diff --git a/.changeset/llm-body-timeout-request-id.md b/.changeset/llm-body-timeout-request-id.md
new file mode 100644
index 000000000..b75ca3a97
--- /dev/null
+++ b/.changeset/llm-body-timeout-request-id.md
@@ -0,0 +1,5 @@
+---
+'@truefoundry/trueforge-core': patch
+---
+
+Stamp `x-tfy-request-id` on each model call and include that id with model name and gateway URL on all LLM error logs so harness logs can be correlated with AI Gateway traces.
diff --git a/packages/trueforge-core/src/core/llm/VercelAILLM.ts b/packages/trueforge-core/src/core/llm/VercelAILLM.ts
index a1dc948d5..64e8ca27b 100644
--- a/packages/trueforge-core/src/core/llm/VercelAILLM.ts
+++ b/packages/trueforge-core/src/core/llm/VercelAILLM.ts
@@ -27,6 +27,7 @@ import type {
   UserContent,
 } from 'ai';
 import { APICallError, jsonSchema, Output, streamText } from 'ai';
+import { randomUUID } from 'node:crypto';
 import type {
   ChatCompletionContentPart,
   ChatCompletionCreateParamsStreaming,
@@ -35,19 +36,22 @@ import type {
 } from 'openai/resources/chat';
 import type { Logger } from 'winston';
 import { ModelProviderError } from '../errors';
-import { describeUnknownError, extractErrorLogFields } from '../util/errorLogFields';
+import { describeUnknownError, extractErrorLogFields, type ErrorLogFields } from '../util/errorLogFields';
 import { modelSsrfFetch } from '../util/outboundFetch';
 import type { ILLM, LLMCreateParams, LLMCreateParamsStreaming } from './ILLM';
 import {
+  getEmptyUsage,
   type CompletionUsage,
   type ExtendedChatCompletionChunk,
-  getEmptyUsage,
   type RawAssistantMessage,
   type RawAssistantMessageWithUsage,
   type ThinkingBlock,
 } from './LLMTypes';
 import { resolveMaxOutputTokens } from './usage';
 
+/** Correlates harness model calls with TrueFoundry AI Gateway request traces. */
+export const X_TFY_REQUEST_ID = 'x-tfy-request-id';
+
 // ---------------------------------------------------------------------------
 // Public config
 // ---------------------------------------------------------------------------
@@ -1374,6 +1378,22 @@ export async function* mapStreamToChunks({
 // VercelAILLM
 // ---------------------------------------------------------------------------
 
+/** Error log fields with gateway correlation id plus model and URL when known. */
+export function llmErrorLogFields(input: {
+  error: unknown;
+  tfyRequestId: string;
+  model: string;
+  gatewayUrl: string | undefined;
+}): ErrorLogFields & { tfy_request_id: string; model: string; gateway_url?: string } {
+  const fields = extractErrorLogFields(input.error);
+  return {
+    ...fields,
+    tfy_request_id: input.tfyRequestId,
+    model: input.model,
+    ...(input.gatewayUrl !== undefined ? { gateway_url: input.gatewayUrl } : {}),
+  };
+}
+
 /** ILLM implementation backed by Vercel AI SDK, supporting multiple LLM providers. */
 export class VercelAILLM implements ILLM {
   private readonly config: VercelAILLMConfig;
@@ -1389,7 +1409,15 @@ export class VercelAILLM implements ILLM {
   async *create(
     body: LLMCreateParamsStreaming,
   ): AsyncGenerator<ExtendedChatCompletionChunk, RawAssistantMessageWithUsage, unknown> {
-    const { providerConfig } = this.config;
+    // Per-call id on x-tfy-request-id so harness error logs can be correlated with gateway traces.
+    const tfyRequestId = randomUUID();
+    const providerConfig: VercelAIProviderConfig = {
+      ...this.config.providerConfig,
+      headers: {
+        ...this.config.providerConfig.headers,
+        [X_TFY_REQUEST_ID]: tfyRequestId,
+      },
+    };
     const languageModel = buildLanguageModel(providerConfig);
     const { provider, model } = providerConfig;
 
@@ -1447,7 +1475,15 @@ export class VercelAILLM implements ILLM {
       if (this.signal?.aborted) {
         this.logger.debug('LLM call aborted', extractErrorLogFields(streamError));
       } else {
-        this.logger.error('Error creating streaming chat completion', extractErrorLogFields(streamError));
+        this.logger.error(
+          'Error creating streaming chat completion',
+          llmErrorLogFields({
+            error: streamError,
+            tfyRequestId,
+            model: providerConfig.name,
+            gatewayUrl: providerConfig.baseUrl,
+          }),
+        );
       }
       throw streamError;
     }
@@ -1486,7 +1522,15 @@ export class VercelAILLM implements ILLM {
       if (this.signal?.aborted) {
         this.logger.debug('LLM stream aborted', extractErrorLogFields(streamError));
       } else {
-        this.logger.error('Error reading LLM stream', extractErrorLogFields(streamError));
+        this.logger.error(
+          'Error reading LLM stream',
+          llmErrorLogFields({
+            error: streamError,
+            tfyRequestId,
+            model: providerConfig.name,
+            gatewayUrl: providerConfig.baseUrl,
+          }),
+        );
       }
       throw streamError;
     }
diff --git a/packages/trueforge-core/tests/core/llm/VercelAILLM.stream.test.ts b/packages/trueforge-core/tests/core/llm/VercelAILLM.stream.test.ts
index 593e2f3bb..8288acac9 100644
--- a/packages/trueforge-core/tests/core/llm/VercelAILLM.stream.test.ts
+++ b/packages/trueforge-core/tests/core/llm/VercelAILLM.stream.test.ts
@@ -15,6 +15,7 @@ import { ModelProviderError } from '../../../src/core/errors';
 import type { ExtendedChatCompletionChunk, RawAssistantMessageWithUsage } from '../../../src/core/llm/LLMTypes';
 import {
   describeStreamError,
+  llmErrorLogFields,
   mapFinishReason,
   mapStreamToChunks,
   normalizeUsage,
@@ -685,3 +686,34 @@ describe('mapStreamToChunks', () => {
     expect(nonFinishChunks).toHaveLength(0);
   });
 });
+
+// ─────────── LLM error correlation ───────────
+
+describe('llmErrorLogFields', () => {
+  it('includes tfy_request_id, model, and gateway_url for gateway correlation', () => {
+    const error = new Error('upstream failed');
+    expect(
+      llmErrorLogFields({
+        error,
+        tfyRequestId: 'req-abc',
+        model: 'truefoundry/acct/gpt',
+        gatewayUrl: 'https://gateway.example/v1',
+      }),
+    ).toMatchObject({
+      error: 'upstream failed',
+      tfy_request_id: 'req-abc',
+      model: 'truefoundry/acct/gpt',
+      gateway_url: 'https://gateway.example/v1',
+    });
+  });
+
+  it('omits gateway_url when the provider has no base URL', () => {
+    const fields = llmErrorLogFields({
+      error: new Error('upstream failed'),
+      tfyRequestId: 'req-abc',
+      model: 'openai/gpt',
+      gatewayUrl: undefined,
+    });
+    expect(fields).not.toHaveProperty('gateway_url');
+  });
+});