assistant-ui--assistant-ui/examples/with-pi

assistant-ui × Pi

A minimal local harness for the @assistant-ui/react-pi adapter, driving the Pi coding agent in-process.

It demonstrates the MVP surface: a thread list, new sessions, a composer with steer / follow-up / stop, streaming assistant responses (text + reasoning), tool cards with streaming output, the blocking host-UI dialogs (confirm / input / select / editor), a model + credential readiness banner, a context-usage indicator, and a read-only workspace browser (components/workspace-browser.tsx backed by /api/pi/fs) for inspecting the agent's working directory. It proves the adapter surface, not a full desktop app shell.

How it fits together

browser                         server (Next.js, Node runtime)
─────────                       ──────────────────────────────
usePiRuntime                    app/api/pi/**            ← route layer
  └ createPiHttpClient  ──HTTP──▶ piClient = createPiNodeClient(...)
       (fetch + SSE)               └ PiThreadSupervisor → Pi SDK (AgentSession)

createPiHttpClient and the route layer are two halves of one PiClient contract: the browser talks HTTP/SSE, the server runs the SDK in-process behind the process-singleton supervisor.

Model resolution

Resolution mirrors Pi's own createAgentSession: if you set PI_PROVIDER + PI_MODEL_ID they win; otherwise the server falls back to Pi's configured default (settings.json's defaultProvider/defaultModel). So if you're authenticated with pi and have a default model picked, no env is required. The resolved model is handed to every new session and seeds the in-app model selector (via @assistant-ui/ui's ModelSelector) and the readiness banner's credential check. The selector is wired to Pi's per-thread setModel, and the composer exposes Pi's thinking-level control. Set PI_CODING_AGENT_DIR to point at a non-default agent config dir (defaults to ~/.pi/agent).

Run it

1. Authenticate Pi once and pick a default model (writes ~/.pi/agent/):

   pnpm dlx @earendil-works/pi-coding-agent
   

2. Start it (no env needed if Pi has a default model):

   pnpm dev
   

   To override the model or workspace, copy .env.example to .env.local and set PI_PROVIDER / PI_MODEL_ID / PI_WORKSPACE_PATH.

The agent reads and writes files and runs shell commands in PI_WORKSPACE_PATH. Point it at a scratch directory.