Automatically deploy the lowest available lobby with exact ID preview

src/lib/server/fleet/create.ts

@@ -48,7 +48,7 @@ export interface CreateServerInput {
     gameMode: GameMode;   // 'zombie' — only value supported today
     mapSlug: string;      // 'cosmodrome'
     plutoKey?: string;    // saved for this server ID when supplied
-    lobby?: number;      // explicit stable identity; otherwise first available
+    expectedName?: string; // optional preview guard; never selects a lobby
     createdBy?: string;   // 'ui' by default
 }
 
@@ -160,15 +160,14 @@ async function createServerUnlocked(input: CreateServerInput): Promise<CreateSer
     }
 
     const baseName = `t5_${input.gameMode}_${mapEntry.slug}`;
-    if (input.lobby !== undefined && (!Number.isInteger(input.lobby) || input.lobby < 1 || input.lobby > 20)) {
-        return { ok: false, kind: 'bad-request', message: 'Lobby must be an integer from 1 to 20' };
-    }
-    const lobby = input.lobby ?? nextLobbyNumber(baseName);
+    const lobby = nextLobbyNumber(baseName);
     if (lobby === null) {
         return { ok: false, kind: 'no-slot', message: `all lobby slots (1..20) for ${baseName} are taken` };
     }
     const name = `${baseName}_${lobby}`;
-    if (getServer(name)) return { ok: false, kind: 'no-slot', message: `${name} is already deployed` };
+    if (input.expectedName !== undefined && input.expectedName !== name) {
+        return { ok: false, kind: 'no-slot', message: 'Available lobby changed. Review the updated server ID and key, then deploy again.' };
+    }
     const plutoKey = input.plutoKey?.trim() || getServerKey(name);
     if (!plutoKey) return { ok: false, kind: 'bad-request', message: `No saved key for ${name}. Enter a Plutonium server key.` };