io.github.btouchard/herald MCP Server

<p align="center"> <h1 align="center">Herald</h1> <p align="center"> <strong>Code from your phone. Seriously.</strong> <br /> <em>The self-hosted MCP bridge between Claude Chat and Claude Code.</em> </p> </p> <p align="center"> <a href="https://go.dev"><img src="https://img.shields.io/badge/Go-1.26+-00ADD8?logo=go&logoColor=white" alt="Go 1.26+"></a> <a href="LICENSE"><img src="https://img.shields.io/badge/License-AGPL--3.0-blue.svg" alt="AGPL-3.0 License"></a> <a href="https://github.com/btouchard/herald/stargazers"><img src="https://img.shields.io/github/stars/btouchard/herald?style=social" alt="GitHub Stars"></a> </p> <p align="center"> <a href="https://btouchard.github.io/herald/">Documentation</a> &middot; <a href="#quick-start">Quick Start</a> &middot; <a href="#how-it-works">How It Works</a> &middot; <a href="#features">Features</a> &middot; <a href="#security">Security</a> &middot; <a href="#roadmap">Roadmap</a> <br /> 🇫🇷 <a href="README_FR.md">Version française</a> </p>

---

<img src="/assets/herald-hero.svg">

You're on the couch. On your phone. You open Claude Chat and type:

"Refactor the auth middleware in my-api to use JWT instead of session cookies. Run the tests."

Four minutes later, it's done. Branch created, code refactored, tests passing, changes committed. Your workstation did all the work. You never opened your laptop.

That's Herald.

The Problem

Claude Chat and Claude Code are two brilliant tools that live in completely separate worlds.

	Claude Chat	Claude Code
Where	Browser, phone, anywhere	Your terminal
What	Conversations, analysis, thinking	Reads, writes, and ships actual code
Gap	Can't touch your codebase	Can't leave your desk

You've been copy-pasting between them. Or worse — you've been waiting until you're back at your desk. That's over.

The Solution

Herald is a self-hosted MCP server that bridges Claude Chat to Claude Code using Anthropic's official Custom Connectors protocol. One Go binary. Zero hacks.

  You (phone/tablet/browser)
       │
       │  "Add rate limiting to the API"
       ▼
  Claude Chat ──── MCP over HTTPS ────► Herald (your workstation)
                                           │
                                           ▼
                                        Claude Code
                                           ├── reads your codebase
                                           ├── writes the code
                                           ├── runs the tests
                                           └── commits to a branch

  You (terminal)
       │
       │  Claude Code calls herald_push
       ▼
  Claude Code ──── MCP ────► Herald ────► Claude Chat picks it up
                                           └── session context, summary,
                                               files modified, git branch

The bridge is bidirectional. Claude Chat dispatches tasks to Claude Code, and Claude Code can push session context back to Herald for remote monitoring and continuation from another device.

Your code never leaves your machine. Herald just orchestrates.

How It Works

You (Claude Chat)          Herald                     Claude Code
─────────────────          ──────                     ───────────
"Refactor auth..."    ──►  start_task
                           → creates branch
                           → spawns Claude Code  ──►  reads codebase
                                                      refactors code
                                                      runs tests
                                                      commits changes
                      ◄──  task_id: herald-a1b2c3d4

"How's it going?"     ──►  check_task
                      ◄──  ✅ Completed (4m 12s)
                           4 files changed (+127/-23)

"Show me the diff"    ──►  get_diff
                      ◄──  auth/middleware.go
                           +func ValidateJWT(...)
                           -func CheckSession(...)

Three tools. That's the core loop. Start, check, get results — all from wherever you are.

