Add a shared visiblePromptText helper and strip reference tokens,
image-generator directives, and model-selection lines from agent thread
summaries and the assistant panel header, so titles show the user's
actual prompt instead of internal directives. Covered by a server test.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Skip WebP re-encoding for PNG/AVIF/BMP uploads and any bitmap that
actually contains alpha, tag transparency-capable canvas uploads with
the transparent-image tone, and detect alpha in merged layers so the
composed node keeps a transparent tone.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>