Remove custom DistillationProvider and simplify mbridge distillation and hf export

examples/puzzletron/mbridge_distillation/README.md

@@ -67,11 +67,11 @@ Run distillation directly from HuggingFace checkpoints (student and teacher) wit
 ```bash
 torchrun --nproc_per_node=8 examples/puzzletron/mbridge_distillation/distill_hf.py \
     --student_hf_path /path/to/student/huggingface/checkpoint \
+    --student_hf_model meta-llama/Llama-3.1-8B-Instruct \
     --teacher_hf_path /path/to/teacher/huggingface/checkpoint \
     --data_paths 1.0 /path/to/hf_datasets/wikitext-103-v1/Salesforce--wikitext_wikitext-103-v1_train_text_document \
     --output_dir /path/to/distilled/checkpoint \
-    --hf-export-path /path/to/exported/hf/model \
-    --hf-model meta-llama/Llama-3.1-8B-Instruct \
+    --hf_export_path /path/to/exported/hf/model \
     --seq_length 4096 \
     --tp_size 8 \
     --pp_size 1 \
@@ -90,7 +90,7 @@ torchrun --nproc_per_node=8 examples/puzzletron/mbridge_distillation/distill_hf.
 
 - Add `--trust_remote_code` if student or teacher checkpoints need HuggingFace custom modeling code.
 - The distilled Megatron-Bridge checkpoint will be saved to `--output_dir/checkpoints/iter_<train_iters>`.
-- Add `--hf-export-path` (or `--hf_export_path`) to automatically export the final checkpoint to HuggingFace format after distillation. When exporting, you must also provide `--hf-model` / `--hf_model` as the HuggingFace model ID for the export template (e.g., `meta-llama/Llama-3.1-8B-Instruct`). It should match the base architecture of the student model. The exported model can be evaluated for accuracy using the evaluation tools described in the main [README.md](../README.md#evaluation).
+- Add `--hf_export_path` to automatically export the final checkpoint to HuggingFace format after distillation. When exporting, you must also provide `--student_hf_model` as the HuggingFace model ID for the export template (e.g., `meta-llama/Llama-3.1-8B-Instruct`). It should match the base architecture of the student model. The exported model can be evaluated for accuracy using the evaluation tools described in the main [README.md](../README.md#evaluation).
 - For production use, use larger datasets like [Nemotron-Pretraining-SFT-v1](https://huggingface.co/datasets/nvidia/Nemotron-Pretraining-SFT-v1) and train for more iterations. See the [Megatron-Bridge distillation tutorial](https://github.com/NVIDIA/Model-Optimizer/tree/main/examples/megatron_bridge#distillation) for best practices.
 
 ## MMLU Evaluation Results

examples/puzzletron/mbridge_distillation/distill_hf.py

@@ -22,11 +22,11 @@
 
 import argparse
 import os
-import traceback
+import shutil
 
-import megatron.bridge.models.distillation_provider
 import torch
 from megatron.bridge import AutoBridge
+from megatron.bridge.models.distillation_provider import convert_to_distillation_provider
 from megatron.bridge.recipes.utils.optimizer_utils import (
     distributed_fused_adam_with_cosine_annealing,
 )
@@ -40,39 +40,16 @@
     TokenizerConfig,
     TrainingConfig,
 )
+from megatron.bridge.training.distill import distill
 from megatron.bridge.training.post_training.distillation import ModelOptDistillConfig
 from megatron.core.datasets.utils import get_blend_from_list
 from megatron.core.distributed import DistributedDataParallelConfig
 
-# Import heterogeneous bridges BEFORE AutoBridge.from_hf_pretrained() is called to ensure
-# registration takes precedence. The @MegatronModelBridge.register_bridge decorator registers
-# bridges when the module is imported. If both LlamaBridge and PuzzletronLlamaAnyModelBridge
-# register for the same source (LlamaForCausalLM), the dispatch system uses the last registration.
-#
-# Note: Currently, bridges are also registered when distillation_provider is imported
-# below (via mbridge/__init__.py), but this import will be needed once DistillationProvider
-# is upstreamed to Megatron-Bridge and we no longer import from modelopt.torch.puzzletron.
