nx_flac_frame_gate.nx

nx_flac_frame_gate.nx -- proves FLAC frame + subframe decoding. T4/T5 assemble REAL frames byte by byte and decode them to samples: a 192-sample CONSTANT frame at 44.1kHz/16-bit mono, and a 3-sample VERBATIM frame using the deferred 8-bit block size. Both exercise the whole path -- sync, flag bytes, UTF-8 frame number, deferred fields, CRC-8, subframe header, sample extraction. T6 is the one that matters for long streams: the header LENGTH is variable (4 flag bytes + a 1-7 byte number + optional deferred block size and rate), and the CRC covers exactly those bytes. A parser with a hard-coded length works on every short file and breaks at frame 128, when the UTF-8 number grows to two bytes. T6 asserts hdrlen 6 for the simple frame and 7 for the deferred-blocksize one. NON-VACUITY: T8 covers refusals -- broken sync, a flipped CRC byte, and the reserved bit set must each be rejected. license_tier: ORIGINAL