Commit Graph
15 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 13a395fdc9 refactor!: scores_with_noise, and History::quality
Two names that described the wrong thing.

`scores_with_sigma(scores, sigma)` reads as "these scores have prior
sigma 2.0". The quantity is observation noise on the score *margin*, in
the units of the scores, and it is spelled `score_sigma` at every config
site — `HistoryBuilder::score_sigma`, `GameOptions::score_sigma`,
`EventKind::Scored { score_sigma }` — so this was the one place the
crate used a third meaning of "sigma" for it. Its own doc had to
disambiguate itself: "`sigma` overrides `HistoryBuilder::score_sigma`".
`scores_with_noise(scores, score_sigma)` on both `Outcome` and
`EventBuilder`.

`predict_quality` predicts nothing. Its own doc says it answers "is this
matchup *fair*", not "what will happen", and the `predict_*` family is
otherwise exactly the methods returning a probability or a distribution
over outcomes. `History::quality` also makes the free/method pair
consistent: free `quality` pairs with `History::quality` the way free
`expected_information_gain` already pairs with
`History::expected_information_gain`. The rule that was already being
followed and never stated — a free function scores a hypothetical from
explicit parameters, the same-named method asks it against the fit — is
now written on the method.

Closes #75. Refs #78 (part 4).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 23:23:12 +02:00
logaritmiskandClaude Opus 5 e4a68ba1a7 fix!: per-key queries report unknown keys instead of a plausible constant
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
2026-09-09 21:13:35 +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 dc1f4d5847 fix!: make the Time generic reachable
`History<T: Time, ..>` has always been generic over the time axis,
`Untimed` has always been exported, and `Drift<T>` is generic specifically
so that "seasonal or calendar-aware drift is expressible without going
through i64". None of it was reachable from a downstream crate.

Every construction route pinned `T = i64`: `History::builder()`,
`History::builder_with_key()`, and the only `Default` impl on
`HistoryBuilder`. Its fields are private and it had no `new`. So all three
escape routes failed to compile, and a consumer with domain timestamps
had to convert to i64 — which is the exact thing the parameter exists to
avoid. One of `History`'s four type parameters was paid for at every
signature and could never be varied.

`Default` is now generic over `T` and `K`, `HistoryBuilder::new()` exists,
and `time_type::<T2>()` / `key_type::<K2>()` join `drift` and `observer`
as type-changing setters:

    History::builder().time_type::<Untimed>().build()
    History::builder().key_type::<String>().build()
    HistoryBuilder::<Season, _, _, String>::new().build()

`key_type` replaces `builder_with_key`, which could not be turbofished —
`K` sat on the impl rather than the function, so callers had to spell
`History::<i64, _, _, String>::builder_with_key()`. 18 call sites across
15 files migrated.

tests/time_axis.rs is the part that matters. NOTHING in the repository
constructed a non-i64 history, which is precisely why this survived, so
the fix is only half done without a test that exercises the generic. It
defines a `Season(u16)` time type and a `SeasonalDrift` that accumulates
between seasons but not within one — the calendar-aware case the trait's
docs cite — and checks the whole path: fit, converge, and read a learning
curve whose times come back as `Season`, not as integers.

Two of the six tests are controls rather than assertions about output.
`Untimed` must ignore drift entirely, since elapsed is always zero, so
gamma 0.0 and gamma 5.0 must agree bit for bit. And a custom `Drift` must
actually widen a gap across seasons, or the test above would pass whether
or not the drift was consulted at all.

The README's ticked "Generalise a time axis" box is now true.

BREAKING CHANGE: `History::builder_with_key()` is removed. Use
`History::builder().key_type::<K>()`.

Closes #68

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-09 20:19:16 +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 8e4d6a637d fix: reject malformed events at the ingestion boundary
A one-team event reached `run_chain`, which builds one diff link per
adjacent pair of teams, leaving it to index `links[1..]` on an empty
vector. That panicked with "range start index 1 out of range for slice
of length 0" — from `History::add_events`, in a release build, through
entirely safe API.

An empty team was the quieter half of the same gap. It contributes no
performance, so a malformed event converged and handed back a finite,
plausible-looking posterior for whoever it was matched against. That is
this crate's characteristic defect: a public surface reporting a
constant that looks like an answer.

A non-finite score was the third. `converge` did report NonFiniteResult,
so it was detected — but a caller reading `current_skill` before
converging was handed `tau: NaN` with nothing to say so.

`NotEnoughTeams` and `EmptyTeam` already existed. They were checked on
the prediction paths and nowhere else, which is exactly why ingestion
could still manufacture the states they describe. The checks go in
`add_events_with_prior` alongside the tie check, for the same reason
that one is there: every ingestion route lands on it, so `record_winner`,
`record_draw` and `EventBuilder` inherit them rather than each needing
their own.

