feat(config): default to WebSocket and migrate saved HTTP settings

apps/admin_console/services/model_settings_service.py

@@ -1,20 +1,18 @@
 """Persist the single Responses endpoint without returning credentials to the browser."""
 
-import os
-import tempfile
-import threading
-from pathlib import Path
 from typing import Literal
 from urllib.parse import urlsplit
 
 from pydantic import BaseModel, Field, SecretStr, field_validator
 
 from artemis.config.agent import load_agent_config
+from artemis.config.environment import (
+    persist_environment as write_environment,
+    TRANSPORT_DEFAULT_VERSION_KEY,
+)
 from artemis.config.paths import get_env_file
 from artemis.config.settings import settings
 
-_write_lock = threading.Lock()
-
 
 class ModelSettingsUpdate(BaseModel):
     base_url: str = "https://api-n-cd.playones.com/v1"
@@ -118,6 +116,8 @@ def save_model_settings(update: ModelSettingsUpdate) -> dict:
         value = getattr(update, field_name)
         if value is not None:
             values[env_name] = str(value)
+    if update.transport is not None:
+        values[TRANSPORT_DEFAULT_VERSION_KEY] = "1"
     if update.api_key and update.api_key.get_secret_value().strip():
         values["OPENAI_API_KEY"] = update.api_key.get_secret_value().strip()
     persist_environment(values)
@@ -142,31 +142,7 @@ def save_model_settings(update: ModelSettingsUpdate) -> dict:
 
 
 def persist_environment(values: dict[str, str]) -> None:
-    with _write_lock:
-        env_path = get_env_file()
-        env_path.parent.mkdir(parents=True, exist_ok=True)
-        original = env_path.read_text(encoding="utf-8") if env_path.exists() else ""
-        # Preserve comments and unrelated variables; quote values to avoid dotenv interpolation.
-        kept = [
-            line
-            for line in original.splitlines()
-            if line.removeprefix("export ").split("=", 1)[0].strip() not in values
-        ]
-        for key, value in values.items():
-            escaped = value.replace("\\", "\\\\").replace("'", "\\'")
-            kept.append(f"{key}='{escaped}'")
-        content = "\n".join(kept) + "\n"
-        fd, temp_name = tempfile.mkstemp(prefix=".env-", dir=env_path.parent)
-        try:
-            with os.fdopen(fd, "w", encoding="utf-8", newline="\n") as stream:
-                stream.write(content)
-                stream.flush()
-                os.fsync(stream.fileno())
-            os.replace(temp_name, env_path)
-        finally:
-            Path(temp_name).unlink(missing_ok=True)
-        for key, value in values.items():
-            os.environ[key] = value
+    write_environment(get_env_file(), values)
 
 
 class CapabilitySettings(BaseModel):