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.

.gitignore

@@ -3,6 +3,7 @@
 .pytest_cache/
 .test-tmp/
 pytest-cache-files-*/
+dist/
 __pycache__/
 *.py[cod]
 *$py.class
@@ -17,4 +18,4 @@ nexus-claude-api.local.json
 .agents
 
 # logs
-logs
+logs

README.md

@@ -9,6 +9,7 @@ AI Nexus currently documents AWS Bedrock Converse API as the workaround while An
 ```powershell
 cd nexus-claude-api
 uv sync --extra dev
+uv run nexus-claude-api config set --api-key "your-nexus-api-key"
 uv run nexus-claude-api start --port 4141 --claude-code
 ```
 
@@ -32,11 +33,17 @@ The printed command ends with `claude --model <configured-model>` so the current
 Credential lookup order:
 
 1. `--api-key`
-2. local `nexus-claude-api.local.json`
+2. user config `~/.config/nexus-claude-api/config.json`
 3. `NEXUS_API_KEY`
 4. `AWS_BEARER_TOKEN_BEDROCK`
 
-For local hardcoded configuration, create `nexus-claude-api.local.json`:
+To write user config:
+
+```powershell
+nexus-claude-api config set --api-key "your-nexus-api-key"
+```
+
+This creates `~/.config/nexus-claude-api/config.json`:
 
 ```json
 {
@@ -44,7 +51,15 @@ For local hardcoded configuration, create `nexus-claude-api.local.json`:
 }
 ```
 
-This file is ignored by git.
+Logs are written to `~/.config/nexus-claude-api/logs/nexus-claude-api.log` by default.
+
+For repository-local development only, pass `--dev` and create `nexus-claude-api.local.json` in the current directory:
+
+```powershell
+uv run nexus-claude-api start --dev --port 4141 --claude-code
+```
+
+In development mode, config is read from `nexus-claude-api.local.json` and logs are written to `logs/nexus-claude-api.log` in the current directory. The local config file is ignored by git.
 
 The service binds to `127.0.0.1` by default and does not persist API keys.
 
@@ -53,3 +68,4 @@ The service binds to `127.0.0.1` by default and does not persist API keys.
 - [PRD](docs/PRD.md)
 - [Requirements Design](docs/REQUIREMENTS_DESIGN.md)
 - [AI Nexus Claude Documentation](docs/AI_NEXUS_CLAUDE.md)
+- [Python Internal Distribution Guide](docs/PACKAGING_DISTRIBUTION.md)

