fix: harden responses streaming and tool-call fallback

Ensure /v1/responses streams always terminate with response.completed and normalize Lingma tool_code fallbacks into structured tool calls, including single-argument forms.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/config.py

@@ -5,6 +5,11 @@ import os
 from dataclasses import dataclass, field
 
 
+
+def _csv_env(raw: str) -> list[str]:
+    return [item.strip() for item in (raw or "").replace("\n", ",").split(",") if item.strip()]
+
+
 @dataclass
 class LingmaAccount:
     username: str
@@ -45,6 +50,7 @@ class Settings:
     session_cache_max_entries: int = 256
     session_cache_ttl_sec: float = 1800.0
     tool_forward_enabled: bool = False
+    tool_allowlist: list[str] = field(default_factory=list)
 
 
 def _bool_env(name: str, default: bool) -> bool:
@@ -177,4 +183,5 @@ def load_settings() -> Settings:
         session_cache_max_entries=int(os.getenv("SESSION_CACHE_MAX_ENTRIES", "256")),
         session_cache_ttl_sec=float(os.getenv("SESSION_CACHE_TTL_SEC", "1800")),
         tool_forward_enabled=_bool_env("TOOL_FORWARD_ENABLED", False),
+        tool_allowlist=_csv_env(os.getenv("TOOL_ALLOWLIST", "")),
     )