Conversations → topic chunks (local model). For each eligible conversation,
render the CHUNK_PROMPT with inlined Meta policy, call the chunk adapter,
repair + validate the emitted anchors, and write pointer rows. Idempotent:
sets chunked_at on success so a re-run is a no-op.
Conversations → topic chunks (local model). For each eligible conversation, render the CHUNK_PROMPT with inlined Meta policy, call the chunk adapter, repair + validate the emitted anchors, and write pointer rows. Idempotent: sets chunked_at on success so a re-run is a no-op.