`apply_anthropic_cache_control` marks an assistant turn with non-empty text by
writing `cache_control` INTO `content` -- `_apply_cache_marker`'s list branch
puts it on the last content block, not at the top level.
`_convert_assistant_message`'s ordered-replay branch rebuilds the message from
`anthropic_content_blocks` and returns early. Its only cache sources are
`_relocated_replay_cache_control` (markers rescued from blocks the replay
sanitizer dropped) and the top-level `m["cache_control"]`; it never reads
`m["content"]`. So for an assistant turn that interleaves signed thinking with
a tool_use AND has preamble text, the breakpoint is dropped.
It is burned, not relocated: `_can_carry_marker` returns True for this message
(non-empty content), so the breakpoint budget already counted it. Hermes'
accounting believes the marker landed.
Measured with the real functions, native layout, same history, only
`anthropic_content_blocks` differing:
normal path 4 breakpoints assistant text block carries cache_control
replay path 3 breakpoints assistant carries NONE
Under the static-prefix layout only two conversation-tier breakpoints exist, so
this halves them. Nothing is logged and the request succeeds with identical
model output, which is why it survives: it recurs on every request for the life
of any Claude thinking+tools session, since the flag rides the message in
`agent.messages`.
#56195 fixed the complementary shape -- blank assistant content, where the
marker lands top-level -- and its regression test pins `"content": ""`. The
non-empty case is the one a Claude 4.5/4.6 tool turn normally produces (a
sentence of preamble before the call) and was never covered.
Harvest an in-`content` marker next to the existing top-level lookup and hand
it to the same `_apply_assistant_cache_control_to_last_cacheable_block` helper.
dsad
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