Nemotron V3 training run

Training recovery, held-out metrics, and the frozen Svelte benchmark verdict.

Final validation loss
0.4401
1.0588 before training
Static-clean answers
0 / 10
Frozen held-out suite
V1 vs V3
7–2
V1 wins; 1 order-sensitive
V2 vs V3
6–4
V2 wins
Verdict

Do not promote V3. Training converged cleanly, but V1 remains decisively better and V2 also wins the direct blinded comparison.

Run and recovery

The adapter trained on 1,080 rows from 270 specs, with 120 validation rows from 30 disjoint specs. Token lengths ranged from 872 to 10,784; the 12,288-token ceiling truncated zero examples.

The machine restarted after step 105. Checkpoint 100 was complete, so training resumed from its adapter, optimizer, scheduler, and RNG state. Five uncheckpointed steps were lost. The resumed job ran at lowered CPU and I/O priority with the noisy vLLM Studio GPU polling service disabled, then completed all 270 optimizer steps and exactly two epochs.

Base model
nvidia/Nemotron-Cascade-8B
Training method
4-bit NF4 QLoRA, rank 32, all linear modules
Final adapter size
349,243,752 bytes
Adapter SHA-256
1389c83c1b6b81806f572761682176a4460818ef258529dba0c4ea91c0fcc514

Learning curve

Held-out validation metrics
StepEpochLossToken accuracy
00.0001.05880.7855
250.1850.62450.8318
1000.7410.47530.8608
1751.2960.44890.8680
2501.8520.44020.8704
2702.0000.44010.8704

The held-out curve improved through the final sweep. This was not a failed optimizer run; the model learned the training distribution successfully.

Frozen benchmark

Static and Fable rubric results on the same 10 held-out prompts
ModelStatic cleanRubric averageDirect evidence
Base0 / 101.30 / 5Baseline
V12 / 101.83 / 5Best
V21 / 101.67 / 5Beats V3, 6–4
V30 / 101.72 / 5Loses to V1, 2–7

V3 produced 10/10 correctly shaped raw answers, but only 7/10 passed policy, 4/10 compiled, 2/10 had zero svelte-check errors, and 1/10 passed the autofixer. The all-or-nothing static score was therefore 0/10. One response hit the 8,192-token generation cap; truncation does not explain the other failures.

Open the interactive per-prompt report and code playground links.

V4 implications

The key lesson is that low held-out language-model loss did not predict executable Svelte quality. V4 should be gated primarily by fresh generated-code validity and prompt fidelity, not by training loss alone.

  • Keep the frozen 10-prompt suite unchanged for direct comparability.
  • Inspect target completion length and document-like verbosity; V3 generated several malformed or over-elaborate components.
  • Favor examples whose behavior is fully specified and validated, while excluding portability-biased contract labels from reward decisions.
  • Run an early checkpoint benchmark before committing to the full schedule; stop if compile-clean rate regresses.