Harden architecture hot paths

packages/engine/src/mission-feature-sync.ts

@@ -0,0 +1,64 @@
+import type { MissionFeature, Task, TaskStore } from "@fusion/core";
+import { getTaskCompletionBlockerForStore } from "./task-completion.js";
+
+export type MissionFeatureSyncTargetStatus = "done" | "in-progress" | "triaged";
+
+export type MissionFeatureSyncDecision =
+  | { kind: "failure"; reason: string }
+  | { kind: "blocked"; reason: string }
+  | { kind: "update"; status: MissionFeatureSyncTargetStatus; reason: string }
+  | { kind: "noop" };
+
+export async function reconcileMissionFeatureState(
+  taskStore: Pick<TaskStore, "getTask">,
+  task: Task,
+  feature: Pick<MissionFeature, "id" | "status">,
+): Promise<MissionFeatureSyncDecision> {
+  if (task.status === "failed" && feature.status === "in-progress") {
+    return {
+      kind: "failure",
+      reason: `task ${task.id} failed while feature ${feature.id} is in-progress`,
+    };
+  }
+
+  if (task.column === "done") {
+    const blocker = await getTaskCompletionBlockerForStore(taskStore, task);
+    if (blocker) {
+      return { kind: "blocked", reason: blocker };
+    }
+
+    if (feature.status !== "done") {
+      return {
+        kind: "update",
+        status: "done",
+        reason: `task ${task.id} completed`,
+      };
+    }
+
+    return { kind: "noop" };
+  }
+
+  if (
+    task.column === "in-progress"
+    && (feature.status === "triaged" || feature.status === "defined")
+  ) {
+    return {
+      kind: "update",
+      status: "in-progress",
+      reason: `task ${task.id} started`,
+    };
+  }
+
+  if (
+    (task.column === "triage" || task.column === "todo")
+    && feature.status === "in-progress"
+  ) {
+    return {
+      kind: "update",
+      status: "triaged",
+      reason: `task ${task.id} returned to triage`,
+    };
+  }
+
+  return { kind: "noop" };
+}