refactor(tasks): extract delivery policy (#57475)

* refactor(tasks): add executor facade

* refactor(tasks): extract delivery policy

src/tasks/task-executor-policy.ts

@@ -0,0 +1,110 @@
+import type { TaskEventRecord, TaskRecord, TaskStatus } from "./task-registry.types.js";
+
+export function isTerminalTaskStatus(status: TaskStatus): boolean {
+  return (
+    status === "succeeded" ||
+    status === "failed" ||
+    status === "timed_out" ||
+    status === "cancelled" ||
+    status === "lost"
+  );
+}
+
+function resolveTaskDisplayTitle(task: TaskRecord): string {
+  return (
+    task.label?.trim() ||
+    (task.runtime === "acp"
+      ? "ACP background task"
+      : task.runtime === "subagent"
+        ? "Subagent task"
+        : task.task.trim() || "Background task")
+  );
+}
+
+function resolveTaskRunLabel(task: TaskRecord): string {
+  return task.runId ? ` (run ${task.runId.slice(0, 8)})` : "";
+}
+
+export function formatTaskTerminalMessage(task: TaskRecord): string {
+  const title = resolveTaskDisplayTitle(task);
+  const runLabel = resolveTaskRunLabel(task);
+  const summary = task.terminalSummary?.trim();
+  if (task.status === "succeeded") {
+    if (task.terminalOutcome === "blocked") {
+      return summary
+        ? `Background task blocked: ${title}${runLabel}. ${summary}`
+        : `Background task blocked: ${title}${runLabel}.`;
+    }
+    return summary
+      ? `Background task done: ${title}${runLabel}. ${summary}`
+      : `Background task done: ${title}${runLabel}.`;
+  }
+  if (task.status === "timed_out") {
+    return `Background task timed out: ${title}${runLabel}.`;
+  }
+  if (task.status === "lost") {
+    return `Background task lost: ${title}${runLabel}. ${task.error ?? "Backing session disappeared."}`;
+  }
+  if (task.status === "cancelled") {
+    return `Background task cancelled: ${title}${runLabel}.`;
+  }
+  const error = task.error?.trim();
+  return error
+    ? `Background task failed: ${title}${runLabel}. ${error}`
+    : `Background task failed: ${title}${runLabel}.`;
+}
+
+export function formatTaskBlockedFollowupMessage(task: TaskRecord): string | null {
+  if (task.status !== "succeeded" || task.terminalOutcome !== "blocked") {
+    return null;
+  }
+  const title = resolveTaskDisplayTitle(task);
+  const runLabel = resolveTaskRunLabel(task);
+  const summary = task.terminalSummary?.trim() || "Task is blocked and needs follow-up.";
+  return `Task needs follow-up: ${title}${runLabel}. ${summary}`;
+}
+
+export function formatTaskStateChangeMessage(
+  task: TaskRecord,
+  event: TaskEventRecord,
+): string | null {
+  const title = resolveTaskDisplayTitle(task);
+  if (event.kind === "running") {
+    return `Background task started: ${title}.`;
+  }
+  if (event.kind === "progress") {
+    return event.summary ? `Background task update: ${title}. ${event.summary}` : null;
+  }
+  return null;
+}
+
+export function shouldAutoDeliverTaskTerminalUpdate(task: TaskRecord): boolean {
+  if (task.notifyPolicy === "silent") {
+    return false;
+  }
+  if (task.runtime === "subagent" && task.status !== "cancelled") {
+    return false;
+  }
+  if (!isTerminalTaskStatus(task.status)) {
+    return false;
+  }
+  return task.deliveryStatus === "pending";
+}
+
+export function shouldAutoDeliverTaskStateChange(task: TaskRecord): boolean {
+  return (
+    task.notifyPolicy === "state_changes" &&
+    task.deliveryStatus === "pending" &&
+    !isTerminalTaskStatus(task.status)
+  );
+}
+
+export function shouldSuppressDuplicateTerminalDelivery(params: {
+  task: TaskRecord;
+  preferredTaskId?: string;
+}): boolean {
+  if (params.task.runtime !== "acp" || !params.task.runId?.trim()) {
+    return false;
+  }
+  return Boolean(params.preferredTaskId && params.preferredTaskId !== params.task.taskId);
+}