The user's ask: if the translation-table fix did not quite catch it, will the
next playtest LOG the artifact? Before this commit, no -- BT_PLANE_AUDIT was
opt-in via env var, and playtest machines set none.
Changes (all engine L4VB16):
* BT_PLANE_AUDIT is now DEFAULT-ON, =0 opts out. Armed cost is a couple of
integer compares per DRAW CALL (not per pixel); confirmed zero log noise
on a clean default-env run post-fix.
* A SECOND trap class: out-of-bounds draw STARTS, checked always-on in
buildDestPointer (the funnel every primitive builds its pointer through).
Release builds compile Verify() to nothing, so a wild start previously
computed a silent rogue pointer into (or past) the shared buffer. Now
logged ([plane] OOB) and CLAMPED in-bounds.
* First detection of each class writes a GLITCH matchlog record
(kind=plane / kind=oob with position+color+mask), so the evidence arrives
with the round logs the operator already collects -- unattended.
* Both existing plane-leak trap levels (display primitives + the port-level
pixmap table scan) flipped to the same default-on gate.
Honest coverage note (in gauges-hud.md): an in-buffer EXTENT overrun from a
valid start (a blit walking past the right/bottom edge into later rows of the
SAME plane) is not trapped -- per-pixel walk checks are too hot. The plane
trap still catches any such overrun whose color leaks planes, which is the
class the night-3 artifacts belonged to.
Verified: full clean rebuild -- 40 pre-existing LNK2019 only (the
engine->game BTMatchLog linkage resolved, /FORCE-trap checked); default-env
probe run: 0 [plane] lines, game unaffected.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
