry(customAuth, "/my/app/models.json"); const { session } = await createAgentSession({ sessionManager: SessionManager.inMemory(), authStorage: customAuth, modelRegistry: customRegistry, }); // No custom models.json (built-in models only) const simpleRegistry = new ModelRegistry(authStorage); ``` > See [examples/sdk/09-api-keys-and-oauth.ts](../examples/sdk/09-api-keys-and-oauth.ts) ### System Prompt ```typescript const { session } = await createAgentSession({ // Replace entirely systemPrompt: "You are a helpful assistant.", // Or modify default (receives default, returns modified) systemPrompt: (defaultPrompt) => { return `${defaultPrompt}\n\n## Additional Rules\n- Be concise`; }, }); ``` > See [examples/sdk/03-custom-prompt.ts](../examples/sdk/03-custom-prompt.ts) ### Tools ```typescript import { codingTools, // read, bash, edit, write (default) readOnlyTools, // read, grep, find, ls readTool, bashTool, editTool, writeTool, grepTool, findTool, lsTool, } from "@mariozechner/pi-coding-agent"; // Use built-in tool set const { session } = await createAgentSession({ tools: readOnlyTools, }); // Pick specific tools const { session } = await createAgentSession({ tools: [readTool, bashTool, grepTool], }); ``` #### Tools with Custom cwd **Important:** The pre-built tool instances (`readTool`, `bashTool`, etc.) use `process.cwd()` for path resolution. When you specify a custom `cwd` AND provide explicit `tools`, you must use the tool factory functions to ensure paths resolve correctly: ```typescript import { createCodingTools, // Creates [read, bash, edit, write] for specific cwd createReadOnlyTools, // Creates [read, grep, find, ls] for specific cwd createReadTool, createBashTool, createEditTool, createWriteTool, createGrepTool, createFindTool, createLsTool, } from "@mariozechner/pi-coding-agent"; const cwd = "/path/to/project"; // Use factory for tool sets const { session } = await createAgentSession({ cwd, tools: createCodingTools(cwd), // Tools resolve paths relative to cwd }); // Or pick specific tools const { session } = await createAgentSession({ cwd, tools: [createReadTool(cwd), createBashTool(cwd), createGrepTool(cwd)], }); ``` **When you don't need factories:** - If you omit `tools`, pi automatically creates them with the correct `cwd` - If you use `process.cwd()` as your `cwd`, the pre-built instances work fine **When you must use factories:** - When you specify both `cwd` (different from `process.cwd()`) AND `tools` > See [examples/sdk/05-tools.ts](../examples/sdk/05-tools.ts) ### Custom Tools ```typescript import { Type } from "@sinclair/typebox"; import { createAgentSession, discoverCustomTools, type CustomTool } from "@mariozechner/pi-coding-agent"; // Inline custom tool const myTool: CustomTool = { name: "my_tool", label: "My Tool", description: "Does something useful", parameters: Type.Object({ input: Type.String({ description: "Input value" }), }), execute: async (toolCallId, params) => ({ content: [{ type: "text", text: `Result: ${params.input}` }], details: {}, }), }; // Replace discovery with inline tools const { session } = await createAgentSession({ customTools: [{ tool: myTool }], }); // Merge with discovered tools const discovered = await discoverCustomTools(); const { session } = await createAgentSession({ customTools: [...discovered, { tool: myTool }], }); // Add paths without replacing discovery const { session } = await createAgentSession({ additionalCustomToolPaths: ["/extra/tools"], }); ``` > See [examples/sdk/05-tools.ts](../examples/sdk/05-tools.ts) ### Hooks ```typescript import { createAgentSession, discoverHooks, type HookFactory } from "@mariozechner/pi-coding-agent"; // Inline hook const loggingHook: HookFactory = (api) => { // Log tool calls api.on("tool_call", async (event) => { console.log(`Tool: ${event.toolName}`); return undefined; // Don't block }); // Block dangerous commands api.on("tool_call", async (event) => { if (event.toolName === "bash" && event.input.command?.includes("rm -rf")) { return { block: true, reason: "Dangerous command" }; } return undefined; }); // Register custom slash command api.registerCommand("stats", { description: "Show session stats", handler: