4 Commits
Author SHA1 Message Date
logaritmiskandClaude Opus 5 85c4d0d87d fix!: correct eight wrong # Errors sections and seal the error variants
Documentation (#78). Every item below was measured against the code
rather than read:

- `expected_information_gain` and `predict_ranking` had `# Errors`
  immediately followed by `# Preconditions`, with the error list stranded
  at the bottom of the latter — rustdoc rendered a BLANK Errors section on
  both. The heading now sits with its content.
- `predict_outcome`, `predict_ranking` and the free
  `expected_information_gain` all omitted `GridTooCoarse`.
- `predict_margin` claimed `JointUnavailable` "if the LATEST slice holds
  ranked events". Measured with an early ranked slice and a late scored
  one: it fails. The condition is *any* slice.
- `add_events` documented three errors and can return five more; it also
  claimed a weights `MismatchedShape` that is unreachable through it,
  since weights arrive one-per-`Member`. That check belongs to
  `EventBuilder::weights`, and the doc now says so.
- `converge` and `converge_partial` both omitted the drift-variance
  `InvalidParameter`.

`History` gains a hand-written `Debug` (#76). Summarising, not
exhaustive — a derived one would print every competitor's skill at every
slice. It exists because without it a consumer cannot `#[derive(Debug)]`
on any struct holding a `History`, which is how both known consumers
store one.

`#[non_exhaustive]` on all 17 `InferenceError` struct variants and on
`Outcome::Scored` (#74). The enum carried the attribute; no variant did,
so adding a field to any of them — and downstream construction of any of
them — were both in the public contract. This crate added two variants in
two days.

The options structs are deliberately NOT sealed. `ConvergenceOptions` and
`GameOptions` are constructed by struct literal at 65 sites of which only
8 use `..default()`, and specifying all three convergence fields is a
natural complete statement rather than a partial one. That is a real
trade-off rather than an oversight, and it is left as a decision on #74.

Also spells `UnknownKeys::Reject` explicitly at both sites that
wildcarded it. `#[non_exhaustive]` on your own enum gives no exhaustiveness
safety net if you then match `_`.

Sealing the variants pushed ten test sites from constructing errors to
`matches!`, which is the better assertion anyway — an `assert_eq!` against
a constructed error breaks whenever a field is added, which is the exact
fragility the attribute exists to prevent.

BREAKING CHANGE: `InferenceError`'s struct variants and `Outcome::Scored`
are `#[non_exhaustive]` — downstream patterns need `..` and downstream
construction is no longer possible.

Refs #78, #76, #74

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 20:49:07 +02:00
logaritmiskandClaude Opus 5 8dff7513f7 fix!: seal ConstantDrift's field so gamma can be validated
`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
2026-09-09 19:11:57 +02:00
logaritmiskandClaude Opus 5 31cf0998b0 test: scale the ceiling sweep by build profile
Each sample runs a full inference pass per outcome, and that is about
19x faster in release: 20 000 samples take 12.1s released against 23s
for 2 000 in debug.

`just test` runs three debug feature combinations and one release one, so
a fixed sample count pays the slow price three times and the fast one
once — exactly backwards. Scaling by `cfg!(debug_assertions)` puts the
search where it is cheap:

  debug    1 000 samples   11.7s
  release 50 000 samples   31.6s

Across the whole `just test` that is 67s against 70s before, for 25x the
samples. The debug run proves the sweep compiles and holds; the release
run is the one that actually searches.

Not moving the suite to release-only, which was the alternative
considered. `debug_assert!` is compiled out in release, and this crate
documents that as load-bearing — several defects have hidden there — so
dropping the debug runs would trade one class of coverage for another
rather than adding any.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 17:27:09 +02:00
logaritmiskandClaude Opus 5 bbc7705c75 fix!: report an unresolvable prediction grid instead of clamping
`grid_shape` asked for 12 nodes across the narrowest feature and then
clamped to MAX_GRID_POINTS with no detection that the request was not
met. Past `step/sigma ~ 1.7` the trapezoid rule stops resolving the
density, and the result is unbounded:

  sigma_a   step/sig_a   P(a first)   exact      total
  2.0e-3      0.86       0.515953    0.515953   1.000000
  1.0e-3      1.72       0.517185    0.515953   1.002388
  1.0e-4     17.17       2.791336    0.515953   5.410065

A probability of 2.79. Reachable through `predict_outcome` with a pinned
reference competitor — a documented pattern — where `predict_outcome` and
`predict_win_probabilities` disagreed 44x and `predict_outcome` was the
wrong one.

There is no useful answer on the far side of that cliff, so this reports
`GridTooCoarse` rather than guessing, and the message points at
`predict_win_probabilities`, which answers the same matchup through
adaptive quadrature and is accurate there to 1e-13. The floor is 4 nodes
per feature rather than the 12 requested, because the request carries
margin: measured accurate to 2.2e-12 at 1.4 nodes per sigma and wrong by
1.2e-3 at 0.7.

This also fixes the `ln k` ceiling violation. `expected_information_gain`
weights `probability * divergence`, so probabilities of 3.97 and 2.62
made it return 3.237828 nats against `ln 2 = 0.693147` — 4.67x over. The
crate's docs call that ceiling its sharpest test and record a prototype
once returning 4.77 nats; it was live again by a different route.

The new sweep then caught a second, independent defect: `kl_divergence`
returned NEGATIVE values, worst -5.55e-17, exactly one ULP of its
`- 1.0`. Rewritten as `0.5*(u - ln1p(u)) + gap^2/(2*var_p)` with
`u = var_q/var_p - 1`, so both terms are non-negative by construction.
It is also more accurate where it matters: at `u = 1e-9` the old form
returned 0.0 where the true value is 2.5e-19, and well-conditioned cases
are unchanged.

tests/prediction_bounds.rs sweeps rather than spot-checks, because a
single fixture cannot defend a bound like this — the previous check
passed throughout. It asserts the sweep still reaches the coarse-grid
regime, so it cannot quietly stop testing the case it was written for.

BREAKING CHANGE: `predict_outcome`, `predict_ranking` and
`expected_information_gain` return `GridTooCoarse` for matchups whose
performance sigmas are too far apart to integrate on one grid. They
previously returned wrong answers, including probabilities above 1.

Closes #55, closes #56

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 17:21:00 +02:00