Add per-game adventure text with RAG-based retrieval

Players can now paste the full text of a freely available adventure
when creating a game, and the DM will follow it instead of inventing
its own plot/NPCs/locations. Reuses the existing rulebook RAG
pipeline (chunking, local embedding) rather than injecting the raw
text into every turn, since real adventure modules range from a few
pages to hundreds — far beyond what fits in a prompt.

- New adventure_chunks table (game-scoped, unlike the global
  rulebook_chunks) + Game.adventure_text storing the raw source.
- ingest_adventure_text() chunks/embeds synchronously during
  POST /api/games when adventure_text is non-empty.
- build_adventure_rag_block() retrieves by similarity to the latest
  player message, scoped to game_id — plus always includes chunk 0
  (the adventure's opening) regardless of the query, since early
  Session-0 messages rarely resemble the adventure's actual hook and
  pure similarity search could miss the beginning entirely.
- System prompt instructs the DM to follow provided adventure
  excerpts strictly, deviating only when players clearly go off-script.
- Frontend: optional adventure-text field in the game creation form,
  a has_adventure flag surfaced as a small badge on the game card and
  session header.

Verified with an isolated two-game test that chunks/retrieval never
leak across games (the critical failure mode here), and live against
x.ai: a custom-written one-shot's specific NPCs, location, and hook
appeared verbatim in the DM's opening scene instead of invented ones.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/api/games.ts

@@ -14,6 +14,7 @@ export interface Game {
   my_character_id: string | null;
   status: "active" | "ended";
   ended_reason: string | null;
+  has_adventure: boolean;
 }
 
 export interface Message {
@@ -47,8 +48,11 @@ export const runGameSetupChat = (messages: Record<string, unknown>[], signal?: A
     signal,
   });
 
-export const createGame = (name: string, description: string) =>
-  apiFetch<Game>("/api/games", { method: "POST", body: JSON.stringify({ name, description }) });
+export const createGame = (name: string, description: string, adventureText?: string) =>
+  apiFetch<Game>("/api/games", {
+    method: "POST",
+    body: JSON.stringify({ name, description, adventure_text: adventureText ?? "" }),
+  });
 
 export const getGame = (id: string) => apiFetch<Game>(`/api/games/${id}`);
 

frontend/src/components/GameCard.tsx

@@ -58,6 +58,7 @@ export default function GameCard({ game }: { game: Game }) {
           {game.player_count} Spieler
           {game.player_names.length > 0 && `: ${game.player_names.join(", ")}`}
         </span>
+        {game.has_adventure && <span>📖 Eigenes Abenteuer</span>}
       </div>
     </Link>
   );

frontend/src/components/GameSetupChat.tsx

@@ -15,6 +15,7 @@ export default function GameSetupChat({ onCreated }: { onCreated: (game: Game) =
   const [proposal, setProposal] = useState<GameSetupProposal | null>(null);
   const [name, setName] = useState("");
   const [description, setDescription] = useState("");
+  const [adventureText, setAdventureText] = useState("");
   const [loading, setLoading] = useState(true);
   const [creating, setCreating] = useState(false);
   const [error, setError] = useState<string | null>(null);
@@ -76,7 +77,7 @@ export default function GameSetupChat({ onCreated }: { onCreated: (game: Game) =
     setCreating(true);
     setError(null);
     try {
-      const game = await createGame(name, description);
+      const game = await createGame(name, description, adventureText);
       onCreated(game);
     } catch {
       setError("Spiel konnte nicht erstellt werden.");
@@ -120,13 +121,30 @@ export default function GameSetupChat({ onCreated }: { onCreated: (game: Game) =
             className="rounded bg-slate-800 px-3 py-2 outline-none focus:ring-2 focus:ring-amber-400"
             rows={3}
           />
+          <div>
+            <textarea
+              placeholder="Abenteuertext (optional) — vollständiger Text eines frei verfügbaren Abenteuers"
+              value={adventureText}
+              onChange={(e) => setAdventureText(e.target.value)}
+              className="w-full rounded bg-slate-800 px-3 py-2 font-mono text-xs outline-none focus:ring-2 focus:ring-amber-400"
+              rows={6}
+            />
+            <p className="mt-1 text-xs text-slate-500">
+              Wenn hier etwas steht, hält sich der Dungeon Master strikt an diesen Text (Handlung, NPCs,
+              Orte, Encounter) statt eigene Inhalte zu erfinden.
+            </p>
+          </div>
           {error && <p className="text-sm text-red-400">{error}</p>}
           <button
             type="submit"
             disabled={creating}
             className="self-start rounded bg-amber-500 px-4 py-2 text-sm font-semibold text-slate-950 hover:bg-amber-400 disabled:opacity-50"
           >
-            {creating ? "Erstelle…" : "Erstellen"}
+            {creating
+              ? adventureText.trim()
+                ? "Erstelle… (Abenteuertext wird verarbeitet, kann etwas dauern)"
+                : "Erstelle…"
+              : "Erstellen"}
           </button>
         </form>
       )}

frontend/src/pages/GameSession.tsx

@@ -163,7 +163,9 @@ export default function GameSession() {
     <div className="mx-auto flex h-[calc(100vh-56px)] max-w-6xl flex-col px-4 py-4">
       <div className="mb-3 flex items-center justify-between">
         <div>
-          <h1 className="text-xl font-bold text-amber-400">{game.name}</h1>
+          <h1 className="text-xl font-bold text-amber-400">
+            {game.name} {game.has_adventure && <span className="text-sm font-normal">📖</span>}
+          </h1>
           <p className="text-xs text-slate-500">{game.description}</p>
         </div>
         <div className="flex gap-2">