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Author SHA1 Message Date
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 eff63dfa2a feat!: make a short fit an error and raise the default iteration cap
`ITERATIONS` was 30, and overrunning it returned `Ok` with
`converged: false`. Both halves were wrong.

The cap is a runaway guard, not a budget: the sweep exits as soon as the
step falls below `epsilon`, so a high cap costs nothing on a history that
converges. Measured on one needing four sweeps, `max_iter` 30 and
100_000 both finish in 4 iterations and ~130us. So 30 could never make
anything faster — it could only stop a healthy history early, and it did:
160 events over 100 competitors already needs 42.

Not scaled to the history, because iteration count tracks how loopy the
graph is rather than how big it is. At a fixed 320 events over 40 slices,
varying only the competitors sharing them: 3 competitors needs 2_789
sweeps, 10 needs 1_068, 100 needs 90, 400 needs 2. Three orders of
magnitude on identical event and slice counts, so any formula in those
two numbers would be badly wrong on some real shape. A single value set
high enough that reaching it means oscillation is the honest version.

With the cap raised, stopping at it means something is genuinely wrong,
so `converge` now returns `InferenceError::NotConverged` rather than a
flag on a success. A short fit is wrong by a little — every rating
finite, the ordering sensible, nothing saying the numbers were still
moving — and a flag has to be checked while `let _ = h.converge()` is the
natural way not to. That is not hypothetical: it is how a real defect hid
in this crate's own test suite.

`converge_partial` returns the short fit for callers who want one. Only a
single existing test needed it, which is the evidence that a capped fit
is a deliberate choice rather than the common case.

Also corrects the `ITERATIONS` docs, which claimed convergence cost is
"roughly linear in the cap". It is linear in the iterations actually run.

BREAKING CHANGE: `History::converge` returns `Err(NotConverged)` where it
previously returned `Ok` with `converged: false`. Callers that want the
old behaviour should use `History::converge_partial`. The default
`max_iter` changes from 30 to 10_000, so a history that was silently
truncated will now converge properly and its numbers will move.

Closes #50

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011hcFjNDmHXZF8URGLku5zZ
2026-09-08 16:04:22 +02:00