Reverse flow: Claude Code → Herald

Working in your terminal and want to continue from your phone? Claude Code pushes its session to Herald:

You (terminal)             Claude Code                Herald
──────────────             ───────────                ──────
"Push this to Herald"  ──►  herald_push
                             → session_id, summary,
                               files, branch       ──►  linked task created
                                                         🔗 visible in list_tasks

You (phone, later)         Claude Chat                Herald
──────────────────         ───────────                ──────
"What sessions are         list_tasks
 waiting for me?"     ──►  (status: linked)      ──►  🔗 herald-a1b2c3d4
                                                         my-api / feat/auth

"Resume that session"  ──► start_task
                            (session_id)          ──►  picks up where you left off

Features

Core

• Native MCP bridge — Uses Anthropic's official Custom Connectors protocol. Not a hack, not a wrapper, not a proxy.
• Async task execution — Start tasks, check progress, get results. Claude Code runs in the background while you do other things.
• Git branch isolation — Each task runs on its own branch. Your main branch stays untouched.
• Session resumption — Multi-turn Claude Code conversations. Pick up where you left off.
• Bidirectional bridge — Claude Code can push session context to Herald via herald_push for remote monitoring and continuation from another device.

Multi-Project

• Multiple projects — Configure as many projects as you need, each with its own settings.
• Per-project tool restrictions — Control exactly which tools Claude Code can use. Full sandboxing per project.

Operations

• MCP push notifications — Herald pushes task updates directly to Claude Chat via MCP server notifications. No polling needed.
• SQLite persistence — Tasks survive server restarts. Full history, fully searchable.

Engineering

• Single binary — One Go executable, ~15MB. No Docker, no runtime, no node_modules.
• Zero CGO — Pure Go. Cross-compiles to Linux, macOS, Windows, ARM.
• 6 dependencies — chi, mcp-go, modernc/sqlite, uuid, yaml, testify. That's the entire dependency tree.

Quick Start

Prerequisites: Claude Code CLI installed, HTTPS via ngrok (built-in) or a domain with reverse proxy.

1. Install

curl -fsSL https://raw.githubusercontent.com/btouchard/herald/main/install.sh | sh

<details> <summary>Or build from source (requires Go 1.26+)</summary>

git clone https://github.com/btouchard/herald.git
cd herald && make build
# Binary is in ./bin/herald

</details>

2. Configure

mkdir -p ~/.config/herald
cp configs/herald.example.yaml ~/.config/herald/herald.yaml
# Edit with your domain and projects (see below)

3. Run

herald serve
# Client secret is auto-generated on first start and displayed in the console

Edit ~/.config/herald/herald.yaml with your domain and projects:

server:
  host: "127.0.0.1"
  port: 8420
  public_url: "https://herald.yourdomain.com"

auth:
  client_id: "herald-claude-chat"

projects:
  my-api:
    path: "/home/you/projects/my-api"
    description: "Main backend API"
    default: true
    allowed_tools:
      - "Read"
      - "Write"
      - "Edit"
      - "Bash(git *)"
      - "Bash(go *)"
      - "Bash(make *)"
    git:
      auto_branch: true
      branch_prefix: "herald/"

Then connect from Claude Chat:

1. Claude Chat → Settings → Custom Connectors
2. Add connector: https://herald.yourdomain.com/mcp
3. Authenticate via OAuth
4. Done — Claude Chat now has 10 new tools to control your workstation

Quick Start with ngrok (No Reverse Proxy Needed)

Don't have a domain or reverse proxy? Use ngrok to expose Herald instantly over HTTPS:

1. Get ngrok auth token

Sign up at ngrok.com (free plan works) and grab your auth token from the dashboard.

2. Enable tunnel in config

Edit ~/.config/herald/herald.yaml:

tunnel:
  enabled: true
  provider: "ngrok"
  authtoken: "2abc..."  # or set HERALD_NGROK_AUTHTOKEN env var
  # domain: "my-herald.ngrok-free.app"  # optional: fixed domain (paid plans)

3. Run Herald

herald serve
# Tunnel URL appears in the banner:
#   Tunnel: https://abc123.ngrok-free.app (ngrok)

Connect from Claude Chat using the ngrok URL shown in the banner. That's it — no Traefik, Caddy, or DNS setup required.

