## MODIFIED Requirements

### Requirement: Runtime task evidence retains UI-tree inspection results

The Runtime SHALL retain, for each step, the UI-tree elements present in
that step's fused `Scene` (the elements produced by
`perception/scene_builder.py::build_scene()` with `source == "ui"`) as a
`ui_tree_results` list on the Timeline record. The Host Agent task-detail
UI SHALL render those elements in a structured, collapsible view. The
Runtime SHALL NOT require a dedicated UI-tree tool call to capture this
data, and SHALL NOT change the tool response contract or duplicate the
result in a separate persistence field.

#### Scenario: A step's scene contains UI-tree elements

- **WHEN** a task step's planning `Scene` contains one or more elements
  with `source == "ui"`
- **THEN** the Timeline record's `ui_tree_results` includes each such
  element's type, visible text or identifier, bounds, and available
  confidence, and the Host Agent task-detail page displays them

#### Scenario: A step's scene has no UI-tree elements

- **WHEN** a task step's planning `Scene` contains no elements with
  `source == "ui"` (e.g. UI-tree parsing failed and degraded to an empty
  list)
- **THEN** the Timeline record's `ui_tree_results` is an empty list and the
  Host Agent task-detail page does not render an empty UI-tree section

#### Scenario: A legacy Timeline record has no `ui_tree_results` field

- **WHEN** a Timeline record was persisted before this field existed
- **THEN** the Runtime exposes it as an empty `ui_tree_results` list
  without failing to render the record