Two iterations ago verify-menu-audio's bit-identity assertion began failing and I
filed three suspects in the port. It is none of them. Three IDENTICAL invocations
give two outcomes, 1.207438 s and 1.300317 s, differing by exactly 4096 samples --
one mixing buffer. The recording quantises to whole buffers and a one-buffer shift
moves the length and alignment of everything in it.
The premise -- cross-run bit-determinism -- was never guaranteed. It held while
timing sat away from a buffer boundary, and a larger export moved it onto one. A
test that passes by luck reports the luck running out as a regression in the code,
which is what it did: two iterations of suspects, and the port was never involved.
The fix keeps exact equality and no threshold, allowing the comparison to slide by
whole buffers -- the one degree of freedom the recorder has. Proved it can still
fail: ctrl against walk differs at every alignment.
Distinct from the earlier entries: this check ran and answered the right question,
resting on a property of the environment nothing verified. State what an assertion
assumes about the machine, not only what it checks.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N7FiFFFwbvG2uxdcEh8HyF
81319ea20e