After iter11 close, both Bug 4 (H.264 partial fill) and Bug 5 (HEVC
all-zero) share the same architectural pattern: libva control payloads
can be made byte-equivalent to kdirect for fields rkvdec consumes,
yet libva produces wrong output while kdirect succeeds.
Remaining unexamined surface = OUTPUT bitstream bytes (source_data
that the kernel reads). iter12 candidate α-16: extend γ infra to
dump source_data pre-QBUF, compare with kdirect.
If bytes match → both bugs are outside libva (kernel/HW state).
If bytes differ → narrow to bitstream-write divergence site.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
