The upload dialog sent `{ file, kind }` only, though `UploadAssetForm` and
`asset-upload-transport.ts` both carry `altText`/`decorative`. Every asset
uploaded through the flagship authoring flow therefore landed as
`altText: null, decorative: false`, and the directive `case-fields.tsx` and
`asset-picker.tsx` build from `asset.decorative ? "" : (asset.altText ?? "")`
could only ever be `alt=""`. The document parsed and previewed correctly and
then failed publish validation with EVIDENCE_ALT_REQUIRED, recoverable only
by hand-editing raw Markdown -- the exact thing the Picker exists to prevent.
The dialog now stages the file instead of uploading on selection, and carries
a decorative checkbox plus an alt-text field (focused as soon as a file is
chosen, submitting on Enter). A decorative asset never demands alt text; a
meaningful one is refused with a stated reason rather than a disabled button.
Insertion is unchanged: both call sites already read the Asset, so they now
insert what it actually carries.
Three new tests drive the whole loop -- upload through the real MOCK
composition, auto-insert, save, validate, preview -- and assert the result is
publishable. The pre-existing loop test no longer needs its hand-edit
workaround.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>