Also corrects documentation that had been stating the opposite of the
code since 8c087ad in 0.4.0. README.md and the `with_prior` /
`with_drift_scale` doc comments all still said competitor configuration
was "captured at first appearance" and had "no effect" on a known key.
It now applies whenever supplied and refits the whole history. A reader
would have concluded late configuration was impossible and built a
workaround for a limitation that does not exist. CI compiles README code
blocks but not prose, which is why it survived three releases.

The comment in tests/degenerate_inputs.rs claiming a one-team event was
"rejected for an unrelated reason" was wrong when written — it panicked.

Refs #18, #26

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-08 12:29:14 +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 2745fbb622 test: add property-based tests, a shared finiteness helper, and boundary inputs
Most of what remained on #26.

**Property tests (`tests/properties.rs`, proptest as a dev-dependency).** Four
invariants over generated 1v1 schedules rather than hand-written fixtures,
which is where this crate's shipped defects actually hid — a linear evidence
product that underflowed only past ~1000 teams, and a batching path no golden
exercised because every golden ingests in one call:

- converged posteriors are always finite with positive sigma
- log-evidence, batch and filtered, is finite and never above zero
- filtered evidence is invariant to whether `converge` has run
- one-at-a-time ingestion reaches the same fixed point as batched

The invariance property was mutation-proved: making `filtered_step` read
`skill.forward` instead of the carried message fails it with
`-1.1038430064192069 -> -1.1135747072822761`.

**Shared finiteness helper (`tests/common/mod.rs`).** `assert_finite` was local
to `degenerate_inputs.rs`. It now also rejects a non-positive sigma, which the
old version let through — `Gaussian::sigma` reports a non-positive precision as
improper rather than trapping, so a collapsed posterior would have passed a
finite-only check.

**Boundary inputs.** Zero and negative weights, out-of-order timestamps, and
extreme beta/sigma combinations. Worth recording that zero weight reaches
`(m - performance.exclude(..)) * (1.0 / w)` — a division by zero — and the
posterior comes out finite anyway; the test pins that rather than asserting
what ought to happen. The weight tests `expect()` the commit rather than
returning early on error, because an early return would have made them vacuous
the moment validation changed. I checked that specifically by turning the
return into a failure and confirming it did not fire.

Not done, and left on #26: benchmark regression gating. Nothing fails on a
regression today; making it fail needs a threshold chosen against how noisy the
shared runner is, which is a policy call rather than a mechanical one.

60 test binaries, up from 56. MSRV 1.85 verified with proptest in the graph.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T5SYDExxL4vZgvunrcNSMc
2026-08-27 18:06:26 +02:00
logaritmiskandClaude Opus 5 1ac3b21db5 fix: enforce EventBuilder weight/team length in release
Part of #18. `EventBuilder::weights` guarded the length match with a
`debug_assert!`, so release builds accepted a mismatch, silently dropped the
weights, and ingested the event anyway. That is the exact shape #18 is about:
validation that exists only where it is least needed.

The setters return `Self` to keep the chain fluent, so they cannot return a
`Result`. The builder now records the first failure and `commit` returns it as
`MismatchedShape`. The weights are not applied on mismatch either, so a
partially-weighted team cannot reach the history by another route.

Two tests in tests/degenerate_inputs.rs, whose CI job runs in release — which
is the only place the old behaviour differed.

The second test needed strengthening before it was worth anything. As first
written it committed a ONE-team event, which ingestion rejects for an unrelated
reason, so it passed under a mutation that disabled the whole check. It now
uses two teams, so ingestion would otherwise succeed and the assertion is
actually load-bearing. Both tests were then mutation-proved together: disabling
the error path in `commit` fails both in release.

#18 stays open. The remaining debug_asserts live in `ranked_with_arena` and
`scored_with_arena`, and promoting those means threading `Result` up through
`Event::compute`, `TimeSlice::iteration`, `log_evidence` and `filtered_step` —
which lands on the public API as `log_evidence() -> Result<f64>` and
`filtered_learning_curve() -> Result<...>`. That is a trade-off about what the
query API should look like, not a mechanical change, so it is not mine to
decide.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T5SYDExxL4vZgvunrcNSMc
2026-08-27 17:53:37 +02:00
logaritmiskandClaude Opus 5 eeb43e3be1 fix: close out four small issues and pin #27's repro
#29 — log_evidence and log_evidence_for took &mut self while mutating
nothing. Loosening them to &self is not source-breaking for ordinary callers
(a &mut reborrows as & transparently) and brings them in line with the
filtered_* accessors added last week.

Not the mechanical change it looked like: under the rayon feature the closure
in log_evidence_internal captured all of &self rather than just the competitor
store, which drags KeyTable<K> in and demands K: Sync from every caller. That
compiled while the method took &mut self and stopped compiling the moment it
did not. Binding `let agents = &self.agents;` before the closure narrows the
capture; the comment there says why, because the next person to inline it will
reintroduce the bound.

#31 — TimeSlice::add_events constructed Skill with ..Default::default() while
filtered_step spells every field out. The design relies on a new Skill field
being a compile error at construction sites rather than a silent default, and
that tripwire only fired at one of the two. Now both.

