7a7aa79eab
On opening the floating AI-chat window from the header on a document page, auto-open the LAST chat bound to that document. Binding reuses the existing ai_chats.page_id (no migration): the bound chat is the requesting user's most-recent non-deleted chat created on that page, so a new chat on the page becomes the bound one for free. Resolution happens only on a genuine closed -> open transition; the provenance badge deep-link is untouched. Server: AiChatRepo.findLatestByPage + POST /ai-chat/bound-chat (BoundChatDto), both read-only and owner/workspace-scoped. Client: getBoundChat service + useOpenAiChatForCurrentPage hook wired into the app-header entry point (fail-soft to a fresh chat; draft/role cleared only on a real switch). Tests: repo scoping/ordering, controller wiring, and hook behavior. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>