Two accessors answered a question about a key the history had never seen
with a well-formed value indistinguishable from a real answer.
`log_evidence_for` filter_map'd unknown keys away. An empty target list
means "no restriction" downstream, so a list of *entirely* unknown keys
returned the whole-history evidence: measured on a two-cohort fixture,
`log_evidence_for(["typo"])` returned exactly `log_evidence()`. On the
one workload it is documented for — leave-one-out cross-validation —
that is the un-held-out score, a plausible number that silently
invalidates the comparison it was computed for. It now returns
`Err(UnknownKey)` naming the offending position.
`learning_curve` and `filtered_learning_curve` returned an empty `Vec`
both for a typo'd key and for a competitor who is registered but has not
played yet. They now return `Option`, so `None` is "never heard of it"
and `Some(vec![])` is "known, no appearances".
Tests carry a control case in each direction, so they cannot pass by
everything returning the same thing.
Closes#66, closes#70.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
`gamma` enters only as `gamma * gamma`, so the sign was squared away:
measured against the old public-field form, `ConstantDrift(-0.0833)`
produced results bit identical to `ConstantDrift(0.0833)`. The sign was
neither rejected nor honoured — it vanished.
It could not be checked while the field was a public tuple position,
because there was nothing to intercept. Validating inside
`variance_for_elapsed` would have been worse: it runs in the sweep, so a
construction-time mistake would panic mid-inference, and `Gaussian::from_ms`
is a worked example of why that is the wrong place — rejecting NaN there
turned the NonFiniteResult reporting path into a crash.
So `ConstantDrift::new` is the only way in and it checks, with `gamma()`
to read the value back. 129 call sites rewritten across src, tests,
benches, examples and the README. The dated plan and spec documents under
docs/superpowers are left alone: they record what was built at the time,
and rewriting them would falsify that.
tests/constructor_validation.rs is the more valuable half. This defect
class was closed three times in one session and reopened twice, because
each fix validated the layer it had just touched and inferred the rest —
`HistoryBuilder`, then `Game`'s own entry points, then the constructors
beneath both. A per-site fix cannot notice the site nobody thought of, so
that file enumerates every public entry point taking a magnitude and
asserts each refuses negative and non-finite values.
It found an eleventh defect on its first run: `HistoryBuilder::score_sigma`
accepted infinity, because `inf > 0.0` is true and the assert only tested
positivity. Fixed, and its own `should_panic` message updated to match.
`Gaussian::from_ms` is deliberately exempt from the non-finite half, for
the reason above: a broken fit produces a NaN sigma legitimately and
`converge` must be allowed to report it.
The convergence-level drift-variance check stays and is now tested through
a custom `Drift` implementation, since `ConstantDrift` can no longer reach
it. That check is the only thing standing between a third-party `Drift`
and a NaN fit.
BREAKING CHANGE: `ConstantDrift`'s field is private. Replace
`ConstantDrift(x)` with `ConstantDrift::new(x)`, and `drift().0` with
`drift().gamma()`. `HistoryBuilder::score_sigma` now rejects infinity.
Closes#65
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
Three things #38 asked for, on a premise that had half dissolved. The
issue argued from "captured at first appearance", "missing it is silent"
and "missing it is permanent"; 8c087ad made configuration apply whenever
supplied and refit the whole history, so two of those are already gone.
What survived is the literal title — no way to say it before the first
event — plus the absence of any way to check.
`register(Member)` states configuration before anything is observed. It
takes the same `Member` ingestion takes, so there is one vocabulary
rather than two, and it creates the competitor immediately, which is what
makes it observable. It reaches a competitor first seen through
`record_winner`, the route #37 deliberately did not extend.
`rating(&key)` reads back what was stored. Every other accessor reports
what inference inferred; this reports what it was told, which is what
makes a configuration mistake detectable from outside the crate at all.
Conflicting configuration is now an error across batches, not only within
one. The `priors` map is rebuilt per `add_events` call, so a second batch
silently overwrote what a first declared, last-write-wins. That cut
directly against the invariant tests/ingestion_equivalence.rs exists to
protect: the same contradictory events errored when batched and
succeeded, order-dependently, when fed one at a time. Detection lives on
a new `declared` map on `History`, because a `Rating` cannot say whether
a value was chosen or inherited from the defaults — which is exactly the
distinction the check needs. Checked before anything mutates, so a
rejected batch leaves the history untouched.
`register` rejects a non-default `weight` rather than ignoring it. Weight
is per-event and has no meaning on a registration, and silently dropping
a field the caller set is the defect this whole area keeps producing.
The declarative `default_rating_for` closure is not here. It is the
better answer for ustat's actual case — thousands of keys matching a
rule, rather than enumerated — but it adds a `Fn` parameter to `History`,
which the issue itself flags as in tension with the crate's posture. That
wants its own decision rather than riding along.
BREAKING CHANGE: two different values for one competitor's `prior` or
`drift_scale` supplied across separate `add_events` calls now return
`ConflictingCompetitorConfig` instead of silently taking the later one.
Refs #38
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
logaritmiskandClaude Opus 5