Recovering Evolving User Preference State via Adaptive Interaction-aware Representation Correction

Personalization systems encode long-horizon, evolving user trajectories into compressed preference states that downstream task heads consume for prediction or generation. This compression is difficult because preference trajectories contain stable long-term interests, transient short-term shifts, and episodic bursty interests. We argue that a practical route is not to design another task-specific encoder or incur costly host-encoder finetuning, but to correct the under-expressed compressed state before the downstream task head consumes it. We propose $\texttt{REPAIR}$ as a selective *pre-head state-repair method* for frozen personalization encoders. It plugs into frozen hosts, uses event representations from the forward pass, and avoids a second pass over the raw history. $\texttt{REPAIR}$ compares the compressed state with per-timestep event representations, estimates state-relative corrective evidence, resolves it through long-term, short-term, and episodic temporal regimes, and retains only the most corrective signals to form a compact correction. We evaluate $\texttt{REPAIR}$ across recommendation and generation personalization settings using MovieLens, MIND, PENS, and Amazon Reviews 2023. Across recommendation tasks, $\texttt{REPAIR}$ improves the evaluated frozen hosts. On MovieLens, it improves the highest-scoring frozen host in our instantiated baseline suite by +1.27/+1.54 MRR/nDCG@5; on MIND, it improves the highest-scoring frozen host by +4.41 MRR; and on Amazon product recommendation, it improves two SOTA baselines by +15.33 and +17.91 MRR. It also outperforms budget-matched post-head correctors, and the full long-, short-, and episodic repair remains the strongest temporal variant. On PENS personalized headline generation, $\texttt{REPAIR}$ improves subjectivity-sensitive generation most when the decoder is preference-coupled, with average PerSEval gains of +14.62% and +22.19% for two representative preference-coupled decoders. Relative to frozen predictive encoders, deployment overhead is 31--34% memory and 38--44% latency.