Allow --mcp flag to accept URLs for streamable-http servers (#8119)

* Allow --mcp flag to accept URLs for streamable-http servers

When a URL starting with http:// or https:// is passed to the --mcp flag,
it will now automatically be configured as a streamable-http MCP server
connection instead of trying to load it from the hub.

This allows users to run:
  cn --mcp https://docs.continue.dev/mcp

The URL will be parsed and configured with:
- type: streamable-http
- url: the provided URL
- name: hostname from the URL

Fixes CON-4285

Generated with [Continue](https://continue.dev)

Co-authored-by: Username <[email protected]>

* fix: tests

---------

Co-authored-by: Continue Agent <[email protected]>
Co-authored-by: Username <[email protected]>
Co-authored-by: Nate <[email protected]>

Author: 3 people

extensions/cli/src/configEnhancer.test.ts

@@ -196,11 +196,12 @@ describe("ConfigEnhancer", () => {
   });
 
   it("should prepend MCPs from --mcp flag", async () => {
-    // Mock loadPackagesFromHub to return test MCPs
-    const { loadPackagesFromHub } = await import("./hubLoader.js");
-    (loadPackagesFromHub as any).mockResolvedValueOnce([
-      { name: "New-MCP", command: "new-mcp" },
-    ]);
+    // Mock loadPackageFromHub to return test MCP (singular call for each MCP)
+    const { loadPackageFromHub } = await import("./hubLoader.js");
+    (loadPackageFromHub as any).mockResolvedValueOnce({
+      name: "New-MCP",
+      command: "new-mcp",
+    });
 
     // Set up existing MCPs in config
     mockConfig.mcpServers = [{ name: "Existing-MCP", command: "existing-mcp" }];
@@ -223,6 +224,70 @@ describe("ConfigEnhancer", () => {
     });
   });
 
+  it("should handle URLs in --mcp flag as streamable-http servers", async () => {
+    // Set up existing MCPs in config
+    mockConfig.mcpServers = [{ name: "Existing-MCP", command: "existing-mcp" }];
+
+    const options: BaseCommandOptions = {
+      mcp: ["https://docs.continue.dev/mcp"],
+    };
+
+    const config = await enhancer.enhanceConfig(mockConfig, options);
+
+    // URL should be converted to streamable-http MCP configuration
+    expect(config.mcpServers).toHaveLength(2);
+    expect(config.mcpServers?.[0]).toEqual({
+      name: "docs.continue.dev",
+      type: "streamable-http",
+      url: "https://docs.continue.dev/mcp",
+    });
+    expect(config.mcpServers?.[1]).toEqual({
+      name: "Existing-MCP",
+      command: "existing-mcp",
+    });
+  });
+
+  it("should handle mix of URLs and hub slugs in --mcp flag", async () => {
+    // Mock loadPackageFromHub to return test MCP for hub slug
+    const { loadPackageFromHub } = await import("./hubLoader.js");
+    (loadPackageFromHub as any).mockResolvedValueOnce({
+      name: "Hub-MCP",
+      command: "hub-mcp",
+    });
+
+    const options: BaseCommandOptions = {
+      mcp: ["https://example.com/mcp", "test/hub-mcp"],
+    };
+
+    const config = await enhancer.enhanceConfig(mockConfig, options);
+
+    expect(config.mcpServers).toHaveLength(2);
+    expect(config.mcpServers?.[0]).toEqual({
+      name: "example.com",
+      type: "streamable-http",
+      url: "https://example.com/mcp",
+    });
+    expect(config.mcpServers?.[1]).toEqual({
+      name: "Hub-MCP",
+      command: "hub-mcp",
+    });
+  });
+
+  it("should handle http:// URLs in --mcp flag", async () => {
+    const options: BaseCommandOptions = {
+      mcp: ["http://localhost:8080/mcp"],
+    };
+
+    const config = await enhancer.enhanceConfig(mockConfig, options);
+
+    expect(config.mcpServers).toHaveLength(1);
+    expect(config.mcpServers?.[0]).toEqual({
+      name: "localhost",
+      type: "streamable-http",
+      url: "http://localhost:8080/mcp",
+    });
+  });
+
   it("should handle workflow integration gracefully when no workflow", async () => {
     // The mocked service container returns null workflow state
     const options: BaseCommandOptions = {

extensions/cli/src/configEnhancer.ts

@@ -171,7 +171,28 @@ export class ConfigEnhancer {
     config: AssistantUnrolled,
     mcps: string[],
   ): Promise<AssistantUnrolled> {
-    const processedMcps = await loadPackagesFromHub(mcps, mcpProcessor);
+    const processedMcps: any[] = [];
+
+    // Process each MCP spec - check if it's a URL or hub slug
+    for (const mcpSpec of mcps) {
+      try {
+        // Check if it's a URL (starts with http:// or https://)
+        if (mcpSpec.startsWith("http://") || mcpSpec.startsWith("https://")) {
+          // Create a streamable-http MCP configuration
+          processedMcps.push({
+            name: new URL(mcpSpec).hostname,
+            type: "streamable-http",
+            url: mcpSpec,
+          });
+        } else {
+          // Otherwise, treat it as a hub slug
+          const hubMcp = await loadPackageFromHub(mcpSpec, mcpProcessor);
+          processedMcps.push(hubMcp);
+        }
+      } catch (error: any) {
+        logger.warn(`Failed to load MCP "${mcpSpec}": ${error.message}`);
+      }
+    }
 
