diff --git a/packages/trueforge/src/apis/turns.ts b/packages/trueforge/src/apis/turns.ts
index 42480a5a5..15684ff9e 100644
--- a/packages/trueforge/src/apis/turns.ts
+++ b/packages/trueforge/src/apis/turns.ts
@@ -135,6 +135,18 @@ export type BeginTurnExecutionDeps = Pick<TurnsRouterDeps, 'activeTurns' | 'even
   skillStore: Pick<ISkillStore, 'resolveTurnSkills'>;
 };
 
+/** Extra LLM/MCP headers resolved after turn id is minted. */
+type ResolveTurnHeaders = (input: { session: SessionHandle; turnId: string }) => Record<string, string>;
+
+interface BeginTurnExecutionParams {
+  session: SessionHandle;
+  input: TurnInputItem[] | undefined;
+  previous_turn_id: string | undefined;
+  userRef: string;
+  turnHeaders?: ResolveTurnHeaders;
+  deps: BeginTurnExecutionDeps;
+}
+
 /**
  * Builds the per-turn resolver. Agent / MCP / sandbox / LLM lookups are wired
  * the same way: async factories over the corresponding stores.
@@ -149,8 +161,7 @@ function createTurnResolver(deps: {
   signal: AbortSignal;
   userRef: string;
   session: SessionHandle;
-  turnId: string;
-  tfyMetadata: Record<string, string> | undefined;
+  turnHeaders: Record<string, string>;
 }): TurnResourceResolver {
   const {
     mcpServerStore,
@@ -162,14 +173,10 @@ function createTurnResolver(deps: {
     signal,
     userRef,
     session,
-    turnId,
-    tfyMetadata,
+    turnHeaders,
   } = deps;
   const tenant_id = session.tenant_id;
   const sessionId = session.session_id;
-  const metadataHeaders = isTrueFoundryModeEnabled()
-    ? gatewayMetadataHeaders(mergeGatewayMetadata({ session, turnId, tfyMetadata }))
-    : {};
 
   return new TurnResourceResolver({
     llm: async name => {
@@ -182,7 +189,7 @@ function createTurnResolver(deps: {
         modelClient: new VercelAILLM({
           providerConfig: {
             ...resolved.providerConfig,
-            headers: { ...resolved.providerConfig.headers, ...metadataHeaders },
+            headers: { ...resolved.providerConfig.headers, ...turnHeaders },
           },
           logger,
           signal,
@@ -207,7 +214,7 @@ function createTurnResolver(deps: {
         url: connection.url,
         headers: withGatewayMetadataHeaders({
           headers: connection.headers,
-          metadataHeaders,
+          metadataHeaders: turnHeaders,
         }),
       };
     },
@@ -386,15 +393,10 @@ export interface TurnEventDrainInput {
  * Shared create-turn engine: persist the turn, start execution, and return the
  * drain inputs. Does not wait for events and does not write HTTP/SSE.
  */
-export async function beginTurnExecution(params: {
-  session: SessionHandle;
-  input: TurnInputItem[] | undefined;
-  previous_turn_id: string | undefined;
-  userRef: string;
-  tfyMetadata?: Record<string, string> | undefined;
-  deps: BeginTurnExecutionDeps;
-}): Promise<{ turn: TurnHandle; drainInput: TurnEventDrainInput }> {
-  const { session, input, previous_turn_id: previousTurnId, userRef, tfyMetadata, deps } = params;
+export async function beginTurnExecution(
+  params: BeginTurnExecutionParams,
+): Promise<{ turn: TurnHandle; drainInput: TurnEventDrainInput }> {
+  const { session, input, previous_turn_id: previousTurnId, userRef, turnHeaders, deps } = params;
   const sessionId = session.session_id;
   const turnId = mintPeeredTurnId(configuration.EXECUTOR_ID);
 
@@ -410,8 +412,7 @@ export async function beginTurnExecution(params: {
     signal: abortController.signal,
     userRef,
     session,
-    turnId,
-    tfyMetadata,
+    turnHeaders: turnHeaders?.({ session, turnId }) ?? {},
   });
 
