7 Commits
Author SHA1 Message Date
logaritmiskandClaude Opus 5 061c481aad refactor!: typed discriminators for InferenceError
Six of fifteen variants carried a `&'static str` discriminator, about
thirty magic strings between them, and the only thing a caller could do
with one was print it. Four new enums replace them:

    Parameter        13 variants, replacing 9 strings in InvalidParameter
    Shape             4 variants, replacing 10 in MismatchedShape
    OutcomeKind       2 variants, replacing WrongOutcomeKind's three fields
    CompetitorField   2 variants, replacing ConflictingCompetitorConfig's

`InvalidProbability` folds into `InvalidParameter` as
`Parameter::PDraw`. It was a bespoke variant for one scalar while every
other scalar shared `InvalidParameter`, and it omitted the parameter
name — so the same parameter had two mechanisms.

`JointUnavailable { reason: &'static str }` splits into `EmptyHistory`,
`JointRequiresScoredEvents` and `NotPositiveDefinite`. The three are
conditions a caller branches on differently — add events, use
`predict_win_probabilities`, or reconsider the priors — and telling them
apart used to mean string-matching English. One test already proved the
distinction was load-bearing: the blanket conversion mapped the
empty-history case onto the ranked one and `an_empty_history_has_no_joint`
caught it immediately.

`NonFiniteResult` splits into `NonFiniteStep { context, step }` and
`NonFiniteSkill { mu, sigma }`. One `step: (f64, f64)` field was
carrying a sweep step from `converge` and a skill's own moments from a
prediction — two situations in one variant, and a field name that could
only be right for one of them.

`InvalidParameter { name: "beta with point-mass skills" }` becomes
`NoPerformanceVariance`. It was never a parameter out of range: both
values are individually valid and it is their combination that leaves
nothing varying.

Three `Display` impls did not meet the standard the others set, and the
typed data is what makes fixing them possible:

    before  drift variance is invalid: NaN
    after   drift variance must be finite and non-negative (got NaN)

    before  kinds: expected length 3, got 2
    after   the outcome describes a different number of teams than the
            event has: expected 3, got 2

    before  Game::ranked: expected Outcome::Ranked, got Outcome::Scored
    after   expected Outcome::Ranked, got Outcome::Scored; call
            Game::scored for a scored outcome

`Parameter::range()` states each parameter's actual bounds, which no
`&'static str` name could have. `error::message_tests` renders every one
and asserts each is a sentence rather than a label, and that the three
above now carry a range or a next step.

The four internal `MismatchedShape` kinds — `results`, `times`, `kinds`,
and the weights array — collapse to `Shape::Internal`, whose `Display`
says plainly that reaching it is a bug in this crate. They are checks on
`add_events_with_prior`'s own parallel arrays and are unreachable
through the public API; they stay checked rather than becoming
`debug_assert!`s, because release is where this crate's defects hide.

Closes #74.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-10 07:31:31 +02:00
logaritmiskandClaude Opus 5 b553c630f5 refactor!: K comes first in History, HistoryBuilder and Joint
`K` is the one type parameter people change, and it was last. Naming a
history in a struct field meant writing all four to say one thing:

    struct Ladder { history: History<i64, ConstantDrift, NullObserver, String> }
    struct Analysis<'h> { joint: Joint<'h, i64, ConstantDrift, NullObserver, &'static str> }

Now:

    struct Ladder { history: History<String> }
    struct Analysis<'h> { joint: Joint<'h> }

`History<K, T, D, O>`, all four defaulted. Bounds may reference later
parameters, so `D: Drift<T> = ConstantDrift` is legal in third position.
`Joint` gains the same defaults, so `Joint<'h, String>` spells it.

72 call sites swapped, and the reorder makes most of them shorter: 18
now read `History<String>` and the `&'static str` ones read `History`.
The two turbofished builders shrink from
`HistoryBuilder::<Untimed, _, _, String>::new()` to
`HistoryBuilder::<String, Untimed>::new()`.

`Joint` keeps `O` structurally, defaulted rather than removed. #72 notes
it never touches the observer, which is true — but it borrows the whole
`&'h History<K, T, D, O>` and calls `History::resolve_terms`, so dropping
the parameter means either a view type or moving that method off
`History`. The default already buys the entire user-visible benefit,
which was the spelling.

Refs #72.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-10 06:49:22 +02:00
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 c12bc830a5 feat!: name the unknown key, expose tail probabilities, flag short fits
Three issues from two downstream consumers, all small, all sharing a
theme: the crate had the information and would not hand it over.

#44 — `UnknownKey { team: 0, member: 0 }` did not say which key. A
consumer upgrading 0.1.2 -> 0.4.1 had every one of 5591 predictions
return this error, fell back to a neutral 0.5, and lost its entire
metadata model for a day. Nothing crashed and nothing logged; it was
found by sweeping an unrelated parameter and noticing the output did not
move. The 0.4.0 change that made unknown keys an error was right — the
error was just too anonymous to act on. It now carries the key's `Debug`
rendering, and its `Display` says what to do about it. The precondition
is documented on every prediction entry point, which the reporter said
would alone have saved the day.

