Crate: uify-core. I/O-free. Safe on any thread including the audio thread.

Top-level

• Sample<G, C> — time-indexed tracker output (value, covariance, confidence, timestamp).
• Timestamp — host-monotonic nanoseconds.
• Confidence — [0, 1] clamped.
• Tracker — trait with Geometry, Covariance, Measurement<'a>, step, reset. step returns TrackerOutput<G, C> = Result<Option<Sample<G, C>>, TrackerError>.
• TrackerError — Lost / Numerical / Backend.
• Sink<G, C> — trait with write(&mut self, &Sample<G, C>). Decouples trackers from concrete transports. Implemented by OscPoint2DSink, RingbufSink, and any user-defined consumer.
• TrackerCommon<F: Clone> — shared bookkeeping for trackers wrapping a recursive filter. Holds the filter, an initial-state snapshot for reset, and last_t. Exposes dt_since(now) and reset().

manifolds::

• LieGroup trait — identity, compose, inverse, exp, log, plus, minus.
• so2, so3, se2, se3 — implemented with right-trivialized exp/log, Taylor cutovers near identity, canonical-hemisphere log. Property tests in tests/manifold_identities.rs enforce the four contract identities for every group.
• sl3 — stub, will land when the planar detector pipeline needs it.

See architecture-manifolds for conventions and property-test requirements.

filters::

• kalman::KalmanFilter<const N: usize> — classical linear KF, generic over state dim. Measurement dim is method-level: update::<const M: usize>(h, z, r). Joseph form throughout so Σ stays SPD.
• ekf_manifold::Ekf3D — manifold EKF hardcoded to SE(3) for now, with a random-walk process model and a direct-pose measurement model. Joseph form. Generalization to EkfManifold<G, P, M> (process + measurement model traits) is deferred until a second consumer surfaces the right trait shape.
• rts_smoother — stub. Offline backward pass for batch-mode replays.

pipeline::

• Stage trait — generic stage in a tracker pipeline.
• Sink<G, C> — see top-level.
• TrackerCommon<F> — see top-level.