refactor(config): improve config loading with validation and error handling

- Replace inline config loading with dedicated functions `_load_config` and `_get_section` (or `_get_base_urls`).
- Add explicit error handling for missing files, invalid JSON, and I/O errors.
- Validate config structure and section types to provide clear runtime errors.
- Centralize logic to avoid code duplication across modules.

cli/utils.py

@@ -1,6 +1,6 @@
 import json
 from pathlib import Path
-from typing import List, Optional, Tuple, Dict
+from typing import List
 
 import questionary
 from rich.console import Console
@@ -10,17 +10,50 @@ from cli.models import AnalystType
 console = Console()
 
 CONFIG_PATH = Path(__file__).resolve().parents[1] / "config.json"
-with CONFIG_PATH.open("r", encoding="utf-8") as config_file:
-    CONFIG = json.load(config_file)
 
-BASE_URLS = [(display, url) for display, url in CONFIG["BASE_URLS"]]
+def _exit_with_config_error(message: str) -> None:
+    console.print(f"\n[red]{message}[/red]")
+    exit(1)
+
+
+def _load_config() -> dict:
+    try:
+        with CONFIG_PATH.open("r", encoding="utf-8") as config_file:
+            return json.load(config_file)
+    except FileNotFoundError:
+        _exit_with_config_error(f"Config file not found: {CONFIG_PATH}")
+    except json.JSONDecodeError as exc:
+        _exit_with_config_error(f"Invalid JSON in config file: {exc}")
+    except OSError as exc:
+        _exit_with_config_error(f"Unable to read config file: {exc}")
+    return {}
+
+
+def _get_config_section(config: dict, key: str, expected_type: type):
+    value = config.get(key)
+    if not isinstance(value, expected_type):
+        _exit_with_config_error(
+            f"Invalid or missing '{key}' in config file: {CONFIG_PATH}"
+        )
+    return value
+
+
+CONFIG = _load_config()
+BASE_URLS = [
+    (display, url)
+    for display, url in _get_config_section(CONFIG, "BASE_URLS", list)
+]
 DEEP_AGENT_OPTIONS = {
-    provider: [(display, value) for display, value in options]
-    for provider, options in CONFIG["DEEP_AGENT_OPTIONS"].items()
+    provider: [(display, model) for display, model in options]
+    for provider, options in _get_config_section(
+        CONFIG, "DEEP_AGENT_OPTIONS", dict
+    ).items()
 }
 SHALLOW_AGENT_OPTIONS = {
-    provider: [(display, value) for display, value in options]
-    for provider, options in CONFIG["SHALLOW_AGENT_OPTIONS"].items()
+    provider: [(display, model) for display, model in options]
+    for provider, options in _get_config_section(
+        CONFIG, "SHALLOW_AGENT_OPTIONS", dict
+    ).items()
 }
 
 TICKER_INPUT_EXAMPLES = "Examples: SPY, CNC.TO, 7203.T, 0700.HK"

tradingagents/default_config.py

@@ -3,11 +3,37 @@ import os
 from pathlib import Path
 
 CONFIG_PATH = Path(__file__).resolve().parents[1] / "config.json"
-with CONFIG_PATH.open("r", encoding="utf-8") as config_file:
-    CONFIG = json.load(config_file)
 
-DEFAULT_LLM_SETTINGS = CONFIG.get("DEFAULT_LLM_SETTINGS", {})
-BASE_URLS = {display.lower(): url for display, url in CONFIG.get("BASE_URLS", [])}
+
+def _load_config() -> dict:
+    try:
+        with CONFIG_PATH.open("r", encoding="utf-8") as config_file:
+            config = json.load(config_file)
+    except FileNotFoundError as exc:
+        raise RuntimeError(f"Config file not found: {CONFIG_PATH}") from exc
+    except json.JSONDecodeError as exc:
+        raise RuntimeError(f"Invalid JSON in config file: {CONFIG_PATH}") from exc
+    except OSError as exc:
+        raise RuntimeError(f"Unable to read config file: {CONFIG_PATH}") from exc
+
+    if not isinstance(config, dict):
+        raise RuntimeError(f"Invalid config format in file: {CONFIG_PATH}")
+    return config
+
+
+def _get_section(config: dict, key: str, expected_type: type):
+    section = config.get(key)
+    if not isinstance(section, expected_type):
+        raise RuntimeError(f"Invalid or missing '{key}' in config file: {CONFIG_PATH}")
+    return section
+
+
+CONFIG = _load_config()
+DEFAULT_LLM_SETTINGS = _get_section(CONFIG, "DEFAULT_LLM_SETTINGS", dict)
+BASE_URLS = {
+    display.lower(): url
+    for display, url in _get_section(CONFIG, "BASE_URLS", list)
+}
 DEFAULT_PROVIDER = DEFAULT_LLM_SETTINGS.get("llm_provider", "openai").lower()
 DEFAULT_BACKEND_URL = BASE_URLS.get(
     DEFAULT_PROVIDER, BASE_URLS.get("openai", "https://api.openai.com/v1")

tradingagents/llm_clients/openai_client.py

@@ -28,14 +28,46 @@ _PASSTHROUGH_KWARGS = (
 )
 
 CONFIG_PATH = Path(__file__).resolve().parents[2] / "config.json"
-with CONFIG_PATH.open("r", encoding="utf-8") as config_file:
-    CONFIG = json.load(config_file)
+
+
+def _load_config() -> dict:
+    try:
+        with CONFIG_PATH.open("r", encoding="utf-8") as config_file:
+            config = json.load(config_file)
+    except FileNotFoundError as exc:
+        raise RuntimeError(f"Config file not found: {CONFIG_PATH}") from exc
+    except json.JSONDecodeError as exc:
+        raise RuntimeError(f"Invalid JSON in config file: {CONFIG_PATH}") from exc
+    except OSError as exc:
+        raise RuntimeError(f"Unable to read config file: {CONFIG_PATH}") from exc
+
+    if not isinstance(config, dict):
+        raise RuntimeError(f"Invalid config format in file: {CONFIG_PATH}")
+    return config
+
+
+def _get_base_urls(config: dict) -> dict[str, str]:
+    base_urls = config.get("BASE_URLS")
+    if not isinstance(base_urls, list):
+        raise RuntimeError(f"Invalid or missing 'BASE_URLS' in config file: {CONFIG_PATH}")
+
+    mapped_urls: dict[str, str] = {}
+    for item in base_urls:
+        if (
+            isinstance(item, list)
+            and len(item) == 2
+            and isinstance(item[0], str)
+            and isinstance(item[1], str)
+        ):
+            mapped_urls[item[0].lower()] = item[1]
+    return mapped_urls
+
+
+CONFIG = _load_config()
 
 load_dotenv()
 
-_BASE_URLS = {
-    display.lower(): url for display, url in CONFIG.get("BASE_URLS", [])
-}
+_BASE_URLS = _get_base_urls(CONFIG)
 _PROVIDER_BASE_URLS = {
     "xai": _BASE_URLS.get("xai", "https://api.x.ai/v1"),
     "openrouter": _BASE_URLS.get("openrouter", "https://openrouter.ai/api/v1"),
@@ -68,7 +100,7 @@ class OpenAIClient(BaseLLMClient):
 
     def get_llm(self) -> Any:
         """Return configured ChatOpenAI instance."""
-        llm_kwargs = {"model": self.model}
+        llm_kwargs: dict[str, Any] = {"model": self.model}
 
         # Provider-specific base URL and auth
         if self.provider in _PROVIDER_BASE_URLS: