WikiChunkCitationPrompt placed the per-batch <chunks> block before the
static rules, output schema and the per-document-stable <candidate_slugs>.
Within one document only ChunksXML changes between batches, so the stable
content trailing the chunks could not form a long common prefix and
providers re-billed the static rules on every citation batch (issue #1687
measured ~6.4% prefix-cache hit rate on wiki synthesis).
Reorder to [rules | output schema | candidate_slugs | chunks] so every
batch after the first shares the long [rules | candidate_slugs] prefix.
No instruction text was dropped; only block order and the inline
above/below directional references changed. Verified the cacheable prefix
grows from 281 to 2366 bytes and is byte-identical across batches.
Addresses #1687
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
adawang
1c735ebb9e