diff --git a/src/agents/anthropic-payload-log.test.ts b/src/agents/anthropic-payload-log.test.ts
index 037093fbbf5..fb3cf18e47d 100644
--- a/src/agents/anthropic-payload-log.test.ts
+++ b/src/agents/anthropic-payload-log.test.ts
@@ -29,7 +29,7 @@ describe("createAnthropicPayloadLogger", () => {
       ],
     };
     const streamFn: StreamFn = ((model, __, options) => {
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       return {} as never;
     }) as StreamFn;
 
diff --git a/src/agents/anthropic-payload-log.ts b/src/agents/anthropic-payload-log.ts
index d80ed551179..2eb5d62e770 100644
--- a/src/agents/anthropic-payload-log.ts
+++ b/src/agents/anthropic-payload-log.ts
@@ -145,7 +145,7 @@ export function createAnthropicPayloadLogger(params: {
           payload: redactedPayload,
           payloadDigest: digest(redactedPayload),
         });
-        return options?.onPayload?.(payload);
+        return options?.onPayload?.(payload, model);
       };
       return streamFn(model, context, {
         ...options,
diff --git a/src/agents/openai-ws-stream.ts b/src/agents/openai-ws-stream.ts
index 04550a665f4..307812e6be5 100644
--- a/src/agents/openai-ws-stream.ts
+++ b/src/agents/openai-ws-stream.ts
@@ -797,7 +797,7 @@ export function createOpenAIWebSocketStreamFn(
         ...(prevResponseId ? { previous_response_id: prevResponseId } : {}),
         ...extraParams,
       };
-      const nextPayload = options?.onPayload?.(payload);
+      const nextPayload = options?.onPayload?.(payload, model);
       const requestPayload = (nextPayload ?? payload) as Parameters<
         OpenAIWebSocketManager["send"]
       >[0];
diff --git a/src/agents/pi-embedded-runner-extraparams.test.ts b/src/agents/pi-embedded-runner-extraparams.test.ts
index 65f3c3648ac..ba51c400627 100644
--- a/src/agents/pi-embedded-runner-extraparams.test.ts
+++ b/src/agents/pi-embedded-runner-extraparams.test.ts
@@ -210,7 +210,7 @@ describe("applyExtraParamsToAgent", () => {
   }) {
     const payload = params.payload ?? { store: false };
     const baseStreamFn: StreamFn = (model, _context, options) => {
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       return {} as ReturnType<StreamFn>;
     };
     const agent = { streamFn: baseStreamFn };
@@ -236,7 +236,7 @@ describe("applyExtraParamsToAgent", () => {
   }) {
     const payload = params.payload ?? {};
     const baseStreamFn: StreamFn = (model, _context, options) => {
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       return {} as ReturnType<StreamFn>;
     };
     const agent = { streamFn: baseStreamFn };
@@ -279,7 +279,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = { model: "deepseek/deepseek-r1" };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -311,7 +311,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = {};
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -335,7 +335,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = { reasoning_effort: "high" };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -360,7 +360,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = { reasoning: { max_tokens: 256 } };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -384,7 +384,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = { reasoning_effort: "medium" };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -591,7 +591,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = { thinking: "off" };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -622,7 +622,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = { thinking: "off" };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -653,7 +653,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = {};
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -677,7 +677,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = { tool_choice: "required" };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -704,7 +704,7 @@ describe("applyExtraParamsToAgent", () => {
       const payload: Record<string, unknown> = {
         tool_choice: { type: "tool", name: "read" },
       };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -729,7 +729,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = {};
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -766,7 +766,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = { tool_choice: "required" };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -791,7 +791,7 @@ describe("applyExtraParamsToAgent", () => {
     const payloads: Record<string, unknown>[] = [];
     const baseStreamFn: StreamFn = (_model, _context, options) => {
       const payload: Record<string, unknown> = {};
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -817,7 +817,7 @@ describe("applyExtraParamsToAgent", () => {
       const payload: Record<string, unknown> = {
         tool_choice: { type: "function", function: { name: "read" } },
       };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -858,7 +858,7 @@ describe("applyExtraParamsToAgent", () => {
         ],
         tool_choice: { type: "tool", name: "read" },
       };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -902,7 +902,7 @@ describe("applyExtraParamsToAgent", () => {
           },
         ],
       };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -941,7 +941,7 @@ describe("applyExtraParamsToAgent", () => {
           },
         ],
       };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -1005,7 +1005,7 @@ describe("applyExtraParamsToAgent", () => {
           },
         },
       };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
@@ -1052,7 +1052,7 @@ describe("applyExtraParamsToAgent", () => {
           },
         },
       };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       payloads.push(payload);
       return {} as ReturnType<StreamFn>;
     };
diff --git a/src/agents/pi-embedded-runner/anthropic-stream-wrappers.ts b/src/agents/pi-embedded-runner/anthropic-stream-wrappers.ts
index 7df67acb37d..efed941762d 100644
--- a/src/agents/pi-embedded-runner/anthropic-stream-wrappers.ts
+++ b/src/agents/pi-embedded-runner/anthropic-stream-wrappers.ts
@@ -319,7 +319,7 @@ export function createAnthropicToolPayloadCompatibilityWrapper(
             );
           }
         }
-        return originalOnPayload?.(payload);
+        return originalOnPayload?.(payload, model);
       },
     });
   };
@@ -351,7 +351,7 @@ export function createAnthropicFastModeWrapper(
             payloadObj.service_tier = serviceTier;
           }
         }
-        return originalOnPayload?.(payload);
+        return originalOnPayload?.(payload, model);
       },
     });
   };
diff --git a/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts b/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts
index 530100b26e7..35a6cefcbd4 100644
--- a/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts
+++ b/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts
@@ -19,7 +19,7 @@ function applyAndCapture(params: {
 
