feat: add source-owned combat mechanic programs

src/lib/builder/loadout-combat.test.ts

@@ -0,0 +1,144 @@
+import { describe, expect, it } from 'vitest';
+import { evaluateMechanicProgram, type MechanicProgram } from '$lib/calculations/mechanic';
+import { createDraft } from './loadout.js';
+import {
+	buildWeaponMechanicTimeline,
+	mechanicModifiersAt,
+	weaponCriticalChance
+} from './loadout-combat.js';
+
+describe('loadout mechanic timeline', () => {
+	it('emits deterministic critical hits from modeled critical chance', () => {
+		const profile = createDraft().combatProfile;
+		profile.encounterSeconds = 4;
+		profile.hitRate = 100;
+		profile.shotsPerBurst = 100;
+		profile.burstPauseSeconds = 0;
+
+		const timeline = buildWeaponMechanicTimeline(
+			{ rpm: 60, magazine: 100, reload_speed: 0 },
+			profile,
+			50
+		);
+		const criticalHits = timeline
+			.filter((event) => event.kind === 'weapon_hit')
+			.map((event) => event.values?.critical);
+
+		expect(criticalHits).toEqual([false, true, false, true, false]);
+	});
+
+	it('derives critical chance through the configured binding transform', () => {
+		expect(weaponCriticalChance(
+			{ critical: 80 },
+			[{
+				attributeId: 'critical',
+				stage: 'critical_chance',
+				operator: 'add',
+				weight: 0.5,
+				hardCap: 30,
+				curveType: 'none'
+			}]
+		)).toBe(30);
+	});
+});
+
+describe('per-shot mechanic modifiers', () => {
+	const program: MechanicProgram = {
+		id: 'phase-order',
+		name: 'Phase order',
+		pools: [{
+			key: 'stacks',
+			label: 'Stacks',
+			scope: 'agent',
+			initial: 0,
+			min: 0,
+			max: 10,
+			expiresAfterSeconds: 10
+		}],
+		clauses: [
+			{
+				id: 'stack-on-hit',
+				when: 'weapon_hit',
+				reducer: { kind: 'none' },
+				mutations: [{ kind: 'add', pool: 'stacks', value: 1 }],
+				outcomes: [
+					{
+						id: 'instant-a',
+						label: 'Instant A',
+						phase: 'on_event',
+						kind: 'attribute_modifier',
+						scope: 'equipped_weapon',
+						value: 2,
+						basis: 'flat',
+						attributeId: 'weapon-damage'
+					},
+					{
+						id: 'after-hit',
+						label: 'After hit',
+						phase: 'after_event',
+						kind: 'attribute_modifier',
+						scope: 'equipped_weapon',
+						value: 100,
+						basis: 'flat',
+						attributeId: 'weapon-damage'
+					},
+					{
+						id: 'active-stacks',
+						label: 'Active stacks',
+						phase: 'while_active',
+						kind: 'attribute_modifier',
+						scope: 'equipped_weapon',
+						value: 3,
+						basis: 'flat',
+						attributeId: 'weapon-damage',
+						statePool: 'stacks',
+						perStack: true
+					}
+				]
+			},
+			{
+				id: 'second-instant',
+				when: 'weapon_hit',
+				reducer: { kind: 'none' },
+				mutations: [],
+				outcomes: [{
+					id: 'instant-b',
+					label: 'Instant B',
+					phase: 'on_event',
+					kind: 'attribute_modifier',
+					scope: 'equipped_weapon',
+					value: 5,
+					basis: 'flat',
+					attributeId: 'weapon-damage'
+				}]
+			}
+		]
+	};
+	const evaluation = evaluateMechanicProgram(
+		program,
+		[
+			{ kind: 'weapon_hit', at: 1, targetId: 'target' },
+			{ kind: 'weapon_hit', at: 2, targetId: 'target' }
+		],
+		{ mode: 'custom', encounterSeconds: 5 }
+	);
+	const source = {
+		status: 'OK' as const,
+		result: evaluation,
+		program,
+		encounterSeconds: 5
+	};
+
+	it('combines same-attribute on-event effects and excludes after-event effects', () => {
+		expect(mechanicModifiersAt(source, 1, 'weapon_hit')).toEqual([{
+			attributeId: 'weapon-damage',
+			scope: 'equipped_weapon',
+			value: 7
+		}]);
+	});
+
+	it('uses the pre-hit active stack state when the triggering hit adds another stack', () => {
+		expect(mechanicModifiersAt(source, 1.5, 'weapon_hit')[0]?.value).toBe(3);
+		expect(mechanicModifiersAt(source, 2, 'weapon_hit')[0]?.value).toBe(10);
+	});
+});