diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1fb1d150fc..aaa3a1403f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -121,6 +121,7 @@ _In development — bullets added per PR; finalized at release._
 
 - **fix(deps): bump undici to 7.28.0 and dompurify to 3.4.11 (security)** — addresses the undici SOCKS5-TLS / cache advisories and the dompurify advisory. ([#4306](https://github.com/diegosouzapw/OmniRoute/pull/4306))
 - **chore(deps): bump actions/checkout from 4 to 7** — CI checkout-action update. ([#4297](https://github.com/diegosouzapw/OmniRoute/pull/4297))
+- **fix(executors): strip `stream_options` for qwen non-streaming / thinking-mode Claude Code requests** — Claude-Code-compatible providers force the executor-level `stream` flag on via `upstreamStream = stream || isClaudeCodeCompatible` (`open-sse/handlers/chatCore.ts`), but the outgoing body keeps the caller's original `stream: false`. The shared `stream && targetFormat === "openai"` branch in `DefaultExecutor.transformRequest` then injected `stream_options: { include_usage: true }` onto a body that still said `stream: false`, and qwen upstream rejected it with `400 "'stream_options' only set this when you set stream: true"`. Same rejection when the body carries `thinking` / `enable_thinking`. The qwen branch now skips the injection (and strips any client-sent `stream_options`) when the body explicitly says `stream: false` or requests thinking, leaving regular qwen streaming requests with the usage injection intact. (thanks @anuragg-saxenaa)
 
 ---
 
diff --git a/open-sse/executors/default.ts b/open-sse/executors/default.ts
index cc2444602a..034477ec48 100644
--- a/open-sse/executors/default.ts
+++ b/open-sse/executors/default.ts
@@ -571,11 +571,31 @@ export class DefaultExecutor extends BaseExecutor {
           withDefaults = withoutStreamOptions;
         }
       } else if (stream && targetFormat === "openai" && requestFormat !== "openai-responses") {
-        if (!credentials?.providerSpecificData?.disableStreamOptions) {
+        // Port of decolua/9router#663 (closes upstream #557): Qwen rejects with
+        // 400 "'stream_options' only set this when you set stream: true" when the
+        // outgoing body carries `stream: false` (Claude Code / Claude-Code-
+        // compatible callers force the executor-level stream flag on via
+        // `upstreamStream = stream || isClaudeCodeCompatible`, but the body keeps
+        // the caller's original `stream: false`). Same upstream also rejects the
+        // injection when `thinking` / `enable_thinking` is set. Skip injection in
+        // those cases instead of unconditionally adding `stream_options`.
+        const defaultsRecord = withDefaults as Record<string, unknown>;
+        const qwenBlocksStreamOptions =
+          this.provider === "qwen" &&
+          (defaultsRecord.stream === false ||
+            Boolean(defaultsRecord.thinking) ||
+            Boolean(defaultsRecord.enable_thinking));
+        if (qwenBlocksStreamOptions) {
+          if (Object.prototype.hasOwnProperty.call(defaultsRecord, "stream_options")) {
+            const withoutStreamOptions = { ...defaultsRecord };
+            delete withoutStreamOptions.stream_options;
+            withDefaults = withoutStreamOptions;
+          }
+        } else if (!credentials?.providerSpecificData?.disableStreamOptions) {
           withDefaults = {
             ...withDefaults,
             stream_options: {
-              ...(((withDefaults as Record<string, unknown>).stream_options as object) || {}),
+              ...((defaultsRecord.stream_options as object) || {}),
               include_usage: true,
             },
           };
diff --git a/tests/unit/qwen-strip-stream-options-claude-code-port663.test.ts b/tests/unit/qwen-strip-stream-options-claude-code-port663.test.ts
new file mode 100644
index 0000000000..f4effdacba
--- /dev/null
+++ b/tests/unit/qwen-strip-stream-options-claude-code-port663.test.ts
@@ -0,0 +1,100 @@
+/**
+ * Port of upstream decolua/9router#663 (closes upstream #557).
+ *
+ * Scenario: Claude Code (or any caller) hits a Qwen model with an OpenAI body
+ * that carries `stream: false`. OmniRoute, however, sets the executor-level
+ * `stream` flag to `true` for Claude-Code-compatible providers via
+ * `upstreamStream = stream || isClaudeCodeCompatible`
+ * (`open-sse/handlers/chatCore.ts`). DefaultExecutor.transformRequest then runs
+ * its `if (stream && targetFormat === "openai")` branch and injects
+ * `stream_options: { include_usage: true }` onto a body that still carries
+ * `stream: false`. Qwen upstream rejects with:
+ *   400 "'stream_options' only set this when you set stream: true"
+ *
+ * Fix mirrors upstream: when the OUTGOING body explicitly says `stream: false`,
+ * do NOT inject `stream_options` regardless of the executor-level `stream` arg.
+ * Same defensive treatment when the body carries `thinking` /
+ * `enable_thinking`, since the upstream PR also exempts those.
+ */
+import test from "node:test";
+import assert from "node:assert/strict";
+import { DefaultExecutor } from "../../open-sse/executors/default.ts";
+
+test("port#663 qwen: body.stream===false → no stream_options even when executor stream=true", () => {
+  const executor = new DefaultExecutor("qwen");
+  const body = {
+    model: "qwen3-coder-plus",
+    messages: [{ role: "user", content: "hi" }],
+    stream: false,
+  };
+  const result = executor.transformRequest(
+    "qwen3-coder-plus",
+    body,
+    /* stream */ true,
+    {}
+  ) as Record<string, unknown>;
+  assert.equal(
+    result.stream_options,
+    undefined,
+    "stream_options must not be injected when body.stream === false"
+  );
+});
+
+test("port#663 qwen: body.thinking truthy → no stream_options injection", () => {
+  const executor = new DefaultExecutor("qwen");
+  const body = {
+    model: "qwen3-coder-plus",
+    messages: [{ role: "user", content: "hi" }],
+    thinking: { type: "enabled" },
+  };
+  const result = executor.transformRequest(
+    "qwen3-coder-plus",
+    body,
+    true,
+    {}
+  ) as Record<string, unknown>;
+  assert.equal(
+    result.stream_options,
+    undefined,
+    "stream_options must not be injected when thinking mode is requested"
+  );
+});
+
+test("port#663 qwen: body.enable_thinking truthy → no stream_options injection", () => {
+  const executor = new DefaultExecutor("qwen");
+  const body = {
+    model: "qwen3-coder-plus",
+    messages: [{ role: "user", content: "hi" }],
+    enable_thinking: true,
+  };
+  const result = executor.transformRequest(
+    "qwen3-coder-plus",
+    body,
+    true,
+    {}
+  ) as Record<string, unknown>;
+  assert.equal(
+    result.stream_options,
+    undefined,
+    "stream_options must not be injected when enable_thinking is true"
+  );
+});
+
+test("port#663 qwen: normal streaming request still injects stream_options.include_usage", () => {
+  const executor = new DefaultExecutor("qwen");
+  const body = {
+    model: "qwen3-coder-plus",
+    messages: [{ role: "user", content: "hi" }],
+  };
+  const result = executor.transformRequest(
+    "qwen3-coder-plus",
+    body,
+    true,
+    {}
+  ) as Record<string, unknown>;
+  assert.deepEqual(
+    result.stream_options,
+    { include_usage: true },
+    "regular qwen streaming requests must keep the include_usage injection"
+  );
+});