arXiv cs.CL
8/5/2026

Stuck on "A": Diagnosing and Repairing Interface Injury in Attention-to-KDA Linearization of a 0.6B Language Model
Short summary
Researchers converted 21 of 28 attention layers in Qwen3-0.6B to KDA linear attention on a single consumer GPU, finding that while perplexity matched the teacher, multiple-choice accuracy stayed near random. A diagnostic revealed the model fixated on answer labels (predicting 'A' 81% of the time) rather than content—an 'interface injury' invisible to standard distillation metrics. A 1,000-step format-targeted KL repair stage fixed the issue (+12.48 points on C-Eval), and the team released code, weights, and full audit trails.
- •21/28 Qwen3-0.6B attention layers converted to KDA linear attention on consumer GPU; perplexity matched teacher but accuracy stayed near random
- •Interface injury diagnosed: model predicts option 'A' 81% of the time regardless of content, invisible to standard distillation metrics
- •1,000-step format-targeted KL repair restores +12.48 points on C-Eval; code, weights, and recipes released
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