cortexlab 0.1.1

LoRA fine-tuning framework for MLX on Apple Silicon with a browser-based Studio UI

CortexLab

LoRA fine-tuning for MLX on Apple Silicon — with a browser-based Studio UI.

CortexLab is a framework for fine-tuning large language models on your Mac. It supports LoRA, QLoRA, DPO, sequence packing, and gradient checkpointing — all running natively on Apple Silicon via MLX. A built-in browser UI (Studio) lets you launch training runs, monitor loss curves in real time, and test your models interactively.

Features

Training

• LoRA and QLoRA (4-bit) fine-tuning with 67% memory reduction
• DPO (Direct Preference Optimization) for alignment training
• Sequence packing for 2-5x speedup on short sequences
• Gradient checkpointing for 40-60% activation memory savings
• Compiled training loop with gradient accumulation
• Cosine, linear, step, and exponential LR schedules with warmup
• Resume from any checkpoint

Models

• Llama 2/3 (all sizes)
• Mistral (mapped to Llama architecture)
• Qwen 2/3/3.5
• Phi-3/4
• Gemma 1/2/3 (1B-27B)
• Automatic Hugging Face model downloading and caching

Studio UI

• Browser-based training dashboard
• Real-time loss curves via WebSocket
• Model library and dataset browser
• Interactive playground for testing fine-tuned models

Data

• 20+ curated datasets across 7 categories (general, code, math, conversation, reasoning, safety, domain)
• Auto-detection of chat, completions, text, and preference formats
• Multi-dataset mixing with weighted sampling
• Data validation with train/val overlap detection

Installation

pip install cortexlab

Requires macOS with Apple Silicon (M1/M2/M3/M4) and Python 3.10+.

Quick Start

1. Install and download a dataset:

pip install cortexlab
cortexlab data catalog
cortexlab data download alpaca-cleaned --max-samples 5000

2. Create a config file (train.yaml):

schema_version: 1

model:
  path: "Qwen/Qwen3-0.6B"

adapter:
  preset: "attention-qv"
  rank: 8
  scale: 16.0

data:
  train: "~/.cortexlab/datasets/raw/alpaca-cleaned/data.jsonl"
  valid: "~/.cortexlab/datasets/raw/alpaca-cleaned/data.jsonl"
  max_seq_length: 512

training:
  batch_size: 4
  num_iters: 500
  learning_rate: 1.0e-4
  optimizer: adamw
  steps_per_save: 100
  steps_per_eval: 100
  steps_per_report: 10

3. Train:

cortexlab train --config train.yaml

CortexLab downloads the model from Hugging Face on first run and caches it locally. All subsequent runs work offline.

Studio UI

Launch the browser-based dashboard:

cortexlab studio
# Opens at http://127.0.0.1:8741

Studio provides:

• Dashboard — Start new training runs, monitor active jobs
• Runs — Browse past runs, compare loss curves
• Models — View downloaded models, check sizes and architectures
• Datasets — Browse and manage your datasets
• Playground — Chat with your fine-tuned models interactively

CLI Reference

Command	Description
cortexlab train --config FILE	Run LoRA/QLoRA/DPO training
cortexlab generate --model MODEL	Generate text (or interactive chat without --prompt)
cortexlab prepare --data FILE --model MODEL	Pre-tokenize a dataset
cortexlab studio	Launch the browser-based Studio UI
cortexlab data catalog	Browse 20+ curated datasets
cortexlab data download DATASET	Download a dataset from the catalog
cortexlab data import FILE --name NAME	Import a local JSONL file
cortexlab data inspect NAME	Preview dataset samples
cortexlab data stats NAME	Show dataset statistics
cortexlab data validate FILE	Validate JSONL format and check for issues
cortexlab data list	List downloaded datasets
cortexlab data delete NAME	Delete a dataset

Library API

All CLI commands are backed by Python functions:

from cortexlab import prepare, train
from cortexlab.config import TrainingConfig

# Pre-tokenize a dataset
prepare(data_path="train.jsonl", model="Qwen/Qwen3-0.6B")

# Train from a config file
config = TrainingConfig.from_yaml("train.yaml")
result = train(config=config)
print(f"Best val loss: {result.best_val_loss:.4f}")

from cortexlab import generate

# Generate text with a fine-tuned adapter
generate(
    model="Qwen/Qwen3-0.6B",
    adapter="~/.cortexlab/runs/my-run/checkpoints/best",
    prompt="Explain quantum computing in simple terms.",
    temperature=0.7,
    max_tokens=256,
)

Supported Models

Architecture	Model Families	Sizes
Llama	Llama 2, Llama 3, Llama 3.1, Llama 3.2	1B - 70B
Mistral	Mistral 7B, Mistral Nemo	7B - 12B
Qwen	Qwen 2, Qwen 2.5, Qwen 3, Qwen 3.5	0.6B - 72B
Phi	Phi-3, Phi-3.5, Phi-4	3.8B - 14B
Gemma	Gemma 1, Gemma 2, Gemma 3	1B - 27B

Models are auto-downloaded from Hugging Face on first use. Use any HF model ID (e.g., meta-llama/Llama-3.2-1B, Qwen/Qwen3-0.6B, google/gemma-3-1b).

