Parent: #846.
Fresh TypeScript 5.7.3 real-file control: a checked JavaScript owner exports /** @type */ const settings = { count: 1, label: "ready" }; a TypeScript importer writes a string to count, a number to label, and reads missing. TypeScript reports TS2322, TS2322, TS2339 at the respective consumer lines. Freshly rebuilt Home reported no diagnostics. The equivalent TypeScript-owned declaration and the unannotated JavaScript object both already produce the three errors in Home, and the checked-JS owner itself understands the annotation. Thus the loss is specifically at Program declaration-schema transfer: jsdoc_types marked finite object type text unsupported, so a source-owned object type was not available to the importer.
Acceptance: source-owned finite JSDoc object members preserve required, nested, optional, and readonly semantics across admitted JS imports; unsupported methods/index signatures are not misrepresented as closed data properties; real CLI agrees with TypeScript on positive and negative controls; Program/parser/CLI/checker regressions pass under the 3,840 MB serial memory guard. A pre-existing optional-property assignment wording mismatch also reproduces with a TypeScript-owned declaration; track separately rather than hiding it here.