refactor(modifiers): use baseAttr for preset source mapping

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

.sisyphus/notepads/polish-t2/learnings.md

@@ -64,3 +64,8 @@ Probable file: add test to `solo-smoke.spec.ts` (T2 added it as the canary) or e
 
 - Implemented the adapter path in `modifiers/registry.ts`: stored descriptors now wrap typed `apply/describe` in `unknown`-accepting closures at registration time.
 - Result: removed the `descriptor as unknown as ModifierDescriptor` storage cast; `schema.ts` parse return also reduced from double-cast to `as ModifierProfile`.
+
+## [2026-04-19 14:01] Task: commit-3 preset source attribution
+
+- Added optional `baseAttr?: ChessAttrKey` to `ModifierDescriptor` and set `hp-bonus` to `baseAttr: "Hp"`.
+- Removed hardcoded `HpBonus`/`RangeBonus` aliasing from `getModifierSource`; source matching now uses `descriptor.baseAttr ?? descriptor.attrName` directly.

packages/chess/src/modifiers/descriptors/hp-bonus.ts

@@ -9,6 +9,7 @@ type Value = z.infer<typeof schema>;
 const descriptor: ModifierDescriptor<Value> = {
   id: "hp-bonus",
   attrName: "HpBonus",
+  baseAttr: "Hp",
   label: "HP Bonus",
   valueSchema: schema,
   stackingRule: "additive",

packages/chess/src/modifiers/source.ts

@@ -32,7 +32,7 @@ export function getModifierSource(
     // 1. Check per-instance modifiers
     if (algebraicSq) {
       const instanceMatch = profile.perInstance.find(
-        (m) => m.kind === modifierKind && m.square === algebraicSq
+        (m) => m.kind === modifierKind && m.square === algebraicSq,
       );
       if (instanceMatch) {
         return { kind: "per-instance", square: instanceMatch.square };
@@ -45,7 +45,7 @@ export function getModifierSource(
         (m) =>
           m.kind === modifierKind &&
           m.pieceType === pieceType &&
-          (m.color === "both" || m.color === color)
+          (m.color === "both" || m.color === color),
       );
       if (typeMatch) {
         return { kind: "per-type", pieceType: typeMatch.pieceType, color: typeMatch.color };
@@ -56,13 +56,10 @@ export function getModifierSource(
   // 3. Check active presets
   const descriptor = MODIFIER_REGISTRY.get(modifierKind);
   if (descriptor) {
-    let attrName = descriptor.attrName as string;
-    if (attrName === "HpBonus") attrName = "Hp";
-    else if (attrName === "RangeBonus") attrName = "Range";
-    
+    const presetAttr = descriptor.baseAttr ?? descriptor.attrName;
     for (const presetEntry of engine.activePresets.list()) {
       const def = PRESET_REGISTRY.get(presetEntry.id);
-      if (def?.pieceAttributes?.includes(attrName as keyof import("../schema.js").ChessAttrMap)) {
+      if (def?.pieceAttributes?.includes(presetAttr)) {
         return { kind: "preset", presetId: presetEntry.id, presetName: def.name };
       }
     }

packages/chess/src/modifiers/types.ts

@@ -98,6 +98,17 @@ export interface ModifierDescriptor<V = unknown> {
   readonly id: ModifierKindId;
   /** The ChessAttrMap key this modifier seeds on piece entities. */
   readonly attrName: ChessAttrKey;
+  /**
+   * Optional: the base piece attribute this modifier augments. When set,
+   * `getModifierSource` uses this (not `attrName`) to match against a
+   * preset's `pieceAttributes` list — e.g. `hp-bonus` augments the `Hp`
+   * attribute declared by the `piece-hp` preset, even though the
+   * modifier itself writes to `HpBonus`.
+   *
+   * Omit for modifiers whose `attrName` is the authoritative attribute
+   * (no preset declares it separately).
+   */
+  readonly baseAttr?: ChessAttrKey;
   /** Human-readable display label for UI. */
   readonly label: string;
   /** Zod schema for the value field — used for validation and UI form generation. */