   const baseStreamFn: StreamFn = (model, _context, options) => {
     captured.headers = options?.headers;
-    options?.onPayload?.({});
+    options?.onPayload?.({}, model);
     return createAssistantMessageEventStream();
   };
   const agent = { streamFn: baseStreamFn };
@@ -97,7 +97,7 @@ describe("extra-params: Kilocode kilo/auto reasoning", () => {
 
     const baseStreamFn: StreamFn = (model, _context, options) => {
       const payload: Record<string, unknown> = { reasoning_effort: "high" };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       capturedPayload = payload;
       return createAssistantMessageEventStream();
     };
@@ -125,7 +125,7 @@ describe("extra-params: Kilocode kilo/auto reasoning", () => {
 
     const baseStreamFn: StreamFn = (model, _context, options) => {
       const payload: Record<string, unknown> = {};
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       capturedPayload = payload;
       return createAssistantMessageEventStream();
     };
@@ -158,7 +158,7 @@ describe("extra-params: Kilocode kilo/auto reasoning", () => {
 
     const baseStreamFn: StreamFn = (model, _context, options) => {
       const payload: Record<string, unknown> = { reasoning_effort: "high" };
-      options?.onPayload?.(payload);
+      options?.onPayload?.(payload, model);
       capturedPayload = payload;
       return createAssistantMessageEventStream();
     };
diff --git a/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts b/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts
index a5b9940279f..5a36c9c5a4d 100644
--- a/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts
+++ b/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts
@@ -13,7 +13,7 @@ type StreamPayload = {
 
