design: syntax — RECORD writer object, INTEGRATE operator, mutable delta tables

- INTEGRATE becomes a read operator (dual of CHANGES) usable in plain MVs, not
  an object kind; it is the typing boundary (mz_timestamp/mz_diff are data inside
  its argument, gone in its result). Fix the dedup example accordingly, and note
  the timestamp-as-data stability pitfall (subject to the compaction clamp).
- DELTA TABLEs are mutable: bounding is ordinary DELETE/UPDATE DML, defined as
  consolidating (retract at original mz_timestamp), distinct from forward age-out.
  The standing OCC pruner is deferred, keeping v1 bounding off the OCC critical path.
- The only new standing object is the RECORD writer; cadence is frontier-driven
  (COMMIT EVERY rejected as an anti-pattern).
- DELTA TABLE domain is inherited from the first RECORD writer by default, with
  IN DOMAIN as escape hatch; multiple writers per table are sound because the
  table-owned reclock recovers the merged A->B mapping; domain bound-once/immutable.
- Record data-domain compaction as a deferred future capability.
- CHANGES is an open PR (#36869), not shipped; keep CHANGES (not DIFFERENTIATE).
- Update the implementation companion to match (architecture, change map, H1/H3,
  phases, open questions).

https://claude.ai/code/session_015YFH7J7PaEqkBSrAQYaq8H

Author: claude