InferenceError gains MismatchedShape (user-input length mismatches),
InvalidProbability (p_draw out of [0, 1]), and ConvergenceFailed
(exceeded max_iter without hitting epsilon). NegativePrecision stays.
History::add_events_with_prior and History::add_events now return
Result<(), InferenceError>. The previous assert! macros checking
composition/results/times/weights shape are replaced by matched
error returns.
Internal debug_assert! macros for arithmetic invariants stay; this
change only affects boundary validation of user input.
Tests updated to call .unwrap() on the Result. The old signatures
will be fully replaced in Task 15 (typed add_events(iter)) and the
nested-Vec wrapper removed in Task 20.
Part of T2 of docs/superpowers/specs/2026-04-23-trueskill-engine-redesign-design.md.
Anders Olsson
a83c9acacb