Embedded layers detected the first-line color (e.g. `fade:red-blue-black-red` in `$febs`) but only seeded the buffer with the first solid color of the fade. The actual gradient wipe never ran, so embeds with bare fade tokens animated a solid fill instead. Mirrors standalone layer0 seeding by calling api.wipe on the embedded buffer once per buffer lifecycle, gated by a `firstLineColorApplied` flag that resets on source/buffer changes. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>