GreenLoop

A spec-to-verified-app system for Claude Code: an npx installer + plugin that takes you from an idea to a working, E2E-verified app through human-gated planning phases and a machine-gated build loop. Every feature must survive a committed, tamper-evident verifier — typecheck + unit + real E2E on a simulator — before the agent is allowed to stop. The loop is only done when the verifier is green: hence the name.

Status: v1 feature-complete, pre-release. Core engine, Claude Code plugin, the expo-react-native profile, guided installer, and the MiniClinic demo are implemented; not yet published to npm, and the full dogfood loop awaits its first provisioned CI run. Design spec: docs/specs/2026-07-08-greenloop-design.md.

Install

npx greenloop          # guided: preflight loop, plugin + Expo MCP registration
npx greenloop --check  # report-only preflight (exit 0 ready / 3 not ready)
npx greenloop --yes    # auto-confirm the safe installs (Maestro)

The installer never half-installs: it auto-installs only Maestro, prints exact instructions for everything else (Xcode, Docker Desktop), and re-checks in a loop until green.

CLIs

All commands run in the target project directory (the app being built) and read greenloop.config.json + progress.json from its root.

Command	Purpose
greenloop-verify <task-id>	The green gate: typecheck → unit → env preflight → E2E, fail-fast. Sole writer of passes in progress.json.
greenloop-doctor	Runs every environment check from config, prints the full ✓/✗ fix-it list.
greenloop-loop <task-id> [max-laps]	Headless laps: runs claude -p with the boss prompt, gates each lap on greenloop-verify. Wrap in timeout 30m ... (macOS: gtimeout, from brew install coreutils) for unattended runs.
greenloop-stop-hook	Claude Code Stop hook: blocks the session from stopping while an active task is red (exit 2). Escape hatch: set "abandoned": true on the task.

Exit-code contract

Code	Meaning
0	Green — all layers passed (passes: true written)
1	Red — a real failure (passes: false written); only the failing tail is printed, full logs in .greenloop/results/<task>/
3	Environment not ready (preflight/doctor failure) — not a code failure; passes untouched
9	Usage error / unknown task

greenloop.config.json

{
  "profile": "expo-react-native",
  "resultsDir": ".greenloop/results",
  "tailLines": 40,
  "verifier": {
    "typecheck": [{ "name": "mobile-tsc", "run": "npm run typecheck -w apps/mobile" }],
    "unit": [{ "name": "mobile-jest", "run": "npm test -w apps/mobile" }],
    "preflight": [{ "name": "backend-up", "run": "curl -sf http://localhost:3001/health", "fixHint": "docker compose up -d" }],
    "e2e": { "adapter": "maestro-ios", "run": "maestro test {flow}" }
  },
  "doctor": [
    { "name": "docker", "run": "docker info", "fixHint": "Start Docker Desktop" }
  ],
  "loop": {
    "allowedTools": "Read,Edit,Write,Bash(greenloop-verify:*),Bash(npm test:*),Bash(npm run typecheck:*),Bash(maestro test:*),Bash(maestro hierarchy:*)",
    "maxTurns": 40
  }
}

{flow} in e2e.run is replaced by the task's flow path from progress.json.

progress.json

{
  "tasks": [
    {
      "id": "s01-login",
      "spec": "Login screen per PRD S-01",
      "acceptance": ["user can log in with phone+PIN"],
      "testIDs": ["login-screen", "phone-input"],
      "flow": ".maestro/s01-login.yaml",
      "active": true,
      "passes": false,
      "abandoned": false,
      "reflexions": []
    }
  ]
}

Rules the whole system depends on:

• greenloop-verify is the only writer of passes. Agents and humans never hand-set it.
• active: true arms the Stop hook; an active, non-passing, non-abandoned task blocks the Claude Code session from stopping.
• Weakening the verifier config or an E2E flow to force a pass is reward hacking; both are committed, so tampering shows in the diff.

The plugin

The Claude Code plugin lives in plugin/ (plugin name: greenloop). Until the guided installer (Plan 4) lands, install it from this repo:

claude plugin marketplace add /path/to/greenloop   # or the GitHub repo once public
claude plugin install greenloop@greenloop

Commands

Command	Phase	Gate
/greenloop	Status router — "You are in <phase>. Next: …"	—
/greenloop:idea	Free-form conversation → drafts prd.md v0	User confirms direction
/greenloop:prd	Gap-hunting iteration loop on the PRD	Zero gaps and user declares final
/greenloop:architecture	Schema / API / offline-sync review + stack confirmation	User approves
/greenloop:scaffold	Births the project from the bound profile + artifacts	User reviews scaffold, fills spiritual-guide.md
/greenloop:feature <id>	The green loop	Machine: greenloop-verify exit 0, then review + commit
/greenloop:overnight <ids>	Unattended greenloop-loop runs	Wake-up ritual: diff review + fresh greenloop-verify
/greenloop:doctor	Environment fix-it list via greenloop-doctor	—

Skills, hook, templates

• Skills (self-contained, no external plugin dependencies): greenloop-prd, greenloop-architecture, greenloop-feature, greenloop-debugging, greenloop-overnight.
• Stop hook: plugin/hooks/verify-before-stop.js blocks the session from stopping while an active task is red. It is a self-contained copy of greenloop-stop-hook (a marketplace install only ships plugin/), kept identical by a parity test.
• Templates (plugin/templates/): the §5 artifact set — prd.md (S-NN screen specs with required testIDs), state.md, debug.md, progress.json, spiritual-guide.md, remaining-tasks.md, CLAUDE.md.

Stack profiles

Swapping stacks swaps more than the E2E command, so the unit of extension is a profile (profiles/<name>/), not a verifier adapter:

File	Consumed by
verifier.json	greenloop-verify — layer commands + e2e adapter
doctor.json	greenloop-doctor — required tools + env checks
toolbelt.md	the build-loop skills — launch, logs, screenshots, view tree
conventions.md	the build-loop skills — testID naming, flow locations, idioms
templates/	/greenloop:scaffold — the project scaffold

A project binds a profile in greenloop.config.json ("profile": "expo-react-native"). loadConfig merges the profile's verifier/doctor defaults under the project's config; a key present in the project config replaces the profile's key wholesale (no deep merging), and an unknown profile name is a hard error — no silent degradation.

v1 ships profiles/expo-react-native (macOS + iOS Simulator): Expo + expo-router + WatermelonDB + Zustand + TanStack Query / Express + Prisma + PostgreSQL + Redis / npm-workspaces monorepo / Maestro E2E. Template dependency versions get exercised and pinned by the MiniClinic demo + CI (Plan 4).

Docs

• docs/tutorial.md — idea → verified app, mirroring demo/miniclinic
• docs/playbook.md — token economy: ccusage, model strategy, cache cadence
• docs/os-matrix.md — OS support and the maestro-android roadmap
• docs/writing-profiles.md — authoring a stack profile
• docs/container-mode.md — optional Docker bypass mode and its caveats

Development

Node >= 20, ESM, zero runtime dependencies. Tests use the built-in runner:

npm test

License

MIT