feat: support extra health state mechanics

src/lib/calculations/mechanic-editor.test.ts

@@ -5,6 +5,7 @@ import {
 	parseConditionalMechanicDraft,
 	readCurrentHealthPercentBand,
 	readEventFieldComparison,
+	registeredEventFields,
 	readStatePoolThreshold,
 	statePoolThresholdPredicate,
 	type ConditionalMechanicDraftV1
@@ -126,6 +127,54 @@ describe('conditional mechanic authoring payload', () => {
 		})).toBeNull();
 	});
 
+	it('exposes typed Extra Health fields and parses their manual editor state', () => {
+		expect(registeredEventFields('extra_health_changed')).toEqual([
+			{ path: 'values.hasExtraHealth', label: 'Has Extra Health', type: 'boolean', required: true },
+			{ path: 'values.currentExtraHealth', label: 'Current Extra Health', type: 'number', minimum: 0 }
+		]);
+		const value = draft();
+		value.clauses[0].event = 'extra_health_changed';
+		value.clauses[0].recipeKey = undefined;
+		value.clauses[0].reducer = { kind: 'none' };
+		value.clauses[0].if = eventFieldComparisonPredicate({
+			path: 'values.hasExtraHealth',
+			operator: 'eq',
+			value: true
+		});
+		const result = parseConditionalMechanicDraft(value, {
+			variantKeys: ['I', 'II'],
+			allowedAttributeIds: new Set(['weapon-damage'])
+		});
+		expect(result.ok).toBe(true);
+		if (!result.ok) return;
+		expect(result.value.programs.I.clauses[0]).toMatchObject({
+			when: 'extra_health_changed',
+			if: value.clauses[0].if
+		});
+	});
+
+	it('rejects an unregistered Extra Health event field deterministically', () => {
+		const value = draft();
+		value.clauses[0].event = 'extra_health_changed';
+		value.clauses[0].recipeKey = undefined;
+		value.clauses[0].reducer = { kind: 'none' };
+		value.clauses[0].if = eventFieldComparisonPredicate({
+			path: 'values.extraHealthActive',
+			operator: 'eq',
+			value: true
+		});
+		const result = parseConditionalMechanicDraft(value, {
+			variantKeys: ['I', 'II'],
+			allowedAttributeIds: new Set(['weapon-damage'])
+		});
+		expect(result.ok).toBe(false);
+		if (!result.ok) {
+			expect(result.errors).toEqual(expect.arrayContaining([
+				expect.stringContaining('is not defined for Extra Health changed')
+			]));
+		}
+	});
+
 	it('round-trips state-pool thresholds and preserves unsupported targeted pools as advanced', () => {
 		const comparison = { pool: 'stacks', operator: 'gte' as const, value: 10 };
 		const predicate = statePoolThresholdPredicate(comparison);