fix: --config flag now fully overrides ~/.strix/cli-config.json (#457)

* fix: --config flag now fully overrides ~/.strix/cli-config.json (fixes #377)

Previously, env vars applied from the default config at module import time
were not cleared when --config was later processed, causing settings from
~/.strix/cli-config.json to leak into runs that specified a custom config.

Track which vars were applied by the initial default-config load in
Config._applied_from_default. In apply_config_override, clear those vars
before applying the custom config so only the custom file's settings take effect.

* Add config override regression test

* Make config override test setup explicit

---------

Co-authored-by: octo-patch <octo-patch@github.com>
Co-authored-by: bearsyankees <bearsyankees@gmail.com>

strix/config/config.py

@@ -2,7 +2,7 @@ import contextlib
 import json
 import os
 from pathlib import Path
-from typing import Any
+from typing import Any, ClassVar
 
 
 STRIX_API_BASE = "https://models.strix.ai/api/v1"
@@ -56,6 +56,10 @@ class Config:
     # Config file override (set via --config CLI arg)
     _config_file_override: Path | None = None
 
+    # Tracks env vars set by the initial default-config load so they can be
+    # cleared when a --config override is later applied (avoids leakage).
+    _applied_from_default: ClassVar[dict[str, str]] = {}
+
     @classmethod
     def _tracked_names(cls) -> list[str]:
         return [
@@ -151,6 +155,11 @@ class Config:
                 os.environ[var_name] = var_value
                 applied[var_name] = var_value
 
+        # Record what was applied from the default config so it can be cleared
+        # if a --config override is later provided (prevents leakage).
+        if cls._config_file_override is None and not force:
+            cls._applied_from_default = applied
+
         return applied
 
     @classmethod

strix/interface/main.py

@@ -6,6 +6,7 @@ Strix Agent Interface
 import argparse
 import asyncio
 import logging
+import os
 import shutil
 import sys
 from pathlib import Path
@@ -528,6 +529,12 @@ def pull_docker_image() -> None:
 
 
 def apply_config_override(config_path: str) -> None:
+    # Clear env vars that were automatically applied from the default config file
+    # so they don't leak into the custom config context.
+    for var_name in Config._applied_from_default:
+        os.environ.pop(var_name, None)
+    Config._applied_from_default = {}
+
     Config._config_file_override = validate_config_file(config_path)
     apply_saved_config(force=True)
 

tests/config/test_config_override.py

@@ -0,0 +1,31 @@
+import json
+import os
+
+from strix.config.config import Config, apply_saved_config
+
+
+def test_apply_config_override_clears_default_only_vars(monkeypatch, tmp_path) -> None:
+    from strix.interface.main import apply_config_override
+
+    default_cfg = tmp_path / "cli-config.json"
+    default_cfg.write_text(
+        json.dumps({"env": {"LLM_API_BASE": "https://default.api", "STRIX_LLM": "default-model"}}),
+        encoding="utf-8",
+    )
+    custom_cfg = tmp_path / "custom.json"
+    custom_cfg.write_text(json.dumps({"env": {"STRIX_LLM": "custom-model"}}), encoding="utf-8")
+
+    monkeypatch.setattr(Config, "_config_file_override", None)
+    monkeypatch.setattr(Config, "_applied_from_default", {})
+    monkeypatch.setattr(Config, "config_dir", classmethod(lambda cls: tmp_path))
+    for var_name in Config._llm_env_vars():
+        monkeypatch.delenv(var_name, raising=False)
+
+    apply_saved_config()
+
+    assert os.environ.get("LLM_API_BASE") == "https://default.api"
+
+    apply_config_override(str(custom_cfg))
+
+    assert os.environ.get("STRIX_LLM") == "custom-model"
+    assert "LLM_API_BASE" not in os.environ