Function groupTasks

packages/shared-domain/src/tasks.ts:283–341

(tasks: VaultTask[], today: Date)

 *  the user's timezone is respected. Waiting overrides everything except Done.
 *  Tasks without a due date land in Today. */
export function groupTasks(tasks: VaultTask[], today: Date): VaultTaskGroups {
  const todayIso = toIsoDate(today)
  const today_: VaultTask[] = []
  const upcoming: VaultTask[] = []
  const waiting: VaultTask[] = []
  const done: VaultTask[] = []
  let overdueCount = 0

  for (const task of tasks) {
    if (task.checked) {
      done.push(task)
      continue
    }
    if (task.waiting) {
      waiting.push(task)
      continue
    }
    if (!task.due) {
      today_.push(task)
      continue
    }
    if (task.due < todayIso) {
      today_.push(task)
      overdueCount += 1
      continue
    }
    if (task.due === todayIso) {
      today_.push(task)
      continue
    }
    upcoming.push(task)
  }

  // Sort each bucket for stable, useful ordering.
  const byDueThenPath = (a: VaultTask, b: VaultTask): number => {
    const ad = a.due ?? '9999-99-99'
    const bd = b.due ?? '9999-99-99'
    if (ad !== bd) return ad < bd ? -1 : 1
    if (a.sourcePath !== b.sourcePath) return a.sourcePath < b.sourcePath ? -1 : 1
    return a.taskIndex - b.taskIndex
  }
  const priorityRank: Record<TaskPriority, number> = { high: 0, med: 1, low: 2 }
  const byPriorityThenDue = (a: VaultTask, b: VaultTask): number => {
    const ap = a.priority ? priorityRank[a.priority] : 3
    const bp = b.priority ? priorityRank[b.priority] : 3
    if (ap !== bp) return ap - bp
    return byDueThenPath(a, b)
  }

  today_.sort(byPriorityThenDue)
  upcoming.sort(byDueThenPath)
  waiting.sort(byPriorityThenDue)
  done.sort((a, b) => {
    if (a.sourcePath !== b.sourcePath) return a.sourcePath < b.sourcePath ? -1 : 1
    return a.taskIndex - b.taskIndex
  })

  return { today: today_, upcoming, waiting, done, overdueCount }