MCP support

Author: josebalius

src/git.ts

@@ -16,6 +16,23 @@ import { existsSync } from "fs";
 
 const DEFAULT_CLONE_DIR = "/tmp/workspace";
 
+// =============================================================================
+// Helpers
+// =============================================================================
+
+/**
+ * Checks if a branch exists on the remote using ls-remote.
+ * This avoids masking auth/network errors as "branch not found".
+ */
+function branchExistsOnRemote(repoLocation: string, branchName: string): boolean {
+    const output = execFileSync("git", ["ls-remote", "--heads", "origin", branchName], {
+        cwd: repoLocation,
+        encoding: "utf-8",
+        stdio: ["pipe", "pipe", "pipe"],
+    }).trim();
+    return output.length > 0;
+}
+
 // =============================================================================
 // Types
 // =============================================================================
@@ -93,20 +110,21 @@ export function cloneRepo(options: CloneRepoOptions): string {
         execFileSync("git", ["checkout", "-f", "HEAD"], { cwd: repoLocation });
 
         if (branchName) {
-            // Try to fetch and reset to the remote branch; create locally if it doesn't exist
-            try {
+            // Check if branch exists on remote before attempting fetch
+            const remoteBranchExists = branchExistsOnRemote(repoLocation, branchName);
+            if (remoteBranchExists) {
                 execFileSync("git", ["fetch", "--depth", "2", "origin", branchName], { cwd: repoLocation, stdio: "pipe" });
-                execFileSync("git", ["checkout", "-B", branchName, `origin/${branchName}`], { cwd: repoLocation });
+                execFileSync("git", ["checkout", "-B", branchName, "FETCH_HEAD"], { cwd: repoLocation });
                 console.log(`[Engine SDK] Checked out existing branch: ${branchName}`);
-            } catch {
+            } else {
                 // Branch doesn't exist on remote — fetch default branch and create new branch from it
                 execFileSync("git", ["fetch", "--depth", "2", "origin"], { cwd: repoLocation, stdio: "pipe" });
                 execFileSync("git", ["checkout", "-B", branchName, "FETCH_HEAD"], { cwd: repoLocation });
                 console.log(`[Engine SDK] Created new branch: ${branchName}`);
             }
         }
     } else {
-        const authenticatedUrl = cloneUrl.replace("://", `://x-access-token:${gitToken}@`);
+        const authHeader = `Authorization: basic ${Buffer.from(`x-access-token:${gitToken}`).toString("base64")}`;
 
         // Try to clone the existing remote branch directly.
         // If the branch doesn't exist yet, fall back to a default clone + new branch.
@@ -116,7 +134,7 @@ export function cloneRepo(options: CloneRepoOptions): string {
                 console.log(`[Engine SDK] Cloning ${repository} (branch: ${branchName}) to ${repoLocation}...`);
                 execFileSync(
                     "git",
-                    ["clone", "-b", branchName, "--single-branch", "--depth", "2", authenticatedUrl, repoLocation],
+                    ["-c", `http.extraHeader=${authHeader}`, "clone", "-b", branchName, "--single-branch", "--depth", "2", cloneUrl, repoLocation],
                     { stdio: "inherit" }
                 );
                 clonedExistingBranch = true;
@@ -127,7 +145,7 @@ export function cloneRepo(options: CloneRepoOptions): string {
 
         if (!clonedExistingBranch) {
             console.log(`[Engine SDK] Cloning ${repository} to ${repoLocation}...`);
-            execFileSync("git", ["clone", "--depth", "2", authenticatedUrl, repoLocation], {
+            execFileSync("git", ["-c", `http.extraHeader=${authHeader}`, "clone", "--depth", "2", cloneUrl, repoLocation], {
                 stdio: "inherit",
             });
 
@@ -137,7 +155,7 @@ export function cloneRepo(options: CloneRepoOptions): string {
             }
         }
 
