Introduce the Electron desktop shell alongside the existing React renderer and local Bun server boundary. The migration keeps the DesktopHost contract explicit across Tauri, Electron, and browser runtimes while adding Electron main/preload services for dialogs, shell, notifications, updates, tray/window lifecycle, terminal, preview WebContentsView, app mode, and release/package validation.
The commit also carries the latest local main desktop command updates, including agent slash entries and hidden-by-default markdown thinking details, so the packaged Electron build matches the current main UX surface.
Constraint: React renderer, local Bun server, REST/WebSocket, and sidecar boundaries must remain reusable during the migration
Constraint: macOS dev packages are ad-hoc signed and cannot prove Developer ID notarization or Gatekeeper release launch
Rejected: Browser-only smoke validation | it cannot exercise native dialogs, keychain prompts, notification behavior, or packaged app startup
Confidence: medium
Scope-risk: broad
Directive: Do not remove Tauri host support until signed Electron release artifacts pass native OS smoke on macOS, Windows, and Linux
Tested: bun run check:desktop
Tested: cd desktop && bun run check:electron
Tested: CSC_IDENTITY_AUTO_DISCOVERY=false bun run electron📦dir
Tested: bun run test:package-smoke --platform macos --package-kind dir --artifacts-dir desktop/build-artifacts/electron
Tested: Computer Use read packaged Electron app window at desktop/build-artifacts/electron/mac-arm64/Claude Code Haha.app
Not-tested: Developer ID signed/notarized Gatekeeper launch
Not-tested: Real OS notification click-to-session action
Not-tested: Windows and Linux packaged app smoke on real hosts
Desktop file attachment selection was inlining every selected file as a data URL before sending the websocket message. Large multi-file sends could inflate the renderer request body by tens of megabytes before the server had a chance to materialize uploads.
Route Tauri file selection through the native dialog so desktop sends absolute paths, while preserving browser fallback data URLs for H5. Cover both active-session and draft-session composers plus a payload-size regression case.
Constraint: Browser/H5 cannot rely on local absolute file paths, so the existing FileReader fallback remains for non-Tauri runtimes.
Rejected: Raise websocket/body limits | would keep renderer memory pressure and still send file bytes unnecessarily.
Confidence: high
Scope-risk: narrow
Directive: Do not reintroduce FileReader data URLs for Tauri desktop file-picker attachments without measuring websocket payload size.
Tested: cd desktop && bun run test src/lib/composerAttachments.test.ts src/components/chat/ChatInput.test.tsx src/pages/EmptySession.test.tsx
Tested: /tmp complex-project reproduction showed 12x3MB old inline payload at 50,333,174 bytes versus path-only payload around 1-2KB
Not-tested: Full desktop lint/build due unrelated existing Sidebar.tsx type errors in the dirty worktree
Related: https://github.com/NanmiCoder/cc-haha/issues/444
