feat(lift): NeurD-backed 2D→3D lift slots on the D3D11 DP

.github/workflows/build-windows.yml

@@ -88,6 +88,12 @@ jobs:
       # Read with LEIALOFT_GITHUB_TOKEN — the same secret the Android arm uses
       # for LeiaInc/CNSDK. Fork PRs have no secret and cannot build this arm.
       SR_SDK_REPO: LeiaInc/SR-SDK-Windows-Releases-Internal-Public
+      # NeurD headers for the 2D->3D lift module (docs/lift-neurd.md), fetched
+      # from the PRIVATE LeiaInc/media_sdk repo into the gitignored
+      # NeurD-SDK-<ref>/include -- never committed. Pin a media_sdk release tag.
+      # KEEP IN SYNC with scripts/build-windows.bat (check_sr_pins.py asserts).
+      NEURD_SDK_REF: v0.4.6
+      NEURD_SDK_REPO: LeiaInc/media_sdk
       GH_TOKEN: ${{ github.token }}
       # SourceForge serves a bot-check page to CI runners, so vcpkg's pthreads
       # port (vcpkg_from_sourceforge) fails its hash on every mirror. This
@@ -103,7 +109,7 @@ jobs:
       # regression originally).
       # #734: runtime v2.0.0 (a8f6e74f) ships the XR_EXT_* → XR_DXR_*
       # extension rename this plug-in's headers now use (ABI unchanged, v4).
-      RUNTIME_REF: v2.16.9
+      RUNTIME_REF: v2.22.0
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -180,6 +186,21 @@ jobs:
             if (-not (Test-Path "$env:SR_V2_DIR/$f")) { throw "SR v2 SDK missing $f" }
           }
 
+      # SOFT: without the headers the lift module compiles out and the plug-in
+      # is otherwise identical, so a missing token or an unreachable repo must
+      # not fail the build -- it is surfaced as a warning annotation instead.
+      - name: Fetch NeurD headers
+        if: needs.DetectChanges.outputs.docs_only != 'true'
+        continue-on-error: true
+        env:
+          GH_TOKEN: ${{ secrets.LEIALOFT_GITHUB_TOKEN }}
+        run: |
+          ./scripts/fetch-neurd-headers.ps1 -Repo $env:NEURD_SDK_REPO -Ref $env:NEURD_SDK_REF -Dest "NeurD-SDK-$env:NEURD_SDK_REF"
+          if ($LASTEXITCODE -ne 0) {
+            Write-Host "::warning::NeurD headers not fetched ($env:NEURD_SDK_REPO@$env:NEURD_SDK_REF) -- this build ships WITHOUT 2D->3D lift."
+            exit 1
+          }
+
       # The plug-in CMake adds the runtime as a subdirectory, so we need
       # all the runtime's own build prereqs (vcpkg, Vulkan SDK, OpenXR
       # loader). Same shape as the runtime's build-windows.yml.
@@ -282,6 +303,8 @@ jobs:
         env:
           LEIASR_SDKROOT: ${{ github.workspace }}/LeiaSR-SDK-${{ env.SR_TAG }}-win64
           LEIASR_V2_SDKROOT: ${{ github.workspace }}/${{ env.SR_V2_DIR }}
+          # Read by src/drv_leia/CMakeLists.txt; absent dir => lift compiles out.
+          NEURD_SDK_ROOT: ${{ github.workspace }}/NeurD-SDK-${{ env.NEURD_SDK_REF }}
         run: |
           cmake -S . -B build -G "Ninja Multi-Config" `
             -DDXR_RUNTIME_SOURCE_DIR="${{ github.workspace }}/displayxr-runtime" `

.gitignore

@@ -28,6 +28,8 @@ __MACOSX/
 # Fetched SR SDK (not committed; downloaded by CI / scripts/build-windows.bat)
 LeiaSR-SDK-*/
 simulatedreality-SDK-*/
+# Fetched NeurD headers (Leia-private; scripts/fetch-neurd-headers.ps1)
+NeurD-SDK-*/
 
 # Installer artifacts (built into _package/)
 DisplayXRLeiaSRSetup-*.exe

CLAUDE.md

@@ -98,6 +98,7 @@ ADR-020 spec: [`displayxr-runtime/docs/adr/ADR-020-plugin-abi-policy.md`](https:
 | `src/drv_leia/leia_display_processor*.{cpp,h}` | Per-API display processors (D3D11, D3D12, GL). Implement `xrt_display_processor_<api>` vtables; the runtime's compositor invokes them per-frame. |
 | `src/drv_leia/leia_sr_*.{cpp,h}` | SR SDK weaver wrappers. The SDK throws `std::runtime_error` as routine internal control flow (~11/frame in some paths) — every call wrapped in try/catch. |
 | `src/drv_leia/leia_bg_capture_win.{cpp,h}` | WGC background capture for compose-under transparency (Leia transparency model). |
+| `src/drv_leia/leia_lift_neurd.{cpp,h}` | 2D→3D lift slots on the D3D11 DP, backed by a dynamically loaded NeurD.dll (absent ⇒ caps unavailable, nothing loaded). Compiles only with the private NeurD headers (fetched at build time, below) AND runtime headers with `XRT_DP_D3D11_HAS_LIFT`; otherwise the slots stay NULL. See [`docs/lift-neurd.md`](docs/lift-neurd.md). |
 | `src/drv_leia/leia_edid_probe.c` | EDID-based hardware detection — answers "is a Leia display attached?" before the SR SDK initializes. |
 | `src/drv_leia_linux/leia_sr_linux.h` | **Linux weaver-backend seam** — interface shaped 1:1 by `docs/leia-linux-sdk-contract.md` (every declaration cites its R-* requirement). Track B implements it against the real SDK. |
 | `src/drv_leia_linux/leia_sr_stub.c` | Track A stub backend: canned panel info + passthrough SBS blit, `TODO(Track B)` at every body. |
@@ -134,6 +135,15 @@ run by `.github/workflows/lint.yml` on every PR, asserts all five pins
 declared exactly once and identically in both files, and that
 `SR_V2_TAG`/`SR_V2_DIR` name the same SR v2 build.
 
