{
  "source_of_truth": "docs/BASELINE_SPEC.md",
  "purpose": "First approximately 2x BP twin rung after the completed 72M FineWeb model",
  "changed_from_72m": {
    "width": "512 -> 768",
    "heads": "8 -> 12",
    "parameters": "72,114,688 -> 135,303,936",
    "training_updates": "440,443 updates to preserve approximately 20 tokens/parameter"
  },
  "held_fixed_from_72m": {
    "layers": 12,
    "head_dim": 64,
    "context": 256,
    "global_sequence_batch": 24,
    "data": "fineweb_edu",
    "vocab": 32768,
    "architecture": "local OLMo2-style",
    "optimizer": "Muon on hidden matrices plus AdamW on remaining parameters",
    "muon_lr": 0.02,
    "adam_side_lr_center": 0.001,
    "weight_decay": 0.1,
    "warmup_steps": 500,
    "schedule": "cosine to 0.1 of peak",
    "precision": "bf16 autocast with fp32 parameters/states"
  },
  "locked_run": {
    "tag": "fw135m_bp",
    "layers": 12,
    "width": 768,
    "heads": 12,
    "head_dim": 64,
    "context": 256,
    "batch": 24,
    "parameters": 135303936,
    "target_tokens_20N": 2706078720,
    "trainer_steps_argument": 440442,
    "actual_updates": 440443,
    "actual_tokens": 2706081792
  },
  "bp_lr_sweep_smallest_rung_only": [0.0007, 0.001, 0.0014],
  "minimum_seeds_before_reporting": 2
}