feat(api): assign and echo request ids

test/api-server_test.ts

@@ -64,6 +64,7 @@ Deno.test('ApiServer serves health metrics and authenticated model listings', as
     assertEquals(healthResponse.status, 200);
     assertEquals(healthBody.status, 'ok');
     assertEquals(healthBody.models, 1);
+    assertEquals(typeof healthResponse.headers.get('x-request-id'), 'string');
 
     const metricsResponse = await fetch(`http://127.0.0.1:${port}/metrics`);
     const metricsBody = await metricsResponse.text();
@@ -79,12 +80,14 @@ Deno.test('ApiServer serves health metrics and authenticated model listings', as
     const authenticatedModels = await fetch(`http://127.0.0.1:${port}/v1/models`, {
       headers: {
         Authorization: 'Bearer valid-key',
+        'X-Request-Id': 'req-test-models',
       },
     });
     const authenticatedBody = await authenticatedModels.json();
     assertEquals(authenticatedModels.status, 200);
     assertEquals(authenticatedBody.object, 'list');
     assertEquals(authenticatedBody.data[0].id, 'meta-llama/Llama-3.1-8B-Instruct');
+    assertEquals(authenticatedModels.headers.get('x-request-id'), 'req-test-models');
 
     const metricsAfterRequests = await fetch(`http://127.0.0.1:${port}/metrics`);
     const metricsAfterRequestsBody = await metricsAfterRequests.text();

ts/api/server.ts

@@ -123,6 +123,7 @@ export class ApiServer {
     res: http.ServerResponse,
   ): Promise<void> {
     const startTime = Date.now();
+    const requestId = this.ensureRequestId(req, res);
 
     // Set CORS headers if enabled
     if (this.config.cors) {
@@ -177,7 +178,7 @@ export class ApiServer {
     // Log request
     const duration = Date.now() - startTime;
     this.recordRequest(path, res.statusCode);
-    logger.dim(`${req.method} ${path} - ${res.statusCode} (${duration}ms)`);
+    logger.dim(`[${requestId}] ${req.method} ${path} - ${res.statusCode} (${duration}ms)`);
   }
 
   /**
@@ -405,6 +406,20 @@ export class ApiServer {
     metric.set(path, (metric.get(path) || 0) + 1);
   }
 
+  private ensureRequestId(req: http.IncomingMessage, res: http.ServerResponse): string {
+    const existing = typeof req.headers['x-request-id'] === 'string'
+      ? req.headers['x-request-id']
+      : undefined;
+    const requestId = existing || this.generateRequestId();
+    req.headers['x-request-id'] = requestId;
+    res.setHeader('X-Request-Id', requestId);
+    return requestId;
+  }
+
+  private generateRequestId(): string {
+    return `req-${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 8)}`;
+  }
+
   private escapeMetricLabel(value: string): string {
     return value.replaceAll('\\', '\\\\').replaceAll('"', '\\"');
   }