fix: use localhost instead of 127.0.0.1 for OAuth callback

This fixes the OAuth flow in WSL2 where 127.0.0.1 inside WSL is not
accessible from the Windows host browser. Using localhost enables
WSL2's built-in localhost forwarding between Windows and WSL.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: dcramer

packages/opencode/src/mcp/oauth-callback.ts

@@ -161,7 +161,7 @@ export namespace McpOAuthCallback {
   export async function isPortInUse(): Promise<boolean> {
     return new Promise((resolve) => {
       Bun.connect({
-        hostname: "127.0.0.1",
+        hostname: "localhost",
         port: OAUTH_CALLBACK_PORT,
         socket: {
           open(socket) {

packages/opencode/src/mcp/oauth-provider.ts

@@ -32,7 +32,7 @@ export class McpOAuthProvider implements OAuthClientProvider {
   ) {}
 
   get redirectUrl(): string {
-    return `http://127.0.0.1:${OAUTH_CALLBACK_PORT}${OAUTH_CALLBACK_PATH}`
+    return `http://localhost:${OAUTH_CALLBACK_PORT}${OAUTH_CALLBACK_PATH}`
   }
 
   get clientMetadata(): OAuthClientMetadata {