refactor(prose): dump/read folds — subtree gets replace per-topic loops (D7, stage 5)

[leeovery]

Stage 5 of the batching programme (design log: #504; base: #508). The dump/read-fold class — and like stage 3, C5 keeps it at zero engine code: manifest get <wu>.<phase> has always returned the whole subtree; the prose just never leaned on it.

What

• sequence-discovery-map — the 2×N per-topic summary/description gets become one {wu}.discovery subtree read (the dump's rows deliberately stay lean — description_present only — so the subtree get is the right channel for the full text).
• read-plans (review) — per-plan format/external_id gets become one {wu}.planning subtree read before the loop; the per-plan loop keeps only the judgment work.
• brief-synthesis — both halves:
  • Lifecycle: split/merge/drop cleanup collects every orphaned brief, then two calls total — one rm -f naming all files, one apply deleting all brief_path pointers (the loud-on-absent guard preserved: only topics that carried the pointer enter the payload).
  • Propagation: reads research+discussion subtrees once (2 calls for any N), collects reconcile_needed flags, lands them in one apply.

Test plan

Prose-only: npm test 1556/1556, conventions lint 27/27, typecheck clean.

🤖 Generated with Claude Code

Stack

1. feat(engine): discovery-map add-batch — the harvest persists in one call (D7) #505
2. feat(engine): manifest apply — batched set/delete across one work unit (D7) #506
3. refactor(prose): task-map family folds onto existing batch forms (D7, stage 3) #507
4. feat(engine): manifest set — two grammars, never mixed #508
5. refactor(prose): dump/read folds — subtree gets replace per-topic loops (D7, stage 5) #509 👈 current
6. feat(engine): commit --plan — plan storage stages from recorded state (D7, stage 6) #510
7. fix: batching-stack review round — re-resolve rewired, guards symmetric, hardening pinned #512
8. fix: deep-dive round 2 — backbone rule flipped, pre-upgrade paths routed, flow bugs closed #513
9. fix(review-r3): engine hardening + crash-resume seams #514
10. feat(scoping): promotion routes through first-phase choice + bridge #515
11. fix(spec): pin the bugfix source name to the topic #516
12. fix(skills): gate-skip sentence accurate in gate-less phases #517
13. fix(review-entry): name the real upstream — specification and plan #518
14. fix(shared): strip triage-landing's unreachable superseded-research arm #519
15. feat(engine): refuse work-unit-level fields that shadow the phases tree #520
16. fix(discovery): first-written briefs join the full brief lifecycle #521
17. test(sim): pipeline simulation — engine driven end-to-end as a black box #522
18. fix(round-4): review findings — backfill keying, ratchet evasion, pull guard #523