Bug 1: retryMessage no longer truncates history on image-only messages.
Content is validated BEFORE truncation — if there's nothing to re-send
(no text, no images, no attachments), the operation bails cleanly.
Bug 2: retryMessage and handleSaveEdit now forward attachments and persona
from the original message. Added rebuildAttachmentDrafts() to reconstruct
ChatAttachmentDraft[] from stored message content (ImageContent blocks)
and metadata.attachments (file/directory refs).
Dead code: Removed MessageBranch components (~210 lines) from message.tsx
and messageBranch i18n keys from en/es common.json. Unused forking artifacts.
Tests: +6 new tests covering image-only retry safety, attachment preservation,
assistant edit-button exclusion, Shift+Enter multiline, and chatStore
editingMessageId set/clear/cleanup. 430 tests green.
Taylor Ho