-        // Configure credentials and remote URL (replace embedded-token URL)
+        // Configure credentials and remote URL
         configureGit();
         console.log(`[Engine SDK] Clone complete.`);
     }
@@ -167,7 +185,7 @@ export function commitAndPush(repoLocation: string, commitMessage: string): Comm
         execFileSync("git", ["commit", "-m", commitMessage], { cwd: repoLocation });
     }
 
-    execFileSync("git", ["push", "--force", "--set-upstream", "origin", "HEAD"], { cwd: repoLocation });
+    execFileSync("git", ["push", "--set-upstream", "origin", "HEAD"], { cwd: repoLocation });
 
     return {
         success: true,

src/index.ts

@@ -119,3 +119,11 @@ export type {
 export { cloneRepo, commitAndPush, finalizeChanges } from "./git.js";
 
 export type { CloneRepoOptions, CommitAndPushResult } from "./git.js";
+
+// =============================================================================
+// MCP Proxy Discovery
+// =============================================================================
+
+export { discoverMCPServers, isMCPProxyAvailable } from "./mcp-proxy.js";
+
+export type { MCPServerEntry, DiscoveredMCPServer } from "./mcp-proxy.js";

src/mcp-proxy.ts

@@ -0,0 +1,84 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *--------------------------------------------------------------------------------------------*/
+
+/**
+ * MCP Proxy Discovery
+ *
+ * Discovers user-provided MCP servers from the platform's MCP proxy.
+ * The proxy runs out-of-process (outside the firewall) and exposes
+ * user MCP servers as HTTP MCP endpoints.
+ */
+
+export interface MCPServerEntry {
+    name: string;
+    proxyEndpoint: string;
+}
+
+export interface DiscoveredMCPServer {
+    type: "http";
+    url: string;
+}
+
+/**
+ * Checks whether the MCP proxy is available at the given URL.
+ */
+export async function isMCPProxyAvailable(proxyUrl: string): Promise<boolean> {
+    try {
+        const response = await fetch(`${proxyUrl}/health`, {
+            signal: AbortSignal.timeout(5000),
+        });
+        return response.ok;
+    } catch {
+        return false;
+    }
+}
+
+/**
+ * Discovers available MCP servers from the proxy and returns configs
+ * ready to pass to the Copilot SDK's createSession mcpServers option.
+ *
+ * Returns an empty object if the proxy is unavailable or has no servers.
+ */
+export async function discoverMCPServers(
+    proxyUrl: string,
+): Promise<Record<string, DiscoveredMCPServer>> {
+    if (!(await isMCPProxyAvailable(proxyUrl))) {
+        console.log(`[MCP] Proxy not available at ${proxyUrl}`);
+        return {};
+    }
+
+    try {
+        const response = await fetch(`${proxyUrl}/mcp/servers`, {
+            signal: AbortSignal.timeout(10000),
+        });
+        if (!response.ok) {
+            console.warn(`[MCP] Failed to list servers: ${response.status}`);
+            return {};
+        }
+
+        const data = (await response.json()) as { servers: MCPServerEntry[] };
+        const servers: Record<string, DiscoveredMCPServer> = {};
+
+        for (const server of data.servers) {
+            const endpoint = server.proxyEndpoint.startsWith("http")
+                ? server.proxyEndpoint
+                : `${proxyUrl}${server.proxyEndpoint}`;
+            servers[server.name] = {
+                type: "http",
+                url: endpoint,
+            };
+        }
+
+        if (Object.keys(servers).length > 0) {
+            console.log(`[MCP] Discovered ${Object.keys(servers).length} servers: ${Object.keys(servers).join(", ")}`);
+        } else {
+            console.log(`[MCP] Proxy available but no servers configured`);
+        }
+
+        return servers;
+    } catch (error) {
+        console.warn(`[MCP] Failed to discover servers: ${error}`);
+        return {};
+    }
+}