Simplify MCP configuration to use multiple --mcp-config flags

- Remove MCP config merging logic from prepareMcpConfig
- Update agent and tag modes to pass multiple --mcp-config flags
- Let Claude handle config merging natively through multiple flags
- Fix TypeScript errors in test file

This approach is cleaner and relies on Claude's built-in support for multiple --mcp-config flags instead of manual JSON merging.

src/mcp/install-mcp-server.ts

@@ -10,7 +10,6 @@ type PrepareConfigParams = {
   repo: string;
   branch: string;
   baseBranch: string;
-  additionalMcpConfig?: string;
   claudeCommentId?: string;
   allowedTools: string[];
   context: GitHubContext;
@@ -57,7 +56,6 @@ export async function prepareMcpConfig(
     repo,
     branch,
     baseBranch,
-    additionalMcpConfig,
     claudeCommentId,
     allowedTools,
     context,
@@ -193,38 +191,8 @@ export async function prepareMcpConfig(
       };
     }
 
-    // Merge with additional MCP config if provided
-    if (additionalMcpConfig && additionalMcpConfig.trim()) {
-      try {
-        const additionalConfig = JSON.parse(additionalMcpConfig);
-
-        // Validate that parsed JSON is an object
-        if (typeof additionalConfig !== "object" || additionalConfig === null) {
-          throw new Error("MCP config must be a valid JSON object");
-        }
-
-        core.info(
-          "Merging additional MCP server configuration with built-in servers",
-        );
-
-        // Merge configurations with user config overriding built-in servers
-        const mergedConfig = {
-          ...baseMcpConfig,
-          ...additionalConfig,
-          mcpServers: {
-            ...baseMcpConfig.mcpServers,
-            ...additionalConfig.mcpServers,
-          },
-        };
-
-        return JSON.stringify(mergedConfig, null, 2);
-      } catch (parseError) {
-        core.warning(
-          `Failed to parse additional MCP config: ${parseError}. Using base config only.`,
-        );
-      }
-    }
-
+    // Return only our GitHub servers config
+    // User's config will be passed as separate --mcp-config flags
     return JSON.stringify(baseMcpConfig, null, 2);
   } catch (error) {
     core.setFailed(`Install MCP server failed with error: ${error}`);