KB: decode the pod's RGB SPLIT -- one VGA port drives THREE mono MFDs

Answering 'how do the panels split RGB into 3 monitors' from primary sources
rather than inference:

- content/GAUGE/L4GAUGE.CFG (the authentic 1996 pod config) configures each
  gauge port with a bit-plane mask AND A COLOUR CHANNEL: Comm=red,
  Mfd2=green, Heat=blue on clut2 (the upper row); Mfd1=red, Mfd3=green on
  clut1 (the lower row, blue spare); sec/radar = full rgb, rotation 270 (the
  portrait CRT).  Eng1/2/3 are the engineering-page twins on the same
  monitors, swapped in/out via reconfigure() with 'blank'.
- L4GraphicsPort::BuildSecondaryColor (L4VB16.cpp) proves the mechanism at
  T0: it walks the palette entries owned by the port's bit group and writes
  exactly ONE component (RedChannel->Red, GreenChannel->Green,
  BlueChannel->Blue, AllChannels->whole triplet); BlankColor blanks the
  group.  So one palettized framebuffer emits three independent pictures on
  the R/G/B analog lines, and the splitter feeds each line to its own mono
  monitor -- which is also what the '1280x480 horizontally spanned' MFD
  surface actually is: two VGA outputs x three channels.

Port consequence recorded: the per-panel window path (BT_POD_SURFACES) is
right for per-panel outputs but WRONG for splitter-wired glass, which needs a
channel-composite mode (three planes -> one RGB image, pure primary tints).
ExpandPlaneToBGRA already does the per-plane half.  Open: how Nick's cart is
actually wired.  Also lands the pod bring-up scratch (ssh helper, layout cfg,
launcher, firestorm repo browser).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scratchpad/pod/fs.py

@@ -0,0 +1,47 @@
+"""Browse the VWE/firestorm gitea repo (read-only) without cloning 10GB."""
+import base64, json, subprocess, sys, urllib.request
+sys.stdout.reconfigure(encoding='utf-8', errors='replace')
+_out = subprocess.run(["git","credential","fill"],
+    input="protocol=https\nhost=mysticmachines.com\n\n",
+    capture_output=True, text=True, cwd=r"C:\git\bt411")
+_c = dict(l.split("=",1) for l in _out.stdout.strip().splitlines() if "=" in l)
+AUTH = "Basic " + base64.b64encode((_c["username"]+":"+_c["password"]).encode()).decode()
+B = "https://mysticmachines.com/api/v1/repos/VWE/firestorm"
+
+def api(p, t=120):
+    r = urllib.request.Request(B+p, headers={"Authorization": AUTH})
+    return json.load(urllib.request.urlopen(r, timeout=t))
+
+def ls(path=""):
+    try:
+        return api("/contents/" + urllib.request.quote(path))
+    except Exception as e:
+        return []
+
+def raw(path, t=120):
+    r = urllib.request.Request(B+"/raw/"+urllib.request.quote(path), headers={"Authorization": AUTH})
+    return urllib.request.urlopen(r, timeout=t).read().decode("utf-8","replace")
+
+if __name__ == "__main__":
+    cmd = sys.argv[1]
+    if cmd == "ls":
+        for e in sorted(ls(sys.argv[2] if len(sys.argv)>2 else ""), key=lambda x: x["type"]+x["name"]):
+            print(f'  {e["type"]:4} {e.get("size",0):>9} {e["path"]}')
+    elif cmd == "cat":
+        print(raw(sys.argv[2])[:int(sys.argv[3]) if len(sys.argv)>3 else 4000])
+
+def subtree(path, recursive=True):
+    """Full file list under a directory, via its tree sha (avoids the 1000-entry
+    truncation of a whole-repo recursive tree)."""
+    e = api("/contents/" + urllib.request.quote(path))
+    # the dir's own sha comes from its parent listing
+    parent = "/".join(path.split("/")[:-1])
+    name = path.split("/")[-1]
+    for it in ls(parent):
+        if it["name"] == name and it["type"] == "dir":
+            sha = it["sha"]
+            break
+    else:
+        return []
+    t = api(f"/git/trees/{sha}?recursive={1 if recursive else 0}&per_page=99999", t=180)
+    return [(x["path"], x.get("size", 0)) for x in t.get("tree", []) if x["type"] == "blob"], t.get("truncated")

scratchpad/pod/podssh.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+# Run a command on the pod (bt411-pod, user 'user') over the tailnet.
+exec ssh -i ~/.ssh/bt411_pod -o BatchMode=yes -o StrictHostKeyChecking=no \
+  -o UserKnownHostsFile=/dev/null -o LogLevel=ERROR -o ConnectTimeout=10 \
+  user@100.107.167.96 "$@"

scratchpad/pod/runpod.bat

@@ -0,0 +1,18 @@
+@echo off
+REM BT411 pod launch -- runs from the game's content dir in the CONSOLE session.
+REM Started via schtasks /IT so the windows land on the REAL panels (an SSH
+REM session is session 0 with a dummy display and would render nowhere).
+cd /d C:\bt411\BT411_4.11.801\content
+
+REM glass cockpit, per-display windows, POD surface mode (bare 640x480 pictures,
+REM no on-screen button banks -- the cab's buttons are physical), sticky layout
+REM loaded from glass_layout.cfg beside this file.
+set BT_GLASS=1
+set BT_GLASS_PANELS=1
+set BT_POD_SURFACES=1
+set BT_GLASS_LAYOUT=load
+set BT_GLASS_LOG=1
+set BT_START_INSIDE=1
+set BT_LOG=podrun.log
+
+start "" ..\build\Release\btl4.exe -egg MP.EGG