feat(engine): apply profile at game start

packages/chess/src/engine.ts

@@ -69,6 +69,15 @@ import { PIECE_TYPE_REGISTRY } from "./presets/piece-type-registry.js";
 // Importing from the barrel guarantees every preset module's
 // side-effect registration has run before the first engine is created.
 import "./presets/index.js";
+// Side-effect import: registers every modifier descriptor AND the
+// `__modifier-profile-integration__` preset with PRESET_REGISTRY, so
+// the engine can activate it when a profile is supplied.
+import "./modifiers/index.js";
+import {
+  applyProfileToSession,
+  MODIFIER_INTEGRATION_PRESET_ID,
+} from "./modifiers/apply.js";
+import type { ModifierProfile } from "./modifiers/types.js";
 
 type MoveGetter = (session: Session, pieceId: EntityId) => LegalMove[];
 
@@ -299,6 +308,21 @@ class PresetStateImpl<T extends Record<string, unknown>>
 export interface EngineOptions {
   readonly activePresets?: ActivePresetSet;
   readonly layout?: StartingLayout;
+  /**
+   * Optional ModifierProfile to apply at game start. When supplied,
+   * the engine:
+   *   1. Applies the layout (as normal).
+   *   2. Calls `applyProfileToSession(session, profile, layout)` to
+   *      seed all modifier facts on piece entities.
+   *   3. Auto-activates the `__modifier-profile-integration__` preset
+   *      (scope=both, permanent) so CaptureFlags, DirectionAdditions,
+   *      and DamageResistance facts drive actual gameplay.
+   *
+   * Order: profile is applied BEFORE `activePresets` activation, so
+   * preset `onActivate` hooks (e.g. piece-hp seeding Hp) observe any
+   * HpBonus the profile contributed.
+   */
+  readonly profile?: ModifierProfile;
 }
 
 export class ChessEngine {
@@ -421,8 +445,39 @@ export class ChessEngine {
 
     const layout = opts.layout ?? CLASSIC_LAYOUT;
     applyLayout(this.session, layout);
+
+    // Profile seeding runs BEFORE the position is recorded for
+    // threefold repetition — the modifier facts are part of the
+    // "initial position" from a repetition-tracking perspective, and
+    // are not expected to change mid-game (profiles hot-swap via
+    // turn-boundary replacement, which re-seeds).
+    if (opts.profile) {
+      applyProfileToSession(this.session, opts.profile, layout);
+    }
+
     recordPosition(this.session);
     this.activePresets = opts.activePresets ?? new ActivePresetSet();
+
+    // When a profile is present, auto-activate the integration preset
+    // so its filterMoves / getExtraMoves / onDamage hooks fire. We
+    // prepend it to whatever the caller provided so it always runs
+    // FIRST in the preset-iteration order (cheap predicate — cheap to
+    // short-circuit).
+    if (opts.profile) {
+      const existing = this.activePresets.list();
+      this.activePresets.replaceAll([
+        {
+          id: MODIFIER_INTEGRATION_PRESET_ID,
+          scope: "both",
+          turnsRemaining: null,
+        },
+        ...existing.map((e) => ({
+          id: e.id,
+          scope: e.scope,
+          turnsRemaining: e.turnsRemaining,
+        })),
+      ]);
+    }
   }
 
   /**