Port SIM_csr_compare gravity-acceleration octant sweep (#207)

[simnaut]

Closes #207. Part of the #99 Tier 3 coverage burn-down.

What

JEOD's SIM_csr_compare (name is historical — JEOD 5.4 ships no CSR coefficient file) loads earth_GGM05C at degree/order 70, places a non-integrating vehicle, and teleports it through sign-permutations of an ISS-like position at t=1..5 s, logging grav_pot / grav_accel / position. Since the body never integrates, this is a per-step gravity-evaluation cross-check, not a trajectory propagation.

Adds:

• A csr_compare_run01 entry + CSR_COMPARE_SNIPPET (DRAscii logger) in trick/generate_references.sh, and the regenerated reference CSV.
• crates/astrodyn_verif_jeod/tests/tier3_sim_csr_compare.rs, which evaluates our GGM05C 70×70 gravity through the production GravityControl::evaluate_accel_only path at each input-deck position and compares against JEOD's logged grav_accel.
• A PERMANENT_GAPS entry (csr_compare) in parity_coverage.rs — the non-integrating gravity-eval has no Bevy-parity counterpart.

Notes

• Computational independence: the sweep positions are JEOD source constants (RUN_01 input deck / iss_typical_state.py), not JEOD output; only the grav_accel compared against is output.
• Frame: the S_define has no RNP object, so JEOD evaluates gravity with the planet-fixed orientation pfix->state.rot.T_parent_this left at its uninitialized identity (spherical_harmonics_calc_nonspherical.cc:109/440). The kernel is therefore passed the identity rotation t_inertial_pfix = Some(&DMat3::IDENTITY) (evaluate_accel_only panics on None for non-spherical gravity) — confirmed correct by the machine-precision result.
• Result: our kernel reproduces JEOD's grav_accel to machine precision (observed per-component max ≤ 4.4e-16 m/s² on a ~7 m/s² signal). Tolerances use a 1e-14 m/s² machine-epsilon floor (1.05× observed would be a sub-ULP/zero tolerance).

Verification

• tier3_csr_compare_gravity_octants — PASS
• parity_topics_are_a_superset_of_tier3_topics — PASS (new PERMANENT_GAPS entry)
• cargo fmt --check, cargo clippy -p astrodyn_verif_jeod -p astrodyn_verif_parity --tests -- -D warnings — clean

Review fixes (07cd668)

• generate_references.sh: added the missing wait $PID_CSR_COMPARE so the regen script can't report success before the sim finishes.
• tier3_sim_csr_compare.rs: corrected the stale module doc that said t_inertial_pfix = None to match the actual Some(&DMat3::IDENTITY), with the JEOD-source rationale above.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Ports JEOD’s SIM_csr_compare gravity-acceleration “octant sweep” into the Rust verification suite by adding reference generation for the sim’s logged gravity outputs and a Tier 3 test that evaluates Astrodyn’s GGM05C 70×70 gravity via the production GravityControl::evaluate_accel_only path and cross-validates against the JEOD CSV.

Changes:

• Added a new CSR_COMPARE_SNIPPET and csr_compare_run01 reference-generation entry to produce a committed DRAscii CSV for SIM_csr_compare.
• Added tier3_sim_csr_compare.rs to compare Astrodyn’s computed grav_accel against JEOD’s logged grav_accel at each teleported position.
• Added a PERMANENT_GAPS entry (csr_compare) to document that this non-integrating per-step gravity evaluation has no Bevy parity counterpart.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
trick/generate_references.sh	Adds DRAscii snippet + background run entry to generate csr_compare_run01 reference CSV.
crates/astrodyn_verif_parity/tests/parity_coverage.rs	Documents csr_compare as a permanent parity gap (non-Simulation::step() comparison).
crates/astrodyn_verif_jeod/tests/tier3_sim_csr_compare.rs	New Tier 3 test that evaluates GGM05C 70×70 accel-only gravity at JEOD deck positions and compares to JEOD CSV.
crates/astrodyn_verif_jeod/test_data/csr_compare_run01_csr_compare.csv	New committed JEOD reference CSV produced by the added DRAscii logging.

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