diff --git a/packages/client/src/ai-direct-generate.test.mjs b/packages/client/src/ai-direct-generate.test.mjs
index 40561604..a39014f9 100644
--- a/packages/client/src/ai-direct-generate.test.mjs
+++ b/packages/client/src/ai-direct-generate.test.mjs
@@ -54,7 +54,11 @@ describe("direct tag suggestions", () => {
             modelId: "meta/llama",
           }), { headers: { "content-type": "application/json" } });
         }
-        if (String(url).includes("integrate.api.nvidia.com")) throw new TypeError("Failed to fetch");
+        if (String(url).includes("integrate.api.nvidia.com")) {
+          expect(init?.method).toBe("POST");
+          expect(new Headers(init?.headers).get("Authorization")).toBe("Bearer edgeever-cors-probe");
+          throw new TypeError("Failed to fetch");
+        }
         return new Response(JSON.stringify({ suggestions: [{ name: "proxied", existing: false }] }), {
           headers: { "content-type": "application/json" },
         });
diff --git a/packages/client/src/ai-direct-stream.test.mjs b/packages/client/src/ai-direct-stream.test.mjs
index 7be6802f..502e3a23 100644
--- a/packages/client/src/ai-direct-stream.test.mjs
+++ b/packages/client/src/ai-direct-stream.test.mjs
@@ -1,5 +1,6 @@
 import { describe, expect, test } from "bun:test";
 import { createEdgeEverClient } from "./index.ts";
+import { probeAiProviderCors } from "./ai-direct-stream.ts";
 
 describe("direct AI generation client", () => {
   test("prepares on the instance then streams from the model provider", async () => {
@@ -56,7 +57,11 @@ describe("direct AI generation client", () => {
       baseUrl: "https://notes.example",
       tryDirectAiGeneration: true,
       fetch: async (url, init) => {
-        urls.push({ url: String(url), method: init?.method ?? "GET" });
+        urls.push({
+          url: String(url),
+          method: init?.method ?? "GET",
+          auth: new Headers(init?.headers).get("Authorization"),
+        });
         if (String(url).endsWith("/direct-target")) {
           return new Response(JSON.stringify({
             provider: "openai-compatible",
@@ -65,6 +70,8 @@ describe("direct AI generation client", () => {
           }), { headers: { "content-type": "application/json" } });
         }
         if (String(url).includes("integrate.api.nvidia.com")) {
+          expect(init?.method).toBe("POST");
+          expect(new Headers(init?.headers).get("Authorization")).toBe("Bearer edgeever-cors-probe");
           throw new TypeError("Failed to fetch");
         }
         return new Response("data: {\"type\":\"text-delta\",\"text\":\"proxied\"}\n\n", {
@@ -78,22 +85,27 @@ describe("direct AI generation client", () => {
       { onEvent: (event) => events.push(event) },
     );
     expect(urls).toEqual([
-      { url: "https://notes.example/api/v1/ai/direct-target", method: "GET" },
-      { url: "https://integrate.api.nvidia.com/v1/chat/completions", method: "OPTIONS" },
-      { url: "https://notes.example/api/v1/ai/generate", method: "POST" },
+      { url: "https://notes.example/api/v1/ai/direct-target", method: "GET", auth: null },
+      { url: "https://integrate.api.nvidia.com/v1/chat/completions", method: "POST", auth: "Bearer edgeever-cors-probe" },
+      { url: "https://notes.example/api/v1/ai/generate", method: "POST", auth: null },
     ]);
     expect(urls.some((call) => call.url.endsWith("/prepare"))).toBe(false);
     expect(events).toEqual([{ type: "text-delta", text: "proxied" }]);
   });
 
   test("direct-connects from the browser after a successful CORS probe", async () => {
-    const urls = [];
+    const calls = [];
     const client = createEdgeEverClient({
       baseUrl: "https://notes.example",
       token: "user-token",
       tryDirectAiGeneration: true,
       fetch: async (url, init) => {
-        urls.push(String(url));
+        const headers = new Headers(init?.headers);
