Complete procedures with a way back.

Add explicit prompt-cache breakpoints to stable Claude tool, system, document, and conversation prefixes; measure creation and read tokens, test invalidation and minimum-size behavior, compare uncached and cached latency, and roll back without corrupting the prompt contract.

Build a long-document assistant that validates and quarantines PDFs, chooses inline or Files API intake deliberately, enables native citations, preserves page-aware citation blocks, refuses unsupported conclusions, and lets reviewers inspect every claim against the original page.

Create a reproducible Linux and NVIDIA benchmark that separates time to first meaningful content, end-to-end latency, exact server-reported token throughput, memory phases, deterministic task quality, long-context retrieval, structured output, and tool-call correctness. Results remain tied to immutable artifacts, scorer revisions, deployment flags, and host state.