fix: add merge-lora arg for model id (#2788)

launcher/src/main.rs

@@ -1193,6 +1193,7 @@ fn download_convert_model(
     huggingface_hub_cache: Option<&str>,
     weights_cache_override: Option<&str>,
     running: Arc<AtomicBool>,
+    merge_lora: bool,
 ) -> Result<(), LauncherError> {
     // Enter download tracing span
     let _span = tracing::span!(tracing::Level::INFO, "download").entered();
@@ -1207,6 +1208,10 @@ fn download_convert_model(
         "--json-output".to_string(),
     ];
 
+    if merge_lora {
+        download_args.push("--merge-lora".to_string());
+    }
+
     // Model optional revision
     if let Some(revision) = &revision {
         download_args.push("--revision".to_string());
@@ -1842,6 +1847,7 @@ fn main() -> Result<(), LauncherError> {
         args.huggingface_hub_cache.as_deref(),
         args.weights_cache_override.as_deref(),
         running.clone(),
+        true, // if its only a lora model - we should merge the lora adapters
     )?;
 
     // Download and convert lora adapters if any
@@ -1875,6 +1881,7 @@ fn main() -> Result<(), LauncherError> {
                     args.huggingface_hub_cache.as_deref(),
                     args.weights_cache_override.as_deref(),
                     running.clone(),
+                    false, // avoid merging lora adapters if using multi-lora
                 )?;
             } else {
                 return Err(LauncherError::ArgumentValidation(format!(