#28 — log_evidence_internal's `forward` flag is a genuine forward-only
quantity only on a history that has never been converged, because iteration
alternates sweeps and the likelihood feeding the forward message absorbs
backward information from the second iteration onward. Documented, with a
pointer to filtered_log_evidence for the quantity that survives convergence.
That trap is one function away from the one #19 was about.

#23 — color_greedy carried #[allow(dead_code)] despite being called by
recompute_color_groups: a mute button on a live function, which is the
specific complaint in that issue.

#27 was already fixed — the guard landed in f4e2922 and the issue was filed
against 7742b2b, which merge-base confirms predates it — but nothing pinned
it. Added the issue's own reproduction, which matters because the two profiles
fail differently and a debug-only test would miss the release path. Removing
both guards reproduces the issue verbatim: "attempt to subtract with overflow"
in debug, "index out of bounds: the len is 0 but the index is
18446744073709551615" in release.

Also amended the filtered-estimates spec (#30): the tolerance-not-bit-identity
caveat is conservative. Forcing the scratch onto the sequential sweep instead
of the grouped one — a far larger perturbation than a permuted event order —
still agrees within 1e-8 under tight convergence.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T5SYDExxL4vZgvunrcNSMc
2026-08-27 17:21:05 +02:00
logaritmisk 9c39d1e681 test: pin the invariants that make filtered estimates trustworthy
The bracket test proves the feature works on one fixture. These pin the bug
class:

- Invariance to converge(). This is the one that matters. Reading
  skill.forward instead of the carried message makes it fail immediately,
  because converge() alternates sweeps and contaminates skill.forward with
  backward information from the second iteration onward. That is the
  property a stored field cannot have, and the reason issue #19's proposed
  fix would not have worked.
- Invariance to ingestion order, the crate's standing invariant.
- One slice has no future to propagate back, so filtered equals smoothed.
- Empty history yields zero and empty maps.

Agreement is to 1e-8 under tight convergence rather than bit-identity:
iteration recomputes the colour partition only when from == 0, so an
incrementally built slice keeps insertion order until the first converge()
reorders it, and the scratch clone inherits whichever order it finds. Same
fixed point, different path to it.
2026-08-27 16:37:21 +02:00
logaritmiskandClaude Opus 5 0f1a1b8911 fix(evidence): accumulate in log space and floor the per-link value
Per-link evidence was multiplied in linear space and logged only at the
end. Each link contributes a probability in (0, 1], so the product over an
n-team game decays geometrically: around a thousand links it flushes to
exactly 0.0 and `ln(0.0)` is `-inf`, which then propagates through the sum
in `History::log_evidence_internal` and takes the whole history with it.
`Game::free_for_all` builds one team per player, so this is reachable at
the competitor counts the T3 benchmarks target.

`Game`, `OwnedGame`, and `time_slice::Event` now carry `log_evidence`
directly, summed over links rather than multiplied then logged.

The cached per-link evidence is also floored at `f64::MIN_POSITIVE`. It
could legitimately reach zero or go negative: `1.0 - cdf(..)` rounds to
zero for a near-certain outcome, and the `erfc` approximation carries
~1e-7 error so `cdf` can exceed 1.0 and make the difference negative —
`ln` of which is NaN.

Existing log-evidence goldens are unchanged, confirming the accumulation
is numerically equivalent in the range where the old form worked.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DnsaJg74eNSva3PJjK2eej
2026-08-04 21:43:57 +02:00
logaritmiskandClaude Opus 5 f4e2922d59 fix: reject ties without draw probability; never report NaN as converged
A tie with `p_draw == 0.0` produced NaN posteriors in release builds and
`converge()` reported `converged: true`, because every comparison against
NaN is false and `tuple_gt` therefore read NaN as "below epsilon".

Two independent defects, fixed together:

- Ingestion now rejects tied outcomes when the draw probability is zero,
  promoting the existing `debug_assert!` in `Game::ranked_with_arena` to a
  real `InferenceError::TieWithoutDrawProbability`. Validation sits in
  `add_events_with_prior`, the chokepoint every route reaches — including
  `record_draw`, which bypasses `Outcome` entirely.
- `converge()` treats a non-finite step as failure and returns
  `InferenceError::NonFiniteResult` rather than claiming convergence.

Also in this change:

- `History::converge()` on an empty history returned a `usize` underflow
  panic from `0..len()-1`; it now short-circuits to a zero-iteration report.
- `Outcome::scores_with_sigma` no longer panics on a non-positive sigma;
  the value is validated at ingestion so callers get an error instead.
- `InferenceError` gains `WrongOutcomeKind`, replacing the misuse of
  `MismatchedShape` for variant mismatches (which rendered as the nonsense
  "expected length 0, got 0"), and is now `#[non_exhaustive]`.

Note `Outcome::winner(w, n)` for n >= 3 ties every loser, so those events
now require a positive `p_draw`. They previously returned NaN.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DnsaJg74eNSva3PJjK2eej
2026-08-04 21:38:29 +02:00