claude desktop: honor multi-root workspaces (each folder a first-class root with its own .claude)

what

let claude desktop code mode open a multi-root workspace — several sibling repos/folders as first-class roots at once — and load each folder's own .claude/ (CLAUDE.md, commands, settings) independently, instead of the single-root model today

vscode already has this via .code-workspace (multi-root), and there's a cluster of related requests on the extension side (#75637, #66877, #36949) — this ask is the desktop app equivalent, focused on per-folder .claude loading

my real setup

a superrepo with 9 sibling repos, each its own git repo + its own .claude/:

• dash lp store (next.js frontends)
• api-server alarm wpp_announcer (node services)
• kizubot (lua core) proxy-watcher (python) decrypted-pokexgames

there's a KIZUBOT.code-workspace that already registers all 9 as one workspace with per-folder settings, ssh remotes and build tasks

the pain

claude desktop opens ONE root, so:

• editing the api-server contract + its consumer in dash at the same time needs two separate sessions with no shared thread
• whichever root i open, the other folders' .claude (their CLAUDE.md, their scoped commands) never load
• i keep bouncing between windows for work that's inherently cross-service

ask

• desktop can open a set of folders as one session (import a .code-workspace, or a native "add folder to workspace")
• each folder keeps and loads its own .claude/ (CLAUDE.md + commands + settings), nearest-folder-wins on conflict
• file picker / @-mention / search span all roots
• one conversation thread across the whole workspace

related: #76111 (nested .claude loading), #75637, #66877, #36949