fix(api): make task updates transactional

src/main/database/task-status-rules.ts

@@ -0,0 +1,60 @@
+export const VALID_TASK_STATUSES = new Set([
+  "backlog",
+  "todo",
+  "in_progress",
+  "in_review",
+  "done",
+  "blocked",
+  "cancelled",
+]);
+
+const STATUSES_THAT_CLEAR_LEASE = new Set<string>([
+  "done",
+  "cancelled",
+  "blocked",
+  "todo",
+  "backlog",
+]);
+
+export function assertValidTaskStatus(status: string): void {
+  if (!VALID_TASK_STATUSES.has(status)) {
+    throw new Error(`Invalid task status: ${status}`);
+  }
+}
+
+export function buildTaskStatusTransition(
+  newStatus: string,
+  timestamp: string,
+): { sets: string[]; values: (string | null)[]; clearsLease: boolean } {
+  const sets: string[] = ["status = ?", "updated_at = ?"];
+  const values: (string | null)[] = [newStatus, timestamp];
+
+  if (newStatus === "in_progress") {
+    sets.push("started_at = COALESCE(started_at, ?)");
+    values.push(timestamp);
+  }
+  if (newStatus === "done") {
+    sets.push("completed_at = ?");
+    values.push(timestamp);
+  } else {
+    sets.push("completed_at = NULL");
+  }
+  if (newStatus === "cancelled") {
+    sets.push("cancelled_at = ?");
+    values.push(timestamp);
+  } else {
+    sets.push("cancelled_at = NULL");
+  }
+  if (newStatus !== "in_progress") {
+    sets.push("checkout_run_id = NULL");
+  }
+  if (newStatus === "todo" || newStatus === "backlog") {
+    sets.push("active_run_id = NULL");
+  }
+
+  return {
+    sets,
+    values,
+    clearsLease: STATUSES_THAT_CLEAR_LEASE.has(newStatus),
+  };
+}