docs/PACKAGING_DISTRIBUTION.md

@@ -0,0 +1,187 @@
+# Python Internal Distribution Guide
+
+This document describes how to distribute `nexus-claude-api` internally without publishing to PyPI.
+
+## Recommended Options
+
+Use one of these two approaches:
+
+- **Wheel distribution**: build a `.whl` file and send it to colleagues. This is best for stable internal releases.
+- **Private Git installation**: let colleagues install directly from the company Git repository. This is best for teammates who can access the source code or need frequent updates.
+
+Both options require:
+
+- Python `>=3.11`
+- Access to PyPI or the company Python package mirror for runtime dependencies
+- A personal AI Nexus API key
+
+Do not share `nexus-claude-api.local.json`, `.env`, logs, or any personal API key.
+
+## Option 1: Build and Share a Wheel
+
+A wheel is the standard Python install package format. It is not an `.exe`; colleagues install it with `pip`, then run the installed `nexus-claude-api` command.
+
+### Publisher Steps
+
+1. Confirm the package version in `pyproject.toml`:
+
+   ```toml
+   [project]
+   name = "nexus-claude-api"
+   version = "0.1.0"
+   ```
+
+   Update the version for every released package. Avoid sending different builds with the same version.
+
+2. Run the supported checks:
+
+   ```powershell
+   uv sync --extra dev
+   uv run pytest
+   uv run nexus-claude-api start --dry-run
+   ```
+
+3. Build the package:
+
+   ```powershell
+   uv build
+   ```
+
+   This creates files under `dist/`, usually:
+
+   ```text
+   dist/nexus_claude_api-0.1.0-py3-none-any.whl
+   dist/nexus_claude_api-0.1.0.tar.gz
+   ```
+
+4. Test the wheel in a clean environment:
+
+   ```powershell
+   py -3.11 -m venv C:\Temp\nexus-claude-api-test
+   C:\Temp\nexus-claude-api-test\Scripts\python.exe -m pip install .\dist\nexus_claude_api-0.1.0-py3-none-any.whl
+   C:\Temp\nexus-claude-api-test\Scripts\nexus-claude-api.exe start --dry-run
+   ```
+
+5. Send only the `.whl` file to colleagues through an approved internal channel.
+
+### Colleague Installation
+
+Install the wheel:
+
+```powershell
+py -3.11 -m pip install .\nexus_claude_api-0.1.0-py3-none-any.whl
+```
+
+Configure the personal Nexus key:
+
+```powershell
+nexus-claude-api config set --api-key "your-nexus-api-key"
+```
+
+Start the local proxy and print the Claude Code helper:
+
+```powershell
+nexus-claude-api start --port 4141 --claude-code
+```
+
+If PowerShell cannot find the installed script, use the module form:
+
+```powershell
+py -3.11 -m nexus_claude_api start --port 4141 --claude-code
+```
+
+### Upgrade
+
+Send a new wheel with a new version, then ask colleagues to run:
+
+```powershell
+py -3.11 -m pip install --upgrade .\nexus_claude_api-0.1.1-py3-none-any.whl
+```
+
+## Option 2: Install from Private Git
+
+Private Git installation avoids manual wheel sharing. It still uses the Python package metadata from `pyproject.toml`, so the installed command is the same.
+
+### Publisher Steps
+
+1. Push the code to the company Git repository.
+
+2. Update the version in `pyproject.toml` for each released version.
+
+3. Tag stable versions:
+
+   ```powershell
+   git tag v0.1.0
+   git push origin v0.1.0
+   ```
+
+   For the next release:
+
+   ```powershell
+   git tag v0.1.1
+   git push origin v0.1.1
+   ```
+
+4. Share an install command that points to a tag:
+
+   ```powershell
+   py -3.11 -m pip install "git+https://company-git.example.com/group/nexus-claude-api.git@v0.1.0"
+   ```
+
+Prefer tags or exact commit SHAs. Avoid asking normal users to install from `main`, because repeated installs can produce different code over time.
+
+### Colleague Installation
+
+Install from the company Git repository:
+
+```powershell
+py -3.11 -m pip install "git+https://company-git.example.com/group/nexus-claude-api.git@v0.1.0"
+```
+
+Configure the personal Nexus key:
+
+```powershell
+nexus-claude-api config set --api-key "your-nexus-api-key"
+```
+
+Start the local proxy:
+
+```powershell
+nexus-claude-api start --port 4141 --claude-code
+```
+
+### Upgrade
+
+Upgrade to a newer tag:
+
+```powershell
+py -3.11 -m pip install --upgrade "git+https://company-git.example.com/group/nexus-claude-api.git@v0.1.1"
+```
+
+### Development Clone
+
+For colleagues who will modify or test the source code:
+
+```powershell
+git clone https://company-git.example.com/group/nexus-claude-api.git
+cd nexus-claude-api
+uv sync --extra dev
+uv run nexus-claude-api start --dry-run
+```
+
+## Choosing Between the Two
+
+- Use **wheel distribution** for normal internal users who only need a stable tool.
+- Use **private Git installation** for colleagues who understand the repository, need fast updates, or help develop the project.
+- Keep version numbers and Git tags aligned. For example, `pyproject.toml` version `0.1.0` should correspond to tag `v0.1.0`.
+
+## Release Checklist
+
+Before sharing a release:
+
+- Run `uv run pytest`.
+- Run `uv run nexus-claude-api start --dry-run`.
+- Test wheel installation in a clean Python environment.
+- If using Git installation, test install from the exact tag.
+- Confirm no personal credentials are included.
+- Confirm `nexus-claude-api.local.json`, `.env`, logs, caches, and `dist/` artifacts are not committed accidentally.

docs/PRD.md

@@ -53,7 +53,8 @@ The proxy defaults to Opus because this deployment is intended for users whose N
 
 ## User Stories
 
-- As a developer, I can store my Nexus key in ignored local config or set `NEXUS_API_KEY`, then run `nexus-claude-api start --claude-code` to get a Claude Code launch command.
+- As a developer, I can store my Nexus key in user config with `nexus-claude-api config set --api-key <key>` or set `NEXUS_API_KEY`, then run `nexus-claude-api start --claude-code` to get a Claude Code launch command.
+- As a contributor working from the repository, I can pass `--dev` to use current-directory development config and logs.
 - As a Claude Code user, I can run coding workflows through local `http://127.0.0.1:4141`.
 - As a Claude Code user, I can receive streaming model output.
 - As a Claude Code user, I can use tool calls and tool results.
@@ -63,7 +64,12 @@ The proxy defaults to Opus because this deployment is intended for users whose N
 ## Acceptance Criteria
 
