Mirrors handle_double_click for the touch pipeline. A double-tap on a
face-up card fires MoveRequestEvent to the best legal destination using
the same priority order (foundation first, tableau second; stack move
as priority 2 when the tapped card is a stack base).
Implementation:
- handle_double_tap reads TouchPhase::Ended events. When
drag.active_touch_id is set and drag.committed is false, the touch
ended without crossing the drag threshold = pure tap. The top card ID
from drag.cards is used as the tracking key.
- DOUBLE_TAP_WINDOW = 0.5s (wider than DOUBLE_CLICK_WINDOW = 0.35s;
touch screens have higher input latency; pinned by a const-assert test).
- System is inserted between touch_follow_drag and touch_end_drag in
the .chain() so drag state is readable before touch_end_drag clears it.
- touch_end_drag's uncommitted-tap cleanup path still fires after
handle_double_tap — the drag.clear() + StateChangedEvent are
harmless in sequence with a MoveRequestEvent already queued.
1 new test (1283 total): double_tap_window_is_wider_than_double_click_window
(compile-time const assert).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
funman300
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