refactor: address code review feedback

- Make getProviderLabel() switch exhaustive with explicit openai/gemini
  arms instead of falling through to env-var checks in default
- Add clarifying comment on additionalProperties override in schema
  normalization

src/components/CostThresholdDialog.tsx

@@ -19,13 +19,11 @@ function getProviderLabel(): string {
       return 'Google Vertex'
     case 'foundry':
       return 'Azure Foundry'
-    default:
-      if (process.env.CLAUDE_CODE_USE_OPENAI === '1' || process.env.CLAUDE_CODE_USE_OPENAI === 'true') {
+    case 'openai':
       return 'OpenAI-compatible API'
-      }
-      if (process.env.CLAUDE_CODE_USE_GEMINI === '1' || process.env.CLAUDE_CODE_USE_GEMINI === 'true') {
+    case 'gemini':
       return 'Gemini API'
-      }
+    default:
       return 'API'
   }
 }

src/services/api/openaiShim.ts

@@ -259,6 +259,8 @@ function normalizeSchemaForOpenAI(
       // OpenAI strict mode requires every property to be listed in required[]
       const allKeys = Object.keys(normalizedProps)
       record.required = Array.from(new Set([...existingRequired, ...allKeys]))
+      // OpenAI strict mode requires additionalProperties: false on all object
+      // schemas — override unconditionally to ensure nested objects comply.
       record.additionalProperties = false
     } else {
       // For Gemini: keep only existing required keys that are present in properties