Complete instant diplomacy response parity

app/game-api/src/maps/mapDefinition.ts

@@ -0,0 +1,37 @@
+import fs from 'node:fs/promises';
+import { existsSync } from 'node:fs';
+import path from 'node:path';
+
+import { MapDefinitionSchema, type MapDefinition } from '@sammo-ts/logic';
+
+const resolveWorkspaceRoot = (): string => {
+    let current = path.resolve(process.cwd());
+    for (let depth = 0; depth <= 6; depth += 1) {
+        if (existsSync(path.join(current, 'pnpm-workspace.yaml'))) {
+            return current;
+        }
+        const parent = path.dirname(current);
+        if (parent === current) {
+            break;
+        }
+        current = parent;
+    }
+    return path.resolve(process.cwd());
+};
+
+const RESOURCE_MAP_ROOT = path.resolve(resolveWorkspaceRoot(), 'resources/map');
+const mapCache = new Map<string, MapDefinition>();
+
+export const loadMapDefinitionByName = async (mapName: string): Promise<MapDefinition> => {
+    if (!/^[a-zA-Z0-9_-]+$/.test(mapName)) {
+        throw new Error(`Invalid map name: ${mapName}`);
+    }
+    const cached = mapCache.get(mapName);
+    if (cached) {
+        return cached;
+    }
+    const raw = await fs.readFile(path.join(RESOURCE_MAP_ROOT, `map_${mapName}.json`), 'utf-8');
+    const map = MapDefinitionSchema.parse(JSON.parse(raw));
+    mapCache.set(mapName, map);
+    return map;
+};