[Init] Initial commit - NetMesh terminal manager

domain/sftpTransferSkip.ts

@@ -0,0 +1,47 @@
+/**
+ * rsync-style "generator" skip: when size and mtime already match the target,
+ * the file does not need to be transferred again.
+ *
+ * SFTP mtimes are typically second-precision; compare on whole seconds so a
+ * local millisecond timestamp does not defeat an otherwise identical remote.
+ */
+
+export type TransferMtimeUnit = "ms" | "s";
+
+export interface TransferSkipIdentity {
+  size: number;
+  lastModified: number;
+  /**
+   * Preferred: adapters declare the unit. Local fs and Netcatty SFTP stats use
+   * milliseconds (`Date` / `mtime * 1000`). Raw ssh2 attrs use seconds.
+   * When omitted, a magnitude heuristic is used only as a legacy fallback.
+   */
+  mtimeUnit?: TransferMtimeUnit;
+}
+
+export function normalizeTransferMtimeSeconds(
+  lastModified: number,
+  mtimeUnit?: TransferMtimeUnit,
+): number {
+  if (!Number.isFinite(lastModified) || lastModified <= 0) return 0;
+  if (mtimeUnit === "ms") return Math.floor(lastModified / 1000);
+  if (mtimeUnit === "s") return Math.floor(lastModified);
+  // Legacy heuristic: magnitudes at/above 1e10 (~year 2286 as seconds) are ms.
+  // Prefer passing mtimeUnit from adapters so early-1970 ms values are exact.
+  return lastModified >= 1e10 ? Math.floor(lastModified / 1000) : Math.floor(lastModified);
+}
+
+export function isUnchangedTransferCandidate(
+  source: TransferSkipIdentity,
+  target: TransferSkipIdentity,
+): boolean {
+  const sourceSize = Number(source.size);
+  const targetSize = Number(target.size);
+  if (!Number.isFinite(sourceSize) || !Number.isFinite(targetSize)) return false;
+  if (sourceSize !== targetSize) return false;
+  if (sourceSize < 0 || targetSize < 0) return false;
+  const sourceMtime = normalizeTransferMtimeSeconds(source.lastModified, source.mtimeUnit);
+  const targetMtime = normalizeTransferMtimeSeconds(target.lastModified, target.mtimeUnit);
+  if (sourceMtime <= 0 || targetMtime <= 0) return false;
+  return sourceMtime === targetMtime;
+}