chore: nightly sync main into dev (05_05_2026)

[svcnvidia-nemo-ci]

Summary

Nightly automated sync of main into dev (2026-05-05).

• Brings in 84 commits from main
• Python lines: +33076 / -5083 across 222 files

Files taken from main (semantic conflicts)

These files have known semantic conflicts where dev's versions reference args
or APIs main has removed/renamed. Taken from main wholesale:

• megatron/training/training.py
• megatron/training/initialize.py
• megatron/training/utils.py
• megatron/training/datasets/data_samplers.py

Files restored from main

• megatron/core/pipeline_parallel/hybrid_cp_schedule.py — provides
  BalancedCPScheduler, required by main's HybridCPDataLoaderWrapper.
  Dev had renamed it to dynamic_cp_schedule.py and then deleted that
  file in PR [Dev] feat: Dynamic CP (part 2) #2000 ("Dynamic CP part 2") in favor of a new in-place
  scheduler. Restored so main's training code continues to import.

Special handling

• megatron/core/datasets/data_schedule.py: kept dev's classes
  (BasePackingScheduler, DpBalancedScheduler, DefaultDynamicCPScheduler,
  wrap_data_iterator, get_batch_on_this_rank_for_sequence_packing) and
  appended main's HybridCPDataLoaderWrapper. Imports unioned (Any, List,
  BalancedCPScheduler added).
• megatron/training/training.py: changed
  if args.hybrid_context_parallel: to
  if getattr(args, 'hybrid_context_parallel', False): since the arg
  no longer exists in dev's arguments.py (replaced by dev's new dynamic
  CP system). The HybridCPDataLoaderWrapper import path remains valid.

Files restored to dev's version

• .github/CODEOWNERS — sync bot must never modify CODEOWNERS.
• pyproject.toml — dev includes fast-hadamard-transform git source and
  newer nvidia-resiliency-ext revision.
• uv.lock — paired with dev's pyproject.toml.
• docker/Dockerfile.ci.dev — uses --group no_pypi_wheels flag matching
  dev's pyproject.toml.

Conflict resolution summary

-X theirs (favor main) was used as the merge strategy. The full
git show --remerge-diff output is attached below for review.

Files that had genuine merge conflicts (25):

• .github/workflows/cicd-main.yml
• docker/Dockerfile.ci.dev (restored to dev)
• docs/conf.py
• examples/mimo/train.py
• megatron/core/datasets/readme.md
• megatron/core/transformer/moe/fused_a2a.py
• megatron/core/transformer/moe/moe_layer.py
• megatron/core/transformer/moe/token_dispatcher.py
• megatron/core/transformer/transformer_config.py
• megatron/core/transformer/transformer_layer.py
• megatron/training/activation_logging.py
• megatron/training/arguments.py
• megatron/training/checkpointing.py
• megatron/training/training.py (taken from main, then patched)
• megatron/training/utils.py (taken from main)
• pretrain_bert.py
• pretrain_gpt.py
• pretrain_mamba.py
• pretrain_vlm.py
• pyproject.toml (restored to dev)
• tests/unit_tests/models/test_hybrid_moe_model.py
• tools/checkpoint/checkpoint_inspector.py
• tools/checkpoint/remap_gpt_dsa_to_mamba.py
• train_rl.py
• uv.lock (restored to dev)

Pre-merge formatting

Ran black==24.4.2 (with --skip-magic-trailing-comma --skip-string-normalization)
and isort==5.13.2 on the full set of changed files. pylint==3.2.6 and
ruff~=0.9 produce zero warnings on the autoformat target set.

🤖 Generated by automated nightly sync bot.

[copy-pr-bot]

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[svcnvidia-nemo-ci]

/ok to test b187f43

[svcnvidia-nemo-ci]

/ok to test e879a55

[svcnvidia-nemo-ci]

/ok to test 4de6661

[svcnvidia-nemo-ci]

/ok to test 3567666

[Phlip79]

/ok to test 9a0cbdd

[Phlip79]

/ok to test 9a0cbdd

[svcnvidia-nemo-ci]

Superseded by today's nightly sync.