diff --git a/packages/core/src/embedding.ts b/packages/core/src/embedding.ts
index 467769f..6c4a580 100644
--- a/packages/core/src/embedding.ts
+++ b/packages/core/src/embedding.ts
@@ -609,6 +609,17 @@ export function _restoreProvider(token: unknown): void {
  *  one-line warning from spamming on every fire-and-forget embed call. */
 let remoteFallbackLogged = false;
 
+/**
+ * Quick sanity check that a string looks like a real API key rather than
+ * a placeholder. Tools like Codex set `OPENAI_API_KEY=nokey` when routing
+ * through a custom base URL — using such a value for real API calls
+ * produces 401 errors.
+ */
+function looksLikeApiKey(key: string): boolean {
+  // Real API keys are at least 20 characters and don't look like
+  // common placeholders.
+  return key.length >= 20;
+}
 
 /**
  * Build a remote `EmbeddingProvider` from whichever API key is in env.
@@ -623,18 +634,23 @@ export function pickRemoteFallback(): {
   name: "voyage" | "openai";
   provider: EmbeddingProvider;
 } | null {
-  if (process.env.VOYAGE_API_KEY) {
+  // Validate keys before using them — tools like Codex/OpenCode often set
+  // OPENAI_API_KEY to a placeholder (e.g. "nokey") when using a custom
+  // OPENAI_BASE_URL. Using such a key for real API calls produces 401 noise.
+  const voyageKey = process.env.VOYAGE_API_KEY;
+  if (voyageKey && looksLikeApiKey(voyageKey)) {
     const d = PROVIDER_DEFAULTS.voyage;
     return {
       name: "voyage",
-      provider: new VoyageProvider(process.env.VOYAGE_API_KEY, d.model, d.dimensions),
+      provider: new VoyageProvider(voyageKey, d.model, d.dimensions),
     };
   }
-  if (process.env.OPENAI_API_KEY) {
+  const openaiKey = process.env.OPENAI_API_KEY;
+  if (openaiKey && looksLikeApiKey(openaiKey)) {
     const d = PROVIDER_DEFAULTS.openai;
     return {
       name: "openai",
-      provider: new OpenAIProvider(process.env.OPENAI_API_KEY, d.model, d.dimensions),
+      provider: new OpenAIProvider(openaiKey, d.model, d.dimensions),
     };
   }
   return null;
diff --git a/packages/core/test/embedding.test.ts b/packages/core/test/embedding.test.ts
index a892aae..bad23be 100644
--- a/packages/core/test/embedding.test.ts
+++ b/packages/core/test/embedding.test.ts
@@ -211,7 +211,7 @@ describe("auto-fallback to remote provider when local provider is unavailable",
 
   test("auto-falls back to Voyage when VOYAGE_API_KEY is set", async () => {
     _markLocalProviderUnavailable();
-    process.env.VOYAGE_API_KEY = "vk-test";
+    process.env.VOYAGE_API_KEY = "vk-test-key-that-is-long-enough";
     const { fetch, calls } = fakeFetch("voyage");
     globalThis.fetch = fetch;
 
@@ -224,7 +224,7 @@ describe("auto-fallback to remote provider when local provider is unavailable",
 
   test("auto-falls back to OpenAI when only OPENAI_API_KEY is set", async () => {
     _markLocalProviderUnavailable();
-    process.env.OPENAI_API_KEY = "sk-test";
+    process.env.OPENAI_API_KEY = "sk-test-key-that-is-long-enough";
     const { fetch, calls } = fakeFetch("openai");
     globalThis.fetch = fetch;
 
@@ -237,8 +237,8 @@ describe("auto-fallback to remote provider when local provider is unavailable",
 
   test("Voyage wins when both keys are set", async () => {
     _markLocalProviderUnavailable();
-    process.env.VOYAGE_API_KEY = "vk-test";
-    process.env.OPENAI_API_KEY = "sk-test";
+    process.env.VOYAGE_API_KEY = "vk-test-key-that-is-long-enough";
+    process.env.OPENAI_API_KEY = "sk-test-key-that-is-long-enough";
     const { fetch, calls } = fakeFetch("voyage");
     globalThis.fetch = fetch;
 
@@ -248,7 +248,7 @@ describe("auto-fallback to remote provider when local provider is unavailable",
 
   test("subsequent embed() calls go directly to the swapped provider (no double fail)", async () => {
     _markLocalProviderUnavailable();
-    process.env.VOYAGE_API_KEY = "vk-test";
+    process.env.VOYAGE_API_KEY = "vk-test-key-that-is-long-enough";
     const { fetch, calls } = fakeFetch("voyage");
     globalThis.fetch = fetch;
 
@@ -290,23 +290,28 @@ describe("pickRemoteFallback", () => {
   });
 
   test("returns Voyage when only VOYAGE_API_KEY is set", () => {
-    process.env.VOYAGE_API_KEY = "vk-test";
+    process.env.VOYAGE_API_KEY = "vk-test-key-that-is-long-enough";
     const result = pickRemoteFallback();
     expect(result?.name).toBe("voyage");
   });
 
   test("returns OpenAI when only OPENAI_API_KEY is set", () => {
-    process.env.OPENAI_API_KEY = "sk-test";
+    process.env.OPENAI_API_KEY = "sk-test-key-that-is-long-enough";
     const result = pickRemoteFallback();
     expect(result?.name).toBe("openai");
   });
 
   test("Voyage wins when both keys are set", () => {
-    process.env.VOYAGE_API_KEY = "vk-test";
-    process.env.OPENAI_API_KEY = "sk-test";
+    process.env.VOYAGE_API_KEY = "vk-test-key-that-is-long-enough";
+    process.env.OPENAI_API_KEY = "sk-test-key-that-is-long-enough";
     const result = pickRemoteFallback();
     expect(result?.name).toBe("voyage");
   });
+
+  test("rejects placeholder API keys (e.g. 'nokey')", () => {
+    process.env.OPENAI_API_KEY = "nokey";
+    expect(pickRemoteFallback()).toBeNull();
+  });
 });
 
 describe("vectorSearch", () => {
diff --git a/packages/gateway/instrument.ts b/packages/gateway/instrument.ts
index eca0445..9567ff4 100644
--- a/packages/gateway/instrument.ts
+++ b/packages/gateway/instrument.ts
@@ -87,6 +87,15 @@ if (sentryEnabled && !Sentry.isInitialized()) {
     /LocalProviderUnavailableError/,
     /ECONNRESET\b/,
     /ECONNREFUSED\b/,
+    // Remote embedding fallback with invalid/placeholder API key
+    /Incorrect API key/i,
+    /onnxruntime/i,
+    /Cannot find package 'onnxruntime-node'/,
+    /LoadLibrary failed/,
+    /Protobuf parsing failed/,
+    // Bun doesn't implement getSystemErrorMap from node:util —
+    // this crashes the Sentry SDK itself during error processing
+    /getSystemErrorMap/,
   ];
 
   Sentry.init({