Note: The ngrok tunnel is optional. If you already have a reverse proxy (Traefik/Caddy), leave tunnel.enabled: false and use your domain as usual.

<details> <summary><strong>Full configuration reference</strong></summary>

server:
  host: "127.0.0.1"          # Always localhost — reverse proxy handles external
  port: 8420
  public_url: "https://herald.yourdomain.com"
  log_level: "info"           # debug, info, warn, error
  log_file: ""                # Optional file path for log output

auth:
  client_id: "herald-claude-chat"
  # client_secret is auto-generated — override with HERALD_CLIENT_SECRET env var if needed
  access_token_ttl: 1h
  refresh_token_ttl: 720h    # 30 days
  redirect_uris:
    - "https://claude.ai/oauth/callback"
    - "https://claude.ai/api/oauth/callback"
    - "https://claude.ai/api/mcp/auth_callback"

database:
  path: "~/.config/herald/herald.db"
  retention_days: 90

execution:
  claude_path: "claude"
  model: "claude-sonnet-4-5-20250929"  # Default model for tasks
  default_timeout: 30m
  max_timeout: 2h
  work_dir: "~/.config/herald/work"
  max_concurrent: 3
  max_prompt_size: 102400    # 100KB
  max_output_size: 1048576   # 1MB
  env:
    CLAUDE_CODE_ENTRYPOINT: "herald"
    CLAUDE_CODE_DISABLE_AUTO_UPDATE: "1"

projects:
  my-api:
    path: "/home/you/projects/my-api"
    description: "Main backend API"
    default: true
    allowed_tools:
      - "Read"
      - "Write"
      - "Edit"
      - "Bash(git *)"
      - "Bash(go *)"
      - "Bash(make *)"
    max_concurrent_tasks: 1
    git:
      auto_branch: true
      auto_stash: true
      auto_commit: true
      branch_prefix: "herald/"

tunnel:
  enabled: false               # Set to true to enable ngrok tunnel
  provider: "ngrok"
  authtoken: ""                # or set HERALD_NGROK_AUTHTOKEN env var
  # domain: ""                 # optional: fixed domain (paid ngrok plans)

rate_limit:
  requests_per_minute: 200
  burst: 100

</details>

MCP Tools

Herald exposes 10 tools that Claude Chat discovers automatically via the MCP protocol:

Tool	What it does
start_task	Launch a Claude Code task. Returns an ID immediately. Supports priority, timeout, session resumption, and Git branch options.
check_task	Check status and progress. Optionally include recent output.
get_result	Get the full result of a completed task (summary, full, or json).
list_tasks	List tasks with filters — status, project, time range.
cancel_task	Cancel a running or queued task. Optionally revert Git changes.
get_diff	Git diff for a task's branch or uncommitted changes.
list_projects	List configured projects with Git status.
read_file	Read a file from a project (path-safe — cannot escape project root).
herald_push	Push a Claude Code session to Herald for remote monitoring and continuation from another device.
get_logs	View logs and activity history.

Security

Herald exposes Claude Code to the network. We take that seriously.

Layer	Protection
Network	Binds to 127.0.0.1 only. HTTPS via built-in ngrok tunnel or reverse proxy (Traefik/Caddy).
Auth	OAuth 2.1 with PKCE. Every request needs a valid Bearer token.
Tokens	Access tokens: 1h. Refresh tokens: 30d, rotated on each use.
Filesystem	Path traversal protection on all file operations. Symlink escapes blocked.
Execution	Per-project tool restrictions. No blanket --dangerously-skip-permissions.
Rate limiting	200 req/min per token (configurable).
Timeouts	Every task has a deadline (default: 30min). No runaway processes.
Prompts	Passed to Claude Code unmodified. No injection, no enrichment, no rewriting.
Audit	Every action logged with timestamp and identity.