 - `uv run nexus-claude-api start --port 4141 --claude-code` starts a local server.
+- `nexus-claude-api config set --api-key <key>` writes user config to `~/.config/nexus-claude-api/config.json`.
 - The server binds to `127.0.0.1` by default.
+- Default startup reads credentials from user config before environment variables.
+- `--dev` startup reads current-directory `nexus-claude-api.local.json` instead of user config.
+- Default logs are written to `~/.config/nexus-claude-api/logs/nexus-claude-api.log`.
+- `--dev` logs are written to current-directory `logs/nexus-claude-api.log`.
 - Missing Nexus credentials fail fast with a clear error.
 - `GET /health` returns healthy status.
 - `GET /v1/models` returns the supported Claude models.
@@ -76,8 +82,10 @@ The proxy defaults to Opus because this deployment is intended for users whose N
 
 ## Security Requirements
 
-- Do not persist API keys automatically.
+- Do not persist API keys automatically during startup.
-- If the user chooses hardcoded local configuration, keep it in ignored `nexus-claude-api.local.json`.
+- Persist API keys only when the user explicitly runs `nexus-claude-api config set --api-key <key>` or manually writes a config file.
+- Store normal user configuration in `~/.config/nexus-claude-api/config.json`.
+- Use ignored current-directory `nexus-claude-api.local.json` only for explicit `--dev` repository-local development mode.
 - Do not print or log API keys.
 - Redact authorization headers in debug logs.
 - Bind locally by default.

