Health Rules¶

Folder Overview¶

This folder defines the rule contracts used by the damage and healing pipelines.

Rules allow behaviour to be extended without modifying core systems.

Purpose¶

Rules provide:

A composable pipeline for damage and healing
A way to inject behaviour externally
Separation between data (Contracts) and behaviour (Rules)

What Lives Here¶

Pipeline Model¶

Damage and healing follow this structure:

PRE Rules → Core Processing → POST Observers

PRE Rules¶

Interfaces:

IDamageRule
IHealRule

Semantics:

Run in ascending Priority
Execute sequentially
Receive a mutable context

They may:

Modify values (Multiplier, FlatDelta, etc.)
Set Cancelled = true to reject the operation
Return false to stop further rule execution

POST Observers¶

Interfaces:

IPostDamageRule
IPostHealRule

Semantics:

Run after evaluation completes
Receive the final context
Act as observers only

They must not:

Mutate internal health state directly
Re-run pipeline logic
Assume they run for rejected operations

Affinity — `IDamageAffinity`¶

Optional multiplier providers.

Return float?
null = no opinion
Combined by the consumer

Used for:

resistances
weaknesses
immunities

Important Notes¶

Behaviour¶

ctx.Cancelled = true marks the operation as rejected
return false stops further PRE rule execution

These are not the same and may be used independently or together.

Constraints¶

PRE rules are expected to:

Be suitable for hot paths
Be designed to avoid allocations
Avoid unintended side effects outside the context

Boundaries¶

Rules should not:

Depend on HealthSystem
Access internal state outside the context
Perform direct mutation of health values
Introduce gameplay systems outside rule scope

Rules operate on context only.

Usage Guidance¶

Use rules to extend behaviour without modifying core systems
Keep rules focused on a single responsibility
Avoid coupling rules to specific implementations

Contracts
Mutation
Lifecycle
Health System