在 v18.2.5 中,Anthropic 提示缓存仍然仅支持头部,尽管有 ab88e931 (对 #12318 的跟进)

Follow-up to #12318: still reproducing on v18.2.5 (fix ab88e931 included) ab88e9313fad ("skip undecoratable tail messages when placing Anthropic cache breakpoints", PR #12332, merged 2026-09-17T12:44Z) is present in v18.2.5 (published 2026-09-17T23:07Z). The frozen head-only cache signature survives it on my machine. ## Environment - omp/18.2.5, macOS 25.6.0 (Darwin 25.6.0), arm64, Apple M4 Max - Anthropic OAuth (Max), Anthropic/Claude-opus-5:high as default role, defaultThinkingLevel: high - providers.cacheRetention: auto, no PI_CACHE_RETENTION in env - 4 MCP servers configured (MongoDB-atlas, tia, unity-mcp, tableplus); memory.backend: hindsight; autolearn.enabled: true; project AGENTS.md context file present - Binary installed 2026-09-18T00:32:33Z; the session below was launched 10s later (2026-09-18T00:32:43Z), so it is unambiguously the 18.2.5 build ## Per-request trace, v18.2.5, single session, consecutive requests From ~/.omp/agent/sessions/<project>/2026-09-18T00-32-43-641Z_*.jsonl (message.usage, provider Anthropic, model Claude-opus-5): t input cacheRead cacheWrite output 00:34:18 44954 27040 0 1057 00:34:32 56054 27040 0 802 00:34:38 65575 27040 0 331 00:34:45 69855 27040 0 237 00:34:50 70349 27040 0 414 00:35:02 71747 27040 0 892 00:35:19 73686 27040 0 1177 00:35:32 75105 27040 0 955 00:35:56 85709 27040 0 1574 00:36:11 88555 27040 0 994 00:36:28 101415 27040 0 1090 00:36:54 102807 27040 0 1765 00:37:07 107968 27040 0 851 00:37:33 110777 27040 0 1599 00:37:54 116589 27040 0 1274 00:38:11 118751 27040 0 563 00:38:44 120605 27040 0 2177 00:38:54 123878 27040 0 627 00:39:04 124615 27040 0 357 00:39:08 127329 27040 0 194 00:39:21 133230 27040 0 895 00:39:34 134581 27040 0 725 00:39:47 137586 27040 0 1015 cache_read pinned at exactly 27,040 (the tools+system head anchor), cache_write 0 on every request including the first, input monotonically tracking the transcript. Session total at 26 requests: 2,707,688 uncached input tokens for 28,039 output tokens (97 input : 1 output). Note the difference from the original report: there is no baseline write at all here. The head anchor was already warm from a previous session sharing the same prefix, so this session never wrote a breakpoint — it only ever read the frozen 27,040 and paid full price for the tail. ## Same machine, versioned boundary The break is at process launch time, not at workload change. Aggregated from session JSONL, provider Anthropic only, uncached input per …