Configuration

Full training config with all options:

schema_version: 1

model:
  path: "Qwen/Qwen3-0.6B"         # HF model ID or local path
  revision: "abc123"                # Optional: pin to specific HF commit
  quantization:                     # Optional: QLoRA (67% memory savings)
    bits: 4
    group_size: 64

adapter:
  preset: "attention-qv"           # attention-qv | attention-all | mlp | all-linear
  # targets: ["*.q_proj", "*.v_proj"]  # Or use custom glob patterns
  rank: 16
  scale: 32.0
  num_layers: 16                    # Optional: apply to last N layers only

data:
  train: "./train.jsonl"
  valid: "./val.jsonl"
  packing: false                    # Sequence packing (2-5x speedup)
  max_seq_length: 2048
  # sources:                        # Multi-dataset mixing
  #   - name: "dataset-a"
  #     weight: 0.7
  #   - name: "dataset-b"
  #     weight: 0.3

training:
  optimizer: adamw                  # adam | adamw | sgd | adafactor
  learning_rate: 1.0e-5
  num_iters: 1000
  batch_size: 4
  grad_accumulation_steps: 1
  gradient_checkpointing: false     # 40-60% memory savings (slight overhead)
  steps_per_save: 100
  steps_per_eval: 200
  steps_per_report: 10
  max_grad_norm: 1.0
  # training_type: dpo              # For DPO training
  # dpo_beta: 0.1

runtime:
  run_dir: "~/.cortexlab/runs"
  seed: 42

Data Formats

CortexLab auto-detects four JSONL formats:

Chat — Multi-turn conversations (loss computed on assistant turns only):

{"messages": [{"role": "user", "content": "Hello"}, {"role": "assistant", "content": "Hi!"}]}

Completions — Prompt-completion pairs:

{"prompt": "Translate to French: Hello", "completion": "Bonjour"}

Text — Raw text for continued pretraining:

{"text": "The quick brown fox jumps over the lazy dog."}

Preference — For DPO alignment training:

{"chosen": [{"role": "user", "content": "..."}, {"role": "assistant", "content": "good"}], "rejected": [{"role": "user", "content": "..."}, {"role": "assistant", "content": "bad"}]}

Advanced Features

QLoRA (4-bit Quantization)

Reduce memory usage by ~67% with minimal quality loss:

model:
  path: "meta-llama/Llama-3.2-3B"
  quantization:
    bits: 4
    group_size: 64

Sequence Packing

Pack multiple short sequences into a single batch for 2-5x speedup:

data:
  packing: true
  max_seq_length: 2048

Gradient Checkpointing

Trade compute for memory — saves 40-60% activation memory:

training:
  gradient_checkpointing: true

DPO Training

Train with Direct Preference Optimization using preference data:

training:
  training_type: dpo
  dpo_beta: 0.1

data:
  train: "./preference_data.jsonl"  # Must use preference format

Multi-Dataset Mixing

Combine multiple datasets with weighted sampling:

data:
  sources:
    - name: "general-chat"
      weight: 0.6
    - name: "code-instruct"
      weight: 0.4
  max_seq_length: 2048

Data Validation

Check your data for issues before training:

cortexlab data validate train.jsonl --val val.jsonl

Resume Training

Resume from any checkpoint:

cortexlab train --config train.yaml --resume ~/.cortexlab/runs/{run_id}/checkpoints/step-0001000

Run Artifacts

Every training run produces structured artifacts:

~/.cortexlab/runs/{run_id}/
├── config.yaml              # Frozen config snapshot
├── manifest.json            # Run metadata + model resolution
├── environment.json         # Environment info
├── checkpoints/
│   ├── step-0000100/
│   │   ├── adapters.safetensors
│   │   ├── optimizer.safetensors
│   │   └── state.json
│   └── best -> step-0000500
└── logs/
    └── metrics.jsonl

Contributing

See CONTRIBUTING.md for development setup, coding standards, and how to submit changes.

License

MIT