diff --git a/src/test-runner/testRunner.ts b/src/test-runner/testRunner.ts
new file mode 100644
index 0000000..11aedfc
--- /dev/null
+++ b/src/test-runner/testRunner.ts
@@ -0,0 +1,165 @@
+import { exec } from 'node:child_process';
+import * as fs from 'node:fs';
+import * as path from 'node:path';
+import { promisify } from 'node:util';
+import { CheckResult } from '../types';
+
+const execAsync = promisify(exec);
+
+export interface TestRunnerOptions {
+  timeoutMs?: number;
+}
+
+export class TestRunner {
+  private timeoutMs: number;
+
+  constructor(options: TestRunnerOptions = {}) {
+    this.timeoutMs = options.timeoutMs ?? 45000; // 45 seconds default timeout
+  }
+
+  /**
+   * Detects package manager based on lockfiles
+   */
+  public detectPackageManager(workspaceRoot: string): 'pnpm' | 'yarn' | 'bun' | 'npm' {
+    if (fs.existsSync(path.join(workspaceRoot, 'pnpm-lock.yaml'))) return 'pnpm';
+    if (fs.existsSync(path.join(workspaceRoot, 'yarn.lock'))) return 'yarn';
+    if (
+      fs.existsSync(path.join(workspaceRoot, 'bun.lockb')) ||
+      fs.existsSync(path.join(workspaceRoot, 'bun.lock'))
+    ) {
+      return 'bun';
+    }
+    return 'npm';
+  }
+
+  private getPackageScripts(workspaceRoot: string): Record<string, string> {
+    const pkgPath = path.join(workspaceRoot, 'package.json');
+    if (!fs.existsSync(pkgPath)) return {};
+    try {
+      const data = JSON.parse(fs.readFileSync(pkgPath, 'utf8'));
+      return data.scripts || {};
+    } catch {
+      return {};
+    }
+  }
+
+  private async executeCommand(
+    cmd: string,
+    cwd: string,
+    name: string
+  ): Promise<CheckResult> {
+    const startTime = Date.now();
+    try {
+      const { stdout } = await execAsync(cmd, {
+        cwd,
+        timeout: this.timeoutMs,
+        maxBuffer: 5 * 1024 * 1024
+      });
+
+      return {
+        name,
+        status: 'PASS',
+        durationMs: Date.now() - startTime,
+        message: 'Completed successfully without errors.',
+        details: stdout.slice(0, 500)
+      };
+    } catch (err: unknown) {
+      const execError = err as { stdout?: string; stderr?: string; message?: string };
+      const output = `${execError.stdout || ''}\n${execError.stderr || ''}`.trim();
+
+      return {
+        name,
+        status: 'FAIL',
+        durationMs: Date.now() - startTime,
+        message: 'Checks reported errors.',
+        details: output.slice(0, 1000) || execError.message
+      };
+    }
+  }
+
+  public async runTypeScriptCheck(workspaceRoot: string): Promise<CheckResult> {
+    const tsconfigPath = path.join(workspaceRoot, 'tsconfig.json');
+    if (!fs.existsSync(tsconfigPath)) {
+      return {
+        name: 'TypeScript',
+        status: 'SKIPPED',
+        message: 'No tsconfig.json found in project root.'
+      };
+    }
+
+    const scripts = this.getPackageScripts(workspaceRoot);
+    const pm = this.detectPackageManager(workspaceRoot);
+
+    let cmd = 'npx tsc --noEmit';
+    if (scripts['typecheck']) {
+      cmd = `${pm} run typecheck`;
+    } else if (scripts['type-check']) {
+      cmd = `${pm} run type-check`;
+    }
+
+    return this.executeCommand(cmd, workspaceRoot, 'TypeScript');
+  }
+
+  public async runLint(workspaceRoot: string): Promise<CheckResult> {
+    const scripts = this.getPackageScripts(workspaceRoot);
+    const pm = this.detectPackageManager(workspaceRoot);
+
+    if (scripts['lint']) {
+      return this.executeCommand(`${pm} run lint`, workspaceRoot, 'ESLint');
+    }
+
+    const hasEslint =
+      fs.existsSync(path.join(workspaceRoot, '.eslintrc.json')) ||
+      fs.existsSync(path.join(workspaceRoot, '.eslintrc.js')) ||
+      fs.existsSync(path.join(workspaceRoot, 'eslint.config.js')) ||
+      fs.existsSync(path.join(workspaceRoot, 'eslint.config.mjs'));
+
+    if (hasEslint) {
+      return this.executeCommand('npx eslint .', workspaceRoot, 'ESLint');
+    }
+
+    return {
+      name: 'ESLint',
+      status: 'SKIPPED',
+      message: 'No lint script or ESLint configuration detected.'
+    };
+  }
+
+  public async runUnitTests(workspaceRoot: string): Promise<CheckResult> {
+    const scripts = this.getPackageScripts(workspaceRoot);
+    const pm = this.detectPackageManager(workspaceRoot);
+
+    if (scripts['test']) {
+      // If the default npm test is "echo \"Error: no test specified\" && exit 1", treat as skipped
+      if (scripts['test'].includes('no test specified')) {
+        return {
+          name: 'Unit Tests',
+          status: 'SKIPPED',
+          message: 'No tests configured in package.json.'
+        };
+      }
+      return this.executeCommand(`${pm} test`, workspaceRoot, 'Unit Tests');
+    }
+
+    return {
+      name: 'Unit Tests',
+      status: 'SKIPPED',
+      message: 'No test script found in package.json.'
+    };
+  }
+
+  public async runBuild(workspaceRoot: string): Promise<CheckResult> {
+    const scripts = this.getPackageScripts(workspaceRoot);
+    const pm = this.detectPackageManager(workspaceRoot);
+
+    if (scripts['build']) {
+      return this.executeCommand(`${pm} run build`, workspaceRoot, 'Build Check');
+    }
+
+    return {
+      name: 'Build Check',
+      status: 'SKIPPED',
+      message: 'No build script found in package.json.'
+    };
+  }
+}