fix(train): tolerate missing/invalid WANDB_API_KEY, surface key length in smoke

train/grpo.py

@@ -120,7 +120,16 @@ def run_grpo(
         ["vllm_gpu_memory_utilization"],
         float(cfg.train.vllm_gpu_memory_utilization),
     )
-    _set_if_supported(["report_to"], ["wandb"])
+    import os
+    wb_key = os.environ.get("WANDB_API_KEY", "").strip()
+    use_wandb = len(wb_key) >= 40 and wb_key.isalnum()
+    _set_if_supported(["report_to"], ["wandb"] if use_wandb else [])
+    if not use_wandb:
+        log.warning(
+            "TRN-03 W&B disabled: WANDB_API_KEY missing or wrong length "
+            "(have %d chars, need 40). Training will continue without "
+            "W&B logging; metrics still printed to stdout.", len(wb_key)
+        )
     _set_if_supported(["logging_steps"], 1)
     # vllm_mode='colocate' alone is a no-op without `use_vllm=True` in TRL 1.2.
     _set_if_supported(["use_vllm"], True)
@@ -134,12 +143,15 @@ def run_grpo(
     grpo_config = GRPOConfig(**kwargs)
 
     # REW-03: wrap reward_fn to log per-component scalars to W&B
-    import wandb  # type: ignore
+    try:
+        import wandb  # type: ignore
+    except ImportError:
+        wandb = None
 
     def _instrumented_reward_fn(prompts, completions, **kwargs):
         rewards = reward_fn(prompts, completions, **kwargs)
         try:
-            if wandb.run is not None:
+            if wandb is not None and wandb.run is not None:
                 log_dict = {
                     "reward/composite_mean": sum(rewards) / max(len(rewards), 1),
                     "reward/composite_std": (

train/smoke_test.py

@@ -28,6 +28,10 @@ def _quick_smoke(env_url: str, output_dir: str) -> dict:
     start = time.time()
     results = {"checks": {}}
 
+    wb_key_len = len(os.environ.get("WANDB_API_KEY", "").strip())
+    log.info("TRN-04 W&B key length: %d (need 40+ for active logging)",
+             wb_key_len)
+
     # 1. Hydra config resolves
     log.info("TRN-04 [quick] step 1: Hydra config resolution...")
     from hydra import initialize, compose