# Roblox Physics

> Design or review Roblox assemblies, constraints, collision, hit detection, and network ownership.

- Skill: `hungrykelvin123/roblox-physics` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add hungrykelvin123/roblox-physics`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hungrykelvin123/roblox-physics/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: HungryKelvin123 (https://skillmd.com/u/hungrykelvin123)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/hungrykelvin123/roblox-physics

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# Roblox physics

Read [`../../references/roblox-engineering.md`](../../references/roblox-engineering.md). Inspect the authored hierarchy, assemblies, roots, anchoring, attachments, constraints, collision groups, and current ownership code before changing behavior.

## Treat simulation as distributed and untrusted

- Decide network ownership at the assembly level as both a responsiveness and authority choice. Client ownership reduces input latency and server work, but the client can manipulate its simulation.
- Keep gameplay-critical assemblies server-owned when practical. For responsive player-controlled physics, assign ownership deliberately and validate server-observed position, speed, state transitions, and outcomes within game-specific tolerances.
- Reapply or release explicit ownership when seats, characters, tools, assemblies, or round state change. Anchoring and reconnecting parts can change the ownership model.
- Do not treat `Touched` alone as proof of authoritative damage, collection, or completion. Confirm server-side identity, spatial plausibility, state, cooldown, and duplicate behavior; use an appropriate ray or swept spatial query for fast motion.
- Prefer attachments and constraints for simulated mechanisms. Apply forces or impulses to the intended assembly instead of fighting physics with repeated per-frame transforms or velocity assignments.
- Make collision groups and query filters explicit. Exclude the source assembly, validate returned instances and ancestry, and separate physical collision from detection when gameplay requires different rules.
- Bound active simulated assemblies, query frequency, and per-frame work. Measure server physics cost, replication, and mobile client behavior before optimizing.

## Deliverable

State the assembly root, owner through each lifecycle state, authority checks, collision and query rules, constraint model, cleanup, and failure behavior. Verify pure hit-validation and state-transition logic locally. Give the user exact Studio checks for ownership visualization, multiple clients, latency, reset, and high-speed contact; never invoke the playtest through MCP.