#43 — `cdf` was `pub(crate)`, so a consumer asking "is this competitor
below the cutoff" approximated it with a `mu + z * sigma` band and had no
way to say what confidence any `z` bought. Adds
`Gaussian::probability_below` / `probability_above`. The second is
separate on purpose: `1 - cdf` collapses to exactly zero past ~8.3
sigma, and a stopping rule is evaluated precisely there. Both route
through the survival function added in 0.4.1, so this is visibility
rather than new numerics.

#50 — `ConvergenceReport` was not `#[must_use]`, so the one signal that
a fit stopped short was trivially discarded. It now is, and that
immediately found 78 sites doing exactly that — including this crate's
own ATP example, which was capped at 10 sweeps when the history needs
30. The example now reads the report and says so.

`ITERATIONS = 30` is documented as the floor it is, with the three
measurements to hand: 400 events over 100 competitors already stops
there at ~7e-3 against a 1e-6 tolerance, the ATP example needs 30 at a
much looser one, and a consumer's 2000-node model needs 76 to 161.

BREAKING CHANGE: `InferenceError::UnknownKey` gains a `key` field, and
the prediction methods now require `K: Debug` in order to fill it.

Closes #43, #50. Refs #44 — its third ask, an opt-in `UnknownKeys::Skip`
mode, is a live API question and deliberately not answered here.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-07 23:41:03 +02:00
logaritmiskandClaude Opus 5 8c087ad015 fix!: apply competitor configuration whenever it is supplied
`Member::with_prior` and `with_drift_scale` were consumed only on the
branch that *creates* a competitor — `priors.remove` sat inside
`if !self.agents.contains(..)`. Supplying either for a key the history
already knew did nothing at all: no error, no warning, and output
computed from the default prior. A prior applied on a competitor's very
first event and was silently discarded ever after.

Configuration now applies whenever supplied. Two details this forced:

Configuration is tracked per *field* rather than as a merged `Rating`.
A member setting only `drift_scale` must not also assert the default
prior, or it would silently undo a prior seeded on an earlier event.

Slice state has to be refreshed. `drift_scale` is re-derived on every
forward pass, but a prior is written into the competitor's earliest
slice once, at ingestion, and `iteration` refreshes only slices after
the first. Without the refresh a late prior would reach the drift terms
and nothing else — a subtler version of the drop being fixed. This was
caught by a test, not by reading the code.

Conflicting values for one competitor within a single batch are now
`ConflictingCompetitorConfig` rather than resolved by iteration order.
Events in a batch are unordered, so "last one wins" would make the
result depend on traversal — and `tests/ingestion_equivalence.rs` exists
to rule exactly that out. Repeating the same value stays inert, which is
the shape callers get when configuration is a property of the domain.

That invariant turned out to be tested only for *unconfigured*
competitors: every helper in that file built members with `Member::new`.
Extended to cover configured ones, including a check that configuration
changes the fit at all, so the order tests cannot pass vacuously.

`with_prior` had no coverage under `tests/` whatsoever, which is how
this survived. Adds `tests/competitor_config.rs`.

`drift_scale_is_ignored_after_first_appearance` asserted the old
behaviour and now asserts the new one. It was written as a deliberate
change-detector — "moving the capture would be a visible break, not a
silent one" — so it inverted rather than being deleted.

Also removes `InferenceError::ConvergenceFailed` and `NegativePrecision`,
which no code path ever constructed: public variants advertising failure
modes no caller could observe. Partial #20 — its other items were
already resolved, except `Outcome::winner` still panicking.

BREAKING CHANGE: `prior` and `drift_scale` now take effect for
competitors the history already knows, where they were previously
ignored; a batch supplying conflicting values for one competitor is now
an error. `InferenceError::ConvergenceFailed` and
`InferenceError::NegativePrecision` are removed.

Closes #10. Refs #20.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-07 15:42:31 +02:00
logaritmiskandClaude Opus 5 617bc07f6f feat: allow drift to vary per competitor via Member::with_drift_scale
Drift was a property of the History, so every competitor drifted at the
same rate and a fixed reference point could not share a graph with moving
competitors. A bot at a known strength, a rating floor, a course
difficulty — all of them drifted along with the players.

Member::with_drift_scale(s) multiplies the drift *variance* a competitor
accumulates, so s is in the same units as gamma: ConstantDrift(g) at
scale s behaves exactly as ConstantDrift(g * s) would for that competitor.
A scalar rather than a per-competitor Drift keeps History's single D type
parameter untouched and stays Copy. 0.0 pins a competitor still.

The scale lives on Rating, beside the drift it scales, and is applied
only through Rating::drift_variance_delta / drift_variance_for_elapsed.
Making those the sole entry points means a caller cannot reach the raw
drift and silently skip a competitor's scale — the filtered pass was
exactly that bug during development, caught because its test was written
before the wiring.

Like with_prior, the scale is competitor configuration captured at first
appearance rather than a per-event override; a competitor that is static
is static, and a scale that changed between events would make the skill
trajectory hard to interpret. Member's docs claimed prior was a per-event
override, which the code has never done — corrected here.

A negative scale is rejected rather than squared into its absolute value,
and a non-finite one rejected outright, both as InvalidParameter.

None means 1.0, so no existing call site changes and no existing fit
moves. Adding a public field to Member does break struct-literal
construction downstream.

Closes #34

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014b6wy2q8rnFK8U8GPJVQNU
2026-09-01 06:29:02 +02:00