async (ctx) => { const entries = ctx.sessionManager.getEntries(); ctx.ui.notify(`${entries.length} entries`, "info"); }, }); // Inject messages api.sendMessage({ customType: "my-hook", content: "Hook initialized", display: false, // Hidden from TUI }, false); // Don't trigger agent turn // Persist hook state api.appendEntry("my-hook", { initialized: true }); }; // Replace discovery const { session } = await createAgentSession({ hooks: [{ factory: loggingHook }], }); // Disable all hooks const { session } = await createAgentSession({ hooks: [], }); // Merge with discovered const discovered = await discoverHooks(); const { session } = await createAgentSession({ hooks: [...discovered, { factory: loggingHook }], }); // Add paths without replacing const { session } = await createAgentSession({ additionalHookPaths: ["/extra/hooks"], }); ``` Hook API methods: - `api.on(event, handler)` - Subscribe to events - `api.sendMessage(message, triggerTurn?)` - Inject message (creates `CustomMessageEntry`) - `api.appendEntry(customType, data?)` - Persist hook state (not in LLM context) - `api.registerCommand(name, options)` - Register custom slash command - `api.registerMessageRenderer(customType, renderer)` - Custom TUI rendering - `api.exec(command, args, options?)` - Execute shell commands > See [examples/sdk/06-hooks.ts](../examples/sdk/06-hooks.ts) and [docs/hooks.md](hooks.md) ### Skills ```typescript import { createAgentSession, discoverSkills, type Skill } from "@mariozechner/pi-coding-agent"; // Discover and filter const allSkills = discoverSkills(); const filtered = allSkills.filter(s => s.name.includes("search")); // Custom skill const mySkill: Skill = { name: "my-skill", description: "Custom instructions", filePath: "/path/to/SKILL.md", baseDir: "/path/to", source: "custom", }; const { session } = await createAgentSession({ skills: [...filtered, mySkill], }); // Disable skills const { session } = await createAgentSession({ skills: [], }); // Discovery with settings filter const skills = discoverSkills(process.cwd(), undefined, { ignoredSkills: ["browser-*"], // glob patterns to exclude includeSkills: ["search-*"], // glob patterns to include (empty = all) }); ``` > See [examples/sdk/04-skills.ts](../examples/sdk/04-skills.ts) ### Context Files ```typescript import { createAgentSession, discoverContextFiles } from "@mariozechner/pi-coding-agent"; // Discover AGENTS.md files const discovered = discoverContextFiles(); // Add custom context const { session } = await createAgentSession({ contextFiles: [ ...discovered, { path: "/virtual/AGENTS.md", content: "# Guidelines\n\n- Be concise\n- Use TypeScript", }, ], }); // Disable context files const { session } = await createAgentSession({ contextFiles: [], }); ``` > See [examples/sdk/07-context-files.ts](../examples/sdk/07-context-files.ts) ### Slash Commands ```typescript import { createAgentSession, discoverSlashCommands, type FileSlashCommand } from "@mariozechner/pi-coding-agent"; const discovered = discoverSlashCommands(); const customCommand: FileSlashCommand = { name: "deploy", description: "Deploy the application", source: "(custom)", content: "# Deploy\n\n1. Build\n2. Test\n3. Deploy", }; const { session } = await createAgentSession({ slashCommands: [...discovered, customCommand], }); ``` > See [examples/sdk/08-slash-commands.ts](../examples/sdk/08-slash-commands.ts) ### Session Management Sessions use a tree structure with `id`/`parentId` linking, enabling in-place branching. ```typescript import { createAgentSession, SessionManager } from "@mariozechner/pi-coding-agent"; // In-memory (no persistence) const { session } = await createAgentSession({ sessionManager: SessionManager.inMemory(), }); // New persistent session const { session } = await createAgentSession({ sessionManager: SessionManager.create(process.cwd()), }); // Continue most recent const { session, modelFallbackMessage } = await createAgentSession({ sessionManager: SessionManager.continueRecent(process.cwd()), }); if (modelFallbackMessage) { console.log("Note:", modelFallbackMessage); } // Open specific file const { session } = await createAgentSession({ sessionManager: