refactor: comprehensive code review fixes across 31 files

Addresses all critical, high, medium, and low issues from full codebase
review. 494 tests pass, ruff clean, ty type-check clean.

Security:
- Add tool_error_handler context manager (exceptions.py) — standardised
  error handling, eliminates 11 bare except-reraise patterns
- Remove unused exception subclasses (ConfigurationError, UnraidAPIError,
  SubscriptionError, ValidationError, IdempotentOperationError)
- Harden GraphQL subscription query validator with allow-list and
  forbidden-keyword regex (diagnostics.py)
- Add input validation for rclone create_remote config_data: injection,
  path-traversal, and key-count limits (rclone.py)
- Validate notifications importance enum before GraphQL request (notifications.py)
- Sanitise HTTP/network/JSON error messages — no raw exception strings
  leaked to clients (client.py)
- Strip path/creds from displayed API URL via _safe_display_url (health.py)
- Enable Ruff S (bandit) rule category in pyproject.toml
- Harden container mutations to strict-only matching — no fuzzy/substring
  for destructive operations (docker.py)

Performance:
- Token-bucket rate limiter (90 tokens, 9 req/s) with 429 retry backoff (client.py)
- Lazy asyncio.Lock init via _get_client_lock() — fixes event-loop
  module-load crash (client.py)
- Double-checked locking in get_http_client() for fast-path (client.py)
- Short hex container ID fast-path skips list fetch (docker.py)
- Cap resource_data log content to 1 MB / 5,000 lines (manager.py)
- Reset reconnect counter after 30 s stable connection (manager.py)
- Move tail_lines validation to module level; enforce 10,000 line cap
  (storage.py, docker.py)
- force_terminal=True removed from logging RichHandler (logging.py)

Architecture:
- Register diagnostic tools in server startup (server.py)
- Move ALL_ACTIONS computation to module level in all tools
- Consolidate format_kb / format_bytes into shared core/utils.py
- Add _safe_get() helper in core/utils.py for nested dict traversal
- Extract _analyze_subscription_status() from health.py diagnose handler
- Validate required config at startup — fail fast with CRITICAL log (server.py)

Code quality:
- Remove ~90 lines of dead Rich formatting helpers from logging.py
- Remove dead self.websocket attribute from SubscriptionManager
- Remove dead setup_uvicorn_logging() wrapper
- Move _VALID_IMPORTANCE to module level (N806 fix)
- Add slots=True to all three dataclasses (SubscriptionData, SystemHealth, APIResponse)
- Fix None rendering as literal "None" string in info.py summaries
- Change fuzzy-match log messages from INFO to DEBUG (docker.py)
- UTC-aware datetimes throughout (manager.py, diagnostics.py)

Infrastructure:
- Upgrade base image python:3.11-slim → python:3.12-slim (Dockerfile)
- Add non-root appuser (UID/GID 1000) with HEALTHCHECK (Dockerfile)
- Add read_only, cap_drop: ALL, tmpfs /tmp to docker-compose.yml
- Single-source version via importlib.metadata (pyproject.toml → __init__.py)
- Add open_timeout to all websockets.connect() calls

Tests:
- Update error message matchers to match sanitised messages (test_client.py)
- Fix patch targets for UNRAID_API_URL → utils module (test_subscriptions.py)
- Fix importance="info" → importance="normal" (test_notifications.py, http_layer)
- Fix naive datetime fixtures → UTC-aware (test_subscriptions.py)

Co-authored-by: Claude <claude@anthropic.com>

unraid_mcp/server.py

@@ -15,8 +15,11 @@ from .config.settings import (
     UNRAID_MCP_HOST,
     UNRAID_MCP_PORT,
     UNRAID_MCP_TRANSPORT,
+    UNRAID_VERIFY_SSL,
     VERSION,
+    validate_required_config,
 )
+from .subscriptions.diagnostics import register_diagnostic_tools
 from .subscriptions.resources import register_subscription_resources
 from .tools.array import register_array_tool
 from .tools.docker import register_docker_tool
@@ -44,9 +47,10 @@ mcp = FastMCP(
 def register_all_modules() -> None:
     """Register all tools and resources with the MCP instance."""
     try:
-        # Register subscription resources first
+        # Register subscription resources and diagnostic tools
         register_subscription_resources(mcp)
-        logger.info("Subscription resources registered")
+        register_diagnostic_tools(mcp)
+        logger.info("Subscription resources and diagnostic tools registered")
 
         # Register all consolidated tools
         registrars = [
@@ -73,6 +77,15 @@ def register_all_modules() -> None:
 
 def run_server() -> None:
     """Run the MCP server with the configured transport."""
+    # Validate required configuration before anything else
+    is_valid, missing = validate_required_config()
+    if not is_valid:
+        logger.critical(
+            f"Missing required configuration: {', '.join(missing)}. "
+            "Set these environment variables or add them to your .env file."
+        )
+        sys.exit(1)
+
     # Log configuration
     if UNRAID_API_URL:
         logger.info(f"UNRAID_API_URL loaded: {UNRAID_API_URL[:20]}...")
@@ -88,6 +101,13 @@ def run_server() -> None:
     logger.info(f"UNRAID_MCP_HOST set to: {UNRAID_MCP_HOST}")
     logger.info(f"UNRAID_MCP_TRANSPORT set to: {UNRAID_MCP_TRANSPORT}")
 
+    if UNRAID_VERIFY_SSL is False:
+        logger.warning(
+            "SSL VERIFICATION DISABLED (UNRAID_VERIFY_SSL=false). "
+            "Connections to Unraid API are vulnerable to man-in-the-middle attacks. "
+            "Only use this in trusted networks or for development."
+        )
+
     # Register all modules
     register_all_modules()