ContextSync MCP

Your Claude Code. Finally knows what you're building.

ContextSync MCP connects Claude Code to your Linear board so every coding session starts fully briefed — your in-progress tickets, acceptance criteria, and latest comments, loaded automatically. No more copy-pasting. No more stale CLAUDE.md files.

See It In Action

You: "What am I working on?"

Claude: I can see from your Linear board that you have 2 active tickets:

**ENG-284 — Refactor auth middleware to use JWT refresh tokens**
Status: In Progress | Priority: High

Description: The current session-based auth needs to be replaced with a
JWT refresh token flow. The access token should expire in 15 minutes.
Refresh tokens persist for 30 days and are rotated on use.

Acceptance Criteria:
- [ ] POST /auth/refresh returns new access + refresh token pair
- [ ] Old refresh token is invalidated after use
- [ ] 401 errors trigger silent refresh in the API client

Latest comment (Sarah, 2h ago): "Make sure we invalidate all refresh
tokens on password change — see thread in #eng-security"

**ENG-291 — Fix pagination bug in issue list endpoint**
Status: In Progress | Priority: Medium
...

Want me to start on ENG-284? I have the full context loaded.

Install (3 steps)

Step 1 — Install

npm install -g @diamondsg/contextsync-mcp

Step 2 — Authenticate with Linear

contextsync auth linear --token lin_api_xxxxxxxxxxxxxxxx

Get your token at linear.app/settings/api → Personal API tokens → Create token.

Step 3 — Add to Claude Code MCP config

Add to ~/.claude/mcp.json (create the file if it doesn't exist):

{
  "mcpServers": {
    "contextsync": {
      "command": "npx",
      "args": ["-y", "@diamondsg/contextsync-mcp"]
    }
  }
}

Restart Claude Code. That's it.

MCP Tools

get_active_context

Returns your currently in-progress Linear issues with full descriptions, acceptance criteria, and recent comments.

When to use: Start of every session. Ask Claude "What am I working on?" and it will call this automatically.

list_project_issues

Lists all issues in a Linear project.

| Parameter | Type | Description | |-----------|------|-------------| | project_id | string | Linear project UUID (from the URL) | | limit | number | Max issues to return (default: 50, max: 100) |

get_issue

Fetches full detail for a specific issue.

| Parameter | Type | Description | |-----------|------|-------------| | issue_id | string | Issue identifier (ENG-284) or Linear UUID |

CLI Reference

# Authenticate with your Linear Personal API Token
contextsync auth linear --token lin_api_xxxxxxxx

# Check auth status and monthly usage
contextsync status

# Remove stored credentials
contextsync logout

Pricing

| | Free | Pro (coming soon) | |--|------|-------------------| | Context fetches/month | 50 | Unlimited | | get_active_context | ✅ | ✅ | | get_issue | ✅ | ✅ | | list_project_issues | ✅ | ✅ | | Write tools (update, comment, create) | ❌ | ✅ |

Free tier is generous enough for daily use. Pro pricing announced soon.

Troubleshooting

"Not authenticated" error:

contextsync auth linear --token <your-token>

keytar native module errors: ContextSync uses your OS keychain for secure storage. If keytar fails to compile, it falls back to ~/.contextsync/.token. To fix on Linux:

sudo apt-get install libsecret-1-dev
npm install -g @diamondsg/contextsync-mcp --build-from-source

Test the MCP server directly:

echo '{"jsonrpc":"2.0","method":"tools/list","id":1}' | node $(npm root -g)/contextsync-mcp/src/server.js

Security

• Your token is stored in your OS keychain (Keychain on macOS, Credential Manager on Windows, libsecret on Linux)
• All Linear API calls go directly from your machine to api.linear.app — no Diamond proxy
• Token never leaves your local environment

Links

• 🌐 diamondsg.dev
• 📦 npm: contextsync-mcp
• 🐛 GitHub Issues

MIT License — Diamond Software Group
ContextSync MCP v1.0.0