A track recognised on 318 of 385 frames was owned on none, so the truth file
named nobody while the matcher was accepting almost continuously.
The correlation discount was an annihilator rather than an attenuator. Weight
was 1 - P(same view), so once a track had one stored view every later frame of
that same face scored ~0.01 and the belief stopped moving. One observation just
over the accept threshold is logit(0.78) ~ 1.27, under the ownership bar — hence
recognised always, owned never.
Two changes, in the order they were found.
Correlated evidence is now attenuated by effective sample size,
n_eff = n / (1 + (n-1)·rho), each frame contributing the marginal gain. That has
the right shape at both ends: uncorrelated evidence accumulates linearly, and a
held pose converges on 1/rho rather than growing without bound. A constant floor
was tried first and rejected — it grows linearly forever, so a long shot could
out-argue genuinely varied evidence purely by lasting longer.
Combination is now weighted lazy-OR: P = 1 - (1-P_old)·(1-p)^w, stored as
log(1-P) so the update is additive and precision stays where it matters as P
approaches 1. Each frame is new evidence that this track is that actor, and the
belief is the probability that at least one sighting was right. It converges
faster than summing log-odds at the same effective count — 2.98 vs 2.53 after
two observations at p=0.78 — which is what a real clip needs.
Note that summing log-odds was already a correct sequential Bayesian update:
the matcher fits with prior 0.5, so logit(p) IS the per-frame log-likelihood
ratio and the running sum carries the prior forward. It was not wrong, it was
slow. What blocked ownership was the discount, not the combination rule.
Also fixes a real correctness bug: the observation count lived on the
discounter, which is shared by every track, so tracks pooled into one effective
sample and each was discounted by how many others happened to be on screen. It
is now a per-track parameter.
The registry's frame scope holds its lock for its lifetime and the mutex is not
recursive, so calling observe() inside a scope self-deadlocks. The pipeline
never does — separate nodes — but the test did, and hung rather than failing.
Documented at the call site.
Verified end to end: the same clip that produced zero actors now identifies
Bing Crosby and Dorothy Lamour with belief 0.97.
Suite: 96 cases, 6142 assertions.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
TRACES: AR-025 | SR-002
Moves two responsibilities inside the registry that callers should never have
been trusted with.
AR-025 — per-frame evidence is discounted for correlation by the registry
itself, via EvidenceDiscounter. Log-odds accumulation is only valid for
independent observations, and consecutive frames of one track are anything but:
near-identical pose, lighting and expression. Accumulated naively, thirty frames
of the same face at the same angle drive the posterior to certainty on what is
effectively one measurement.
Each observation is weighted by how much it adds — a view already contributed
counts for ~nothing, a genuinely new pose counts in full. This reuses the
novelty judgement gallery expansion already makes rather than inventing a second
one. The discounter is a separate class the registry holds, so it stays testable
and swappable, but it is a constructor argument rather than an option: there is
no correct way to accumulate without it.
AR-024 — observe() takes a calibrated probability and converts to log-odds
internally. A caller can no longer hand it a raw cosine, which would have been
silently wrong rather than obviously so. Retiring the remaining raw-cosine
constants in the tracker is still open.
DeadTrack now reports effective_obs alongside observations: the raw count and
the evidence that actually counted. A large gap between them is a track the
camera stared at, and worth seeing.
Three tests, one of which is the point: two tracks given the same number of
observations at the same posterior, one repeating a single view and one seeing
eight distinct ones, must not end up equally confident. Without discounting they
would be identical.
Fixed a test that asserted a belief swap on tied evidence. A tie leaves
ownership where it is — a challenger must out-accumulate the incumbent, since
one contrary observation is noise. The original test passed only because it fed
raw log-odds directly.
Suite: 78 cases, 3245 assertions. Coverage 20/63 to 22/63.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
TRACES: AR-024, AR-025 | SR-002
dtourolleandClaude Opus 5