This directory contains a port of the pi-mono project from Mario Zechner to Swift, as I need to embed this into an iPad app:

https://github.com/badlogic/pi-mono

It is split up slightly differently.

Subagents (in-process)

PiSwift supports delegating work to specialized subagents without spawning a subprocess. Subagents are defined by user-editable Markdown files and run in-process with isolated context.

Agent locations

• User agents: ~/.pi/agent/agents
• Project agents: .pi/agents (nearest parent of the current working directory)

Agent file format

Each agent is a .md file with YAML-style frontmatter. The body becomes the agent’s system prompt.

Example:

---
name: worker
description: General-purpose subagent
model: gpt-5.2
tools: read,edit,write,bash
outputFormat: |
  ## Completed
  ## Files Changed
  ## Notes
---

You are a worker agent with full capabilities.

Supported frontmatter keys:

• name (required): agent name used in tool calls.
• description: shown in listings and error messages.
• tools: comma-separated tool names. Use all to enable all built-in tools (excluding subagent).
• model: model pattern (e.g. openai/gpt-5.2 or gpt-5.2).
• outputFormat: appended to the system prompt as an “Output format” section.

Subagent tool usage

The subagent tool supports three modes:

1. Single:

{ "agent": "worker", "task": "Summarize the tests in Tests/." }

2. Parallel:

{ "tasks": [
  { "agent": "worker", "task": "Scan Sources/ for concurrency violations." },
  { "agent": "reviewer", "task": "Review README for updates." }
] }

3. Chain:

{ "chain": [
  { "agent": "planner", "task": "Plan the fix for X." },
  { "agent": "worker", "task": "Implement the plan:\n{previous}" }
] }

Optional parameters:

• agentScope: user, project, or both (default: user).
• cwd: per-task working directory (single/parallel/chain items).

Notes

• Subagents run in-process; no subprocess is spawned.
• If tools is omitted, the default coding toolset is used.
• If model is omitted, the main agent’s selected model is used.

Prompt templates

Prompt templates are Markdown files that expand when you type /name in the prompt.

Locations:

• User templates: ~/.pi/agent/prompts
• Project templates: .pi/prompts (nearest parent of the current working directory)

Template body supports $1, $2, $ARGUMENTS, and $@ substitutions.

Default model priority

When no model is selected, the default fallback order is:

1. anthropic: claude-sonnet-4-5
2. openai: gpt-5.2
3. openai-codex: gpt-5.2-codex
4. opencode: claude-opus-4-5

Strict concurrency + errors

This port uses strict concurrency (no @unchecked Sendable). Data races are fixed at the source. Errors use Swift enums that conform to LocalizedError instead of NSError.

Sample subagent

See examples/subagents/fetcher.md for a sample agent that uses curl via the bash tool to fetch files from the internet.