update design

design/registry/entities.yaml

@@ -108,6 +108,39 @@ entries:
     source: design/gdd/shop.md
     description: Hard cap on player gold. AddGold silently discards excess above this value.
 
+  # ─── Tag System (design/gdd/tag-system.md) ───────────────────────────────
+
+  - name: MaxEffectiveStack
+    type: constant
+    value: 3
+    unit: stacks
+    source: design/gdd/tag-system.md
+    description: Cap on effective Fire DOT stack count. Clamps TotalStack to prevent runaway burn damage.
+
+  - name: FireDOTDamageFormula
+    type: formula
+    variables:
+      - name: BaseBurnDamage
+        symbol: B
+        type: float
+        description: Base burn damage per tick from TagConfig.txt ParamJson
+      - name: TotalStack
+        symbol: S
+        type: int
+        description: Tag occurrence count (1–3) on the tower
+      - name: MaxEffectiveStack
+        symbol: M
+        type: int
+        description: Cap on effective stack; currently 3
+      - name: SeverityBonus
+        symbol: sev
+        type: float
+        description: From enemy debuff state; 0 if no other modifiers
+    output:
+      range: float
+      description: "FinalBurnDamagePerTick = B × Clamp(S, 1, M) × (1 + sev)"
+    source: design/gdd/tag-system.md
+
   # ─── Event System (design/gdd/event-system.md) ────────────────────────
 
   - name: EventSelectionSeedFormula