fix: apply Crafting Efficiency cost reduction to all fabrication paths

- Add getCraftingCostReduction() and applyCostReduction() helpers in crafting-fabricator.ts
- Apply cost reduction in deductMaterials() and checkFabricatorCosts()
- Apply cost reduction in startFabricatorCrafting() and cancelEquipmentCrafting() pipeline
- Update canCraftRecipe() in fabricator-recipes.ts to accept costReduction param
- Update FabricatorSubTab and MaterialRecipeCard UIs to display discounted costs
- Spec formula: actualCost = ceil(baseCost × (1 - craftingCostReduction / 100))

Fixes #316

src/lib/game/crafting-fabricator.ts

@@ -6,6 +6,7 @@ import type { ElementState } from './types';
 import type { FabricatorRecipe } from './data/fabricator-recipes';
 import { FABRICATOR_RECIPES } from './data/fabricator-recipes';
 import { useManaStore } from './stores/manaStore';
+import { computeDisciplineEffects } from './effects/discipline-effects';
 
 // ─── Lookup ───────────────────────────────────────────────────────────────────
 
@@ -13,6 +14,27 @@ export function getFabricatorRecipe(recipeId: string): FabricatorRecipe | undefi
   return FABRICATOR_RECIPES.find(r => r.id === recipeId);
 }
 
+// ─── Crafting Cost Reduction ──────────────────────────────────────────────────
+
+/**
+ * Returns the current crafting cost reduction percentage from discipline effects.
+ * Spec: actualCost = baseCost × (1 - craftingCostReduction / 100), capped at 75%.
+ */
+export function getCraftingCostReduction(): number {
+  const disciplineEffects = computeDisciplineEffects();
+  const raw = disciplineEffects.bonuses.craftingCostReduction || 0;
+  return Math.min(75, raw);
+}
+
+/**
+ * Apply cost reduction to a material amount, rounding up to ensure
+ * the player never pays more than the displayed reduced cost.
+ */
+export function applyCostReduction(baseAmount: number, costReduction: number): number {
+  if (costReduction <= 0) return baseAmount;
+  return Math.max(1, Math.ceil(baseAmount * (1 - costReduction / 100)));
+}
+
 // ─── Cost Check ───────────────────────────────────────────────────────────────
 
 export interface FabricatorCostCheck {
@@ -26,11 +48,14 @@ export function checkFabricatorCosts(
   materials: Record<string, number>,
   rawMana: number,
   elements: Record<string, ElementState>,
+  costReduction?: number,
 ): FabricatorCostCheck {
+  const reduction = costReduction ?? getCraftingCostReduction();
   const missingMaterials: Record<string, number> = {};
   let canCraft = true;
 
-  for (const [matId, required] of Object.entries(recipe.materials)) {
+  for (const [matId, rawRequired] of Object.entries(recipe.materials)) {
+    const required = applyCostReduction(rawRequired, reduction);
     const available = materials[matId] || 0;
     if (available < required) {
       missingMaterials[matId] = required - available;
@@ -116,9 +141,12 @@ export function refundFabricatorMana(
 export function deductMaterials(
   recipe: FabricatorRecipe,
   materials: Record<string, number>,
+  costReduction?: number,
 ): Record<string, number> {
+  const reduction = costReduction ?? getCraftingCostReduction();
   const newMaterials = { ...materials };
-  for (const [matId, amount] of Object.entries(recipe.materials)) {
+  for (const [matId, rawAmount] of Object.entries(recipe.materials)) {
+    const amount = applyCostReduction(rawAmount, reduction);
     newMaterials[matId] = (newMaterials[matId] || 0) - amount;
     if (newMaterials[matId] <= 0) delete newMaterials[matId];
   }

src/lib/game/data/fabricator-recipes.ts

@@ -236,11 +236,16 @@ export function canCraftRecipe(
   materials: Record<string, number>,
   manaAmount: number,
   manaType?: string,
+  costReduction?: number,
 ): { canCraft: boolean; missingMaterials: Record<string, number>; missingMana: number } {
+  const reduction = costReduction ?? 0;
   const missingMaterials: Record<string, number> = {};
   let canCraft = true;
 
-  for (const [matId, required] of Object.entries(recipe.materials)) {
+  for (const [matId, rawRequired] of Object.entries(recipe.materials)) {
+    const required = reduction > 0
+      ? Math.max(1, Math.ceil(rawRequired * (1 - reduction / 100)))
+      : rawRequired;
     const available = materials[matId] || 0;
     if (available < required) {
       missingMaterials[matId] = required - available;

src/lib/game/stores/pipelines/equipment-crafting.ts

@@ -10,6 +10,8 @@ import {
   deductMaterials,
   makeFabricatorProgress,
   refundFabricatorMana,
+  getCraftingCostReduction,
+  applyCostReduction,
 } from '../../crafting-fabricator';
 import { useManaStore } from '../manaStore';
 import { useCombatStore } from '../combatStore';
@@ -72,11 +74,13 @@ export function cancelEquipmentCrafting(get: GetFn, set: SetFn): void {
       const refunded = refundFabricatorMana(recipe, manaRefund, rawMana, elements);
       useManaStore.setState({ rawMana: refunded.rawMana, elements: refunded.elements });
 
-      // Refund materials
+      // Refund materials — use reduced amounts (what player actually paid)
+      const reduction = getCraftingCostReduction();
       const currentMaterials = get().lootInventory.materials;
       const refundedMaterials = { ...currentMaterials };
-      for (const [matId, amount] of Object.entries(recipe.materials)) {
-        const refundAmount = Math.floor(amount * remainingFraction);
+      for (const [matId, rawAmount] of Object.entries(recipe.materials)) {
+        const reducedAmount = applyCostReduction(rawAmount, reduction);
+        const refundAmount = Math.floor(reducedAmount * remainingFraction);
         if (refundAmount > 0) {
           refundedMaterials[matId] = (refundedMaterials[matId] || 0) + refundAmount;
         }
@@ -132,6 +136,7 @@ export function startFabricatorCrafting(recipeId: string, get: GetFn, set: SetFn
   const deducted = deductFabricatorMana(recipe, rawMana, elements);
   if (!deducted) return false;
 
+  // deductMaterials already applies cost reduction internally via getCraftingCostReduction()
   const newMaterials = deductMaterials(recipe, state.lootInventory.materials);
   const progress = makeFabricatorProgress(recipeId, recipe.equipmentTypeId, recipe.craftTime, recipe.manaCost);