+        calls.push({
+          url: String(url),
+          method: init?.method ?? "GET",
+          auth: headers.get("Authorization"),
+        });
         if (String(url).endsWith("/direct-target")) {
           return new Response(JSON.stringify({
             provider: "openai-compatible",
@@ -101,8 +113,17 @@ describe("direct AI generation client", () => {
             modelId: "openai/gpt-4o-mini",
           }), { headers: { "content-type": "application/json" } });
         }
-        if (String(url).includes("openrouter.ai") && (init?.method ?? "GET") === "OPTIONS") {
-          return new Response(null, { status: 204 });
+        if (String(url).includes("openrouter.ai")) {
+          if (headers.get("Authorization") === "Bearer edgeever-cors-probe") {
+            return new Response("{}", { status: 401 });
+          }
+          expect(headers.get("Authorization")).toBe("Bearer or-key");
+          return new Response([
+            `data: {"choices":[{"delta":{"content":"<edgeever-result-x>\\nHello"}}]}`,
+            `data: {"choices":[{"delta":{"content":"</edgeever-result-x>"},"finish_reason":"stop"}]}`,
+            "data: [DONE]",
+            "",
+          ].join("\n\n"), { headers: { "content-type": "text/event-stream" } });
         }
         if (String(url).endsWith("/prepare")) {
           return new Response(JSON.stringify({
@@ -116,14 +137,6 @@ describe("direct AI generation client", () => {
             resultBoundary: { start: "<edgeever-result-x>", end: "</edgeever-result-x>" },
           }), { headers: { "content-type": "application/json" } });
         }
-        if (String(url).includes("openrouter.ai")) {
-          return new Response([
-            `data: {"choices":[{"delta":{"content":"<edgeever-result-x>\\nHello"}}]}`,
-            `data: {"choices":[{"delta":{"content":"</edgeever-result-x>"},"finish_reason":"stop"}]}`,
-            "data: [DONE]",
-            "",
-          ].join("\n\n"), { headers: { "content-type": "text/event-stream" } });
-        }
         throw new Error(`unexpected ${url}`);
       },
     });
@@ -132,11 +145,11 @@ describe("direct AI generation client", () => {
       { action: "summarize", title: "Note", contentMarkdown: "Body" },
       { onEvent: (event) => events.push(event) },
     );
-    expect(urls).toEqual([
-      "https://notes.example/api/v1/ai/direct-target",
-      "https://openrouter.ai/api/v1/chat/completions",
-      "https://notes.example/api/v1/ai/generate/prepare",
-      "https://openrouter.ai/api/v1/chat/completions",
+    expect(calls).toEqual([
+      { url: "https://notes.example/api/v1/ai/direct-target", method: "GET", auth: "Bearer user-token" },
+      { url: "https://openrouter.ai/api/v1/chat/completions", method: "POST", auth: "Bearer edgeever-cors-probe" },
+      { url: "https://notes.example/api/v1/ai/generate/prepare", method: "POST", auth: "Bearer user-token" },
+      { url: "https://openrouter.ai/api/v1/chat/completions", method: "POST", auth: "Bearer or-key" },
     ]);
     expect(events.filter((event) => event.type === "text-delta").map((event) => event.text).join("")).toBe("Hello");
   });
@@ -166,3 +179,73 @@ describe("direct AI generation client", () => {
     expect(events).toEqual([{ type: "text-delta", text: "proxied" }]);
   });
 });
+
+describe("AI provider CORS probe", () => {
+  const openaiTarget = {
+    provider: "openai-compatible",
+    baseUrl: "https://api.example/v1",
+    modelId: "demo",
+  };
+
+  test("POSTs a dummy key and treats a readable 401 as CORS success", async () => {
+    let cancelled = false;
+    const body = new ReadableStream({
+      start() {},
+      cancel() {
+        cancelled = true;
+      },
+    });
+    const allowed = await probeAiProviderCors(openaiTarget, async (url, init) => {
+      expect(String(url)).toBe("https://api.example/v1/chat/completions");
+      expect(init?.method).toBe("POST");
