feat: add CI quality gates with Biome linting and coverage thresholds

.github/workflows/ci.yml

@@ -7,6 +7,18 @@ on:
     branches: [main]
 
 jobs:
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 20
+          cache: npm
+      - run: npm ci
+      - run: npm run lint
+
   typecheck:
     name: Typecheck
     runs-on: ubuntu-latest
@@ -29,12 +41,12 @@ jobs:
           node-version: 20
           cache: npm
       - run: npm ci
-      - run: npm run test:run
+      - run: npx vitest run --coverage
 
   build:
     name: Build
     runs-on: ubuntu-latest
-    needs: [typecheck, test]
+    needs: [lint, typecheck, test]
     steps:
       - uses: actions/checkout@v6
       - uses: actions/setup-node@v6

CONTRIBUTING.md

@@ -42,6 +42,17 @@ npm run test:run      # Run tests once and exit
 
 All tests must pass before submitting a pull request.
 
+## Linting
+
+This project uses [Biome](https://biomejs.dev/) for linting and formatting:
+
+```bash
+npm run lint          # Check for lint and formatting issues
+npm run lint:fix      # Auto-fix issues
+```
+
+CI enforces linting — run `npm run lint` before pushing.
+
 ## Building and Running
 
 To build the TypeScript code:
@@ -58,6 +69,7 @@ npm start
 
 - Use TypeScript for all code
 - Follow ESM module conventions (this project uses `"type": "module"`)
+- Run `npm run lint` to check formatting and lint rules ([Biome](https://biomejs.dev/) enforces style automatically)
 - Keep code readable and maintainable
 - Comments should explain the "why", not the "what"
 

biome.json

@@ -0,0 +1,24 @@
+{
+  "$schema": "https://biomejs.dev/schemas/2.4.4/schema.json",
+  "files": {
+    "includes": ["src/**/*.ts"]
+  },
+  "linter": {
+    "enabled": true,
+    "rules": {
+      "recommended": true
+    }
+  },
+  "formatter": {
+    "enabled": true,
+    "indentStyle": "space",
+    "indentWidth": 2,
+    "lineWidth": 100
+  },
+  "javascript": {
+    "formatter": {
+      "quoteStyle": "double",
+      "trailingCommas": "all"
+    }
+  }
+}

package.json

@@ -19,6 +19,8 @@
     "dev": "tsc --watch",
     "start": "node dist/index.js",
     "prepublishOnly": "npm run build",
+    "lint": "biome check src/",
+    "lint:fix": "biome check --write src/",
     "test": "vitest",
     "test:run": "vitest run"
   },
@@ -47,6 +49,7 @@
     "zod": "^4.3.6"
   },
   "devDependencies": {
+    "@biomejs/biome": "2.4.4",
     "@types/node": "^25.3.0",
     "@vitest/coverage-v8": "^4.0.18",
     "typescript": "^5.9.3",

src/index.ts

@@ -2,12 +2,9 @@
 
 import { Server } from "@modelcontextprotocol/sdk/server/index.js";
 import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
-import {
-  CallToolRequestSchema,
-  ListToolsRequestSchema,
-} from "@modelcontextprotocol/sdk/types.js";
-import { tools, executeTool } from "./tools.js";
+import { CallToolRequestSchema, ListToolsRequestSchema } from "@modelcontextprotocol/sdk/types.js";
 import { getModels } from "./pricing.js";
+import { executeTool, tools } from "./tools.js";
 
 const server = new Server(
   {

src/pricing.test.ts

@@ -1,5 +1,5 @@
-import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
-import { existsSync, readFileSync, writeFileSync, mkdirSync } from "node:fs";
+import { existsSync, mkdirSync, writeFileSync } from "node:fs";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
 // Mock fs so disk cache doesn't interfere
 vi.mock("node:fs", () => ({
@@ -303,9 +303,7 @@ describe("pricing module", () => {
       });
 
       const { refreshPrices } = await loadPricing();
-      await expect(refreshPrices()).rejects.toThrow(
-        "Failed to fetch pricing data: 503",
-      );
+      await expect(refreshPrices()).rejects.toThrow("Failed to fetch pricing data: 503");
     });
   });
 
@@ -435,10 +433,9 @@ describe("pricing module", () => {
       const { refreshPrices } = await loadPricing();
       await refreshPrices();
 
-      expect(mkdirSync).toHaveBeenCalledWith(
-        expect.stringContaining(".cache"),
-        { recursive: true },
-      );
+      expect(mkdirSync).toHaveBeenCalledWith(expect.stringContaining(".cache"), {
+        recursive: true,
+      });
     });
   });
 });