Fleet Worker

Spawn headless OpenCode workers on cheap models — delegate expensive tool-using tasks to a fleet of parallel workers with isolated git worktrees. Optional Brick routing selects the optimal model per task automatically.

MIT License Node.js TypeScript MCP Brick Routing

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MCP Activation Keywords

Le seguenti keyword attivano questo MCP in Claude Code / OpenCode:

Keyword	Azione
fleet-worker	Attivazione generica
delegate to GLM	Usa regolo/glm5.2-beta come worker
spawn a GLM worker	Idem
cheap parallel agent	Spawn worker su modello economico
grunt worker	Worker per task ripetitivi
offload to glm	Delega task a GLM
z.ai worker	Worker su endpoint z.ai
GLM-5.2 worker	Worker su glm5.2
sonnet worker	Worker Sonnet
haiku worker	Worker Haiku
cheap coding agent	Worker economico generico
fan out workers	Spawn multipli in parallelo
non-Anthropic model in OpenCode	Worker su modello non-Anthropic
ANTHROPIC_BASE_URL worker	Worker su endpoint custom
fleet-worker list models	fleet_worker_list_models
fleet-worker spawn	fleet_worker_spawn
fleet-worker collect	fleet_worker_collect
fleet-worker status	fleet_worker_status
fleet-worker cancel	fleet_worker_cancel

Aggiungi al tuo .claude/hooks/PreToolUse o usa direttamente i tool MCP via Claude Code.

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What Is This?

mcp-fleet-worker is an MCP server that lets you spawn headless OpenCode workers on any model configured in your opencode.json — from local Ollama models to cheap remote providers like GLM via z.ai.

Each worker runs in an isolated git worktree with its own CLAUDE_CONFIG_DIR, so multiple workers run side-by-side without conflicting. Workers are treated as disposable "grunt agents": a powerful orchestrator (Opus) fans out tasks, collects results, and lands the completed branches.

Why?

• Cost optimization: run cheap models (GLM-5.2, Haiku, Sonnet) for routine coding tasks, reserve Opus for orchestration
• Parallel execution: spawn N workers simultaneously, each in its own worktree
• Isolation: each worker gets a fresh git branch + scratch directory
• Fleet-ops ready: designed to pair with fleet-ops for test-gated landing

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Technology Stack

Technology	Version	Purpose
Node.js	>= 18	Runtime
TypeScript	5.3	Language
@modelcontextprotocol/sdk	^1.0.0	MCP server framework
zod	^3.23.0	Runtime schema validation
git worktree	system	Worker isolation
OpenCode	any	Spawned agent process
Brick (optional)	SR1	Smart model routing via Regolo API

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Architecture

                    ┌─────────────────────────────────┐
                    │       Claude Code (Opus)         │
                    │    (orchestrator / caller)        │
                    └──────────┬──────────────────────┘
                               │ MCP (stdio)
                    ┌──────────▼──────────────────────┐
                    │     mcp-fleet-worker server      │
                    │                                   │
                    │  ┌─ fleet_worker_spawn            │
                    │  ├─ fleet_worker_collect          │
                    │  ├─ fleet_worker_status           │
                    │  ├─ fleet_worker_list_models      │
                    │  └─ fleet_worker_cancel           │
                    └──────────┬──────────────────────┘
                               │
                    ┌──────────▼──────────────────────┐
                    │      Git Worktree (.fleet-work/) │
                    │                                   │
                    │  worker-1/  ← branch `fleet/id1` │
                    │  worker-2/  ← branch `fleet/id2` │
                    │  ...                              │
                    └──────────┬──────────────────────┘
                               │
                    ┌──────────▼──────────────────────┐
                    │   ~/.fleet-worker/scratch/<id>/  │
                    │   (CLAUDE_CONFIG_DIR per worker) │
                    └─────────────────────────────────┘

Flow

1. Caller sends a prompt + optional model to fleet_worker_spawn
2. Server creates an isolated git worktree (.fleet-work/<id>/) with a dedicated branch (fleet/<id>)
3. Server spawns opencode run -m <model> --agent coder --auto --dir <worktree> --format json "<prompt>"
4. Caller polls fleet_worker_collect or waits for completion
5. Worker finishes → output is captured → fleet_worker_cancel cleans up worktree + scratch dir

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Getting Started

Prerequisites

• Node.js >= 18
• npm or pnpm
• OpenCode installed (the opencode CLI in PATH)
• A git repository to use as the worker base directory

Installation

# Clone
git clone https://github.com/alexgenovese/mcp-fleet-worker.git
cd mcp-fleet-worker

# Install deps
npm install

# Build
npm run build

# Test
node dist/index.js

Configuration

Add to your opencode.json (or to your MCP hub config):

{
  "mcpServers": {
    "mcp-fleet-worker": {
      "command": "node",
      "args": ["/path/to/mcp-fleet-worker/dist/index.js"],
      "env": {
        "FLEET_WORKER_BASE_DIR": "/path/to/your/git/repo",
        "FLEET_WORKER_DEFAULT_MODEL": "regolo/glm5.2-beta",
        "FLEET_WORKER_BRICK_URL": "https://api.regolo.ai",
        "FLEET_WORKER_BRICK_API_KEY": "your-regolo-api-key",
        "OPENCODE_PATH": "opencode"
      }
    }
  }
}

Environment Variables:

