Host-agent console showed OCR/UI-tree overlay boxes misaligned with the
displayed screenshot. Two independent causes, both confirmed with real
task data and pixel-level measurement of a user-provided screenshot:
1. perception/ui_parser.py parses XCUITest UI-tree bounds as iOS logical
points, while scene_builder.py's Scene.width/height (via infer_png_size)
and OCR bounds are in screenshot pixels, never reconciled (2.0x on
Retina devices). build_scene() now detects the scale from the first
x==0,y==0 UI element and rescales OCR bounds down to points-space,
reporting Scene.width/height in points too. No-op for Android, where
UiAutomator2 bounds already match pixels 1:1. This also fixes tap()
landing at the wrong location for OCR-matched text, and lets the IOU
fusion between UI-tree and OCR elements actually fire on iOS.
2. runtime/task.py captured `scene` (OCR/UI-tree data) before the LLM
planning call, but re-captured `before_screenshot` for each step
afterward - a real time gap during which on-screen content (e.g. a
keyboard) could shift, producing a directional drift between the
overlay and the displayed image. The first step of each plan batch
now reuses the screenshot already taken for planning instead of
capturing a new one; later steps in a multi-step batch still take a
fresh capture (left unresolved, scoped out by request).
Regression tests added for both the scale reconciliation (using real
828x1792 vs 414x896 numbers) and the screenshot reuse behavior.