Pi Agent

Use this skill when the user wants to operate Pi or build on top of Pi. Pi is a minimal terminal coding harness extended through TypeScript extensions, skills, prompt templates, themes, packages, custom models/providers, SDK integrations, RPC mode, JSON event streams, and TUI components.

First Decision

Pick the reference before answering or coding:

Build-On-Pi Defaults

Prefer the SDK for Node/TypeScript apps that need type safety, direct state access, in-process custom tools/extensions, or custom resource loading. Use createAgentSession() for a single stable session; use createAgentSessionRuntime() when the app must replace sessions through new/resume/fork/clone/import flows. Auth and model lookup go through ModelRuntime.create().

Prefer RPC mode when the client is not Node.js, needs process isolation, or wants a language-agnostic JSONL protocol. Start with pi --mode rpc --no-session for stateless subprocess integration, then add session flags when persistence matters. Split records on \n only — Node readline is not protocol-compliant.

For RPC clients, correlate responses by unique request id, not arrival order, and keep consuming events after a successful prompt response. Success means accepted, queued, or handled; it is not completion. Subscribe before sending the prompt, and wait for agent_settled for runs that actually start, because agent_end may precede retries or queued work. If the response reports disposition: "handled", no run started and no settled event is owed. See the upstream RPC lifecycle.

Prefer JSON mode for one-shot command-line pipelines that only need streamed events, not bidirectional control: pi --mode json "prompt".

Use extensions for Pi-native behavior: custom tools, command handlers, event hooks, provider registration, custom compaction, path protection, project trust policy, UI prompts, widgets, and TUI components.

Use packages when sharing or installing reusable extensions, skills, prompt templates, or themes across machines or projects.

Safety Defaults

Pi is local and not sandboxed by default. Treat extensions, packages, skills, shell commands, and project-local .pi resources as code with the permissions of the Pi process. Project trust only guards which project inputs load — it is not a sandbox. For untrusted repos or unattended automation, isolate with Docker, OpenShell, Gondolin, a VM, or a remote sandbox.

Do not store secrets in project files. Prefer env vars, ~/.pi/agent/auth.json, OAuth via /login, or command-backed secret lookups in models.json/provider config.

Common Commands

npm install -g --ignore-scripts @earendil-works/pi-coding-agent
pi
pi -p "Summarize this codebase"
pi --mode json "List files"
pi --mode rpc --no-session
pi --provider anthropic --model claude-sonnet-4-5
pi --model sonnet:high "Solve this complex problem"
pi --tools read,grep,find,ls -p "Review this repository"
pi --tui-mode fullscreen
pi install npm:pi-subagents
pi update --all

Source Coverage

These references were reviewed against the official Pi 0.99.2 release (2026-09-30), its published npm runtime and declarations, and current Pi documentation. Source: earendil-works/pi v0.99.2. Ecosystem contracts were checked against published pi-subagents 0.74.0, pi-mcp-adapter 4.0.0, pi-interview 0.13.0, and pi-web-access 0.35.0 sources. These releases are the compatibility baseline, not interchangeable historical APIs.

Local checks cover CLI/RPC control, SDK sessions and transcript projection, mocked model/tool execution, extension loading, and example configuration/schema contracts. Authentication flows, paid model/search calls, graphical UI, and external sandboxes are documentation-verified only; deployment examples requiring them are illustrative. Check pi --version, pi --help, the installed package README, and TypeScript declarations before adapting examples to another release. Pi 0.99 includes native MCP; pi-subagents 0.74 removes workflowScript; adapter 4.0 uses mcp-adapter.json and /mcp-adapter.