Read app content on a draft

Alpha. The app sub-resource may change shape without a deprecation cycle while apps mature. The document routes are stable.

Read the app content on a named draft — the draft-side counterpart of GET …/app, and the read half of the draft write loop: app writes are last-write-wins whole-document replaces, so fetch the draft’s latest HTML here before building the next PUT …/draft/{draftIdentifier}/app body. Same response shape as the published read. Writes cap the HTML at 2 MiB — apps saved before the cap may read back larger, and a body over the cap is rejected on the way back in. The published document’s content is unaffected by draft edits — read it via GET …/app.

A draft with no app is a 404 — including a draft that carries a dashboard, which can never carry an app.

A document carries at most one of a dashboard or an app — never both; workbook-only is valid. The app HTML and settings live only at the app sub-resource routes; the document read carries an app slice pointing here, and the whole-document PATCH accepts that slice back only as it was read.