Initial implementation: DAGFormer Phase 1

- olmo_graph.py: Modified OLMo2-1B forward with per-head routing via 256x256 adjacency matrix A
  - Proportional attribution for post-norm decomposition
  - All 6 GPU sanity checks pass (baseline diff = 0.000001)
- predictor.py: Qwen3-Embedding encoder + MLP decoder + Gumbel-Sigmoid + cascading gate
- pipeline.py: End-to-end glue (predictor -> A -> OLMo -> NLL)
- trainer.py: Full training loop with DDP, gradient accumulation, eval, checkpointing
- dolma.py: Streaming Dolma v1.7 with sequence packing
- 43/43 unit tests pass

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/src/utils/logging.py b/src/utils/logging.py
new file mode 100644
index 0000000..a9b3b10
--- /dev/null
+++ b/src/utils/logging.py
@@ -0,0 +1,63 @@
+"""Wandb integration for DAGFormer training.
+
+Logs all metrics from CLAUDE.md §7.
+"""
+
+from __future__ import annotations
+
+from typing import Any, Optional
+
+import wandb
+
+
+def init_wandb(
+    project: str,
+    run_name: str,
+    config: dict[str, Any],
+) -> Optional[wandb.sdk.wandb_run.Run]:
+    """Initialize wandb run.
+
+    Args:
+        project: wandb project name
+        run_name: run display name
+        config: full config dict to log
+
+    Returns:
+        wandb run object (or None if wandb init fails)
+    """
+    try:
+        run = wandb.init(
+            project=project,
+            name=run_name,
+            config=config,
+        )
+        return run
+    except Exception as e:
+        print(f"WARNING: wandb init failed: {e}. Continuing without wandb.")
+        return None
+
+
+def log_metrics(
+    metrics: dict[str, float],
+    step: int,
+    run: Optional[wandb.sdk.wandb_run.Run] = None,
+) -> None:
+    """Log metrics to wandb.
+
+    Args:
+        metrics: dict of metric_name → value
+        step: global training step
+        run: wandb run (if None, prints to stdout instead)
+    """
+    if run is not None:
+        wandb.log(metrics, step=step)
+    else:
+        # Fallback: print metrics
+        parts = [f"{k}={v:.4f}" if isinstance(v, float) else f"{k}={v}" for k, v in metrics.items()]
+        print(f"[step {step}] {', '.join(parts)}")
+
+
+def finish_wandb(run: Optional[wandb.sdk.wandb_run.Run] = None) -> None:
+    """Finish wandb run."""
+    if run is not None:
+        wandb.finish()