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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 6139061740 fix: keep the truncated variance representable in the far tail
`v_w` returned `w` and let `trunc` form `1 - w`. `w` tends to 1 out in
the tail, so that subtraction lost about log10(alpha^2) digits — and the
quantity it was destroying is perfectly representable.

Two separate cancellations, fixed separately.

The non-tie half: `half_line_truncation` now returns `1 - w` computed
symbolically rather than as `1 - v*gap`. With `alpha*gap = 1 - inv^2*b`
the leading ones cancel on paper instead of in floating point. Measured
against the exact truncated variance:

  alpha    before          after
  1e6      8.9e-5 rel      0.0 rel (exact)
  1e8      returns 0.0     0.0 rel (exact)

At 1e8 the old form gave `sigma_trunc = 0`, and `from_ms(mu, 0.0)` is a
point mass whose `mu()` is inf/inf = NaN. `beta(1e-8).sigma(1e-8)` with
priors 1000 apart went from Err + NaN skills to a finite fit.

The tie half is a different subtraction — `w = v^2 - u`, where both grow
as alpha^2 while their difference stays O(1). The existing escape hatch
could not cover it: it keys on `alpha * width >= HALF_LINE_WINDOW`, how
many window-widths from the mean the window sits, and a NARROW window
fails that however deep it is. Measured at alpha 1e6 with a 1e-6 window
it kept four digits and returned `1 - w = -2.4e-4` where the truth is
+2.8e-13. One step earlier it was quietly wrong instead: `1 - w = 1.0`
exactly, a truncation reported as a no-op, where the truth was 5e-17.

Over a narrow window the density is a truncated exponential in
`s = (x - alpha)/width`, whose mean and variance are closed forms, so
`v = alpha + width*m(t)` and `1 - w = width^2 * V(t)` with no large
subtraction at all. Validated against high-precision quadrature: v exact
to 4e-10, `1 - w` to 4e-10 across the region it is used in.

The crossover is on `alpha / width` rather than on either alone, because
that ratio is what says how many digits the subtraction has left — and
the approximation is most accurate exactly where the subtraction is
worst, since both improve as the window narrows.

Defaults are bit-identical (pi 0.02398318151216503 before and after).

Tests: the three reproductions from the issue, the narrow-window form
against pinned quadrature values, and a continuity sweep across all three
tie branches — a misplaced crossover is the real risk here, and a jump at
a boundary is visible even without pinning absolute values.

Closes #60

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 17:42:16 +02:00
logaritmiskandClaude Opus 5 c65373f476 fix!: propagate NaN through the convergence reduction
`tuple_max` compared with a plain `>`, which is false against NaN, so a
NaN accumulator was replaced by the next finite delta. The fold runs over
`TimeSlice::posteriors()`, a HashMap, so whether a NaN survived to `step`
depended on per-process hash order.

Measured before, four competitors in one slice with one pathological
pair, same binary and input, 30 separate processes:

  16  Ok  converged=true, iterations=1, a = Gaussian { pi: NaN, tau: NaN }
  14  Err NonFiniteResult

After: 30/30 Err. A coin flip on whether a NaN fit was reported as an
error or as a successful, converged fit — inside the guard whose entire
purpose is "NaN is never convergence".

`f64::max` would not have fixed it. It also ignores NaN by design, which
is the same defect wearing a standard-library name, and a test pins that
we do not use it.

`Gaussian::delta` had to be fixed FIRST, and that ordering is the whole
subtlety. Two identical improper messages produced `(0.0, NaN)` — not
from `mu()`, which is guarded and returns 0.0, but from `inf - inf` in
the sigma component. That NaN is reachable in ordinary healthy inference:
once a pairing is more than about nine cavity-sigma apart the truncation
is a no-op and the chain compares one identity message against another.
Propagating NaN without fixing `delta` would therefore have turned
correct fits into NonFiniteResult errors. `delta` now answers the
identical-message case in natural space before touching the accessors.

My first version of the `delta` test asserted `mu()` was NaN. It is not;
the accessor guards `pi <= 0.0`. The test caught my own wrong premise,
and the doc comment is corrected to match.

BREAKING CHANGE: a fit that produced NaN in a non-final reduction
position previously returned `Ok` with `converged: true` and a NaN
posterior; it now returns `Err(NonFiniteResult)`. That was always the
documented intent.

Closes #58

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 16:59:56 +02:00
logaritmiskandClaude Opus 5 a18df521eb test: cover non-finite results and color-group disjointness
The two gaps #26 named that were never filled.

NonFiniteResult had no test at all — the name appeared in `tests/` only
inside a doc comment, and it is the sub-claim in that issue's title. It
turns out to be very much reachable, and from *finite* inputs: sigma at
1e300, beta at 1e300, sigma at 1e-300, score_sigma at 1e-300, and scores
at 1e308 all overflow inside inference, where the boundary checks cannot
see them. That matters because the failure is silent by default — NaN
fails every comparison, so a naive `step < epsilon` reads a NaN step as
converged, which is why the crate has `step_converged`/`step_is_finite`.
Pinned from outside, including that `converge_partial` does not launder a
breakdown into an `Ok`, and with a control asserting merely extreme
parameters still converge so the suite cannot pass by always failing.

Color-group disjointness was #26's fourth acceptance criterion and had
only five hand-written cases. Now a proptest over three shapes: a dense
pool where collisions force colors to multiply, a sparse one where most
events are independent, and repeated members within a single event.

Two of my first assertions were wrong about the code rather than the
reverse. A competitor named twice *within* one event is not a collision —
`color_greedy` collects each event's members into a set for that reason.
And contiguity is not a property of `color_greedy`: it holds only after
`recompute_color_groups` reorders events so each color occupies one
range. The test now asserts what is actually promised — that the reorder
is always *possible*, since the parallel sweep slices `&mut` sub-ranges
from those groups and overlapping ranges would be unsound.

Refs #26

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-08 21:09:25 +02:00