Pi

Pi is one of Z.E.N.'s three built-in providers, alongside Claude and Codex. You can use Pi to run any node, set it as your workflow default, or mix it into a workflow that uses different providers per step.

Use Pi for a single node

nodes:
  - id: summarize
    provider: pi
    model: pi-default
    prompt: |
      Summarize the morning Slack into a five-bullet brief.

The provider: pi field tells Z.E.N. which provider to call for this node. Everything else (variables, dependencies, output capture) works the same as any other prompt node.

Use Pi as your default

In ~/.zen/config.yaml:

assistants:
  default: pi
  pi:
    model: pi-default

Every node that doesn't override provider: will use Pi. Override on the nodes where you specifically want Claude or Codex.

Configuration

Pi uses Pi's SDK in-process. It does not launch the Pi TUI. The workflow working directory is passed to Pi as cwd, so project-local Pi resources are resolved from that directory.

Basic global setup:

assistants:
  default: pi
  pi:
    model: google/gemini-2.5-pro

Project or instance-scoped Pi setup:

assistants:
  pi:
    model: zai/glm-5-turbo
    agentDir: /Volumes/4/data-mom/.pi-agent
    authPath: ~/.pi/agent/auth.json
    modelsJsonPath: /Volumes/4/data-mom/.pi-agent/models.json

agentDir, authPath, and modelsJsonPath can point at the same Pi setup or be split. When authPath is omitted and agentDir is set, Z.E.N. uses <agentDir>/auth.json. When modelsJsonPath is omitted and agentDir is set, Z.E.N. uses <agentDir>/models.json.

Custom providers belong in Pi's models.json. Z.E.N. passes that registry to Pi and lets Pi resolve provider auth, headers, local provider settings, and keyless provider behavior.

Extensions

Pi extensions run in-process with Z.E.N.'s server permissions, so only load extensions you trust.

assistants:
  pi:
    model: google/gemini-2.5-pro
    extensionMode: explicit
    extensionPaths:
      - /Volumes/4/data-mom/.pi-agent/extensions/my-extension
    interactive: true
    extensionFlags:
      plan: true

extensionMode controls discovery:

• none: load no Pi extensions.
• explicit: load only extensionPaths.
• default: request normal Pi discovery from the configured agentDir and the workflow cwd, plus any extensionPaths.

enableExtensions remains supported as a compatibility alias. enableExtensions: true maps to extensionMode: default; enableExtensions: false maps to extensionMode: none.

Normal Pi discovery can include project-local .pi extension code. To keep server-side runs deterministic across old and new Pi SDKs, Z.E.N. only opens normal discovery when trustProjectExtensions: true is set. Without that trust flag, extensionMode: default loads only explicit extensionPaths. extensionMode: explicit is the safest option for repeatable workflows.

What you can do with Pi

Anything you'd do with Claude or Codex. Run a single node with Pi as the provider, set it as your default, or mix it across a workflow when one step is better suited to Pi than the others. The provider sits behind the same node interface as the rest.