GACC-Bench: Benchmarking Goal-Adaptive Context Compression Ability across Large Language Models

Context compression in long-running applications of large language models (LLMs) must preserve goal-relevant information, often before specific downstream questions are known. We introduce GACC-Bench, a benchmark for Goal-Adaptive Context Compression that evaluates how reliably LLMs adapt information retention to specified high-level goals. For each source context, we derive one or more high-level goals by grouping source-grounded questions according to shared downstream objectives. The benchmark contains 500 goals and 2,571 questions over 281 document and agent-trace contexts from seven collections spanning diverse domains, with all instances reviewed by human experts. The compressor receives a source context, a goal, and a context-length budget, with the associated evaluation questions withheld. A fixed reader answers these questions individually using the same compressed context. Our evaluation of ten LLM compressors reveals substantial gaps to full-context performance even for the best-performing model, particularly in supporting correct answers to every question associated with a goal. Compared with goal-agnostic compression, target-goal conditioning consistently improves accuracy, whereas mismatched-goal conditioning reduces it. GACC-Bench is available at https://github.com/weiting24/GACC-Bench.