Allow skipping config validation in preview

Author: PaulJPhilp

packages/mcp-server/src/server/errorHandler.ts

@@ -21,6 +21,7 @@ import {
     RateLimitError,
     RequestValidationError,
     ValidationError,
+    ConfigurationError,
 } from "../errors";
 import { FileSizeError, NonTypeScriptError } from "../services/review-code";
 
@@ -172,6 +173,19 @@ export function errorToResponse(
         });
       }
 
+      case "ConfigurationError": {
+        const e = error as ConfigurationError;
+        const response: ApiErrorResponse = {
+          error: e.message,
+          status: "configuration_error",
+          details: { key: e.key, expected: e.expected, received: e.received },
+        };
+        return NextResponse.json(response, {
+          status: 500,
+          headers: baseHeaders,
+        });
+      }
+
       case "PatternLoadError": {
         const e = error as PatternLoadError;
         const response: ApiErrorResponse = {

packages/mcp-server/src/services/config/helpers.ts

@@ -244,8 +244,12 @@ export function loadConfig(): Effect.Effect<MCPConfig, ConfigurationError> {
         DEFAULT_CONFIG.tracingSamplingRate,
     };
 
-    // Validate configuration
-    yield* validateConfig(config);
+    // Validate configuration unless explicitly skipped (useful for preview debugging)
+    if (process.env.SKIP_CONFIG_VALIDATE !== "true") {
+      yield* validateConfig(config);
+    } else {
+      console.warn("[Config] SKIP_CONFIG_VALIDATE=true - skipping config validation");
+    }
 
     return config;
   });