First on-glass closed-loop run (NP3 ↔ .173, canary 0.23.10498) proved the
transport and both endpoints work — and exposed the controller chasing a
statistic that cannot respond: under period-spanning arrival jitter the
client's latch DISTRIBUTION is ~uniform mod the refresh, so shifting its
mean (the hold — provably reaching the client: the paced-drop bursts locked
to each wrap) cannot move its MEDIAN. The controller stepped +2 ms/s in one
direction forever, wrapping the period every ~4 s, and every wrap coalesced
~30 frames at the client — a periodic hiccup that must not ship.
The controller now remembers its last error: three consecutive steps that
fail to move it ≥1.5 ms freeze the hold (kept, not zeroed) and log; a later
report whose error moved re-arms stepping — a tight-jitter regime still
locks exactly as designed. Controller v2 (a circular phase statistic with a
coherence gate, per the design doc's follow-ups) replaces the median
outright; this freeze stays as its safety net.
Gate: docker amd64 clippy --all-targets -D warnings (host, nvenc) clean.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehlerandClaude Fable 5
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