KB: step-4 closeout -- Steam wire documented, live-test procedure, router

docs/GLASS_COCKPIT.md gains the step-4 ledger (seam/transport/lobby + THE
FAKEIP LESSON); NEW context/steam-networking.md topic (+ router row) and
docs/STEAM_TEST.md (the 2-machine live procedure = the step-4 exit criterion
on user hardware).  context/glass-cockpit.md: steps 3+4 status.  Final purity
re-check: pod build clean, forced-walk mission runs, ZERO glass/steam tags in
the pod log.

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

context/glass-cockpit.md

@@ -61,9 +61,15 @@ copied from them.
   (`BT_BUTTON_TRAP=1` restores) — each `[FAIL]` log = a missing L4 override to reconstruct.
   Verified: authentic-path input (engine push → streamed `.CTL` → mapper), panel-click
   survival, 2-node loopback MP un-regressed on the pod build. Detail: `docs/GLASS_COCKPIT.md`.
-- Step 3 (miniconsole): pending. Architecture: the console stays a WIRE PEER — an in-process
-  worker-thread console client over loopback; no engine-loop hooks.
-- Step 4 (Steam): pending.
+- **Step 3 (miniconsole): DONE 2026-07-17 [T2].** `game/glass/btl4fe.*` (menu + console-shape
+  egg writer, golden-tested vs MP.EGG) + `btl4console.*` (the marshal: a worker-thread console
+  CLIENT speaking the btconsole.py wire verbatim; `content\marshal.log`). ZERO engine hooks —
+  the engine runs the stock console ladder. Per-mission process relaunch; `BT_FE_*` env arms the
+  marshal (menu relaunches clear it). Verified: solo cycle (menu→mission→60s clock→stop→menu)
+  and menu-hosted 2-node LAN.
+- **Step 4 (Steam): CODE COMPLETE 2026-07-18 [T2 single-machine].** See [[steam-networking]] —
+  the wire seam + `L4STEAMNET` identity-token transport + `btl4lobby`. Live 2-account
+  cross-machine session pending (`docs/STEAM_TEST.md`).
 
 ## Key Relationships
 - Extends: [[pod-hardware]] (RIO input path) · Uses: [[gauges-hud]] dev-gauge modes ·

context/steam-networking.md

@@ -0,0 +1,46 @@
+---
+id: steam-networking
+title: "Steam networking — the BT_STEAM wire (transport + lobby)"
+status: living
+source_sections: "docs/GLASS_COCKPIT.md §4; docs/STEAM_TEST.md; commits e79e8fa/48ede2f/f703bb1"
+related_topics: [glass-cockpit, multiplayer]
+key_terms: [PadRIO, miniconsole]
+open_questions: ["live 2-account cross-machine session (docs/STEAM_TEST.md) — the step-4 exit criterion"]
+---
+# Steam networking — the BT_STEAM wire
+
+Internet MP for the glass cockpit (dev tooling; gate `BT_STEAM`, requires `BT_GLASS`).
+**Status: CODE COMPLETE 2026-07-18; single-machine verified; live 2-machine test pending.**
+
+## The three layers
+1. **The wire seam** (`L4NET.CPP`, always compiled): file-local `BTNetSend/Recv/Accept/Close`
+   wrappers around the 9 raw Winsock sites — pure code motion when OFF; under `BT_STEAM` each
+   offers the op to the transport first. Est. delegates: `CheckSocket` (peer address),
+   `OpenConnection` TCP_OPEN head, `GetMyAddress` (self token).
+2. **The transport** (`engine/MUNGA_L4/L4STEAMNET.*`, gated): `ISteamNetworkingSockets`
+   pseudo-SOCKETs (`0x5EA0xxxx`); engine TCP byte stream over reliable-NoNagle messages with
+   per-connection reassembly rings (recv: empty→`WSAEWOULDBLOCK`, closed→0); listen channels
+   console=0 / game=1 (`CreateListenSocketP2P`); install on env `BT_STEAM_NET=1`; degrades to
+   Winsock at every failure. Pump = `SteamAPI_RunCallbacks` AND sockets `RunCallbacks` (the
+   general dispatch carries the async results — sockets-only pumping stalls).
+3. **The lobby** (`game/glass/btl4lobby.*`, gated): ISteamMatchmaking room (`btl4=1` list
+   filter); pilots publish name/mech/color; the host's GO mints the roster and signals.
+
+## THE TOKEN MODEL (the FakeIP lesson) [T2]
+FakeIP does NOT survive the per-mission process relaunch (live-disproven prior-art assumption:
+menu and mission processes got different FakeIPs; the pod timed out dialing its own stale
+address). Roster addresses are therefore **opaque ipv4-shaped tokens** — `169.254.77.N`, port
+1501=console / 1502=game — minted by the HOST at GO and mapped to **Steam identities**;
+connections ride `ConnectP2P(identity, channel)`. Handoff to mission processes via env:
+`BT_FE_MYFAKE` (own token → `GetMyAddress` self-match) + `BT_FE_STEAMMAP`
+(`ip=steamid64;...`). The engine's roster matching, Waterloo swap logic, and self-identification
+all run UNCHANGED on tokens.
+
+## Testing
+Single-machine (verified): lobby-of-1 GO → token map → egg roster token → mission runs over the
+stock console ladder. Live 2-machine procedure + checklist: `docs/STEAM_TEST.md`. AppID 480
+(Spacewar) via auto-written gitignored `content/steam_appid.txt`.
+
+## Key Relationships
+- Rides: [[glass-cockpit]] miniconsole (marshal has a Steam-wire branch) · Extends:
+  [[multiplayer]] (the arcade mesh, unchanged above the seam)