An isolated real-XAML/native drawing probe for #853 reproduced drawn ROI scopes remaining in "Preparing" despite successful native computation. The UI compared ROI doubles exactly, while native/src/rpc/Json.cpp uses the default six-significant-digit numeric formatter. Pointer coordinates such as 0.19999998807907104 and widths such as 0.2250000201165676 return as 0.2 and 0.225, rejecting a valid current-revision result.
Preview requests also replace the pending shared handle with a zero-size waiting handle. RefreshRoi then cleared the guide source dimensions during a gesture, preventing subsequent pointer updates until another native frame arrived.
Fix within #853: measurement matching tolerates at most 0.0000005 normalized-coordinate formatting error while requiring exact shape and selection revision; retain the last positive source geometry during pending measurements. Stored numeric values remain unchanged. No changes to Program scheduling, source grade, sampling resolution, or production outputs.
Acceptance: arbitrary drawn-coordinate measurement reaches the real XAML scopes; multiple consecutive pointer updates reach the requested endpoint; cancellation restores the previous ROI; older selection revisions and different shapes remain rejected. Geometry/protocol tests and the isolated native UI probe cover these paths. This is an ROI interaction defect, not evidence of the root cause of production delivery misses.
An isolated real-XAML/native drawing probe for #853 reproduced drawn ROI scopes remaining in "Preparing" despite successful native computation. The UI compared ROI doubles exactly, while native/src/rpc/Json.cpp uses the default six-significant-digit numeric formatter. Pointer coordinates such as 0.19999998807907104 and widths such as 0.2250000201165676 return as 0.2 and 0.225, rejecting a valid current-revision result.
Preview requests also replace the pending shared handle with a zero-size waiting handle. RefreshRoi then cleared the guide source dimensions during a gesture, preventing subsequent pointer updates until another native frame arrived.
Fix within #853: measurement matching tolerates at most 0.0000005 normalized-coordinate formatting error while requiring exact shape and selection revision; retain the last positive source geometry during pending measurements. Stored numeric values remain unchanged. No changes to Program scheduling, source grade, sampling resolution, or production outputs.
Acceptance: arbitrary drawn-coordinate measurement reaches the real XAML scopes; multiple consecutive pointer updates reach the requested endpoint; cancellation restores the previous ROI; older selection revisions and different shapes remain rejected. Geometry/protocol tests and the isolated native UI probe cover these paths. This is an ROI interaction defect, not evidence of the root cause of production delivery misses.