Enhance user configuration management and logging

- Introduced user configuration command to set API key.
- Updated README and documentation for user config and logging paths.
- Refactored logging to support user-specific log files.
- Added tests for user configuration and logging behavior.

tests/test_cli.py

@@ -1,10 +1,16 @@
 from __future__ import annotations
 
+import json
 import shutil
 from pathlib import Path
 
 from nexus_claude_api.cli import main
-from nexus_claude_api.config import Settings, load_local_config
+from nexus_claude_api.config import (
+    Settings,
+    load_local_config,
+    load_user_config,
+    write_user_config,
+)
 from nexus_claude_api.shell import generate_claude_code_powershell
 
 
@@ -41,6 +47,8 @@ def test_claude_code_command_uses_custom_model() -> None:
 
 def test_missing_api_key_fails(monkeypatch) -> None:
     tmp_path = _workspace_tmp("missing-key")
+    user_config = tmp_path / ".config" / "nexus-claude-api" / "config.json"
+    monkeypatch.setattr("nexus_claude_api.config.USER_CONFIG_FILE", user_config)
     monkeypatch.delenv("NEXUS_API_KEY", raising=False)
     monkeypatch.delenv("AWS_BEARER_TOKEN_BEDROCK", raising=False)
     monkeypatch.chdir(tmp_path)
@@ -54,8 +62,43 @@ def test_missing_api_key_fails(monkeypatch) -> None:
     assert exit_code == 2
 
 
-def test_local_config_api_key(monkeypatch) -> None:
-    tmp_path = _workspace_tmp("local-config")
+def test_user_config_api_key(monkeypatch) -> None:
+    tmp_path = _workspace_tmp("user-config")
+    user_config = tmp_path / ".config" / "nexus-claude-api" / "config.json"
+    monkeypatch.setattr("nexus_claude_api.config.USER_CONFIG_FILE", user_config)
+    write_user_config({"api_key": "user-test-key"})
+
+    settings = Settings.from_values(require_api_key=False)
+
+    assert settings.api_key == "user-test-key"
+    assert load_user_config()["api_key"] == "user-test-key"
+    shutil.rmtree(tmp_path, ignore_errors=True)
+
+
+def test_dev_local_config_api_key(monkeypatch) -> None:
+    tmp_path = _workspace_tmp("dev-local-config")
+    monkeypatch.chdir(tmp_path)
+    (tmp_path / "nexus-claude-api.local.json").write_text(
+        '{"api_key": "local-test-key"}',
+        encoding="utf-8",
+    )
+
+    try:
+        settings = Settings.from_values(require_api_key=False, dev=True)
+
+        assert settings.api_key == "local-test-key"
+        assert load_local_config()["api_key"] == "local-test-key"
+    finally:
+        monkeypatch.chdir(Path(__file__).parents[1])
+        shutil.rmtree(tmp_path, ignore_errors=True)
+
+
+def test_default_mode_ignores_local_config(monkeypatch) -> None:
+    tmp_path = _workspace_tmp("default-ignores-local")
+    user_config = tmp_path / ".config" / "nexus-claude-api" / "config.json"
+    monkeypatch.setattr("nexus_claude_api.config.USER_CONFIG_FILE", user_config)
+    monkeypatch.delenv("NEXUS_API_KEY", raising=False)
+    monkeypatch.delenv("AWS_BEARER_TOKEN_BEDROCK", raising=False)
     monkeypatch.chdir(tmp_path)
     (tmp_path / "nexus-claude-api.local.json").write_text(
         '{"api_key": "local-test-key"}',
@@ -65,13 +108,51 @@ def test_local_config_api_key(monkeypatch) -> None:
     try:
         settings = Settings.from_values(require_api_key=False)
 
-        assert settings.api_key == "local-test-key"
-        assert load_local_config()["api_key"] == "local-test-key"
+        assert settings.api_key is None
     finally:
         monkeypatch.chdir(Path(__file__).parents[1])
         shutil.rmtree(tmp_path, ignore_errors=True)
 
 
+def test_api_key_precedence_config_before_environment(monkeypatch) -> None:
+    tmp_path = _workspace_tmp("config-precedence")
+    user_config = tmp_path / ".config" / "nexus-claude-api" / "config.json"
+    monkeypatch.setattr("nexus_claude_api.config.USER_CONFIG_FILE", user_config)
+    monkeypatch.setenv("NEXUS_API_KEY", "env-key")
+    write_user_config({"api_key": "config-key"})
+
+    settings = Settings.from_values(require_api_key=False)
+
+    assert settings.api_key == "config-key"
+    shutil.rmtree(tmp_path, ignore_errors=True)
+
+
+def test_api_key_argument_overrides_config(monkeypatch) -> None:
+    tmp_path = _workspace_tmp("arg-precedence")
+    user_config = tmp_path / ".config" / "nexus-claude-api" / "config.json"
+    monkeypatch.setattr("nexus_claude_api.config.USER_CONFIG_FILE", user_config)
+    write_user_config({"api_key": "config-key"})
+
+    settings = Settings.from_values(api_key="arg-key", require_api_key=False)
+
+    assert settings.api_key == "arg-key"
+    shutil.rmtree(tmp_path, ignore_errors=True)
+
+
+def test_config_set_writes_user_config(monkeypatch) -> None:
+    tmp_path = _workspace_tmp("config-set")
+    user_config = tmp_path / ".config" / "nexus-claude-api" / "config.json"
+    monkeypatch.setattr("nexus_claude_api.config.USER_CONFIG_FILE", user_config)
+
+    exit_code = main(["config", "set", "--api-key", "written-key"])
+
+    assert exit_code == 0
+    assert json.loads(user_config.read_text(encoding="utf-8")) == {
+        "api_key": "written-key"
+    }
+    shutil.rmtree(tmp_path, ignore_errors=True)
+
+
 def _workspace_tmp(name: str) -> Path:
     path = Path(__file__).parents[1] / ".test-tmp" / name
     shutil.rmtree(path, ignore_errors=True)