[model] gemma4 (#10346)

.ai/CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Commands
+
+```bash
+# Code style (auto-fix)
+make style
+
+# Code quality check (no modifications)
+make quality
+
+# Run all tests
+make test
+
+# Run a single test file
+WANDB_DISABLED=true pytest -vv --import-mode=importlib tests/path/to/test_file.py
+
+# Run tests matching a pattern
+WANDB_DISABLED=true pytest -vv --import-mode=importlib tests/ -k "test_name"
+
+# License header check
+make license
+
+# Build package
+make build
+```
+
+The project uses `uv` as the preferred package manager. Commands automatically use `uv run` / `uvx` if `uv` is available.
+
+## Architecture
+
+LlamaFactory has two parallel architectures controlled by the `USE_V1` environment variable:
+
+- **v0 (default):** `api, webui > chat, eval, train > data, model > hparams > extras`
+- **v1 (experimental, `USE_V1=1`):** `trainers > core > accelerator, plugins, config > utils`
+
+Most active development happens in v0. The v1 architecture lives in `src/llamafactory/v1/`.
+
+### Entry Points
+
+CLI entry point is `llamafactory-cli` / `lmf` → `src/llamafactory/cli.py:main()`, which dispatches to `launcher.py` based on `USE_V1`.
+
+Available subcommands: `train`, `chat`, `api`, `export`, `webchat`, `webui`, `env`, `version`, `help`.
+
+### Training Flow (v0)
+
+```
+run_exp() [tuner.py]
+  → read_args() → parse YAML/JSON config
+  → get_train_args() → produces typed argument dataclasses
+  → routes to: run_sft / run_dpo / run_ppo / run_rm / run_pt / run_kto
+  → optional: export_model()
+```
+
+Training is invoked with a YAML config: `llamafactory-cli train examples/train_lora/llama3_lora_sft.yaml`
+
+### Configuration System
+
+All training parameters are YAML/JSON config files. Argument parsing in `src/llamafactory/hparams/parser.py` produces four typed dataclasses:
+- `ModelArguments` — model/tokenizer selection, quantization
+- `DataArguments` — datasets, templates, preprocessing
+- `FinetuningArguments` — LoRA rank/target, training method (sft/dpo/ppo/rm/pt/kto)
+- `TrainingArguments` — extends HuggingFace's `TrainingArguments`
+
+### Key Modules
+
+| Module | Purpose |
+|--------|---------|
+| `src/llamafactory/model/loader.py` | Loads model + tokenizer; applies quantization, LoRA, patches |
+| `src/llamafactory/model/patcher.py` | Model-specific compatibility patches |
+| `src/llamafactory/data/template.py` | Prompt templates; `TEMPLATES` dict maps model family → format |
+| `src/llamafactory/data/mm_plugin.py` | Multi-modal (image/video/audio) data handling |
+| `src/llamafactory/data/processor/` | Per-stage data processors (supervised, pairwise, pretrain, etc.) |
+| `src/llamafactory/train/sft/` | SFT trainer; other stages follow same structure |
+| `src/llamafactory/chat/` | Inference engines: `hf_engine`, `vllm_engine`, `sglang_engine`, `kt_engine` |
+| `src/llamafactory/extras/constants.py` | Enums and constants used across the project |
+
+### Adding Support for a New Model
+
+1. Add a prompt template to `src/llamafactory/data/template.py` in the `TEMPLATES` dict
+2. Add any necessary model patches in `src/llamafactory/model/patcher.py`
+3. Add multi-modal support in `src/llamafactory/data/mm_plugin.py` if needed
+
+### Distributed Training
+
+Multi-GPU automatically uses `torchrun`. Additional backends:
+- **Ray:** Optional Ray cluster support
+- **HyperParallel FSDP2:** `src/llamafactory/train/hyper_parallel/`
+- **Megatron-core:** `src/llamafactory/train/mca/`
+
+### Testing
+
+- `tests/` — v0 tests; `tests_v1/` — v1 tests
+- Most training tests require GPU hardware
+- pytest markers: `@pytest.mark.slow`, `@pytest.mark.runs_on(['cuda'])`
+- Always set `WANDB_DISABLED=true` when running tests
+
+### Code Style
+
+- Ruff for linting and formatting (line length 119, Google-style docstrings)
+- Python 3.11+ syntax
+- Double quotes for strings
+- All new files must include Apache 2.0 license header (checked by `make license`)