# Security Model

Client‑side prediction keeps gameplay responsive, but authority lives on the server. This page explains what data is trusted, how inputs are validated, and patterns to avoid client‑driven exploits.

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**Trust Model**

* Server authoritative: Only player inputs are accepted from clients. Game state is never trusted from clients.
* Server re‑simulates using received inputs and produces the authoritative state. Clients reconcile to that.
* Ownership enforced: The server only accepts inputs for an identity from its owner.

Implications:

* A client can’t force state (position, health, spawns) — it can only propose inputs for identities it owns.
* Desyncs are corrected by reconciliation; local client changes that don’t match server simulation are discarded visually over time.

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**Input Validation**

* Sanitize Inputs: Implement `SanitizeInput(ref INPUT)` to clamp, normalize, and drop invalid or out‑of‑range values. This runs on the server before simulation.
* Extrapolate Input: For remote players, the client may extrapolate locally to smooth visuals. This is not trusted — the server still simulates from received inputs only.
* Repeat Input Factor: Cap how many ticks a prior input is reused for remote interpolation; prevents long input stretching.

Checklist:

* Clamp analog ranges (e.g., normalize movement vectors).
* Gate one‑shot actions (fire/jump) with game‑side cooldowns, not just input booleans.
* Ignore inputs that don’t make sense for the current owned state (e.g., jump while already in the air if your design disallows it).