Pretrained text encoders are prone to shortcut learning, relying on token-label correlations that fail once the distribution shifts in deployment. Existing shortcut mitigation methods mainly operate at training time and assume access to training data, training dynamics, or shortcut annotations, which are hardly available during deployment, where only the converged model remains. We show that this model alone suffices to mitigate shortcuts during deployment: a biased model internalizes a signal of its learned shortcuts that can be captured via unsupervised gradient-based attribution. We further prove that deployment-time mitigation is information-theoretically upper-bounded by training-time mitigation. Nevertheless, exploiting this gradient signal, our proposed unsupervised deployment-time shortcut mitigation framework for pretrained text encoders, Shortcut Guardrail, recovers substantial performance under shortcut distribution shift, matching or outperforming training-time baselines across sentiment classification, toxicity detection, and natural language inference.

Automated LLM workflow design often relies on expensive per-task search, which is computationally expensive and does not explicitly reuse structural knowledge across tasks. We propose SWIFT (Synthesizing Workflows via Few-shot Transfer), which reuses prior search trajectories and demonstrations to synthesize target-task workflows without iterative target-task optimization. SWIFT distills compositional heuristics and output-interface contracts from source-task trajectories, then conditions a single LLM generation pass on these priors and cross-task workflow demonstrations to produce an executable workflow. Across 5 benchmarks, SWIFT outperforms the SOTA search-based baseline while reducing marginal per-task optimization cost by three orders of magnitude given an existing source bank. It also improves performance on 4 additional held-out benchmarks and transfers from GPT-4o-mini to Grok, Qwen, and Gemma execution backbones. These results suggest that prior workflow search can expose reusable structural priors that reduce optimization cost while preserving or improving accuracy on related tasks.