{
  "description": "To-do app event vectors: ensures todo fold handlers produce consistent state. Source of truth: web/static/apps/todo.js",
  "app": "todo",
  "source": "web/static/apps/todo.js",
  "state_shape": { "items": [{ "id": "string", "text": "string", "done": "boolean", "doneAt": "number (epoch ms)", "by": "string (sender name)" }] },
  "vectors": [
    {
      "name": "todo_add",
      "description": "Add a to-do item (checked off = false by default).",
      "event": {
        "type": "todo.add",
        "id": "todo-1",
        "text": "buy milk",
        "name": "Alice"
      },
      "expected_state_update": {
        "items": [
          {
            "id": "todo-1",
            "text": "buy milk",
            "done": false,
            "doneAt": 0,
            "by": "Alice"
          }
        ]
      },
      "expected_chat_projection": {
        "text": "added “buy milk”",
        "action": true
      },
      "expected_group_chat_projection": {
        "text": "added “buy milk” to the to-dos",
        "action": true
      }
    },
    {
      "name": "todo_done",
      "description": "Check off a to-do (mark as done with a timestamp for the grace period animation).",
      "event": {
        "type": "todo.done",
        "id": "todo-1",
        "ts": 1700000000000
      },
      "initial_state": {
        "items": [
          {
            "id": "todo-1",
            "text": "buy milk",
            "done": false,
            "doneAt": 0,
            "by": "Alice"
          }
        ]
      },
      "expected_state_update": {
        "items": [
          {
            "id": "todo-1",
            "text": "buy milk",
            "done": true,
            "doneAt": 1700000000000,
            "by": "Alice"
          }
        ]
      },
      "note": "doneAt drives the grace-period animation (the check fills immediately, the row stays visible ~750ms, then tucks into Completed — the Reminders-style completion flourish, no countdown ring). No chat projection for done/reopen/remove (only add shows as an action line)."
    },
    {
      "name": "todo_reopen",
      "description": "Uncheck a to-do (mark as not done, clear the doneAt timestamp).",
      "event": {
        "type": "todo.reopen",
        "id": "todo-1"
      },
      "initial_state": {
        "items": [
          {
            "id": "todo-1",
            "text": "buy milk",
            "done": true,
            "doneAt": 1700000000000,
            "by": "Alice"
          }
        ]
      },
      "expected_state_update": {
        "items": [
          {
            "id": "todo-1",
            "text": "buy milk",
            "done": false,
            "doneAt": 0,
            "by": "Alice"
          }
        ]
      }
    },
    {
      "name": "todo_remove",
      "description": "Delete a to-do item permanently.",
      "event": {
        "type": "todo.remove",
        "id": "todo-1"
      },
      "initial_state": {
        "items": [
          {
            "id": "todo-1",
            "text": "buy milk",
            "done": false,
            "doneAt": 0,
            "by": "Alice"
          },
          {
            "id": "todo-2",
            "text": "call mum",
            "done": false,
            "doneAt": 0,
            "by": "Alice"
          }
        ]
      },
      "expected_state_update": {
        "items": [
          {
            "id": "todo-2",
            "text": "call mum",
            "done": false,
            "doneAt": 0,
            "by": "Alice"
          }
        ]
      }
    },
    {
      "name": "todo_move_after",
      "description": "Reorder: move an item to immediately follow `after` in the array (drag-to-reorder).",
      "event": {
        "type": "todo.move",
        "id": "todo-1",
        "after": "todo-2"
      },
      "initial_state": {
        "items": [
          { "id": "todo-1", "text": "buy milk", "done": false, "doneAt": 0, "by": "Alice" },
          { "id": "todo-2", "text": "call mum", "done": false, "doneAt": 0, "by": "Alice" },
          { "id": "todo-3", "text": "water plants", "done": false, "doneAt": 0, "by": "Alice" }
        ]
      },
      "expected_state_update": {
        "items": [
          { "id": "todo-2", "text": "call mum", "done": false, "doneAt": 0, "by": "Alice" },
          { "id": "todo-1", "text": "buy milk", "done": false, "doneAt": 0, "by": "Alice" },
          { "id": "todo-3", "text": "water plants", "done": false, "doneAt": 0, "by": "Alice" }
        ]
      },
      "note": "No chat projection — reorders are silent, like done/remove. The list renders newest-first (_index desc), so 'after' anchors in ARRAY order: following todo-2 in the array displays ABOVE it."
    },
    {
      "name": "todo_move_to_start",
      "description": "Reorder: an empty `after` moves the item to the array's start (the visual bottom of a newest-first list).",
      "event": {
        "type": "todo.move",
        "id": "todo-3",
        "after": ""
      },
      "initial_state": {
        "items": [
          { "id": "todo-1", "text": "buy milk", "done": false, "doneAt": 0, "by": "Alice" },
          { "id": "todo-2", "text": "call mum", "done": false, "doneAt": 0, "by": "Alice" },
          { "id": "todo-3", "text": "water plants", "done": false, "doneAt": 0, "by": "Alice" }
        ]
      },
      "expected_state_update": {
        "items": [
          { "id": "todo-3", "text": "water plants", "done": false, "doneAt": 0, "by": "Alice" },
          { "id": "todo-1", "text": "buy milk", "done": false, "doneAt": 0, "by": "Alice" },
          { "id": "todo-2", "text": "call mum", "done": false, "doneAt": 0, "by": "Alice" }
        ]
      }
    },
    {
      "name": "todo_move_unknown_anchor",
      "description": "Reorder resilience: moving after an id that no longer exists (removed concurrently) is a no-op.",
      "event": {
        "type": "todo.move",
        "id": "todo-1",
        "after": "todo-gone"
      },
      "initial_state": {
        "items": [
          { "id": "todo-1", "text": "buy milk", "done": false, "doneAt": 0, "by": "Alice" },
          { "id": "todo-2", "text": "call mum", "done": false, "doneAt": 0, "by": "Alice" }
        ]
      },
      "expected_state_update": {
        "items": [
          { "id": "todo-1", "text": "buy milk", "done": false, "doneAt": 0, "by": "Alice" },
          { "id": "todo-2", "text": "call mum", "done": false, "doneAt": 0, "by": "Alice" }
        ]
      }
    },
    {
      "name": "todo_grace_period_partition",
      "description": "Grace period: active (not done or recently checked within 750ms) vs. archived (done + >750ms ago).",
      "note": "This is derived in render from Date.now() and doneAt, never by a timer mutating state. Native should implement the same partitioning logic: a done item with doneAt > (now - 750) stays in 'active', others move to 'Completed' section.",
      "constants": {
        "TODO_GRACE_MS": 750
      }
    }
  ]
}