SessionManager.open("/path/to/session.jsonl"), }); // List available sessions const sessions = SessionManager.list(process.cwd()); for (const info of sessions) { console.log(`${info.id}: ${info.firstMessage} (${info.messageCount} messages)`); } // Custom session directory (no cwd encoding) const customDir = "/path/to/my-sessions"; const { session } = await createAgentSession({ sessionManager: SessionManager.create(process.cwd(), customDir), }); ``` **SessionManager tree API:** ```typescript const sm = SessionManager.open("/path/to/session.jsonl"); // Tree traversal const entries = sm.getEntries(); // All entries (excludes header) const tree = sm.getTree(); // Full tree structure const path = sm.getPath(); // Path from root to current leaf const leaf = sm.getLeafEntry(); // Current leaf entry const entry = sm.getEntry(id); // Get entry by ID const children = sm.getChildren(id); // Direct children of entry // Labels const label = sm.getLabel(id); // Get label for entry sm.appendLabelChange(id, "checkpoint"); // Set label // Branching sm.branch(entryId); // Move leaf to earlier entry sm.branchWithSummary(id, "Summary..."); // Branch with context summary sm.createBranchedSession(leafId); // Extract path to new file ``` > See [examples/sdk/11-sessions.ts](../examples/sdk/11-sessions.ts) and [docs/session.md](session.md) ### Settings Management ```typescript import { createAgentSession, SettingsManager, SessionManager } from "@mariozechner/pi-coding-agent"; // Default: loads from files (global + project merged) const { session } = await createAgentSession({ settingsManager: SettingsManager.create(), }); // With overrides const settingsManager = SettingsManager.create(); settingsManager.applyOverrides({ compaction: { enabled: false }, retry: { enabled: true, maxRetries: 5 }, }); const { session } = await createAgentSession({ settingsManager }); // In-memory (no file I/O, for testing) const { session } = await createAgentSession({ settingsManager: SettingsManager.inMemory({ compaction: { enabled: false } }), sessionManager: SessionManager.inMemory(), }); // Custom directories const { session } = await createAgentSession({ settingsManager: SettingsManager.create("/custom/cwd", "/custom/agent"), }); ``` **Static factories:** - `SettingsManager.create(cwd?, agentDir?)` - Load from files - `SettingsManager.inMemory(settings?)` - No file I/O **Project-specific settings:** Settings load from two locations and merge: 1. Global: `~/.pi/agent/settings.json` 2. Project: `/.pi/settings.json` Project overrides global. Nested objects merge keys. Setters only modify global (project is read-only for version control). > See [examples/sdk/10-settings.ts](../examples/sdk/10-settings.ts) ## Discovery Functions All discovery functions accept optional `cwd` and `agentDir` parameters. ```typescript import { getModel } from "@mariozechner/pi-ai"; import { AuthStorage, ModelRegistry, discoverAuthStorage, discoverModels, discoverSkills, discoverHooks, discoverCustomTools, discoverContextFiles, discoverSlashCommands, loadSettings, buildSystemPrompt, } from "@mariozechner/pi-coding-agent"; // Auth and Models const authStorage = discoverAuthStorage(); // ~/.pi/agent/auth.json const modelRegistry = discoverModels(authStorage); // + ~/.pi/agent/models.json const allModels = modelRegistry.getAll(); // All models (built-in + custom) const available = await modelRegistry.getAvailable(); // Only models with API keys const model = modelRegistry.find("provider", "id"); // Find specific model const builtIn = getModel("anthropic", "claude-opus-4-5"); // Built-in only // Skills const skills = discoverSkills(cwd, agentDir, skillsSettings); // Hooks (async - loads TypeScript) const hooks = await discoverHooks(cwd, agentDir); // Custom tools (async - loads TypeScript) const tools = await discoverCustomTools(cwd, agentDir); // Context files const contextFiles = discoverContextFiles(cwd, agentDir); // Slash commands const commands = discoverSlashCommands(cwd, agentDir); // Settings (global + project merged) const settings = loadSettings(cwd, agentDir); // Build system prompt manually const prompt = buildSystemPrompt({ skills, contextFiles, appendPrompt: "Additional