fix: explicit JSON template for NPC gen + improved chat memory (20 turns)

index.html

@@ -751,7 +751,7 @@
       removeMessage(typingId);
       appendDisplay("npc", response);
       chatHistory.push({ role: "user", content: userText }, { role: "assistant", content: response });
-      chatHistory = chatHistory.slice(-20);
+      chatHistory = chatHistory.slice(-40); // keep 40 messages for richer NPC memory
       messageCount    = new_msg_count;
       unlockedSecrets = Array.from(new Set([...unlockedSecrets, ...newly_unlocked]));
       updateFriendship(friendship_label, friendship_pct);

model_engine.py

@@ -263,49 +263,74 @@ def analyze_image(image_path: str) -> str:
 
 def _npc_generation_prompt(description: str) -> str:
     """Build the primary JSON-only NPC generation prompt."""
-    return f"""
-SYSTEM: You are the NPCverse character engine. Transform the visual description
-into a vivid RPG character while preserving factual visual inspiration.
-
-Return ONLY valid JSON. Do not include backticks, markdown, comments, or preamble.
-
-Required JSON keys:
-name, title, class, level, rarity, alignment, lore, stats, passive_ability,
-ultimate, weakness, faction, world, opening_line, quests, secrets, emoji.
-
-Rules:
-- level must be an integer.
-- stats must be a dict with integer values from 1 to 100 for exactly:
-  strength, intelligence, charisma, luck, stealth, chaos.
-- passive_ability must be a dict with keys: name, description.
-- ultimate must be a dict with keys: name, description.
-- quests must be a list of exactly 3 dicts, each with keys:
-  title, description, reward, rarity.
-- secrets must be a list of exactly 3 strings.
-- emoji must be a single emoji character.
-
-Visual description:
-{description}
-""".strip()
+    return f"""You are the NPCverse character engine. Transform the visual description below into a vivid RPG character.
+
+Return ONLY a valid JSON object. No backticks, no markdown, no extra text before or after.
+
+You MUST include every single key shown in the template below. Do not skip any key.
+
+JSON template (replace all placeholder values):
+{{
+  "name": "<unique fantasy name inspired by appearance>",
+  "title": "<short evocative title, e.g. 'Wanderer of the Neon Wilds'>",
+  "class": "<creative RPG class name>",
+  "level": <integer 1-20>,
+  "rarity": "<one of: Common, Uncommon, Rare, Epic, Legendary>",
+  "alignment": "<e.g. Chaotic Good, Lawful Neutral, True Neutral>",
+  "lore": "<2-3 sentence backstory inspired by their appearance>",
+  "stats": {{
+    "strength": <1-100>,
+    "intelligence": <1-100>,
+    "charisma": <1-100>,
+    "luck": <1-100>,
+    "stealth": <1-100>,
+    "chaos": <1-100>
+  }},
+  "passive_ability": {{
+    "name": "<passive skill name>",
+    "description": "<what it does>"
+  }},
+  "ultimate": {{
+    "name": "<ultimate skill name>",
+    "description": "<what it does>"
+  }},
+  "weakness": "<one sentence describing their weakness or flaw>",
+  "faction": "<name of the group or faction they belong to>",
+  "world": "<name of the realm or world they come from>",
+  "opening_line": "<first thing they say when summoned, in character, 1-2 sentences>",
+  "quests": [
+    {{"title": "<quest 1 title>", "description": "<quest 1 desc>", "reward": "<item name>", "rarity": "Common"}},
+    {{"title": "<quest 2 title>", "description": "<quest 2 desc>", "reward": "<item name>", "rarity": "Rare"}},
+    {{"title": "<quest 3 title>", "description": "<quest 3 desc>", "reward": "<item name>", "rarity": "Epic"}}
+  ],
+  "secrets": [
+    "<secret 1 about this character>",
+    "<secret 2 about this character>",
+    "<secret 3 about this character>"
+  ],
+  "emoji": "<single emoji that represents this character>"
+}}
+
+Visual description to transform:
+{description}""".strip()
 
 
 def _npc_retry_prompt(description: str) -> str:
     """Build a shorter strict prompt for retrying malformed JSON."""
-    return f"""
-Return ONLY one valid JSON object for an RPG NPC based on this description:
-{description}
+    return f"""Output ONLY a valid JSON object. No markdown. No extra text.
+
+Create an RPG character from this description: {description}
 
-Use exactly these top-level keys:
-name, title, class, level, rarity, alignment, lore, stats, passive_ability,
-ultimate, weakness, faction, world, opening_line, quests, secrets, emoji.
+Required JSON — include ALL these keys:
+{{"name":"","title":"","class":"","level":1,"rarity":"Common","alignment":"","lore":"",
+"stats":{{"strength":50,"intelligence":50,"charisma":50,"luck":50,"stealth":50,"chaos":50}},
+"passive_ability":{{"name":"","description":""}},
+"ultimate":{{"name":"","description":""}},
+"weakness":"","faction":"","world":"","opening_line":"",
+"quests":[{{"title":"","description":"","reward":"","rarity":"Common"}},{{"title":"","description":"","reward":"","rarity":"Rare"}},{{"title":"","description":"","reward":"","rarity":"Epic"}}],
+"secrets":["","",""],"emoji":"⚔"}}
 
-stats keys: strength, intelligence, charisma, luck, stealth, chaos.
-passive_ability keys: name, description.
-ultimate keys: name, description.
-quests: exactly 3 objects with title, description, reward, rarity.
-secrets: exactly 3 strings.
-No markdown. No extra text.
-""".strip()
+Fill in all empty string values with creative content based on the description.""".strip()
 
 
 @spaces.GPU
@@ -356,7 +381,7 @@ def _normalize_history(history: list) -> list[dict[str, str]]:
     """Convert common Gradio chat history formats into MiniCPM messages."""
     normalized: list[dict[str, str]] = []
 
-    for exchange in history[-10:]:
+    for exchange in history[-20:]:  # keep last 20 turns for richer memory
         if isinstance(exchange, dict):
             role = exchange.get("role")
             content = exchange.get("content")
@@ -389,8 +414,7 @@ def chat_respond(
         friendship_label = get_friendship_label(msg_count)
         passive = npc.get("passive_ability", DEFAULT_NPC["passive_ability"])
 
-        system_prompt = f"""
-You are {npc_name}, an NPC in NPCverse. ALWAYS stay in character.
+        system_prompt = f"""You are {npc_name}, an NPC in NPCverse. ALWAYS stay in character.
 
 Name: {npc_name}
 Class: {npc.get("class", DEFAULT_NPC["class"])}
@@ -403,9 +427,15 @@ Current friendship level: {friendship_label}
 Unlocked secrets by index:
 {_format_unlocked_secrets(npc, unlocked_secrets)}
 
+IMPORTANT memory rules:
+- You have access to the full conversation history below. Read it carefully.
+- Remember everything the user has told you (their name, choices, quests, preferences).
+- Reference past exchanges naturally — if they told you their name, use it; if they completed a quest, acknowledge it.
+- Never contradict something you said earlier in this conversation.
+- Stay consistent with your established personality throughout.
+
 Respond naturally as this character. Keep replies concise, flavorful, and interactive.
-Never say you are an AI model or break character.
-""".strip()
+Never say you are an AI model or break character.""".strip()
 
         msgs = [
             {"role": "user", "content": [{"type": "text", "text": system_prompt}]},