GET /api/apps/radio opens the firmware's serial port and sends 0x0730 for all sixteen slots, so the answer comes from the running firmware rather than from our reading of the file -- which is the check that matters, because the bytes can be right and the firmware still refuse a slot. Measured through the page after installing Beam.app into slot 0: slot 0 -> Beam 1.0, 1100 B, crc 0xd976058, shortcut beam, committed; slots 1..3 -> status 2 with unrelated data, the resource-block overlap the install guard refuses. A button beside the table asks it and shows the answer in its own column.
The server gives its own emulator a serial port (--serial-port, default 4445) and uvk5_slots_serial.Radio gained a public app_info(slot), so nothing reaches into a private helper. uvk5_apps.parse_radio_reply decodes the answer and is tested without a radio. Also recorded: QEMU needs the mingw64 DLLs on PATH, and started by hand without them it exits before opening QMP, which surfaces only as 'QMP socket never appeared'.
The Labs edition's apps live in the external flash, in the region its own App/apps/app_overlay.h defines (16 slots of 8 KiB from 0x102000, a 64-byte FAP1 header at the slot base, code one 4 KiB sector later), and upstream installs them from UVStudio over WebSerial. The page owns the image, so this adds GET /api/apps, POST /api/apps/<n> and POST /api/apps/<n>/erase, which put the same bytes at the same offsets with no serial protocol and no browser permission.
Measured on a real image while wiring it up: every one of the 16 slots already held data that is neither empty nor an app -- the localised build's factory resource block overlaps 0x102000 -- so install now refuses to overwrite anything that is not an app unless asked (--force, ?force=1), naming what is there. And _edit_flash edits a copy, which is why the source image shows no changed bytes; the first test read that as 'the install did nothing' and now checks FlashSlot.path. Tests: test_uvk5_apps grew to 20, test_webui.TestAppEndpoints adds 7 over the endpoints.
The Labs edition runs overlay apps (Tetris, Breakout, Plasma, Cube3D, Beam, Beacon, FoxHunt, BroadcastFM) that upstream UVStudio installs over WebSerial. This page owns the flash image, so the same bytes go to the same offsets with no serial protocol and no browser permission: APP_REGION_BASE 0x102000, APP_SLOT_STRIDE 0x2000, APP_CODE_OFFSET 0x1000, 16 slots, taken from the firmware's own App/apps/app_overlay.h rather than inferred.
tools/uvk5_apps.py parses and validates the 64-byte FAP1 header (zlib CRC-32 over the code, vma 0x20000280, name, version, capabilities), lists, installs and erases slots, and refuses what the firmware would show as APP ERROR. test_uvk5_apps covers those refusals plus install/erase/list round trips, and parses a real upstream Beam.app when one has been downloaded. The header struct was 60 bytes at first -- a missing vma field -- which the real file's bytes showed at once.
mckero