[Init] Initial commit - NetMesh terminal manager

application/state/sftp/transferRetry.ts

@@ -0,0 +1,68 @@
+import { isSessionError } from "./errors";
+
+/**
+ * Errors that are worth an automatic one-shot retry (WinSCP/FileZilla-style
+ * "network blip" recovery). Permanent failures (auth, permission, missing
+ * path) should not be retried.
+ */
+export function isTransientTransferError(err: unknown): boolean {
+  if (isSessionError(err)) return true;
+  if (!(err instanceof Error)) return false;
+  const msg = err.message.toLowerCase();
+  return (
+    msg.includes("econnreset")
+    || msg.includes("etimedout")
+    || msg.includes("econnrefused")
+    || msg.includes("epipe")
+    || msg.includes("socket hang up")
+    || msg.includes("network")
+    || msg.includes("temporarily unavailable")
+    || msg.includes("try again")
+    || msg.includes("broken pipe")
+  );
+}
+
+export function isTransferCancelledError(err: unknown): boolean {
+  if (!(err instanceof Error)) return false;
+  const msg = err.message.toLowerCase();
+  return msg.includes("transfer cancelled") || msg.includes("transfer canceled");
+}
+
+export interface RunWithTransferRetryOptions {
+  retries?: number;
+  delayMs?: number;
+  shouldRetry?: (err: unknown, attempt: number) => boolean;
+  onRetry?: (err: unknown, attempt: number) => void;
+}
+
+/**
+ * Run an async transfer step with a small number of automatic retries for
+ * transient network / session failures.
+ */
+export async function runWithTransferRetry<T>(
+  work: (attempt: number) => Promise<T>,
+  options: RunWithTransferRetryOptions = {},
+): Promise<T> {
+  const retries = Math.max(0, options.retries ?? 1);
+  const delayMs = Math.max(0, options.delayMs ?? 400);
+  const shouldRetry = options.shouldRetry ?? ((err, attempt) => (
+    attempt < retries
+    && !isTransferCancelledError(err)
+    && isTransientTransferError(err)
+  ));
+
+  let lastError: unknown;
+  for (let attempt = 0; attempt <= retries; attempt += 1) {
+    try {
+      return await work(attempt);
+    } catch (err) {
+      lastError = err;
+      if (!shouldRetry(err, attempt)) throw err;
+      options.onRetry?.(err, attempt + 1);
+      if (delayMs > 0) {
+        await new Promise((resolve) => setTimeout(resolve, delayMs * (attempt + 1)));
+      }
+    }
+  }
+  throw lastError;
+}