pi-dev-loop

Autonomous development loop engine for pi — verify-driven iteration with error tracking and regression detection.

Prerequisites

• pi

• Subagent capability (recommended) — the dev loop uses subagent() for process isolation. Install pi-subagents:

  pi add npm:pi-subagents
  

  Without it, the dev loop still works — the orchestrator does the work directly.

Architecture

Three-layer isolation (with subagents):

┌─ Orchestrator (main session) ───────────────────┐
│  Tracks error registry, dispatches work,         │
│  never writes code directly.                     │
├─ Impl Subagents (forked) ───────────────────────┤
│  Follow TDD: failing test → implement → verify   │
├─ Review Subagents (fresh, read-only) ───────────┤
│  Independently evaluate code with zero context   │
└──────────────────────────────────────────────────┘

Quick Start

Start a loop from conversation (the agent picks it up):

loop_start({ goal: "Fix type errors in src/user.ts" })

Or via commands:

/loop goal "Implement registration module"

Subcommands

Command	Description
/loop goal <desc> [options]	Start a verification-driven loop
/loop stop	Stop active loop
/loop pause	Pause loop (preserve state)
/loop resume	Resume paused loop
/loop status	Show loop state + error registry
/loop history	Show iteration history

Options for /loop goal:

• --verify <cmd> — add verification command (repeatable; auto-detected otherwise)
• --max-iterations <N> — max iterations before auto-pause (default 20)

Verification-Driven Stopping

The dev loop requires verification commands to pass before advancing. Errors are tracked across iterations with SHA-256 fingerprinting, detecting:

• Regressed errors — previously fixed errors that reappeared
• New errors — introduced by the current iteration's changes
• Persistent errors — unresolved across multiple iterations

The engine auto-rollbacks on regression when git snapshots are enabled.

Project Layout

pi-dev-loop/
├── src/                     # Core modules
│   ├── state.ts             # DevLoopState, ErrorRecord types + serialization
│   ├── error-registry.ts    # Fingerprinting, mergeRegistry, parseOutput
│   ├── verify-config.ts     # --verify arg parsing, buildConfig
│   ├── git.ts               # Snapshot, rollback, pruning
│   ├── subagent-task.ts     # Context packing for impl/review subagents
│   ├── session-prompt.ts    # Iteration prompt builder
│   └── auto-detect.ts       # Auto-detect verify commands from project
├── extensions/pi-dev-loop/  # pi extension entry point
│   └── index.ts             # Commands, tools, events, decision engine
├── skills/pi-dev-loop/      # Agent behavior guide
├── prompts/                 # Prompt templates
├── tests/                   # Bun test suite
└── docs/
    ├── specs/               # Design documents
    └── plans/               # Implementation plans

Development

bun test              # Run all tests
bun run typecheck     # TypeScript check

This project follows design-confirm-implement → TDD → planned execution → review → verify.

License

MIT © 2026 Sason Wong