docs/REQUIREMENTS_DESIGN.md

@@ -54,16 +54,41 @@ Primary command:
 uv run nexus-claude-api start --port 4141 --claude-code
 ```
 
+User configuration command:
+
+```powershell
+nexus-claude-api config set --api-key <key>
+```
+
 Options:
 
 - `--host`: default `127.0.0.1`
 - `--port`, `-p`: default `4141`
 - `--endpoint-url`: default `https://genai-nexus.api.corpinter.net`
-- `--api-key`: optional; fallback to ignored local config, `NEXUS_API_KEY`, then `AWS_BEARER_TOKEN_BEDROCK`
+- `--api-key`: optional; overrides config files and environment variables
 - `--model`: default `claude-opus-4.6`
 - `--small-model`: default `claude-opus-4.6`
 - `--claude-code`: print Claude Code launch command
 - `--verbose`, `-v`: debug logging without secrets
+- `--dev`: use current-directory development config and logs
+- `--dry-run`: validate config and print helper output without starting the server
+
+Credential lookup order:
+
+1. `--api-key`
+2. Current-mode config file
+3. `NEXUS_API_KEY`
+4. `AWS_BEARER_TOKEN_BEDROCK`
+
+Config file paths:
+
+- Default mode: `~/.config/nexus-claude-api/config.json`
+- Development mode with `--dev`: current-directory `nexus-claude-api.local.json`
+
+Log file paths:
+
+- Default mode: `~/.config/nexus-claude-api/logs/nexus-claude-api.log`
+- Development mode with `--dev`: current-directory `logs/nexus-claude-api.log`
 
 When `--claude-code` is used, print a PowerShell command that sets:
 
@@ -89,7 +114,7 @@ Expose:
 
 `ANTHROPIC_AUTH_TOKEN` is printed as `dummy` because Claude Code expects an Anthropic auth token variable to exist. This local proxy does not validate that inbound token by default. It is not the Nexus key.
 
-Inbound authentication headers are accepted for compatibility but not validated by default because the service is local. Outbound Nexus authentication uses `--api-key`, ignored local `nexus-claude-api.local.json`, `NEXUS_API_KEY`, or `AWS_BEARER_TOKEN_BEDROCK`.
+Inbound authentication headers are accepted for compatibility but not validated by default because the service is local. Outbound Nexus authentication uses `--api-key`, the current-mode config file, `NEXUS_API_KEY`, or `AWS_BEARER_TOKEN_BEDROCK`.
 
 ## Model Mapping
 
@@ -182,7 +207,7 @@ Return Anthropic-compatible errors:
 Status mapping:
 
 - invalid request: `400`
-- missing local Nexus credential: startup failure
+- missing Nexus credential: startup failure
 - Nexus auth failure: `401` or `403`
 - Nexus throttling: `429`
 - Nexus network/timeout: `502` or `504`
@@ -215,3 +240,14 @@ CLI tests:
 - `nexus-claude-api --help`
 - Claude Code command generation.
 - Missing API key validation.
+- User config writing with `nexus-claude-api config set --api-key <key>`.
+- Default-mode user config lookup from `~/.config/nexus-claude-api/config.json`.
+- Default mode ignores current-directory `nexus-claude-api.local.json`.
+- Development mode uses current-directory `nexus-claude-api.local.json`.
+- `--api-key` overrides config files and config files override environment variables.
+
+Logging tests:
+
+- Default-mode log path resolves to `~/.config/nexus-claude-api/logs/nexus-claude-api.log`.
+- Development-mode log path resolves to current-directory `logs/nexus-claude-api.log`.
+- Verbose logging enables debug details without logging secrets.

src/nexus_claude_api/cli.py

@@ -5,6 +5,7 @@ import sys
 
 import uvicorn
 
+import nexus_claude_api.config as config
 from nexus_claude_api.config import (
     DEFAULT_ENDPOINT_URL,
     DEFAULT_HOST,
@@ -13,7 +14,7 @@ from nexus_claude_api.config import (
     DEFAULT_SMALL_MODEL,
     Settings,
 )
-from nexus_claude_api.logging_config import configure_logging
+from nexus_claude_api.logging_config import configure_logging, resolve_log_file
 from nexus_claude_api.server import create_app
 from nexus_claude_api.shell import generate_claude_code_powershell
 
@@ -31,11 +32,21 @@ def build_parser() -> argparse.ArgumentParser:
     start.add_argument("--small-model", default=DEFAULT_SMALL_MODEL)
     start.add_argument("--claude-code", action="store_true")
     start.add_argument("--verbose", "-v", action="store_true")
+    start.add_argument(
+        "--dev",
+        action="store_true",
+        help="Use local development config and logs in the current directory.",
+    )
     start.add_argument(
         "--dry-run",
         action="store_true",
         help="Validate config and print helper output without starting the server.",
     )
+
+    config = subparsers.add_parser("config", help="Manage user configuration")
+    config_subparsers = config.add_subparsers(dest="config_command")
+    config_set = config_subparsers.add_parser("set", help="Write user configuration")
+    config_set.add_argument("--api-key", required=True)
     return parser
 
 
@@ -44,10 +55,21 @@ def main(argv: list[str] | None = None) -> int:
     args = parser.parse_args(argv)
     if args.command == "start":
         return run_start(args)
+    if args.command == "config":
+        return run_config(args, parser)
     parser.print_help()
     return 0
 
 
+def run_config(args: argparse.Namespace, parser: argparse.ArgumentParser) -> int:
+    if args.config_command == "set":
+        config_path = config.write_user_config({"api_key": args.api_key})
+        print(f"Wrote user config to {config_path}")
+        return 0
+    parser.parse_args(["config", "--help"])
+    return 0
+
+
 def run_start(args: argparse.Namespace) -> int:
