diff --git a/src/lib/providers/validation.ts b/src/lib/providers/validation.ts
index 083f41c078..5825d71308 100644
--- a/src/lib/providers/validation.ts
+++ b/src/lib/providers/validation.ts
@@ -445,16 +445,22 @@ async function validateAnthropicCompatibleProvider({ apiKey, providerSpecificDat
 async function validateSearchProvider(
   url: string,
   init: RequestInit
-): Promise<{ valid: boolean; error: string | null }> {
+): Promise<{ valid: boolean; error: string | null; unsupported: false }> {
   try {
     const response = await fetch(url, init);
-    if (response.ok) return { valid: true, error: null };
+    if (response.ok) return { valid: true, error: null, unsupported: false };
     if (response.status === 401 || response.status === 403) {
-      return { valid: false, error: "Invalid API key" };
+      return { valid: false, error: "Invalid API key", unsupported: false };
     }
-    return { valid: false, error: `Validation failed: ${response.status}` };
+    // For provider setup we only need to confirm authentication passed.
+    // Search providers may return non-auth statuses for exhausted credits,
+    // rate limiting, or request-shape quirks while still accepting the key.
+    if (response.status < 500) {
+      return { valid: true, error: null, unsupported: false };
+    }
+    return { valid: false, error: `Validation failed: ${response.status}`, unsupported: false };
   } catch (error: any) {
-    return { valid: false, error: error.message || "Validation failed" };
+    return { valid: false, error: error.message || "Validation failed", unsupported: false };
   }
 }
 
diff --git a/tests/unit/search-provider-validation.test.mjs b/tests/unit/search-provider-validation.test.mjs
new file mode 100644
index 0000000000..f05aa51864
--- /dev/null
+++ b/tests/unit/search-provider-validation.test.mjs
@@ -0,0 +1,50 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+const { validateProviderApiKey } = await import("../../src/lib/providers/validation.ts");
+
+test("serper validation accepts authenticated non-auth upstream errors", async () => {
+  const originalFetch = globalThis.fetch;
+
+  globalThis.fetch = async () =>
+    new Response(JSON.stringify({ error: "credits_exhausted" }), {
+      status: 402,
+      headers: { "content-type": "application/json" },
+    });
+
+  try {
+    const result = await validateProviderApiKey({
+      provider: "serper-search",
+      apiKey: "valid-serper-key",
+    });
+
+    assert.equal(result.valid, true);
+    assert.equal(result.error, null);
+    assert.equal(result.unsupported, false);
+  } finally {
+    globalThis.fetch = originalFetch;
+  }
+});
+
+test("serper validation still rejects unauthorized keys", async () => {
+  const originalFetch = globalThis.fetch;
+
+  globalThis.fetch = async () =>
+    new Response(JSON.stringify({ error: "Unauthorized" }), {
+      status: 403,
+      headers: { "content-type": "application/json" },
+    });
+
+  try {
+    const result = await validateProviderApiKey({
+      provider: "serper-search",
+      apiKey: "bad-serper-key",
+    });
+
+    assert.equal(result.valid, false);
+    assert.equal(result.error, "Invalid API key");
+    assert.equal(result.unsupported, false);
+  } finally {
+    globalThis.fetch = originalFetch;
+  }
+});