linear-local-dev-loop

Linear Local Dev Loop

Overview

Set up an efficient local development workflow for building Linear integrations. Covers project scaffolding, environment config, test utilities, webhook tunneling with ngrok, and integration testing with vitest.

Prerequisites

• Node.js 18+ with TypeScript
• @linear/sdk package
• Separate Linear workspace or team for development (recommended)
• ngrok or cloudflared for webhook tunnel testing

Instructions

Step 1: Project Scaffolding

set -euo pipefail
mkdir linear-integration && cd linear-integration
npm init -y
npm install @linear/sdk dotenv
npm install -D typescript @types/node vitest tsx

# TypeScript config
npx tsc --init --target ES2022 --module NodeNext --moduleResolution NodeNext --strict

Step 2: Environment Configuration

# .env (never commit)
cat > .env << 'EOF'
LINEAR_API_KEY=lin_api_dev_xxxxxxxxxxxx
LINEAR_WEBHOOK_SECRET=whsec_dev_xxxxxxxxxxxx
LINEAR_DEV_TEAM_KEY=DEV
NODE_ENV=development
EOF

# .env.example (commit this for onboarding)
cat > .env.example << 'EOF'
LINEAR_API_KEY=lin_api_your_key_here
LINEAR_WEBHOOK_SECRET=
LINEAR_DEV_TEAM_KEY=DEV
NODE_ENV=development
EOF

echo -e ".env\n.env.local\n.env.*.local" >> .gitignore

Step 3: Client Module with Connection Verification

// src/client.ts
import { LinearClient } from "@linear/sdk";
import "dotenv/config";

let _client: LinearClient | null = null;

export function getClient(): LinearClient {
  if (!_client) {
    const apiKey = process.env.LINEAR_API_KEY;
    if (!apiKey) throw new Error("LINEAR_API_KEY not set — copy .env.example to .env");
    _client = new LinearClient({ apiKey });
  }
  return _client;
}

export async function verifyConnection(): Promise<void> {
  const client = getClient();
  const viewer = await client.viewer;
  const teams = await client.teams();
  console.log(`[Linear] Connected as ${viewer.name} (${viewer.email})`);
  console.log(`[Linear] Teams: ${teams.nodes.map(t => t.key).join(", ")}`);
}

Step 4: Test Data Utilities

// src/test-utils.ts
import { getClient } from "./client";

const TEST_PREFIX = "[DEV-TEST]";

export async function getDevTeam() {
  const client = getClient();
  const teamKey = process.env.LINEAR_DEV_TEAM_KEY ?? "DEV";
  const teams = await client.teams({ filter: { key: { eq: teamKey } } });
  const team = teams.nodes[0];
  if (!team) throw new Error(`Team ${teamKey} not found — set LINEAR_DEV_TEAM_KEY`);
  return team;
}

export async function createTestIssue(title?: string) {
  const client = getClient();
  const team = await getDevTeam();
  const result = await client.createIssue({
    teamId: team.id,
    title: `${TEST_PREFIX} ${title ?? new Date().toISOString()}`,
    description: "Automated test issue — safe to delete",
    priority: 4, // Low
  });
  return result.issue;
}

export async function cleanupTestIssues() {
  const client = getClient();
  const team = await getDevTeam();
  const issues = await client.issues({
    filter: {
      team: { id: { eq: team.id } },
      title: { startsWith: TEST_PREFIX },
    },
    first: 100,
  });

  let deleted = 0;
  for (const issue of issues.nodes) {
    await issue.delete();
    deleted++;
  }
  console.log(`Cleaned up ${deleted} test issues`);
}

Step 5: Integration Tests with Vitest

// tests/linear.integration.test.ts
import { describe, it, expect, afterAll } from "vitest";
import { getClient } from "../src/client";
import { createTestIssue, cleanupTestIssues, getDevTeam } from "../src/test-utils";

describe("Linear Integration", () => {
  afterAll(async () => {
    await cleanupTestIssues();
  });

  it("authenticates successfully", async () => {
    const client = getClient();
    const viewer = await client.viewer;
    expect(viewer.name).toBeDefined();
    expect(viewer.email).toBeDefined();
  });

  it("creates and updates an issue", async () => {
    const client = getClient();
    const issue = await createTestIssue("vitest create");
    expect(issue).toBeDefined();
    expect(issue?.title).toContain("[DEV-TEST]");

    // Update it
    await client.updateIssue(issue!.id, { priority: 2 });
    const updated = await client.issue(issue!.id);
    expect(updated.priority).toBe(2);
  });

  it("queries workflow states", async () => {
    const team = await getDevTeam();
    const states = await team.states();
    const types = states.nodes.map(s => s.type);
    expect(types).toContain("unstarted");
    expect(types).toContain("completed");
  });
});

Step 6: Package Scripts

{
  "scripts": {
    "dev": "tsx watch src/index.ts",
    "verify": "tsx src/verify-connection.ts",
    "test": "vitest run",
    "test:watch": "vitest --watch",
    "cleanup": "tsx src/cleanup.ts"
  }
}

Step 7: Webhook Local Development with ngrok

# Terminal 1: Start your webhook server
npm run dev

# Terminal 2: Expose port 3000 via ngrok
ngrok http 3000
# Copy the https://xxxx.ngrok-free.app URL

# Register webhook in Linear:
# Settings > API > Webhooks > New webhook
# URL: https://xxxx.ngrok-free.app/webhooks/linear
# Select: Issues, Comments

Minimal webhook receiver for local testing:

// src/webhook-dev.ts
import express from "express";
import crypto from "crypto";

const app = express();
app.post("/webhooks/linear", express.raw({ type: "*/*" }), (req, res) => {
  const body = req.body.toString();
  const sig = req.headers["linear-signature"] as string;
  const secret = process.env.LINEAR_WEBHOOK_SECRET!;

  if (secret && sig) {
    const expected = crypto.createHmac("sha256", secret).update(body).digest("hex");
    if (sig !== expected) {
      console.warn("Signature mismatch — check LINEAR_WEBHOOK_SECRET");
    }
  }

  const event = JSON.parse(body);
  console.log(`[Webhook] ${event.type}.${event.action}:`, event.data?.identifier ?? event.data?.id);
  res.json({ ok: true });
});

app.listen(3000, () => console.log("Webhook server on http://localhost:3000"));

Error Handling

Error	Cause	Solution
LINEAR_API_KEY not set	Missing .env	Copy .env.example to .env and fill in values
Team DEV not found	Wrong team key	Set LINEAR_DEV_TEAM_KEY to a valid team key
Cannot find module	TypeScript path issue	Check tsconfig.json module resolution
Webhook not received	Tunnel not running	Start ngrok http 3000 and register the URL
Authentication required	Expired dev API key	Regenerate in Linear Settings > Account > API

Examples

Quick Connection Test Script

// src/verify-connection.ts
import { verifyConnection } from "./client";
verifyConnection()
  .then(() => console.log("Connection OK"))
  .catch((err) => { console.error("Connection FAILED:", err.message); process.exit(1); });

Resources

• Linear SDK Documentation
• Linear Webhooks
• Vitest Documentation
• ngrok Quickstart