When Top-1 Fails: Calibrating LoRA Monitors for Masked Diffusion LMs
On the map: Diffusion models → Discrete and text diffusion
Abstract (arXiv)
Discrete diffusion language model (DLM) fine-tuning inherits inexpensive diagnostics from denoising-time confidence monitors, but their PEFT-training meaning is untested. We test top-1 argmax concentration as a collapse warning. Across 816 LoRA/PEFT configurations from three DLM families, the warning fires for every configuration while logs record 0/816 actual collapses at the 200 step horizon, giving zero precision. The cause is pre-equilibrium saturation: top-1 concentration is already high before optimization and quickly becomes insensitive to final training stability. We then evaluate max LoRA gradient norm, a parameter-side signal that samples gradient routing rather than token concentration. On a pooled held-out LLaDA-family split, a train-optimized threshold identifies top-decile final-loss configurations with precision 0.68 and F1=0.79, above the all-positive top-1 baseline even at the lower split-bootstrap confidence bound. Autoregressive controls and cross-family threshold failures bound the result to short-horizon DLM-LoRA inspection rather than a universal collapse detector. Workflow: drop top-1 as a PEFT alarm, log max-gradient early in training, and calibrate thresholds per DLM family before routing runs for inspection.
Key facts. No citing papers in the map yet (data through 14 Oct 2026). Placed in Discrete and text diffusion, one of 14 directions in Diffusion models. Builds on 20 of its 34 references that are in the map. First posted on arXiv 23 Jun 2026.
Builds on
20 of 34 references.
Closest ancestors · 4
Same direction, newest first
- 2026Layer Collapse in Diffusion Language Models7 May
- 2026Tuning the Implicit Regularizer of Masked Diffusion Language Models: Enhancing Generalization via Insights from k-Parity30 Jan
- 2025LLaDA-MoE: A Sparse MoE Diffusion Language Model29 Sep
- 2025Dream 7B: Diffusion Large Language Models21 Aug
Other references · 16
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- 2025LoRA-MGPO: Mitigating Double Descent in Low-Rank Adaptation via Momentum-Guided Perturbation Optimizationcited by 10
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- 2026NaRA: Noise-Aware LoRA for Parameter-Efficient Fine-Tuning of Diffusion LLMscited by 4
- 2026Benchmarking Recursive-Collapse Warning Claims Under Matched False-Positive Controlcited by 1
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