The prepush guard blocked any push whose added lines exceeded the engine's
1 MiB cap with engine.input_too_large — a size error naming no credential —
which trains people onto GSTACK_REDACT_PREPUSH=skip. Scan in 768 KiB
line-aligned slices instead (no pattern is multi-line, so a boundary cannot
bisect a secret); a single oversized line still goes to the engine intact and
fails closed. Also suppress card/phone matches whose span sits ENTIRELY
inside a UUID — digit-only UUID fixtures were 14 of 21 MEDIUM findings on an
ordinary branch, the noise level that stops people reading MEDIUM at all.
Fixes#2304.
Contributed by @luckywenapere (PR #2543).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>