+      expect(init?.mode).toBe("cors");
+      const headers = new Headers(init?.headers);
+      expect(headers.get("Authorization")).toBe("Bearer edgeever-cors-probe");
+      expect(headers.get("Content-Type")).toBe("application/json");
+      expect(headers.get("Accept")).toBe("text/event-stream");
+      expect(JSON.parse(String(init?.body)).stream).toBe(true);
+      return new Response(body, { status: 401 });
+    });
+    expect(allowed).toBe(true);
+    expect(cancelled).toBe(true);
+  });
+
+  test("sends Anthropic and Google dummy credentials on the real provider paths", async () => {
+    const anthropicAllowed = await probeAiProviderCors({
+      provider: "anthropic",
+      baseUrl: "https://api.anthropic.com/v1",
+      modelId: "claude",
+    }, async (url, init) => {
+      expect(String(url)).toBe("https://api.anthropic.com/v1/messages");
+      expect(init?.method).toBe("POST");
+      expect(new Headers(init?.headers).get("x-api-key")).toBe("edgeever-cors-probe");
+      return new Response("{}", { status: 401 });
+    });
+    const googleAllowed = await probeAiProviderCors({
+      provider: "google",
+      baseUrl: "https://generativelanguage.googleapis.com/v1beta",
+      modelId: "models/gemini-2.5-flash",
+    }, async (url, init) => {
+      expect(String(url)).toBe("https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash:streamGenerateContent?alt=sse");
+      expect(init?.method).toBe("POST");
+      expect(new Headers(init?.headers).get("x-goog-api-key")).toBe("edgeever-cors-probe");
+      return new Response("{}", { status: 403 });
+    });
+    expect(anthropicAllowed).toBe(true);
+    expect(googleAllowed).toBe(true);
+  });
+
+  test("returns false when the browser blocks the probe", async () => {
+    const allowed = await probeAiProviderCors(openaiTarget, async () => {
+      throw new TypeError("Failed to fetch");
+    });
+    expect(allowed).toBe(false);
+  });
+
+  test("rethrows when the caller aborts the probe", async () => {
+    const signal = AbortSignal.abort();
+    await expect(probeAiProviderCors(openaiTarget, async () => {
+      throw new DOMException("The operation was aborted.", "AbortError");
+    }, signal)).rejects.toMatchObject({ name: "AbortError" });
+  });
+});
diff --git a/packages/client/src/ai-direct-stream.ts b/packages/client/src/ai-direct-stream.ts
index b1d1b83f..4c200d71 100644
--- a/packages/client/src/ai-direct-stream.ts
+++ b/packages/client/src/ai-direct-stream.ts
@@ -126,7 +126,15 @@ export const probeAiProviderCors = async (
     resultBoundary: { start: "<edgeever-result-probe>", end: "</edgeever-result-probe>" },
   });
   try {
-    await fetchImpl(request.url, { method: "OPTIONS", mode: "cors", signal });
+    // POST with the dummy key so the browser preflight matches the real direct request.
+    const response = await fetchImpl(request.url, {
+      method: "POST",
+      mode: "cors",
+      headers: request.headers,
+      body: request.body,
+      signal,
+    });
+    await response.body?.cancel().catch(() => {});
     return true;
   } catch (error) {
     if (signal?.aborted) throw error;
diff --git a/packages/client/src/companion-direct-stream.test.mjs b/packages/client/src/companion-direct-stream.test.mjs
index de2eb1fa..b8d0b985 100644
--- a/packages/client/src/companion-direct-stream.test.mjs
+++ b/packages/client/src/companion-direct-stream.test.mjs
@@ -95,6 +95,8 @@ describe("direct companion client", () => {
           }), { headers: { "content-type": "application/json" } });
         }
         if (String(url).includes("integrate.api.nvidia.com")) {
+          expect(init?.method).toBe("POST");
+          expect(new Headers(init?.headers).get("Authorization")).toBe("Bearer edgeever-cors-probe");
           throw new TypeError("Failed to fetch");
         }
         return new Response("data: {\"type\":\"text-delta\",\"text\":\"proxied\"}\n\n", {