+**NeurD headers (2D→3D lift) follow the same rule.** They are Leia-private
+and come from the private **`LeiaInc/media_sdk`** repo at `NEURD_SDK_REF`
+(pinned next to the SR pins in both files, also checked by
+`check_sr_pins.py`), fetched by `scripts/fetch-neurd-headers.ps1` into the
+gitignored `NeurD-SDK-<ref>/`. **Never commit or mirror them.** Your `gh`
+account (and CI's `LEIALOFT_GITHUB_TOKEN`) needs read access to
+`media_sdk`; without it the fetch fails SOFT and the plug-in builds without
+lift. Details: [`docs/lift-neurd.md`](docs/lift-neurd.md).
+
 ### Linux
 ```bash
 ./scripts/build-linux.sh            # Track A stub: .so + displayxr-cli, stage manifest, selftest

CMakeLists.txt

@@ -162,9 +162,13 @@ endif()
 # This plug-in MUST be built against headers that ship the matching major,
 # or the runtime will log "ABI major mismatch — plugin_api=N, runtime
 # expects M ... skipping (ADR-020 rule 3)" and fall back to sim_display.
+# v2.22.0 (from v2.16.9): the first runtime that ships the D3D11 DP lift slots
+# (XRT_DP_D3D11_HAS_LIFT, runtime#1781) and the lift-only factory
+# (XRT_PLUGIN_IFACE_HAS_D3D11_LIFT_FACTORY). Appended and struct_size-gated,
+# plug-in ABI still v5; an older pin compiles the NeurD lift module OUT.
 # The rule-5 CI self-check below asserts this value equals the workflow's
 # runtime checkout ref so the two can't drift.
-set(DXR_RUNTIME_GIT_TAG "v2.16.9" CACHE STRING
+set(DXR_RUNTIME_GIT_TAG "v2.22.0" CACHE STRING
     "Runtime git ref to fetch. Must equal the workflow's runtime checkout ref (rule-5 CI check enforces).")
 # Linux carries its own pin so it can move independently of the Windows
 # installer's derived MIN_RUNTIME_VERSION (same reason as _ANDROID below).

docs/README.md

@@ -14,13 +14,15 @@ Leia is the first 3D-display vendor integrated into DisplayXR. This directory do
 | Display processor (per API) | `leia_display_processor.{cpp,h}` (base), `leia_display_processor_d3d11.{cpp,h}`, `leia_display_processor_d3d12.{cpp,h}`, `leia_display_processor_gl.{cpp,h}` |
 | Weaver (per API) | `leia_sr.{cpp,h}` (base + eye tracking), `leia_sr_d3d11.{cpp,h}`, `leia_sr_d3d12.{cpp,h}`, `leia_sr_gl.{cpp,h}` |
 | Background capture (transparency) | `leia_bg_capture_win.{cpp,h}` |
+| 2D→3D lift (NeurD, D3D11) | `leia_lift_neurd.{cpp,h}` (+ private NeurD headers fetched at build time) |
 | Shaders | `shaders/` |
 
 ## Docs in this directory
 
 - **[Weaver internals](weaver.md)** — DX11 / DX12 / OpenGL / Vulkan weaver creation, inputs, weave() flow, DPI handling, phase math.
 - **[Transparency model](transparency.md)** — current primary path: WGC compose-under-bg on D3D11 / D3D12 / Vulkan. Replaces the older chroma-key approach for those APIs.
 - **[Chroma-key overlay (legacy / OpenGL fallback)](chroma-key-overlay.md)** — fallback path; still the only transparency path on the Leia OpenGL DP.
+- **[2D→3D lift via NeurD](lift-neurd.md)** — the D3D11 DP's `lift_*` slots: dynamic NeurD.dll load, one-per-process activation (licence network failure = *activating*, retried), the shared-texture device bridge to NeurD's own D3D11 device, tracked-eye → NeurD viewpoint mapping, the `DXR_LEIA_LIFT*` knobs, and how to verify with `displayxr-cli lift caps|probe`.
 - **[Late latching](late-latching.md)** — which backends implement it (D3D11/GL automatic, VK needs our submit hook, D3D12 is a stub), what `srWeaverIsLateLatchingEnabled` hides, the once-per-frame / deferred-context contract from the shipped header, and the dot test — including why `pattern = 450` makes it lie.
 - **[SR panel readiness and late geometry](sr-readiness.md)** — the boot race (SR "default display" until the FPC serial link answers; never while the panel sleeps), the two readiness signals that actually work (`Global\sharedDeviceSerialMemory` count byte, a *fresh* valid display handle), the ONE shared startup budget (`DXR_LEIA_SR_READY_TIMEOUT_S`, default 20 s), the 1 Hz late-identification watcher that re-derives geometry and updates the live head device in place, and the `get_display_info` contract with the runtime (#266).
 - **[Window phase snapping](window-phase-snapping.md)** — the SR weaver's automatic `WndProc` subclassing for lenticular phase alignment during window drag (Windows), and the resolved `WndProcDispatcher` race.