Begin implementation of Step 1. Implementation interrupted when I ran out of credits at openrouter. Credits added. Now trying to figure out how to restart the process...

tests/test_config.py

@@ -0,0 +1,33 @@
+"""Tests for transcription.config — settings loading, provider defaults, and paths."""
+
+from transcription.config import Provider, Settings
+
+
+class TestSettingsLoading:
+    """Verify Settings construction and required-field validation."""
+
+    def test_loads_from_env(self):
+        """Settings constructs when OPENROUTER_API_KEY is provided."""
+
+    def test_requires_api_key(self):
+        """Settings raises ValidationError when OPENROUTER_API_KEY is missing."""
+
+
+class TestProviderSettings:
+    """Verify provider enum defaults and validation."""
+
+    def test_defaults_to_openrouter(self):
+        """Default provider is openrouter when not explicitly set."""
+
+    def test_rejects_invalid_value(self):
+        """Setting PROVIDER to an invalid value raises ValidationError."""
+
+    def test_optional_fields_default_to_none(self):
+        """provider_model, openrouter_http_referer, and openrouter_app_title are None when unset."""
+
+
+class TestPathSettings:
+    """Verify filesystem path field types."""
+
+    def test_path_fields_are_path_objects(self):
+        """upload_dir and prompt_dir are Path instances."""