Training Check
Periodically read WandB metrics during training to catch problems early. Do not wait until training finishes to discover it was a waste of GPU time.
Context: $ARGUMENTS
Constants
- WANDB_ENTITY and WANDB_PROJECT: read from CLAUDE.md or passed as argument (format:
entity/project/run_id) - CHECK_INTERVAL: starts at 10 minutes, then gradually increases if consistently healthy: 10 min → 20 min → 30 min → 60 min (cap)
- REVIEWER_MODEL =
gpt-5.4— used via Codex MCP for ambiguous cases only
When to Use
- After training is confirmed running (session alive, loss decreasing for first few steps)
- Set up via CronCreate to fire periodically during training
- This skill checks training QUALITY, not process HEALTH. Process health (session alive, GPU utilization) is watchdog.py's job.
Workflow
Step 1: Read WandB Metrics
import wandb
api = wandb.Api()
run = api.run("<entity>/<project>/<run_id>")
history = run.history()If WandB is unreachable (API error, network issue), fall back to reading the log file directly via SSH:
ssh server "tail -100 /path/to/training.log"Check these signals:
- Loss trend: Is training loss decreasing over the last N steps?
- Eval metrics: Are evaluation metrics improving (or at least not degrading)?
- NaN / Inf: Any NaN or Inf values in loss or gradients?
- Spikes: Sudden large jumps in loss (>10x normal variance)?
- Learning rate: Is the schedule behaving as expected?
- Gradient norm: Exploding or vanishing?
Step 2: Judgment
| Signal | Judgment | Action |
|---|---|---|
| NaN/Inf in loss | Clearly bad | Stop training, investigate |
| Loss diverging (increasing for >N steps) | Clearly bad | Stop training, investigate |
| Eval metrics significantly worse than baseline | Clearly bad | Stop training, investigate |
| Loss decreasing, metrics improving | Clearly fine | Continue, increase check interval |
| Loss flat but not diverging | Unsure | → Step 3 (Codex judgment) |
| Metrics noisy, can't tell trend | Unsure | → Step 3 (Codex judgment) |
| Slightly worse than baseline but still early | Unsure | → Step 3 (Codex judgment) |
Step 3: Codex Judgment (only when unsure)
Only escalate to Codex when the signal is ambiguous. For clearly good or clearly bad signals, act directly.
mcp__codex__codex:
config: {"model_reasoning_effort": "high"}
prompt: |
TRAINING HEALTH CHECK — need your judgment on ambiguous metrics.
Run: <entity>/<project>/<run_id>
Current epoch/step: X / Y total
Training loss (last 10 checkpoints): [values]
Eval metrics (last 3 evals): [values]
Baseline reference: [numbers from paper/reproduction]
What I'm unsure about: [specific concern]
Please respond with exactly one of:
- STOP: clearly problematic, should kill training
- CONTINUE: looks fine, check again next interval
- WAIT: not enough data to judge, check again soonerStep 4: Act
| Decision | Action |
|---|---|
| Stop | Kill the training session. Save the WandB run URL, key metrics, and reason for stopping. Log to project notes for debugging. |
| Continue | Do nothing. Will be invoked again at next interval (increase interval if consistently healthy). |
| Wait | Do nothing but keep the current short interval (don't increase). |
Integration with Watchdog
Training-check and watchdog.py operate at different levels:
| Layer | Tool | What it checks | Frequency |
|---|---|---|---|
| Process health | watchdog.py | Session alive? GPU active? | Every 60s (continuous) |
| Training quality | training-check | Loss trend? Metrics improving? | Every 10-60 min (periodic) |
Use both together:
- Watchdog catches crashes and idle GPUs immediately
- Training-check catches subtle quality issues (loss plateau, metric degradation)
Rules
- Do not stop training on first sign of noise — some loss spikes are normal. Look at trends over multiple checkpoints.
- When stopping training, always save the WandB run URL and key metrics as evidence.
- If both WandB and log files are unreachable, report the connectivity issue and try again next interval. Do not assume training is broken.
- Gradually increase check interval when healthy (10 → 20 → 30 → 60 min). Reset to 10 min after any anomaly.
- This skill is meant to be automated via CronCreate — do not ask the user whether to set it up. Just set it.
CronCreate Setup Example
After training is confirmed stable:
CronCreate (recurring, every 10 minutes initially):
"Run /training-check for wandb run <entity>/<project>/<run_id>"As the check interval increases, delete the old CronCreate job and create a new one with the longer interval.