instructions", cwd, }); ``` ## Return Value `createAgentSession()` returns: ```typescript interface CreateAgentSessionResult { // The session session: AgentSession; // Custom tools (for UI setup) customToolsResult: { tools: LoadedCustomTool[]; setUIContext: (ctx, hasUI) => void; }; // Warning if session model couldn't be restored modelFallbackMessage?: string; } ``` ## Complete Example ```typescript import { getModel } from "@mariozechner/pi-ai"; import { Type } from "@sinclair/typebox"; import { AuthStorage, createAgentSession, ModelRegistry, SessionManager, SettingsManager, readTool, bashTool, type HookFactory, type CustomTool, } from "@mariozechner/pi-coding-agent"; // Set up auth storage (custom location) const authStorage = new AuthStorage("/custom/agent/auth.json"); // Runtime API key override (not persisted) if (process.env.MY_KEY) { authStorage.setRuntimeApiKey("anthropic", process.env.MY_KEY); } // Model registry (no custom models.json) const modelRegistry = new ModelRegistry(authStorage); // Inline hook const auditHook: HookFactory = (api) => { api.on("tool_call", async (event) => { console.log(`[Audit] ${event.toolName}`); return undefined; }); }; // Inline tool const statusTool: CustomTool = { name: "status", label: "Status", description: "Get system status", parameters: Type.Object({}), execute: async () => ({ content: [{ type: "text", text: `Uptime: ${process.uptime()}s` }], details: {}, }), }; const model = getModel("anthropic", "claude-opus-4-5"); if (!model) throw new Error("Model not found"); // In-memory settings with overrides const settingsManager = SettingsManager.inMemory({ compaction: { enabled: false }, retry: { enabled: true, maxRetries: 2 }, }); const { session } = await createAgentSession({ cwd: process.cwd(), agentDir: "/custom/agent", model, thinkingLevel: "off", authStorage, modelRegistry, systemPrompt: "You are a minimal assistant. Be concise.", tools: [readTool, bashTool], customTools: [{ tool: statusTool }], hooks: [{ factory: auditHook }], skills: [], contextFiles: [], slashCommands: [], sessionManager: SessionManager.inMemory(), settingsManager, }); session.subscribe((event) => { if (event.type === "message_update" && event.assistantMessageEvent.type === "text_delta") { process.stdout.write(event.assistantMessageEvent.delta); } }); await session.prompt("Get status and list files."); ``` ## RPC Mode Alternative For subprocess-based integration, use RPC mode instead of the SDK: ```bash pi --mode rpc --no-session ``` See [RPC documentation](rpc.md) for the JSON protocol. The SDK is preferred when: - You want type safety - You're in the same Node.js process - You need direct access to agent state - You want to customize tools/hooks programmatically RPC mode is preferred when: - You're integrating from another language - You want process isolation - You're building a language-agnostic client ## Exports The main entry point exports: ```typescript // Factory createAgentSession // Auth and Models AuthStorage ModelRegistry discoverAuthStorage discoverModels // Discovery discoverSkills discoverHooks discoverCustomTools discoverContextFiles discoverSlashCommands // Helpers loadSettings buildSystemPrompt // Session management SessionManager SettingsManager // Built-in tools (use process.cwd()) codingTools readOnlyTools readTool, bashTool, editTool, writeTool grepTool, findTool, lsTool // Tool factories (for custom cwd) createCodingTools createReadOnlyTools createReadTool, createBashTool, createEditTool, createWriteTool createGrepTool, createFindTool, createLsTool // Types type CreateAgentSessionOptions type CreateAgentSessionResult type CustomTool type HookFactory type Skill type FileSlashCommand type Settings type SkillsSettings type Tool ``` For hook types, import from the hooks subpath: ```typescript import type { HookAPI, HookMessage, HookFactory, HookEventContext, HookCommandContext, ToolCallEvent, ToolResultEvent, } from "@mariozechner/pi-coding-agent/hooks"; ``` For message utilities: ```typescript import { isHookMessage, createHookMessage } from "@mariozechner/pi-coding-agent"; ``` For config utilities: ```typescript import { getAgentDir } from "@mariozechner/pi-coding-agent/config"; ```