Architecture

Claude Chat (mobile/web)
  → HTTPS (MCP Streamable HTTP + OAuth 2.1)
  → Traefik / Caddy (TLS termination)
  → Herald (Go binary, port 8420)
    ├── MCP Handler (/mcp)
    ├── OAuth 2.1 Server (PKCE, token rotation)
    ├── Task Manager (goroutine pool, priority queue)
    ├── Executor Registry (pluggable backends, default: Claude Code)
    ├── SQLite (persistence)
    └── MCP Notifications (server push via SSE)

Design principles: single binary (everything compiled into one Go executable), async-first (each task is a goroutine), stateless MCP with stateful backend, fail-safe (Herald crash doesn't kill running Claude Code processes).

<details> <summary><strong>Tech stack</strong></summary>

Component	Choice	Why
Language	Go 1.26	Single binary, cross-compilation, goroutines
MCP	mcp-go	Streamable HTTP, official protocol support
Router	chi	Lightweight, stdlib-compatible
Database	modernc.org/sqlite	Pure Go, zero CGO
Logging	log/slog	Go stdlib, structured
Config	gopkg.in/yaml.v3	Standard YAML

6 direct dependencies. No ORM. No logging framework. No build toolchain.

</details>

Deployment

Herald runs best as a native binary (direct access to Claude Code and your files). Docker is available as an option.

<details> <summary><strong>Docker Compose with Traefik</strong></summary>

services:
  traefik:
    image: traefik:v3
    command:
      - "--entrypoints.websecure.address=:443"
      - "--certificatesresolvers.le.acme.email=you@example.com"
      - "--certificatesresolvers.le.acme.storage=/letsencrypt/acme.json"
      - "--certificatesresolvers.le.acme.httpchallenge.entrypoint=web"
    ports:
      - "443:443"
    volumes:
      - "./letsencrypt:/letsencrypt"

  herald:
    build: .
    network_mode: host
    volumes:
      - "~/.config/herald:/root/.config/herald"
      - "~/projects:/root/projects:ro"
    labels:
      - "traefik.http.routers.herald.rule=Host(`herald.yourdomain.com`)"
      - "traefik.http.routers.herald.tls.certresolver=le"
      - "traefik.http.services.herald.loadbalancer.server.port=8420"

</details>

Roadmap

Version	Status	Focus
v0.1	✅ Done	Core MCP server, async tasks, Git integration, OAuth 2.1, SQLite
v0.2	🚧 In progress	Shared memory — bidirectional context between Claude Chat and Claude Code
v0.3	🚀 Future	Stable API, plugin system

Have an idea? Open an issue. We build what users need.

Contributing

Herald is in early alpha — the best time to shape a project.

# Get started
git clone https://github.com/btouchard/herald.git
cd herald
make build && make test

# Create your branch
git checkout -b feat/your-feature

# Code, test, lint
make lint && make test

# Open a PR

Commit messages follow Conventional Commits (feat:, fix:, refactor:, docs:).

Whether it's a bug fix, a new notification backend, or a documentation improvement — all contributions are welcome.

Why Herald?

	Herald	Copy-paste workflow	Other tools
Official protocol	MCP Custom Connectors	N/A	Custom APIs, fragile
Your code stays local	Always	Yes	Depends
Works from phone	Native	No	Rarely
Self-hosted	100%	N/A	Often SaaS
Dependencies	6	N/A	50-200+
Setup time	~5 minutes	N/A	30min+
CGO required	No	N/A	Often

Herald uses the same protocol Anthropic built for their own integrations. No reverse engineering, no unofficial APIs, no hacks that break on the next update.

---

<p align="center"> <a href="LICENSE"><strong>AGPL-3.0 License</strong></a> — Built by <a href="https://kolapsis.com"><strong>Benjamin Touchard</strong></a> <br /><br /> If Herald saves you time, <a href="https://github.com/btouchard/herald">leave a star</a>. It helps others find the project. </p>