     settings = Settings.from_values(
         host=args.host,
@@ -57,12 +79,15 @@ def run_start(args: argparse.Namespace) -> int:
         model=args.model,
         small_model=args.small_model,
         verbose=args.verbose,
+        dev=args.dev,
     )
 
     if not settings.api_key:
         print(
-            "Missing Nexus API key. Add nexus-claude-api.local.json, set "
+            "Missing Nexus API key. Run "
-            "NEXUS_API_KEY or AWS_BEARER_TOKEN_BEDROCK, or pass --api-key.",
+            "`nexus-claude-api config set --api-key <key>`, set NEXUS_API_KEY "
+            "or AWS_BEARER_TOKEN_BEDROCK, pass --api-key, or use --dev with "
+            "nexus-claude-api.local.json.",
             file=sys.stderr,
         )
         return 2
@@ -74,7 +99,10 @@ def run_start(args: argparse.Namespace) -> int:
     if args.dry_run:
         return 0
 
-    log_file = configure_logging(verbose=settings.verbose)
+    log_file = configure_logging(
+        verbose=settings.verbose,
+        log_file=resolve_log_file(dev=args.dev),
+    )
     print(f"Writing detailed logs to {log_file}")
     app = create_app(settings)
     uvicorn.run(

src/nexus_claude_api/config.py

@@ -13,6 +13,8 @@ DEFAULT_OPUS_MODEL = "claude-opus-4.6"
 DEFAULT_MODEL = DEFAULT_OPUS_MODEL
 DEFAULT_SMALL_MODEL = DEFAULT_OPUS_MODEL
 LOCAL_CONFIG_FILENAME = "nexus-claude-api.local.json"
+USER_CONFIG_DIR = Path.home() / ".config" / "nexus-claude-api"
+USER_CONFIG_FILE = USER_CONFIG_DIR / "config.json"
 
 
 MODEL_ID_MAP = {
@@ -48,12 +50,13 @@ class Settings:
         small_model: str = DEFAULT_SMALL_MODEL,
         verbose: bool = False,
         require_api_key: bool = True,
+        dev: bool = False,
     ) -> "Settings":
-        local_config = load_local_config()
+        config = load_config(dev=dev)
         resolved_api_key = (
             api_key
-            or local_config.get("api_key")
+            or config.get("api_key")
-            or local_config.get("nexus_api_key")
+            or config.get("nexus_api_key")
             or os.environ.get("NEXUS_API_KEY")
             or os.environ.get("AWS_BEARER_TOKEN_BEDROCK")
         )
@@ -78,6 +81,30 @@ def resolve_backend_model(model: str) -> str:
 
 
 def load_local_config(path: str | Path = LOCAL_CONFIG_FILENAME) -> dict[str, str]:
+    return load_config_file(path)
+
+
+def load_user_config(path: str | Path | None = None) -> dict[str, str]:
+    return load_config_file(path or USER_CONFIG_FILE)
+
+
+def load_config(*, dev: bool = False) -> dict[str, str]:
+    if dev:
+        return load_local_config()
+    return load_user_config()
+
+
+def write_user_config(config: dict[str, str], path: str | Path | None = None) -> Path:
+    config_path = Path(path or USER_CONFIG_FILE)
+    config_path.parent.mkdir(parents=True, exist_ok=True)
+    config_path.write_text(
+        json.dumps(config, indent=2, sort_keys=True) + "\n",
+        encoding="utf-8",
+    )
+    return config_path
+
+
+def load_config_file(path: str | Path) -> dict[str, str]:
     config_path = Path(path)
     if not config_path.exists():
         return {}

src/nexus_claude_api/logging_config.py

@@ -3,9 +3,13 @@ from __future__ import annotations
 import logging
 from pathlib import Path
 
+import nexus_claude_api.config as config
 
-LOG_DIR = Path("logs")
+LOCAL_LOG_DIR = Path("logs")
-LOG_FILE = LOG_DIR / "nexus-claude-api.log"
+LOCAL_LOG_FILE = LOCAL_LOG_DIR / "nexus-claude-api.log"
+USER_LOG_DIR = config.USER_CONFIG_DIR / "logs"
+USER_LOG_FILE = USER_LOG_DIR / "nexus-claude-api.log"
+LOG_FILE = USER_LOG_FILE
 LOG_FORMAT = "%(asctime)s %(levelname)s %(name)s: %(message)s"
 
 
@@ -24,3 +28,9 @@ def configure_logging(*, verbose: bool = False, log_file: Path = LOG_FILE) -> Pa
     app_logger.propagate = False
 
     return log_file
+
+
+def resolve_log_file(*, dev: bool = False) -> Path:
+    if dev:
+        return LOCAL_LOG_FILE
+    return config.USER_CONFIG_DIR / "logs" / "nexus-claude-api.log"

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:
+def test_user_config_api_key(monkeypatch) -> None:
-    tmp_path = _workspace_tmp("local-config")
+    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 settings.api_key is None
-        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_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)

tests/test_logging_config.py

@@ -1,8 +1,9 @@
 from __future__ import annotations
 
 import logging
+from pathlib import Path
 
-from nexus_claude_api.logging_config import configure_logging
+from nexus_claude_api.logging_config import configure_logging, resolve_log_file
 
 
 def test_configure_logging_writes_app_logs_to_file_without_console(
@@ -55,3 +56,17 @@ def test_configure_logging_verbose_writes_debug_app_logs_to_file(
         app_logger.handlers.extend(original_handlers)
         app_logger.setLevel(original_level)
         app_logger.propagate = original_propagate
+
+
+def test_resolve_log_file_uses_user_config_dir_by_default(
+    tmp_path,
+    monkeypatch,
+) -> None:
+    user_config_dir = tmp_path / ".config" / "nexus-claude-api"
+    monkeypatch.setattr("nexus_claude_api.config.USER_CONFIG_DIR", user_config_dir)
+
+    assert resolve_log_file() == user_config_dir / "logs" / "nexus-claude-api.log"
+
+
+def test_resolve_log_file_uses_local_logs_in_dev_mode() -> None:
+    assert resolve_log_file(dev=True) == Path("logs") / "nexus-claude-api.log"