   // First turn only: derive the title from the first user message. The store
@@ -461,14 +462,7 @@ export async function beginTurnExecution(params: {
  * Non-stream create-turn: begin execution and resolve once the first event is
  * dual-written so immediate subscribe cannot 412. Same as `stream: false`.
  */
-export async function startTurnInProcess(params: {
-  session: SessionHandle;
-  input: TurnInputItem[] | undefined;
-  previous_turn_id: string | undefined;
-  userRef: string;
-  tfyMetadata?: Record<string, string> | undefined;
-  deps: BeginTurnExecutionDeps;
-}): Promise<TurnHandle> {
+export async function startTurnInProcess(params: BeginTurnExecutionParams): Promise<TurnHandle> {
   const { turn, drainInput } = await beginTurnExecution(params);
 
   // Same unawaited drain scheduling as Hono streamSSE's run(cb).
@@ -775,14 +769,17 @@ export function createTurnsRouter(deps: TurnsRouterDeps) {
     }
 
     const rawTfyMetadata = c.req.header(X_TFY_METADATA);
-    const tfyMetadata = rawTfyMetadata === undefined ? undefined : parseGatewayMetadataHeader(rawTfyMetadata);
+    const requestMetadata = rawTfyMetadata === undefined ? undefined : parseGatewayMetadataHeader(rawTfyMetadata);
 
-    const turnParams = {
+    const turnParams: BeginTurnExecutionParams = {
       session,
       input: body.input,
       previous_turn_id: body.previous_turn_id,
       userRef: requestContext.subject.id,
-      tfyMetadata,
+      turnHeaders: ({ session: turnSession, turnId }) =>
+        isTrueFoundryModeEnabled()
+          ? gatewayMetadataHeaders(mergeGatewayMetadata({ session: turnSession, turnId, requestMetadata }))
+          : {},
       deps: {
         ...deps,
         modelProviderStore: deps.resolveModelProviderStore(c, referencedAgent),
diff --git a/packages/trueforge/src/runtime/sessionResources.ts b/packages/trueforge/src/runtime/sessionResources.ts
index ce75c31ef..0834209f3 100644
--- a/packages/trueforge/src/runtime/sessionResources.ts
+++ b/packages/trueforge/src/runtime/sessionResources.ts
@@ -72,14 +72,14 @@ export function buildGatewayMetadata(input: { session: SessionHandle; turnId: st
   return metadata;
 }
 
-/** Inbound x-tfy-metadata first; harness tfg.* always win */
+/** Caller requestMetadata first; harness tfg.* always win */
 export function mergeGatewayMetadata(input: {
   session: SessionHandle;
   turnId: string;
-  tfyMetadata?: Record<string, string> | undefined;
+  requestMetadata?: Record<string, string> | undefined;
 }): Record<string, string> {
   return {
-    ...input.tfyMetadata,
+    ...input.requestMetadata,
     ...buildGatewayMetadata({ session: input.session, turnId: input.turnId }),
   };
 }
diff --git a/packages/trueforge/tests/unit/runtime/sessionResources.test.ts b/packages/trueforge/tests/unit/runtime/sessionResources.test.ts
index 376665160..39cad7143 100644
--- a/packages/trueforge/tests/unit/runtime/sessionResources.test.ts
+++ b/packages/trueforge/tests/unit/runtime/sessionResources.test.ts
@@ -80,7 +80,7 @@ describe('buildGatewayMetadata', () => {
 });
 
 describe('mergeGatewayMetadata', () => {
-  it('keeps tfyMetadata keys and overwrites spoofed tfg.* fields so order is maintained', async () => {
+  it('keeps requestMetadata keys and overwrites spoofed tfg.* fields so order is maintained', async () => {
     const session = await createGatewayMetadataSession({
       agent: { type: 'reference', id: 'agent-1', name: 'my-agent' },
     });
@@ -89,7 +89,7 @@ describe('mergeGatewayMetadata', () => {
       mergeGatewayMetadata({
         session,
         turnId: 'turn-1',
-        tfyMetadata: {
+        requestMetadata: {
           env: 'prod',
           [`${TFG_METADATA_PREFIX}.session_id`]: 'spoofed-session',
           [`${TFG_METADATA_PREFIX}.turn_id`]: 'spoofed-turn',
@@ -106,7 +106,7 @@ describe('mergeGatewayMetadata', () => {
     });
   });
 
-  it('matches harness-only stamps when tfyMetadata is absent', async () => {
+  it('matches harness-only stamps when requestMetadata is absent', async () => {
     const session = await createGatewayMetadataSession({
       agent: { type: 'reference', id: 'agent-1', name: 'my-agent' },
     });