fix(connection): handle stale connection state

src/lib/connectionHealth.ts

@@ -0,0 +1,25 @@
+const CONNECTION_ERROR_PATTERNS = [
+  "connection",
+  "broken pipe",
+  "reset by peer",
+  "timed out",
+  "closed",
+  "eof",
+  "i/o error",
+];
+
+export function staleConnectionMessage(error: unknown): string {
+  if (error instanceof Error) return error.message;
+  return String(error);
+}
+
+export function shouldMarkDisconnected(error: unknown): boolean {
+  const message = staleConnectionMessage(error).toLowerCase();
+  return CONNECTION_ERROR_PATTERNS.some((pattern) => message.includes(pattern)) || hasConnectionOsError(message);
+}
+
+function hasConnectionOsError(message: string): boolean {
+  const osErrorCodes = new Set(["10053", "10054", "10057", "10058", "10060", "10061"]);
+  const match = message.match(/os error\s+(\d+)/);
+  return !!match && osErrorCodes.has(match[1]);
+}