vt: clamp stale scroll margins to screen bounds#908
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July 5, 2026 07:50
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Summary
Clamp horizontal and vertical scroll margins to the current screen bounds when they are stored on
Screen.Why
A terminal app can emit
DECSTBMorDECSLRMusing a stale size while a resize is racing through the PTY. Without clamping,Screen.scrollcan retain an out-of-bounds bottom/right edge, and a later reverse-index / scroll operation can driveInsertLineAreapast the buffer bounds.Changes
setHorizontalMarginsto[0,width]setVerticalMarginsto[0,height]left >= right/top >= bottombehaviorDECSTBM, staleDECSLRM, and the reverse-index crash pathTest
go test ./...invt/