+# Import to register heterogeneous bridges (side effect)
 import modelopt.torch.puzzletron.export.mbridge  # noqa: F401
 import modelopt.torch.utils.distributed as dist
-
-# Use local copy of distillation_provider with fix for heterogeneous models
-# TODO: Remove this local copy once fix is upstreamed to Megatron-Bridge
-from modelopt.torch.puzzletron.export.mbridge.distillation_provider import (
-    DistillationProvider,
-    convert_to_distillation_provider,
-)
-from modelopt.torch.puzzletron.export.mbridge.export_mbridge_to_hf import (
-    export_to_hf_and_copy_config,
-)
 from modelopt.torch.utils import print_rank_0
 
-# Patch upstream module BEFORE importing distill() so isinstance checks work with our local DistillationProvider
-# This must happen before distill() is imported because distill.py imports DistillationProvider at module load time
-megatron.bridge.models.distillation_provider.DistillationProvider = DistillationProvider
-
-# Import distill() AFTER patching so it uses the patched DistillationProvider
-from megatron.bridge.training.distill import distill  # noqa: E402
-
 SEED = 1234
 
 
@@ -84,13 +61,13 @@ def get_args():
         "--student_hf_path",
         type=str,
         required=True,
-        help="HuggingFace model name or path for the student (e.g. Qwen/Qwen3-0.6B)",
+        help="HuggingFace model path for the student in puzzletron any_model format",
     )
     parser.add_argument(
         "--teacher_hf_path",
         type=str,
         required=True,
-        help="HuggingFace model name or path for the teacher (e.g. Qwen/Qwen3-8B)",
+        help="HuggingFace model path for the teacher in puzzletron any_model format",
     )
     parser.add_argument("--trust_remote_code", action="store_true", help="Trust remote code")
     # Parallelism arguments
@@ -145,28 +122,30 @@ def get_args():
     # Export arguments
     parser.add_argument(
         "--hf_export_path",
-        "--hf-export-path",
         type=str,
         default=None,
         help=(
             "Path where to save the HuggingFace export. "
-            "If provided, exports checkpoint to HF format after distillation."
+            "If provided, exports last iteration checkpoint to HF format after distillation."
         ),
     )
     parser.add_argument(
-        "--hf_model",
-        "--hf-model",
+        "--student_hf_model",
         type=str,
-        required=True,
-        help="HuggingFace model ID to use as template for export (e.g., meta-llama/Llama-3.1-8B-Instruct). "
-        "Should match the base architecture of the student model.",
+        required=False,
+        default=None,
+        help="HuggingFace model ID to use as template for export (e.g., Qwen/Qwen3-0.6B). "
+        "Should match the base architecture of the student model if --hf_export_path is provided.",
     )
     args = parser.parse_args()
 
     # Sanity checks
     if not args.use_mock_data and not args.data_paths:
         raise ValueError("Must provide either --data_paths or set --use_mock_data.")
 
+    if args.hf_export_path and not args.student_hf_model:
+        raise ValueError("Must provide --student_hf_model if --hf_export_path is provided.")
+
     print_rank_0("\n==================== Arguments ====================")
     for k, v in args.__dict__.items():
         print_rank_0(f"{k:<35} {v}")
@@ -288,42 +267,34 @@ def _build_model_provider(hf_path):
 
     # Export to HuggingFace format if hf_export_path is provided
     if args.hf_export_path:
-        # Wait for all ranks to finish distillation before export
-        if torch.distributed.is_initialized():
-            torch.distributed.barrier()
-
+        print_rank_0(f"Exporting final distilled ckpt to HF format to {args.hf_export_path}")
         # Save rank before destroying process group (dist.rank() won't work after destruction)
         is_rank_0 = dist.rank() == 0
 
         # Destroy process group on all ranks - export_ckpt will create its own temporary one
         # This prevents cleanup from hanging (cleanup tries to barrier, but rank 0 would be gone)
-        if torch.distributed.is_initialized():
-            torch.distributed.destroy_process_group()
+        dist.cleanup()
 
         # Only rank 0 exports
         if is_rank_0:
-            try:
-                export_to_hf_and_copy_config(
-                    student_hf_path=args.student_hf_path,
-                    checkpoint_dir=checkpoint_dir,
-                    train_iters=args.train_iters,
-                    hf_export_path=args.hf_export_path,
-                    hf_model=args.hf_model,
-                    trust_remote_code=args.trust_remote_code,
-                )
-            except Exception as e:
-                print(f"⚠️  Export failed: {e}")
-                traceback.print_exc()
+            export_bridge = AutoBridge.from_hf_pretrained(
+                args.student_hf_model, trust_remote_code=args.trust_remote_code
+            )
+            export_bridge.export_ckpt(
+                megatron_path=f"{checkpoint_dir}/iter_{args.train_iters:07d}",
+                hf_path=args.hf_export_path,
+                show_progress=True,
+                strict=True,
+            )
+
+            # save config from student_model to hf_export_path
+            shutil.copy(f"{args.student_hf_path}/config.json", f"{args.hf_export_path}/config.json")
 
 
 if __name__ == "__main__":
     dist.setup()
     args = get_args()
     try:
         main(args)
-    except Exception as e:
-        print_rank_0(f"✗ MAIN FAILED: {type(e).__name__}: {e}")
-        print_rank_0(f"Traceback:\n{traceback.format_exc()}")
-        raise
     finally:
         dist.cleanup()