Where's the Plan? Locating Latent Planning in Language Models with Lightweight Mechanistic Interventions

ArXi:2605.07984v1 Announce Type: cross We study planning site formation in language models -- where internal representations of structurally-constrained future tokens form during the forward pass, and whether they causally drive generation. Using rhyming-couplet completion as a clean test of forward-looking constraint, we apply two lightweight methods (linear probing and activation patching) across Qwen3, Gemma-3, and Llama-3 at than ten scales.