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PR-OPD: Privileged representation self-distillation for agentic RL

L1 representation-alignment objective. Implements stop-gradient privileged alignment across layers and response tokens.

Paper information

Field Details
Paper arXiv v1
Institution University of Florida (first author affiliation)
First public release 2026-09-29 (arXiv v1)
Original source code Yes: balibata/PR-OPD
Adapter pr-opd
Local reproduction code src/auto_research/post_training/latest_20260930_followup.py

Background and main changes

After a GRPO warm start, the policy writes a hindsight skill for each completed trajectory. Run two forward passes on the same response with ordinary context and skill context. The latter is a stop-gradient teacher. PR-OPD aligns projected hidden states at each layer and response token, then combines alignment with the reward objective. Inference removes the skill and teacher branch.

Key figure from the paper

PR-OPD representation channel

Figure 1 motivates representation alignment by contrasting sparse probability signals with widespread hidden-state changes. From the paper; copyright belongs to the authors.

Local reproduction

Tests cover zero loss for identical representations, positive loss for different ones, masking and teacher stop-gradient. See three-seed mechanism results. ALFWorld, WebShop and the GRPO warm start were not run. The paper's maximum +14.0 points cannot be claimed here.