diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6559fe86225..23eed3c22da 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -261,6 +261,7 @@ Docs: https://docs.openclaw.ai
 - UI/Control chat tool streaming: render tool events live in webchat without requiring refresh by enabling `tool-events` capability, fixing stream/event correlation, and resetting/reloading stream state around tool results and terminal events. (#39104) Thanks @jakepresent.
 - Models/provider apiKey persistence hardening: when a provider `apiKey` value equals a known provider env var value, persist the canonical env var name into `models.json` instead of resolved plaintext secrets. (#38889) Thanks @gambletan.
 - Discord/model picker persistence check: add a short post-dispatch settle delay before reading back session model state so picker confirmations stop reporting false mismatch warnings after successful model switches. (#39105) Thanks @akropp.
+- Agents/OpenAI WS compat store flag: omit `store` from `response.create` payloads when model compat sets `supportsStore: false`, preventing strict OpenAI-compatible providers from rejecting websocket requests with unknown-field errors. (#39113) Thanks @scoootscooob.
 
 ## 2026.3.2
 
diff --git a/src/agents/openai-ws-stream.test.ts b/src/agents/openai-ws-stream.test.ts
index b467de80262..00d0a3df64c 100644
--- a/src/agents/openai-ws-stream.test.ts
+++ b/src/agents/openai-ws-stream.test.ts
@@ -634,6 +634,8 @@ describe("createOpenAIWebSocketStreamFn", () => {
     releaseWsSession("sess-incremental");
     releaseWsSession("sess-full");
     releaseWsSession("sess-tools");
+    releaseWsSession("sess-store-default");
+    releaseWsSession("sess-store-compat");
   });
 
   it("connects to the WebSocket on first call", async () => {
@@ -691,6 +693,73 @@ describe("createOpenAIWebSocketStreamFn", () => {
     expect(Array.isArray(sent.input)).toBe(true);
   });
 
+  it("includes store:false by default", async () => {
+    const streamFn = createOpenAIWebSocketStreamFn("sk-test", "sess-store-default");
+    const stream = streamFn(
+      modelStub as Parameters<typeof streamFn>[0],
+      contextStub as Parameters<typeof streamFn>[1],
+    );
+
+    const completed = new Promise<void>((res, rej) => {
+      queueMicrotask(async () => {
+        try {
+          await new Promise((r) => setImmediate(r));
+          const manager = MockManager.lastInstance!;
+          manager.simulateEvent({
+            type: "response.completed",
+            response: makeResponseObject("resp_store_default", "ok"),
+          });
+          for await (const _ of await resolveStream(stream)) {
+            // consume
+          }
+          res();
+        } catch (e) {
+          rej(e);
+        }
+      });
+    });
+    await completed;
+
+    const sent = MockManager.lastInstance!.sentEvents[0] as Record<string, unknown>;
+    expect(sent.store).toBe(false);
+  });
+
+  it("omits store when compat.supportsStore is false (#39086)", async () => {
+    releaseWsSession("sess-store-compat");
+    const noStoreModel = {
+      ...modelStub,
+      compat: { supportsStore: false },
+    };
+    const streamFn = createOpenAIWebSocketStreamFn("sk-test", "sess-store-compat");
+    const stream = streamFn(
+      noStoreModel as Parameters<typeof streamFn>[0],
+      contextStub as Parameters<typeof streamFn>[1],
+    );
+
+    const completed = new Promise<void>((res, rej) => {
+      queueMicrotask(async () => {
+        try {
+          await new Promise((r) => setImmediate(r));
+          const manager = MockManager.lastInstance!;
+          manager.simulateEvent({
+            type: "response.completed",
+            response: makeResponseObject("resp_no_store", "ok"),
+          });
+          for await (const _ of await resolveStream(stream)) {
+            // consume
+          }
+          res();
+        } catch (e) {
+          rej(e);
+        }
+      });
+    });
+    await completed;
+
+    const sent = MockManager.lastInstance!.sentEvents[0] as Record<string, unknown>;
+    expect(sent).not.toHaveProperty("store");
+  });
+
   it("emits an AssistantMessage on response.completed", async () => {
     const streamFn = createOpenAIWebSocketStreamFn("sk-test", "sess-2");
     const stream = streamFn(
diff --git a/src/agents/openai-ws-stream.ts b/src/agents/openai-ws-stream.ts
index b7449f30991..d7fd1db99c6 100644
--- a/src/agents/openai-ws-stream.ts
+++ b/src/agents/openai-ws-stream.ts
@@ -589,10 +589,15 @@ export function createOpenAIWebSocketStreamFn(
         extraParams.reasoning = reasoning;
       }
 
+      // Respect compat.supportsStore — providers like Gemini reject unknown
+      // fields such as `store` with a 400 error.  Fixes #39086.
+      const supportsStore = (model as { compat?: { supportsStore?: boolean } }).compat
+        ?.supportsStore;
+
       const payload: Record<string, unknown> = {
         type: "response.create",
         model: model.id,
-        store: false,
+        ...(supportsStore !== false ? { store: false } : {}),
         input: inputItems,
         instructions: context.systemPrompt ?? undefined,
         tools: tools.length > 0 ? tools : undefined,