Addresses review feedback on #68744: downscaling inside
attachmentPreviewDataUrl made previewUrl the 2048px PNG, but current main
(d8cb73b4ab) feeds that field to ImageLightbox and useImageDownload, so
large attachments would open and download at reduced resolution.
- attachmentPreviewDataUrl returns the full-resolution data URL again
- ComposerAttachment gains thumbnailUrl?: string (store/composer.ts)
- attachImagePath stores previewUrl (full-res) + thumbnailUrl (downscaled)
- Attachment pill renders thumbnailUrl ?? previewUrl; lightbox/download
keep the full-res previewUrl
- optimisticAttachmentRef prefers thumbnailUrl for the in-flight bubble
display ref (same main-thread decode freeze at send time)
- Attachment-level regression test in use-composer-actions.test.ts:
full-res previewUrl preserved while thumbnailUrl is a separate
downscaled value (4000x3000 -> 2048x1536)
David Metcalfe
485e1e8f69