     // Clone the config to avoid mutating the original
     const modifiedConfig = { ...config };

extensions/cli/src/services/workflow-integration.test.ts

@@ -554,11 +554,19 @@ describe("Workflow Integration Tests", () => {
         tools: "owner/mcp1, another/mcp2:specific_tool",
       };
 
-      mockLoadPackageFromHub.mockResolvedValue(workflowWithTools);
-      mockLoadPackagesFromHub.mockResolvedValue([
-        { name: "mcp1" },
-        { name: "mcp2" },
-      ]);
+      // Clear the default mock and setup specific mocks
+      mockLoadPackageFromHub.mockReset();
+      // First call loads the workflow file
+      mockLoadPackageFromHub.mockResolvedValueOnce(workflowWithTools);
+      // Second call loads the workflow model
+      mockLoadPackageFromHub.mockResolvedValueOnce({
+        name: "gpt-4-workflow",
+        provider: "openai",
+      });
+      // Third call loads mcp1
+      mockLoadPackageFromHub.mockResolvedValueOnce({ name: "mcp1" });
+      // Fourth call loads mcp2
+      mockLoadPackageFromHub.mockResolvedValueOnce({ name: "mcp2" });
 
       await workflowService.initialize("owner/workflow");
 
@@ -573,6 +581,7 @@ describe("Workflow Integration Tests", () => {
       );
 
       expect(enhancedConfig.mcpServers).toHaveLength(3);
+      // MCPs are prepended in the order they are loaded
       expect(enhancedConfig.mcpServers?.[0]).toEqual({ name: "mcp1" });
       expect(enhancedConfig.mcpServers?.[1]).toEqual({ name: "mcp2" });
       expect(enhancedConfig.mcpServers?.[2]).toEqual({ name: "existing-mcp" });
@@ -584,7 +593,8 @@ describe("Workflow Integration Tests", () => {
         tools: undefined,
       };
 
-      mockLoadPackageFromHub.mockResolvedValue(workflowWithoutTools);
+      mockLoadPackageFromHub.mockReset();
+      mockLoadPackageFromHub.mockResolvedValueOnce(workflowWithoutTools);
       await workflowService.initialize("owner/workflow");
 
       const baseConfig = {
@@ -607,13 +617,22 @@ describe("Workflow Integration Tests", () => {
         tools: "owner/mcp1, owner/mcp1:tool1, owner/mcp1:tool2",
       };
 
-      mockLoadPackageFromHub.mockResolvedValue(workflowWithDuplicateTools);
-      mockLoadPackagesFromHub.mockResolvedValue([{ name: "mcp1" }]);
+      // Clear the default mock and setup specific mocks
+      mockLoadPackageFromHub.mockReset();
+      // First call loads the workflow file
+      mockLoadPackageFromHub.mockResolvedValueOnce(workflowWithDuplicateTools);
+      // Second call loads the workflow model
+      mockLoadPackageFromHub.mockResolvedValueOnce({
+        name: "gpt-4-workflow",
+        provider: "openai",
+      });
+      // Third call: The parseWorkflowTools will extract only unique MCP servers, so only one loadPackageFromHub call
+      mockLoadPackageFromHub.mockResolvedValueOnce({ name: "mcp1" });
 
       await workflowService.initialize("owner/workflow");
 
       const baseConfig = {
-        mcpServers: [{ name: "mcp1" }], // Already exists
+        mcpServers: [{ name: "existing-mcp" }], // Changed to avoid confusion
       };
 
       const enhancedConfig = await configEnhancer.enhanceConfig(
@@ -622,10 +641,10 @@ describe("Workflow Integration Tests", () => {
         workflowService.getState(),
       );
 
-      // Should not deduplicate since we simplified the logic
+      // parseWorkflowTools deduplicates, so we only get mcp1 once
       expect(enhancedConfig.mcpServers).toHaveLength(2);
       expect(enhancedConfig.mcpServers?.[0]).toEqual({ name: "mcp1" });
-      expect(enhancedConfig.mcpServers?.[1]).toEqual({ name: "mcp1" });
+      expect(enhancedConfig.mcpServers?.[1]).toEqual({ name: "existing-mcp" });
     });
   });
 });