feat(mcp): add OAuth redirect URI configuration for MCP servers (#21385)

Co-authored-by: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>

packages/opencode/src/mcp/index.ts

@@ -286,6 +286,7 @@ export namespace MCP {
               clientId: oauthConfig?.clientId,
               clientSecret: oauthConfig?.clientSecret,
               scope: oauthConfig?.scope,
+              redirectUri: oauthConfig?.redirectUri,
             },
             {
               onRedirect: async (url) => {
@@ -716,13 +717,16 @@ export namespace MCP {
         if (mcpConfig.type !== "remote") throw new Error(`MCP server ${mcpName} is not a remote server`)
         if (mcpConfig.oauth === false) throw new Error(`MCP server ${mcpName} has OAuth explicitly disabled`)
 
-        yield* Effect.promise(() => McpOAuthCallback.ensureRunning())
+        // OAuth config is optional - if not provided, we'll use auto-discovery
+        const oauthConfig = typeof mcpConfig.oauth === "object" ? mcpConfig.oauth : undefined
+
+        // Start the callback server with custom redirectUri if configured
+        yield* Effect.promise(() => McpOAuthCallback.ensureRunning(oauthConfig?.redirectUri))
 
         const oauthState = Array.from(crypto.getRandomValues(new Uint8Array(32)))
           .map((b) => b.toString(16).padStart(2, "0"))
           .join("")
         yield* auth.updateOAuthState(mcpName, oauthState)
-        const oauthConfig = typeof mcpConfig.oauth === "object" ? mcpConfig.oauth : undefined
         let capturedUrl: URL | undefined
         const authProvider = new McpOAuthProvider(
           mcpName,
@@ -731,6 +735,7 @@ export namespace MCP {
             clientId: oauthConfig?.clientId,
             clientSecret: oauthConfig?.clientSecret,
             scope: oauthConfig?.scope,
+            redirectUri: oauthConfig?.redirectUri,
           },
           {
             onRedirect: async (url) => {