Future Probe Controlled Generation enables steering of reasoning models without quality degradation
Researchers introduce Future Probe Controlled Generation (FPCG), a text-level steering method for large reasoning models (LRMs) that trains activation probes to predict future behavior likelihoods from intermediate reasoning steps rather than detecting behavior in already-generated text. The probes achieve 64–91% accuracy in predicting the most likely future behavior, revealing a distinct class of internal prediction features separate from detection features. FPCG steers model outputs by sampling candidate sentences and selecting the best according to these probes, achieving steering with minimal output quality degradation and succeeding in cases where activation steering fails. The work provides a principled distinction between detection and prediction features as intervention targets for controlling LRM behavior.
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Probe Trajectories Reveal Reasoning Dynamics in Large Reasoning Models
This paper investigates whether hidden representations of Large Reasoning Models (LRMs) can predict future model behavior by analyzing probe trajectories—the continuous evolution of concept probabilities across Chain-of-Thought reasoning tokens. The authors find that temporal trajectory features (volatility, trend, steady-state) significantly outperform single static probes, with max-pooling achieving up to 95% AUROC across safety and mathematics domains. Two methodological insights are offered: template-based training data matches dynamically generated responses in quality, and pooling strategy is critical to probe performance. The work positions probe trajectories as a complementary safety monitoring framework for LRMs where CoT faithfulness cannot be assumed.
ACTS: Agentic Chain-of-Thought Steering for efficient and controllable LLM reasoning
Researchers introduce Agentic Chain-of-Thought Steering (ACTS), a framework that formulates inference-time reasoning control as a Markov decision process, where a controller agent adaptively steers a frozen reasoner by issuing reasoning strategy directives and steering phrases at each step. The controller is initialized from synthetic steering trajectories with multi-budget augmentation and further optimized via reinforcement learning with budget-conditioned reward shaping. ACTS matches full-thinking performance with significant token savings and enables controllable accuracy-efficiency trade-offs across multiple benchmarks and reasoner models.
RePro: Retrospective Progress-Aware Self-Refinement for LLM Agent Training
Researchers introduce RePro (Retrospective Progress-Aware Training), a framework addressing the gap between step-wise RL optimization and metacognitive task-progress awareness in LLM agents. The approach uses a forward-then-reflect rollout paradigm where agents execute actions online and then retrospectively assess step-wise progress given the completed trajectory and known outcome. Evaluated on WebShop, ALFWorld, and Sokoban, RePro achieves up to 12% absolute success rate gains over baseline Qwen-family models without requiring continuous external supervision.
Study finds thinking mode in LRMs shifts instruction-following errors by constraint type rather than uniformly degrading performance
A new arXiv paper investigates how enabling built-in chain-of-thought reasoning ('Thinking ON/OFF') in Qwen3 and Hunyuan models affects instruction following on IFEval. Aggregate pass-rate changes are small but 10-20% of prompts switch outcomes, with 'Planning' constraints (global counting, structure) improving under thinking while 'Precision' constraints (exact local form) consistently worsen. Activation patching and trace-relevance analyses reveal an execution gap: thinking traces engage with Planning constraints but fail to translate that engagement into compliance, while Precision failures are more mechanistically recoverable. The findings have practical implications for when to enable reasoning modes in instruction-following applications.
Fixed-Point Reasoning Model (FPRM): Stable looped Transformers with adaptive compute via fixed-point halting
Researchers introduce FPRM, a Transformer-based Fixed-Point Reasoning Model that uses fixed-point convergence as a halting mechanism in looped architectures, addressing signal propagation problems through pre-norm layers and residual scaling. Looped architectures provide inductive bias for compositional reasoning, but suffer from depth-induced signal degradation when halting is deferred; FPRM resolves this while enabling compute to scale with task difficulty. The model is evaluated on Sudoku, Maze, state-tracking, and ARC-AGI benchmarks. This contributes to the growing body of work on adaptive-compute and iterative-refinement architectures for reasoning.
Question-Answering as Hidden State Probing for Test-Time Reasoning Intervention
This paper proposes using question-asking as an inference-time intervention to surface information about an LLM's hidden state during chain-of-thought reasoning. The authors train a probe on a student model's hidden states before and after question generation, finding it predictive of final answer correctness even before the teacher responds—suggesting self-diagnosis during question generation carries meaningful signal. They frame question-asking as a sequential decision problem with a gating policy, but find a gap between detection and recovery: interventions are as likely to harm correct trajectories as to fix incorrect ones. The results have implications for the limits of LLM self-refinement under uncertainty.
Framework for quantifying faithful confidence expression in large reasoning models
A new arXiv preprint introduces a framework to measure faithful calibration (FC) in large reasoning models (LRMs)—the alignment between a model's intrinsic confidence and its linguistically expressed confidence. The authors analyze linguistic decisiveness against three internal uncertainty sources (token probabilities, hidden states, sampled response consistency) and introduce prefix-conditioned sampling to handle structural variation in chain-of-thought traces. Applying the framework across leading models, they find FC is a significant and distinct failure mode for LRMs: extended reasoning traces do not automatically improve calibration, prompt interventions that help non-reasoning models fail in the reasoning setting, and different confidence estimators produce divergent assessments of the same traces.
FORGE: Self-Evolving Agent Memory via Population Broadcast Without Weight Updates
FORGE (Failure-Optimized Reflective Graduation and Evolution) is a staged, population-based protocol that evolves prompt-injected natural-language memory for hierarchical ReAct agents without any gradient updates. It wraps a Reflexion-style inner loop where a reflection agent converts failed trajectories into textual heuristics or few-shot demonstrations, then propagates the best-performing instance's memory across a population between stages. Evaluated on CybORG CAGE-2 (a stochastic network-defense POMDP), FORGE improves average return by 1.7–7.7× over zero-shot and 29–72% over Reflexion across all 12 model-representation conditions tested with four LLM families. Notably, weaker models benefit disproportionately, suggesting the method may help close capability gaps rather than amplify already-strong models.