docs: validation-rules.mdx says a value sent for a stored-expression field is "not refused and not reported", and the data-engine strip table has no stored_expression row #25089

Filing gate ③ a follow-up owed by landing work, from the contract review of PR #25086 (card #25000) and that PR's dev report. Filed by the domain:spec seat 3 (session session_01D6F9axfoPzR7t8G1J7Ytzz). ⛔ Not a claim.

The stale text (origin/main)

• content/docs/data-modeling/validation-rules.mdx:368 says a value a caller sends for a stored-expression field is "not refused and not reported as dropped".
  • The "not reported" half has been false since spec(data): once PR #24673 lands, a client value for a stored-expression field is overwritten with no report — DroppedFieldsEvent.reason has no value for "written, but recomputed", so onFieldsDropped / droppedFields stay silent #24690 (PR feat(spec,objectql): report a caller value a stored expression replaced, as DroppedFieldsEvent reason stored_expression #24778, 7532ea3c08): objectql reports it through onFieldsDropped / droppedFields under reason: 'stored_expression'.
  • Once PR fix(objectql)!: under strictReadonlyWrites, a write whose value a stored expression replaces is refused, and nothing is written #25086 lands, the "not refused" half is false under strictReadonlyWrites, where such a write is refused with ERR_READONLY_FIELD_REJECTED.
• content/docs/kernel/contracts/data-engine.mdx: the strip/drop table has no stored_expression row, although its strict section (around :388-411) already says strict coverage follows what onFieldsDropped reports.

Candidate shape (for triage)

Hand-written docs only, so skip-changeset applies:

• reword validation-rules.mdx:368: the value is replaced by the computed one and reported under stored_expression, and refused under strictReadonlyWrites;
• add the stored_expression row to the data-engine.mdx table.

Order: land after PR #25086.

Dedupe

Parent cards: #24690 and #25000. Matched open and closed issues in this repo updated since 2026-10-15 on validation-rules.mdx together with stored_expression. The hits are PRs only: #24673 and #24734, which wrote the current text, and #25086. None of them is a card for this correction. New.