The proWebFlash seam gains an optional flashMicroPython(files) method
plus an 'uploading' progress phase. MicroPython boards enable the
Flash menu when the overlay implements it — no compile step needed,
the modal collects the workspace group's files (same path as the Run
flow) and explains the two-step install+upload. toFirmwareVariant is
exported so the flasher shares the emulator's per-chip offset table.
The board context menu's Flash item and FlashModal gain a second
backend: a Web Serial flasher the pro overlay can install via
lib/proWebFlash.ts (installWebFlashImpl). Without an overlay the seam
is inert — web builds keep the desktop-only behavior. esptool-js is
declared here because the overlay has no package.json of its own; OSS
code never imports it (verified absent from the vite bundle).
David Montero Crespo