 function runOpenRouterPayload(payload: StreamPayload, modelId: string) {
   const baseStreamFn: StreamFn = (model, _context, options) => {
-    options?.onPayload?.(payload);
+    options?.onPayload?.(payload, model);
     return createAssistantMessageEventStream();
   };
   const agent = { streamFn: baseStreamFn };
diff --git a/src/agents/pi-embedded-runner/extra-params.ts b/src/agents/pi-embedded-runner/extra-params.ts
index e5fe0b2a19f..a9d5085e013 100644
--- a/src/agents/pi-embedded-runner/extra-params.ts
+++ b/src/agents/pi-embedded-runner/extra-params.ts
@@ -235,7 +235,7 @@ function createGoogleThinkingPayloadWrapper(
             thinkingLevel,
           });
         }
-        return onPayload?.(payload);
+        return onPayload?.(payload, model);
       },
     });
   };
@@ -268,7 +268,7 @@ function createZaiToolStreamWrapper(
           // Inject tool_stream: true for Z.AI API
           (payload as Record<string, unknown>).tool_stream = true;
         }
-        return originalOnPayload?.(payload);
+        return originalOnPayload?.(payload, model);
       },
     });
   };
@@ -315,7 +315,7 @@ function createParallelToolCallsWrapper(
         if (payload && typeof payload === "object") {
           (payload as Record<string, unknown>).parallel_tool_calls = enabled;
         }
-        return originalOnPayload?.(payload);
+        return originalOnPayload?.(payload, model);
       },
     });
   };
diff --git a/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts b/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts
index 2dab69cd15a..f7262a66798 100644
--- a/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts
+++ b/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts
@@ -22,7 +22,7 @@ type ToolStreamCase = {
 function runToolStreamCase(params: ToolStreamCase) {
   const payload: Record<string, unknown> = { model: params.model.id, messages: [] };
   const baseStreamFn: StreamFn = (model, _context, options) => {
-    options?.onPayload?.(payload);
+    options?.onPayload?.(payload, model);
     return {} as ReturnType<StreamFn>;
   };
   const agent = { streamFn: baseStreamFn };
diff --git a/src/agents/pi-embedded-runner/moonshot-stream-wrappers.ts b/src/agents/pi-embedded-runner/moonshot-stream-wrappers.ts
index 7eca8c17dbd..c066a168a0f 100644
--- a/src/agents/pi-embedded-runner/moonshot-stream-wrappers.ts
+++ b/src/agents/pi-embedded-runner/moonshot-stream-wrappers.ts
@@ -89,7 +89,7 @@ export function createSiliconFlowThinkingWrapper(baseStreamFn: StreamFn | undefi
             payloadObj.thinking = null;
           }
         }
-        return originalOnPayload?.(payload);
+        return originalOnPayload?.(payload, model);
       },
     });
   };
@@ -139,7 +139,7 @@ export function createMoonshotThinkingWrapper(
             }
           }
         }
-        return originalOnPayload?.(payload);
+        return originalOnPayload?.(payload, model);
       },
     });
   };
diff --git a/src/agents/pi-embedded-runner/openai-stream-wrappers.ts b/src/agents/pi-embedded-runner/openai-stream-wrappers.ts
index b0be191247f..d0b483e83ec 100644
--- a/src/agents/pi-embedded-runner/openai-stream-wrappers.ts
+++ b/src/agents/pi-embedded-runner/openai-stream-wrappers.ts
@@ -281,7 +281,7 @@ export function createOpenAIResponsesContextManagementWrapper(
             compactThreshold,
           });
         }
-        return originalOnPayload?.(payload);
+        return originalOnPayload?.(payload, model);
       },
     });
   };
@@ -306,7 +306,7 @@ export function createOpenAIFastModeWrapper(baseStreamFn: StreamFn | undefined):
             model,
           });
         }
-        return originalOnPayload?.(payload);
+        return originalOnPayload?.(payload, model);
       },
     });
   };
@@ -335,7 +335,7 @@ export function createOpenAIServiceTierWrapper(
             payloadObj.service_tier = serviceTier;
           }
         }
-        return originalOnPayload?.(payload);
+        return originalOnPayload?.(payload, model);
       },
     });
   };
diff --git a/src/agents/pi-embedded-runner/proxy-stream-wrappers.ts b/src/agents/pi-embedded-runner/proxy-stream-wrappers.ts
index a5f9f5b1d85..4f77c31cfdd 100644
--- a/src/agents/pi-embedded-runner/proxy-stream-wrappers.ts
+++ b/src/agents/pi-embedded-runner/proxy-stream-wrappers.ts
@@ -92,7 +92,7 @@ export function createOpenRouterSystemCacheWrapper(baseStreamFn: StreamFn | unde
             }
           }
         }
-        return originalOnPayload?.(payload);
+        return originalOnPayload?.(payload, model);
       },
     });
   };
@@ -113,7 +113,7 @@ export function createOpenRouterWrapper(
       },
       onPayload: (payload) => {
         normalizeProxyReasoningPayload(payload, thinkingLevel);
-        return onPayload?.(payload);
+        return onPayload?.(payload, model);
       },
     });
   };
@@ -138,7 +138,7 @@ export function createKilocodeWrapper(
       },
       onPayload: (payload) => {
         normalizeProxyReasoningPayload(payload, thinkingLevel);
-        return onPayload?.(payload);
+        return onPayload?.(payload, model);
       },
     });
   };
diff --git a/src/agents/pi-embedded-runner/run/attempt.ts b/src/agents/pi-embedded-runner/run/attempt.ts
index 0b3d246fe04..78b3a173ce7 100644
--- a/src/agents/pi-embedded-runner/run/attempt.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.ts
@@ -414,14 +414,14 @@ export function wrapOllamaCompatNumCtx(baseFn: StreamFn | undefined, numCtx: num
       ...options,
       onPayload: (payload: unknown) => {
         if (!payload || typeof payload !== "object") {
-          return options?.onPayload?.(payload);
+          return options?.onPayload?.(payload, model);
         }
         const payloadRecord = payload as Record<string, unknown>;
         if (!payloadRecord.options || typeof payloadRecord.options !== "object") {
           payloadRecord.options = {};
         }
         (payloadRecord.options as Record<string, unknown>).num_ctx = numCtx;
-        return options?.onPayload?.(payload);
+        return options?.onPayload?.(payload, model);
       },
     });
 }