Hierarchical Tag Paths

Tags are defined as dot-separated strings 

Effects.Debuff.Poison, Ability.Active.Sprint, Player.State.Stunned. 

The hierarchy is not just naming convention; the system understands it. Every segment is a real node, so querying Effects.Debuff can automatically match anything beneath it.

Use this when you want broad queries without enumerating every specific case. A damage system checking for any debuff asks once about Effects.Debuff instead of listing Poison, Slow, Burn, and every future variant you might add.

Arithmetic Operations

Rather than getting and setting values manually, you apply operations 

Set, Add, Subtract, Multiply, Divide, Min, Max. 

Operations are data, not code, so they can be authored in the Inspector and triggered from events without writing a single line.

Use this anywhere stacking, capping, or scaling matters: adding armor stacks, draining a resource to a floor of zero with Subtract, capping a buff at a maximum with Min.

Tags as Enumerations

A tag’s value can itself be the hash of another tag path. Set Player.Class to the hash of Classes.Warrior and you have a type-safe, hierarchy-aware enum that works inside the same system as everything else.

Use this to replace string or integer enums for things like character class, elemental affinity, or faction — and gain hierarchy for free. A query for Classes.Melee would match a character whose class is Classes.Melee.Warrior without any extra code.

Hierarchical Queries

The collection query methods Contains, ContainsAll, ContainsAny and ContainsNone all accept an exactMatch flag. 

With exact match off (the default), a query on a parent tag matches any descendant present in the collection. With exact match on, only that specific tag qualifies.

Use this to write conditions that stay correct as your tag library grows. An immunity check for Effects.Debuff doesn’t need updating when you add a new debuff type; it catches it automatically.

Condition Expressions

A condition pairs a tag with a comparison operator and a value: Effects.Debuff.Poison Exists, Player.Health Less 25, Ability.Cooldown Equal 0. Conditions evaluate against a live collection, and the right-hand value can itself be another tag’s current value for tag-vs-tag comparisons.

Use this for ability unlock checks, status effect triggers, AI decision conditions, anywhere you need to express “this collection is in this state” as data rather than as bespoke code.

Compound Condition Logic

Multiple conditions combine with AND, OR, and XOR operators, evaluated with explicit precedence: AND binds tightest, then OR, then XOR. An empty condition list always evaluates true.

Use this to express complex gate logic in the Inspector “stunned AND (no mana OR silenced)” without writing custom evaluation code. Conditions authored as a list are reusable across any number of triggers, objects, or scenes.

Zero Runtime String Cost

Tags are 8-byte hashes computed at load time from the dot-path strings. At runtime, comparisons, queries, and collection operations work entirely on integers. No string allocations, no dictionary key strings, no garbage.

Use the Foundation package anywhere performance matters — high-frequency update loops, large numbers of entities, jobs and Burst-compiled code all benefit from the flat numeric representation.