Companion to website#170. Section 6.0b's assignment for Phase 4 - ENGAGEMENT.md's
as-built and BACKEND_DESIGN.md's table inventory - plus the two corrections
building it forced on this document's own design sections.
ENGAGEMENT.md
- Phase 4 is split 4a / 4b, with what each owes.
- Section 7.1 Q2 and Q4 answered, so seven of eight are settled and only Q8
(android CI) is open.
- The as-built: the gate order and why two of its placements are load-bearing,
the segment rule the design never stated (not is legal only inside an and,
and contributes no ceiling), dormancy three ways and why audience_segment_id
has no foreign key, the conditions grammar's two fail-closed properties, and
why emit does not await the engine.
- Section 4.1's cooldown statement and section 4.2a's dedupe index are
corrected in place, so the design sections stop teaching the two defects.
BACKEND_DESIGN.md
- Five new tables in the schema inventory, each with the reasoning a reader
would otherwise have to reconstruct: why subject_key is in the primary key,
why the dedupe index is scoped, why the send log survives an account
deletion and is not a second address book, and why a rule points at a
segment without a foreign key doing it.
No route table changes - Phase 4a adds no routes.
Co-Authored-By: Claude <noreply@anthropic.com>
wtclaude
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