KateRTX OS · multi-tab SPV seats · SDF bus · designer headers
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Product path · not demo · ESSIE hotswap · JSON + long details

WHAT
  Tabbed "OS" surface: each open SPV is a live seat (not remount-on-focus).
  Seats speak SDF frames on BGS/BGF with mode insecure | secure | broadcast.
  SPV designer <header> faces become desktop icons + Start launchers.

STACK (linear pins)
  BGS  ground   · field_one(v)=v|1
  BGF  measure  · (a-b)|1 · SPV free rides
  BGL  secure   · surface|1 · field hygiene
  SDF  place    · shell · raised · store · message envelope
  SPV  free     · |1 · never folds into SDF/BGS

FILES
  js/bus.js              · BGRTX_BUS / BGRTX_SDF
  js/desktop.js          · multi-seat tabs · launchers · bus UI
  css/shell.css          · seat panes · bus-bar · designer faces
  spvs/headers.json      · designer header catalog (generated)
  spvs/manifest.json     · plugs + os block
  bin/pack-os-desktop    · rebuild out/desktop_os.html
  bin/pack_os_desktop.py · packer + header parse
  out/desktop_os.html    · offline pack

BUS MODES (easily selectable)
  insecure   · open lab channel · all seats may hear
  secure     · token ring · secure peers / explicit `to`
  broadcast  · force * delivery · every listener

  UI: tabbar SDF [INSEC|SEC|BC] | [BGF|BGS]
  Chat: /bus secure · /lane BGF · /say hello · /peers · /spit
  Context menu: Bus · insecure/secure/broadcast · Lane · BGF/BGS
  API: BGRTX_BUS.setMode('secure'); BGRTX_BUS.setLane('BGS');
       BGRTX_SPV.speak('ping', { text: 'hi' }, { to: 'seat:term' });

SDF FRAME (JSON · long details welcome)
  {
    "v": 1,
...
full: docs/OS_TABBED_BUS.txt