Guard against duplicate narrative entries

tools/engine_lib/state.py

@@ -112,8 +112,6 @@ def validate_update_size(name: str, new_content: str, path: Path) -> bool:
 
 def apply_state(result: TurnResult) -> None:
     """Write state changes from a TurnResult to disk."""
-    if result.ambience:
-        AMBIENCE_PATH.write_text(result.ambience.strip().lower() + "\n")
     if result.changes:
         CHANGES_PATH.write_text("\n".join(result.changes) + "\n")
     else:

tools/engine_lib/tools_handler.py

@@ -4,8 +4,8 @@ import json
 import random
 import re
 
-from .paths import CHAR_PATH, WORLD_PATH
-from .state import read_file, validate_update_size, update_journal, append_llm_log
+from .paths import AMBIENCE_PATH, CHAR_PATH, WORLD_PATH
+from .state import read_file, validate_update_size, update_journal, append_llm_log, get_valid_ambiences
 
 
 TOOL_REGISTRY: dict[str, dict] = {
@@ -168,6 +168,20 @@ def tool_journal_update(args: dict) -> str:
     return "Journal updated."
 
 
+def tool_finalize_turn(args: dict) -> str:
+    """Validate ambience and write to AMBIENCE_PATH."""
+    raw = (args or {}).get("ambience", "").strip().lower()
+    if not raw:
+        AMBIENCE_PATH.write_text("silence\n")
+        return "Ambience set to silence."
+    valid = get_valid_ambiences()
+    if raw not in valid:
+        append_llm_log(f"\n[WARN] invalid ambience '{raw}', allowed: {sorted(valid)}")
+        return f"**Error:** invalid ambience '{raw}'. Allowed: {', '.join(sorted(valid))}."
+    AMBIENCE_PATH.write_text(raw + "\n")
+    return f"Ambience set to {raw}."
+
+
 def execute_tool(tool_name: str, args: dict) -> str:
     """Execute a tool by name. Returns result string."""
     fn_map = {
@@ -181,6 +195,7 @@ def execute_tool(tool_name: str, args: dict) -> str:
         "replace_note": tool_replace_note,
         "world_update": tool_world_update,
         "journal_update": tool_journal_update,
+        "finalize_turn": tool_finalize_turn,
     }
     fn = fn_map.get(tool_name)
     if not fn:
@@ -227,6 +242,9 @@ def describe_change(tool_name: str, args: dict) -> str:
         for d in args.get("done", []):
             parts.append(f"✅ {d}")
         return "; ".join(parts) if parts else ""
+    elif tool_name == "finalize_turn":
+        a = args.get("ambience", "")
+        return f"♫ {a}" if a else ""
     return ""