Variable	Default	Description
FLEET_WORKER_BASE_DIR	process.cwd()	Git repo for worktree isolation
FLEET_WORKER_DEFAULT_MODEL	regolo/gemma4-31b	Fallback model when routing is off/unavailable
FLEET_WORKER_BRICK_URL	(empty)	Brick API URL (Regolo). When set, enables smart routing
FLEET_WORKER_BRICK_API_KEY	(empty)	API key for Brick (Regolo API key)
OPENCODE_PATH	opencode	Path to opencode binary
XDG_CONFIG_HOME	unset for worker	Stripped so worker uses fresh config

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Brick Smart Routing (Optional)

When FLEET_WORKER_BRICK_URL and FLEET_WORKER_BRICK_API_KEY are set, fleet_worker_spawn without an explicit model parameter will call Brick's /v1/routing/test endpoint to select the optimal model based on:

• Capability — 6 dimensions (coding, math_reasoning, creative_synthesis, instruction_following, planning_agentic, world_knowledge)
• Complexity — easy / medium / hard
• Cost — penalizes expensive models for simple tasks

How It Works

fleet_worker_spawn(prompt="fix typo in README.md")
  ↓
  Brick analyzes prompt → complexity: easy, capability: {instruction_following: 0.9}
  ↓
  Brick selects: ollama/qwen3:4b (cheapest capable model)
  ↓
  Worker spawns on ollama/qwen3:4b
  ↓
  fleet_worker_status shows: routed=true, costSavings=95%

When Routing Kicks In

Call	Behavior
fleet_worker_spawn(prompt="...", model="regolo/glm5.2-beta")	Explicit model → no routing, use specified model
fleet_worker_spawn(prompt="...") + Brick configured	Brick routes automatically
fleet_worker_spawn(prompt="...") + Brick not configured	Falls back to FLEET_WORKER_DEFAULT_MODEL

Cost Savings Tracking

Every routed worker records its costSavings percentage (estimated vs. using the fallback model). This appears in:

• fleet_worker_spawn response (routing.costSavings)
• fleet_worker_status output (per-worker costSavings)
• fleet_worker_collect result (routing.costSavings)

See USE_CASES.md for detailed cost-saving scenarios for developers and CTOs.

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Project Structure

mcp-fleet-worker/
├── src/
│   ├── index.ts              # MCP server entry point
│   ├── types.ts              # WorkerSpec, WorkerProcess, WorkerStatus
│   ├── lib/
│   │   ├── models.ts         # opencode.json parser (JSONC-aware)
│   │   ├── router.ts         # Brick routing client (Regolo API)
│   │   ├── worktree.ts       # Git worktree create/remove/cleanup
│   │   ├── config.ts         # Scratch directory (~/.fleet-worker/)
│   │   ├── id.ts             # Short UUID generator (8 chars)
│   │   └── worker-manager.ts # Spawn/track/kill opencode children
│   └── tools/
│       └── register.ts       # 5 MCP tool handlers
├── dist/                     # Compiled JavaScript
├── package.json
├── tsconfig.json
└── README.md

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Key Features

1. Multi-Model Support

Reads all providers and models from opencode.json — Ollama, GLM, custom OpenAI-compatible endpoints. Use fleet_worker_list_models to see what's available.

2. Git Worktree Isolation

Each worker runs in a dedicated git worktree (git worktree add -b fleet/<id>), so multiple workers can modify the same repo simultaneously without merge conflicts at runtime.

3. Background Execution

Workers spawn as child processes with captured stdout/stderr. Collect results async via fleet_worker_collect.

4. Cleanup

fleet_worker_cancel with cleanup: true removes:

• The worktree directory (.fleet-work/<id>/)
• The local git branch (fleet/<id>)
• The scratch config dir (~/.fleet-worker/scratch/<id>/)

5. JSONC Parsing

Reads opencode.json even with comments (// and /* */) — no need to strip them manually.

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MCP Tools

fleet_worker_list_models

List all available models grouped by provider, with context window and cost info.

fleet_worker_spawn

Spawn a headless worker on any model.

Parameter	Type	Default	Description
prompt	string	required	Task prompt for the worker
model	string	env/FALLBACK	provider/model-id format
agent	string	coder	OpenCode agent type
worktree	string	FLEET_WORKER_BASE_DIR	Git repo path
branch	string	fleet/<id>	Git branch name
maxTurns	number	50	Max interaction turns
timeout	number	300	Timeout in seconds

fleet_worker_collect

Get a worker's result.

Parameter	Type	Default	Description
workerId	string	required	Worker ID from spawn
wait	boolean	false	Block until completion
timeout	number	30	Max wait in seconds

fleet_worker_status

List all workers with status, model, branch, elapsed time.

fleet_worker_cancel

Stop and clean up a worker.

Parameter	Type	Default	Description
workerId	string	required	Worker ID to cancel
cleanup	boolean	true	Remove worktree + scratch

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Development Workflow

1. Install → npm install
2. Build → npm run build
3. Watch → npm run dev (tsc --watch)
4. Test locally → node dist/index.js (then connect with MCP inspector or Claude Desktop)

To test with the MCP inspector:

npx @modelcontextprotocol/inspector node dist/index.js

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Testing

# Type check
npx tsc --noEmit

# Build
npm run build

# Quick smoke test (list models)
node -e "
import('./dist/index.js').then(() => console.log('Server loads OK'))
"

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License

MIT © Alex Geno