orts

Express coordinate reference frames, time scales, and state representations in the type system, and test them with property-based tests — durable design guidance for orts/arika that holds whether you extend the current types or redesign them. Use when implementing, refactoring, or rethinking frame/scale code: adding a frame, scale, or transform; typing vectors, epochs, covariances, or rotations; deciding which time scale a transform takes; isolating EOP dependencies; choosing an interpolation space; or writing tests for rotation and scale-conversion invariants — and also when reviewing or verifying frame/scale code for type-safety. Companion to `coordinate-time-systems`, which covers the domain concerns (which frame/scale/representation, the traps).

Reason about coordinate reference frames and time scales correctly (any astrodynamics work) — which frame/scale/representation a value is actually in, the concerns to resolve before trusting it, and what to look up. Use when interpreting or choosing frames (ECI/ECEF, GCRS/ITRS/CIRS/TIRS, J2000/EME2000, TEME, ICRF, LVLH/RTN/RSW, body-fixed), time scales (TAI/UTC/UT1/TT/TDB/GPS), or state representations (Cartesian/Keplerian/equinoctial); or when reasoning about frame/scale conversions, covariance transforms, interpolation, leap seconds, ERA/GMST/GAST, EOP/ΔUT1, polar motion, frame bias, or realizations — and also when reviewing or verifying frame/time/coordinate work (use it as a checklist of the traps, even for code you could write unaided). The companion skill `coordinate-time-implementation` covers expressing and testing these in orts/arika code.

Run an external AI code review to get independent feedback on code changes. Use this skill when the user asks for a code review, says "コードレビューして", "レビュー", "変更を見て", "code review", or wants external feedback on their recent commits or uncommitted changes.

A knowledgeable neighbor who offers a fresh perspective on architecture, design decisions, and test strategy. Use proactively when a second opinion would improve quality, or when the user says "別の視点が欲しい", "設計を相談したい", "相談", "smart-friend に聞いて", or asks for feedback on their approach.

Reference for generating Orekit cross-validation fixtures. Covers orekit-jpype setup, force model matching, CSSI space weather, and fixture generation patterns.

Guidelines for E2E testing the orts viewer with Playwright. Covers DuckDB query-level data verification, canvas pixel analysis, and common pitfalls.

Check if package names are available on crates.io and npm. Use when naming a new library or crate.

Resume from a previous interrupted Claude Code session. Checks conversation logs, git status, and pending work to reconstruct context.