diff --git a/src/lib/error-capture.ts b/src/lib/error-capture.ts
new file mode 100644
index 0000000..171c9b5
--- /dev/null
+++ b/src/lib/error-capture.ts
@@ -0,0 +1,27 @@
+// Captures the original Error out-of-band so server.ts can recover the stack
+// when h3 has already swallowed the throw into a generic 500 Response.
+
+let lastCapturedError: { error: unknown; at: number } | undefined;
+const TTL_MS = 5_000;
+
+function record(error: unknown) {
+  lastCapturedError = { error, at: Date.now() };
+}
+
+if (typeof globalThis.addEventListener === "function") {
+  globalThis.addEventListener("error", (event) => record((event as ErrorEvent).error ?? event));
+  globalThis.addEventListener("unhandledrejection", (event) =>
+    record((event as PromiseRejectionEvent).reason),
+  );
+}
+
+export function consumeLastCapturedError(): unknown {
+  if (!lastCapturedError) return undefined;
+  if (Date.now() - lastCapturedError.at > TTL_MS) {
+    lastCapturedError = undefined;
+    return undefined;
+  }
+  const { error } = lastCapturedError;
+  lastCapturedError = undefined;
+  return error;
+}