[Init] Initial commit - NetMesh terminal manager

application/state/sftp/transferControlEpoch.ts

@@ -0,0 +1,43 @@
+/**
+ * Monotonic control epoch per transfer id.
+ *
+ * Pause soft-drain / watchdogs capture an epoch when they start. Resume (or a
+ * newer pause) bumps the epoch so every in-flight soft-drain becomes a no-op
+ * instead of racing the live stream. Process-global so it survives panel unmount.
+ */
+
+const epochs = new Map<string, number>();
+// A scalar generation prevents ABA when a settled task id is reused. It does
+// not retain task ids, while making every new control round process-unique.
+let nextEpoch = 0;
+
+export function getTransferControlEpoch(taskId: string): number {
+  return epochs.get(taskId) ?? 0;
+}
+
+/** Bump and return the new epoch. Call on intentional Pause and Resume. */
+export function bumpTransferControlEpoch(taskId: string): number {
+  const next = nextEpoch + 1;
+  nextEpoch = next;
+  epochs.set(taskId, next);
+  return next;
+}
+
+export function isTransferControlEpochCurrent(taskId: string, epoch: number): boolean {
+  return epochs.get(taskId) === epoch;
+}
+
+/** Release control epochs after the transfer tree has fully settled. */
+export function settleTransferControlEpochTree(
+  rootTaskId: string,
+  childIds: readonly string[] = [],
+): void {
+  epochs.delete(rootTaskId);
+  for (const childId of childIds) epochs.delete(childId);
+}
+
+/** Test helper. */
+export function resetTransferControlEpochsForTests(): void {
+  epochs.clear();
+  nextEpoch = 0;
+}