NEXUS Combat is a deterministic combat foundation for Unity. Every hit resolves through one ordered pipeline - arguments, stamina, cooldown, journal replay check, victim state, guard layer, mitigation, seeded critical roll, journal - and returns a full result object. Nothing mutates your scene silently.

GUARD LAYER

Block keeps 25% of incoming damage (chip damage floor 1) and drains stamina by guard damage; ranged and magic attacks add +50% guard pressure. Parry covers a 6-tick window; dodge covers 8 ticks. A block that would eat more stamina than the defender has left breaks the guard: chip damage lands, result GuardBroken.

COMBOS, ABILITIES, STATUSES

Combo chains are validated data (unknown attacks rejected at construction, repeated steps legal). Abilities gate on cost, stun, and per-tick cooldowns. Status effects: poison stacks to 3, burn/stun/weaken refresh in place, per-tick decay driven by one deterministic Tick().

REPLAY-PROOF JOURNAL

Every resolution carries a fixed key. A repeated key is refused BEFORE damage is computed and surfaces as DuplicateResolution - replays become observable instead of silent double-hits. The journal folds a rolling checksum you can print.

DETERMINISTIC BY CONSTRUCTION

The critical roll is a seeded LCG: same seed + same inputs = same battle (pinned by tests). All windows are ticks - frame rate never touches combat math.

ENGINE-FREE DOMAIN

The Domain assembly compiles with engine references disabled (noEngineReferences: true), so dedicated-server projects link it directly. 12 domain sources, 68 EditMode tests, MIT license, zero dependencies.

Start with the guided showcase: open Samples/CombatShowcase.unity, press Strike, then Replay Last - and watch the journal refuse the duplicate in one click.