chore: import upstream snapshot with attribution

tests/unit/executor-default-strip-client-metadata.test.ts

@@ -0,0 +1,83 @@
+/**
+ * Port of decolua/9router commit d652300e:
+ * Cerebras returns 400 (wrong_api_format) and Mistral returns 422
+ * (extra_forbidden) when the forwarded body contains `client_metadata`
+ * (an OpenAI-Codex/Claude-CLI passthrough field that has no equivalent
+ * on these upstreams). Strip it on the executor's transformRequest path
+ * before sending the request downstream.
+ */
+
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { DefaultExecutor } from "../../open-sse/executors/default.ts";
+
+const STREAM = true;
+const CREDENTIALS = { apiKey: "k" } as Record<string, unknown>;
+
+function bodyWithClientMetadata() {
+  return {
+    model: "any",
+    messages: [{ role: "user", content: "hi" }],
+    client_metadata: { foo: "bar" },
+    stream: STREAM,
+  };
+}
+
+test("DefaultExecutor.transformRequest strips client_metadata for cerebras", () => {
+  const executor = new DefaultExecutor("cerebras");
+  const out = executor.transformRequest(
+    "any",
+    bodyWithClientMetadata(),
+    STREAM,
+    CREDENTIALS
+  ) as Record<string, unknown>;
+  assert.equal(
+    Object.prototype.hasOwnProperty.call(out, "client_metadata"),
+    false,
+    "cerebras forward body must not contain client_metadata"
+  );
+});
+
+test("DefaultExecutor.transformRequest strips client_metadata for mistral", () => {
+  const executor = new DefaultExecutor("mistral");
+  const out = executor.transformRequest(
+    "any",
+    bodyWithClientMetadata(),
+    STREAM,
+    CREDENTIALS
+  ) as Record<string, unknown>;
+  assert.equal(
+    Object.prototype.hasOwnProperty.call(out, "client_metadata"),
+    false,
+    "mistral forward body must not contain client_metadata"
+  );
+});
+
+test("DefaultExecutor.transformRequest strips client_metadata for nvidia (port from 9router#1887)", () => {
+  const executor = new DefaultExecutor("nvidia");
+  const out = executor.transformRequest(
+    "any",
+    bodyWithClientMetadata(),
+    STREAM,
+    CREDENTIALS
+  ) as Record<string, unknown>;
+  assert.equal(
+    Object.prototype.hasOwnProperty.call(out, "client_metadata"),
+    false,
+    "nvidia forward body must not contain client_metadata"
+  );
+});
+
+test("DefaultExecutor.transformRequest preserves client_metadata for other providers", () => {
+  // Sanity check: the strip must be scoped, not global. Openai keeps it
+  // (codex flow needs it), the cerebras/mistral strip is the only carve-out.
+  const executor = new DefaultExecutor("openai");
+  const out = executor.transformRequest(
+    "any",
+    bodyWithClientMetadata(),
+    STREAM,
+    CREDENTIALS
+  ) as Record<string, unknown>;
+  assert.deepEqual(out.client_metadata, { foo: "bar" });
+});