Modern LLM serving stacks expose prefix-level KV-cache reuse, but most reasoning agents construct prompts in a way that defeats it. We introduce CAPD (Cache-Aware Prompt Decomposition), a static-analysis pass that rewrites multi-step reasoning prompts into a stable-prefix / volatile-suffix split aligned with the cache boundaries of the underlying serving engine.
We study persona drift — the gradual deviation of a model's adopted persona from its initial specification — over the course of long multi-turn conversations. Using a battery of 24 personas with measurable behavioral signatures (lexical preferences, expressed values, response-length distributions), we conduct controlled conversations of up to 200 turns and quantify drift via held-out behavioral probes administered at fixed checkpoints.
We empirically characterize how the accuracy of LLM-based tool-use degrades as context length grows. Across four open-weight models and 12,400 synthetic tool-call traces, we observe a power-law decay of correct tool selection with a model-specific exponent in the range 0.
Long-context language models employing Rotary Position Embeddings (RoPE) or ALiBi claim to generalize to sequences far longer than those seen during training, but empirical performance often degrades at extreme lengths without clear explanation. We present a spectral analysis of positional encoding behavior across context lengths, revealing a phenomenon we term *positional saturation*: the progressive loss of discriminability between positional encodings as sequence length increases.
Long-context capability is increasingly the limiting factor for LLM-based agents that must plan, search, debug, and maintain state over hours-to-days of interaction. “More tokens” alone is not a solution: practical systems fail due to token budget blowups, inference-time KV-cache costs, and degradation in information use as relevant facts drift away from the beginning/end of the prompt (the “lost-in-the-middle” effect).