elodin-dev - SKILL.md Agent Skill

name: elodin-dev description: Develop and contribute to the Elodin codebase. Use when building Elodin from source, running tests, modifying core libraries, working on the Rust workspace, or onboarding as a contributor.

Elodin Development

Elodin is a monorepo for aerospace simulation and flight software. The stack:

nox-py — Python SDK (JAX + PyO3 bindings; includes ECS in src/)
nox — Tensor compiler (→ Cranelift-MLIR / JAX)
Impeller2 — High-performance pub-sub telemetry protocol
Elodin-DB — Time-series telemetry database
Elodin Editor — 3D viewer and graphing tool (Bevy + Egui)
Roci — Reactive flight software framework
Aleph — NixOS configuration for Jetson Orin flight computers

Architecture

Python Simulations (nox-py)
        │
   ┌────┴────┬──────────────┐
   │         │              │
 NOX      Impeller2     Elodin-DB
Compiler  (Telemetry)   (Storage)
   │         │              │
Cranelift/ Stellarator    Elodin
  JAX      (Async RT)     Editor
                │
         ┌──────┴──────┐
       Roci          Aleph
    (Flight SW)   (Hardware)

Key integration points:

nox-py → nox → Cranelift-MLIR (default) or JAX (simulation compilation)
nox-py → impeller2 → elodin-db (telemetry)
elodin-editor → impeller2 → elodin-db (visualization)
roci → impeller2 → elodin-db (flight software telemetry)

Prerequisites

Determinate Systems Nix
Just (brew install just / apt install just)
git-lfs (git lfs install globally)
Arm macOS strongly preferred for build speed

Development Environment

Always work inside the Nix shell. It provides Rust, Python, C/C++ toolchains, cloud tools, and git-lfs.

nix develop                              # Enter unified dev shell
nix develop --command "cargo build"      # One-off command

Build Commands

just install

# Run an example
elodin editor examples/three-body/main.py

CI Checks

All changes must pass these before merge. See ci-checks.md for details.

cargo fmt                                 # Rust formatting
cargo test                                # Rust tests
cargo clippy -- -Dwarnings                # Rust lints (warnings = errors)
ruff format --check && ruff check --fix   # Python formatting + lints
alejandra                                 # Nix formatting

Workspace Structure

The Cargo workspace has 57 members. Key crates by area:

Area	Crates
Simulation	`nox`, `elodin-macros`, `nox-py`, `nox-frames`, `cranelift-mlir`
Database	`db`, `db/cli`, `db/eql`, `db/tests`
Telemetry	`impeller2`, `impeller2/{bevy,stellar,bbq,frame,kdl,wkt}`
Editor	`elodin-editor`, `apps/elodin`
Runtime	`stellarator`, `stellarator/{buf,macros,maitake}`
Flight SW	`roci`, `roci/{macros,adcs}`
FSW Apps	`serial-bridge`, `mekf`, `msp-osd`, `lqr`, `blackbox`, `gstreamer`, `video-streamer`
Utilities	`wmm`, `s10`, `video-toolbox`

Working from Repository Root

Always run commands from the repo root. This prevents path confusion across the many workspace members and aligns with how CI runs.

Component-Specific Skills

For deeper work on specific areas, see:

Editor: .cursor/skills/elodin-editor-dev/
Python SDK: .cursor/skills/nox-py-dev/
Database: .cursor/skills/elodin-db/
Aleph/NixOS: .cursor/skills/elodin-aleph/
Nix environment: .cursor/skills/elodin-nix/