In ydoc mode the collab room owns a document's state — items reach it at
commit time, layout heads at save time (syncLayoutFromSave). The raw CAS
PUT on Ctrl+S was only ever the file-list registration + fallback copy,
but for a file the listing already marks hasYdoc/isLive it bumps the
revision for nothing, can 409 the target into the durable save-blocked
banner, and leaves a shadow row the ydoc supersedes on every read.
registerSaveHook gains `uploadPolicy(relPath) → "upload" | "room"`;
WasmTool marks the boot listing's ydoc/live files "room" (ydoc mode only).
Files with no row yet (created sheets, the synthesized .kicad_pro) still
upload; onSavedText still runs for room-backed saves.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012Wd1r3ewftpV1DBSEArpRa
5650e6193f