docs(windows-host): NVENC live-validated on RTX 4090 + real-GPU box notes

Mark DXGI capture + NVENC as live-validated (720p60/1080p60), record the
real-GPU test box (192.168.1.174), the Session-0→Session-1 Interactive
scheduled-task launch, the VM-built-exe-runs-with-driver-DLL trick, and
the SudoVDA-output-under-the-rendering-GPU gotcha. Refresh remaining gaps
(SendInput in-session, ViGEm input/rumble, Moonlight-on-GPU, static-frame
pacing).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/windows-host.md

@@ -12,11 +12,15 @@ control interface — **no driver to write or WHQL-sign.**
 History: scoped 2026-06-10 (4-agent read of the host crate); SudoVDA path 2026-06-11; this concrete
 plan + dev box + SudoVDA protocol + no-GPU strategy added 2026-06-14 (12-agent research pass).
 
-## Status (2026-06-15) — all host backends landed; runnable on Windows
+## Status (2026-06-15) — full pipeline live-validated on an RTX 4090
 
 Every OS-touching backend is implemented behind the existing traits and **builds clean on
 `x86_64-pc-windows-msvc`** (and Linux unaffected). `serve --native` / `m3-host` **run on Windows**
-(identity in `%APPDATA%`/`HOME`, QUIC bound, mDNS advertising, accepting sessions — validated live).
+(identity in `%APPDATA%`, QUIC bound, mDNS advertising, accepting sessions). The **full native
+pipeline is validated live on a real RTX 4090** (Windows 11): SudoVDA virtual display → DXGI
+Desktop Duplication (D3D11 zero-copy) → **NVENC HEVC** → punktfunk/1 → Rust reference client, at
+720p60 and 1080p60 (0 mismatched frames, p50 1.6 / 3.45 ms cross-machine, ffmpeg-decodes clean),
+coexisting with a running Apollo (two concurrent NVENC sessions).
 
 | Backend | State | GPU-less validation on the VM |
 |---|---|---|
@@ -24,8 +28,8 @@ Every OS-touching backend is implemented behind the existing traits and **builds
 | Input (SendInput) | ✅ done | compiles; live injection needs an interactive session (not SSH) |
 | Software encode (openh264) | ✅ done | **live: m0 synthetic→openh264→core FEC loopback, 120/120, 0 mismatches** |
 | Audio (WASAPI loopback) | ✅ done | live: init chain opens (silent VM → no samples) |
-| Capture (DXGI Desktop Duplication) | ✅ done | helpers unit-tested; DuplicateOutput needs a GPU-activated monitor |
+| Capture (DXGI Desktop Duplication) | ✅ **live on RTX 4090** | SudoVDA monitor → D3D11 zero-copy duplication; output is enumerated under the *rendering* GPU, not the SudoVDA LUID (search all adapters) |
-| NVENC (D3D11, `--features nvenc`) | ✅ compiles+links | needs a GPU at runtime |
+| NVENC (D3D11, `--features nvenc`) | ✅ **live on RTX 4090** | 720p60 + 1080p60 HEVC end-to-end to the Rust client; ffmpeg-decodes clean; ran alongside Apollo (2 NVENC sessions) |
 | Run host (serve/m3-host) | ✅ live | m3-host starts + listens; `c_abi_connection_roundtrip` passes |
 | Gamepad (ViGEm) | ✅ done | compiles incl. rumble back-channel; live needs ViGEmBus + a physical pad |
 | Host→client audio wiring | ✅ done | builds on MSVC; `m3` `audio_thread` active on Windows (silent VM → no samples to send) |
@@ -34,9 +38,26 @@ Every OS-touching backend is implemented behind the existing traits and **builds
 | Game library (Steam discovery) | ✅ done | Windows Steam roots (Program Files) + VDF other-drive libraries; custom store already cross-platform. Non-default Steam install dir (registry) not yet covered |
 
 **Remaining for full parity:**
-- **Live GPU/in-session validation** — SudoVDA monitor activation, DXGI capture, NVENC encode,
+- **SendInput injection** — needs the interactive session (works once the host runs in Session 1;
-  SendInput injection, and the ViGEm rumble path all need a real GPU and/or an interactive (console)
+  not yet exercised live).
-  session + a physical pad, not SSH/Session-0.
+- **ViGEm rumble + gamepad input** — the pad is created live (ViGEmBus connected); the rumble
+  back-channel + input still need a physical pad to verify.
+- **GameStream (Moonlight) path on a GPU box** — not yet run live (its fixed ports collide with
+  Apollo, so stop Apollo first).
+- **Frame pacing on static content** — DXGI duplication is change-driven, so a blank/idle virtual
+  display delivers only ~12 fps (181/177 frames over ~15 s); a rendering app drives the full rate.
+
+### Real-GPU test box (RTX 4090, `ssh "Enrico Bühler"@192.168.1.174`)
+
+Windows 11, RTX 4090 (driver 596.36) + AMD iGPU, SudoVDA + Apollo (sunshine) installed. SSH lands in
+**Session 0 (non-interactive)** — DXGI duplication + SendInput need the **interactive Session 1**, so
+launch the host there via an Interactive scheduled task (admin SSH session is the same user):
+`Register-ScheduledTask -Principal (New-ScheduledTaskPrincipal -UserId (whoami) -LogonType
+Interactive -RunLevel Highest)`, then `Start-ScheduledTask`. The host runs with desktop access; read
+its redirected log over SSH. `nvEncodeAPI64.dll` ships with the driver, so a VM-built `--features
+nvenc` exe runs here as-is (no SDK install). The 4090's Ada NVENC has no consumer session cap, so the
+host encodes alongside Apollo. **Gotcha:** the SudoVDA monitor is rendered by — and DXGI-enumerated
+under — the 4090, not the SudoVDA adapter LUID (the capturer searches all adapters; see the fix).
 
 All Windows backends are `clippy -D warnings` and `rustfmt` clean on `x86_64-pc-windows-msvc` (the
 Windows-only modules are cfg-excluded from Linux CI, so run clippy on the VM after touching them — its