feat(FN-3596): unify board/list task ordering, split TaskDetailModal test m

The merge introduces a major TaskDetailModal test refactor (splitting a 6.7K-line monolith into five focused suites), significant merger improvements including autostash race-rescue, deduplication, and advisory logging for destructive operations, a new TUI narrow-mode log-split feature for the dashb

Fusion-Task-Id: FN-3596

packages/core/src/__tests__/task-priority.test.ts

@@ -6,6 +6,8 @@ import {
   isTaskPriority,
   normalizeTaskPriority,
   sortTasksByPriorityThenAgeAndId,
+  compareTaskIdNumeric,
+  sortTasksForDisplayColumn,
 } from "../task-priority.js";
 import {
   DEFAULT_TASK_PRIORITY,
@@ -55,9 +57,42 @@ describe("task-priority", () => {
     expect(compareTasksByPriorityThenAgeAndId(tasks[0], tasks[1])).toBeGreaterThan(0);
   });
 
+  it("compares numeric IDs with locale fallback", () => {
+    expect(compareTaskIdNumeric("FN-2", "FN-10")).toBeLessThan(0);
+    expect(compareTaskIdNumeric("TASK-B", "TASK-A")).toBeGreaterThan(0);
+  });
+
+  it("applies board/list default ordering semantics by column", () => {
+    const base = {
+      createdAt: "2026-01-01T00:00:00.000Z",
+      updatedAt: "2026-01-01T00:00:00.000Z",
+      columnMovedAt: "2026-01-01T00:00:00.000Z",
+    };
+
+    const todoSorted = sortTasksForDisplayColumn([
+      { ...base, id: "FN-003", column: "todo", priority: "low" as TaskPriority, createdAt: "2026-01-01T00:00:00.000Z" },
+      { ...base, id: "FN-001", column: "todo", priority: "urgent" as TaskPriority, createdAt: "2026-01-02T00:00:00.000Z" },
+      { ...base, id: "FN-002", column: "todo", priority: "high" as TaskPriority, createdAt: "2026-01-01T12:00:00.000Z" },
+    ], "todo");
+    expect(todoSorted.map((task) => task.id)).toEqual(["FN-001", "FN-002", "FN-003"]);
+
+    const inReviewSorted = sortTasksForDisplayColumn([
+      { ...base, id: "FN-010", column: "in-review", status: "review-ready", priority: "urgent" as TaskPriority },
+      { ...base, id: "FN-011", column: "in-review", status: "merging-fix", priority: "high" as TaskPriority },
+    ], "in-review");
+    expect(inReviewSorted.map((task) => task.id)).toEqual(["FN-011", "FN-010"]);
+
+    const doneSorted = sortTasksForDisplayColumn([
+      { ...base, id: "FN-020", column: "done", priority: "urgent" as TaskPriority, columnMovedAt: "2026-01-01T08:00:00.000Z" },
+      { ...base, id: "FN-021", column: "done", priority: "low" as TaskPriority, columnMovedAt: "2026-01-01T09:00:00.000Z" },
+    ], "done");
+    expect(doneSorted.map((task) => task.id)).toEqual(["FN-021", "FN-020"]);
+  });
+
   it("re-exports priority helpers from the core index", () => {
     expect(core.TASK_PRIORITIES).toEqual(TASK_PRIORITIES);
     expect(core.DEFAULT_TASK_PRIORITY).toBe("normal");
     expect(core.normalizeTaskPriority("bogus")).toBe(DEFAULT_TASK_PRIORITY);
+    expect(typeof core.sortTasksForDisplayColumn).toBe("function");
   });
 });

packages/core/src/index.ts

@@ -309,8 +309,10 @@ export {
   compareTaskPriority,
   compareTasksByPriorityThenAgeAndId,
   sortTasksByPriorityThenAgeAndId,
+  compareTaskIdNumeric,
+  sortTasksForDisplayColumn,
 } from "./task-priority.js";
-export type { TaskPrioritySortable } from "./task-priority.js";
+export type { TaskPrioritySortable, TaskColumnSortable } from "./task-priority.js";
 export {
   mapFeatureToTaskHandoff,
   mapRoadmapToMissionHandoff,

packages/core/src/task-priority.ts

@@ -7,6 +7,13 @@ export interface TaskPrioritySortable {
   priority?: TaskPriority | null;
 }
 
+export interface TaskColumnSortable extends TaskPrioritySortable {
+  column: string;
+  status?: string | null;
+  columnMovedAt?: string;
+  updatedAt?: string;
+}
+
 const PRIORITY_RANK: Record<TaskPriority, number> = {
   low: 0,
   normal: 1,
@@ -40,7 +47,7 @@ export function compareTaskPriority(a: unknown, b: unknown): number {
   return getTaskPriorityRank(b) - getTaskPriorityRank(a);
 }
 
-function compareTaskId(a: string, b: string): number {
+export function compareTaskIdNumeric(a: string, b: string): number {
   const aNum = Number.parseInt(a.slice(a.lastIndexOf("-") + 1), 10);
   const bNum = Number.parseInt(b.slice(b.lastIndexOf("-") + 1), 10);
 
@@ -65,7 +72,7 @@ export function compareTasksByPriorityThenAgeAndId<T extends TaskPrioritySortabl
     return a.createdAt.localeCompare(b.createdAt);
   }
 
-  return compareTaskId(a.id, b.id);
+  return compareTaskIdNumeric(a.id, b.id);
 }
 
 /**
@@ -76,3 +83,47 @@ export function sortTasksByPriorityThenAgeAndId<T extends TaskPrioritySortable>(
 ): T[] {
   return [...tasks].sort(compareTasksByPriorityThenAgeAndId);
 }
+
+function getDoneSortTimestamp(task: TaskColumnSortable): number {
+  const timestamp = task.columnMovedAt ?? task.updatedAt ?? task.createdAt;
+  const parsed = Date.parse(timestamp);
+  return Number.isFinite(parsed) ? parsed : 0;
+}
+
+function isMergeActiveStatus(status: string | null | undefined): boolean {
+  return status === "merging" || status === "merging-pr" || status === "merging-fix";
+}
+
+/**
+ * Column-aware default ordering shared by board and list surfaces.
+ */
+export function sortTasksForDisplayColumn<T extends TaskColumnSortable>(tasks: readonly T[], column: string): T[] {
+  if (column === "todo") {
+    return sortTasksByPriorityThenAgeAndId(tasks);
+  }
+
+  return [...tasks].sort((a, b) => {
+    if (column === "done") {
+      const timestampCmp = getDoneSortTimestamp(b) - getDoneSortTimestamp(a);
+      if (timestampCmp !== 0) {
+        return timestampCmp;
+      }
+      return compareTaskIdNumeric(a.id, b.id);
+    }
+
+    if (column === "in-review") {
+      const aIsMerging = isMergeActiveStatus(a.status);
+      const bIsMerging = isMergeActiveStatus(b.status);
+      if (aIsMerging !== bIsMerging) {
+        return aIsMerging ? -1 : 1;
+      }
+    }
+
+    const priorityCmp = compareTaskPriority(a.priority, b.priority);
+    if (priorityCmp !== 0) {
+      return priorityCmp;
+    }
+
+    return compareTaskIdNumeric(a.id, b.id);
+  });
+}