fix: restore fail-fast behavior for non-discovery mode (issues #1, #7)

Agent-Id: agent-02660ea0-b190-4940-802f-62ed81e5543d

Author: richhankins

src/bin/cmd-mcp.ts

@@ -42,10 +42,17 @@ const stdioCommand = new Command("stdio")
         store = await CompositeStoreReader.fromSpecs(specs);
         discovery = false;
       } else {
-        // Discovery mode only: use FilesystemStore
+        // No flags: restore original behavior - fail fast if no indexes
         store = new FilesystemStore();
-        indexNames = undefined;
-        discovery = true;
+        const availableIndexes = await store.list();
+        if (availableIndexes.length === 0) {
+          console.error("Error: No indexes found.");
+          console.error("The MCP server requires at least one index to operate.");
+          console.error("Run 'ctxc index --help' to see how to create an index.");
+          process.exit(1);
+        }
+        indexNames = availableIndexes;
+        discovery = false;
       }
 
       // Start MCP server (writes to stdout, reads from stdin)
@@ -103,10 +110,17 @@ const httpCommand = new Command("http")
         store = await CompositeStoreReader.fromSpecs(specs);
         discovery = false;
       } else {
-        // Discovery mode only: use FilesystemStore
+        // No flags: restore original behavior - fail fast if no indexes
         store = new FilesystemStore();
-        indexNames = undefined;
-        discovery = true;
+        const availableIndexes = await store.list();
+        if (availableIndexes.length === 0) {
+          console.error("Error: No indexes found.");
+          console.error("The MCP server requires at least one index to operate.");
+          console.error("Run 'ctxc index --help' to see how to create an index.");
+          process.exit(1);
+        }
+        indexNames = availableIndexes;
+        discovery = false;
       }
 
       // Parse CORS option

src/clients/mcp-server.ts

@@ -106,12 +106,13 @@ export async function createMCPServer(
   // Create shared runner for multi-index operations
   // Build User-Agent for analytics tracking
   const clientUserAgent = buildClientUserAgent("mcp");
-  
+
   const runner = await MultiIndexRunner.create({
     store: config.store,
     indexNames: config.indexNames,
     searchOnly: config.searchOnly,
     clientUserAgent,
+    discovery: config.discovery,
   });
 
   const { indexNames, indexes } = runner;

src/clients/multi-index-runner.ts

@@ -41,6 +41,13 @@ export interface MultiIndexRunnerConfig {
    * When provided, this is passed to SearchClient instances for API requests.
    */
   clientUserAgent?: string;
+  /**
+   * Discovery mode flag.
+   * When true: allow empty index list (user can add indexes later via CLI)
+   * When false: require at least one valid index to be loaded
+   * @default false
+   */
+  discovery?: boolean;
 }
 
 /**
@@ -122,6 +129,7 @@ export class MultiIndexRunner {
   static async create(config: MultiIndexRunnerConfig): Promise<MultiIndexRunner> {
     const store = config.store;
     const searchOnly = config.searchOnly ?? false;
+    const discovery = config.discovery ?? false;
 
     // Discover available indexes
     const allIndexNames = await store.list();
@@ -158,7 +166,11 @@ export class MultiIndexRunner {
       }
     }
 
-    // Allow empty - server can start with no indexes and user can add via CLI
+    // In fixed mode (non-discovery), require at least one valid index
+    if (!discovery && validIndexNames.length === 0) {
+      throw new Error("No valid indexes loaded. Fixed mode requires at least one index.");
+    }
+
     return new MultiIndexRunner(store, validIndexNames, indexes, searchOnly, config.clientUserAgent, originalIndexNames);
   }