# TeamsISO Phase B-2 — Real NDI Interop Plan

**Goal:** Production `INdiInterop` implementation in `TeamsISO.Engine.NdiInterop` against NDI SDK 6, a managed BGRA scaler with aspect modes, an NDI version constant, and a `TeamsISO.Console` headless smoke runner that wires up the engine end-to-end. After this phase the engine can drive real Teams NDI streams once run on a Windows box with the NDI runtime installed.

**Architecture:** P/Invoke against `Processing.NDI.Lib.x64.dll`. Frame marshalling translates NDI's `video_frame_v2_t` to/from our managed `RawFrame`/`ProcessedFrame`. Receive in BGRA color space (`NDIlib_recv_color_format_e_BGRX_BGRA`) so the scaler doesn't need to handle UYVY in v1.0. Memory management: every captured frame is freed via `NDIlib_recv_free_video_v2` once we've copied its pixels into a managed buffer.

**Tech Stack:** .NET 8, `System.Runtime.InteropServices`, plain C# scaler (managed BGRA nearest-neighbor; libyuv is a v1.5 perf optimization). The console runner uses the existing `EngineLogging.CreateConsole`.

**Source spec:** `docs/superpowers/specs/2026-05-07-teamsiso-v1-design.md`

## Tasks

1. **NDI native bindings:** `NdiNative.cs` with all `[DllImport]` declarations needed (`initialize`, `destroy`, `find_create_v2/destroy/get_current_sources`, `recv_create_v3/destroy/capture_v3/free_video_v2`, `send_create/destroy/send_video_v2`, `version`). Define `NDIlib_video_frame_v2_t`, `NDIlib_source_t`, `NDIlib_recv_create_v3_t`, `NDIlib_send_create_t` structs with explicit layout.
2. **Handles:** `NdiPInvokeFindHandle`, `NdiPInvokeReceiverHandle`, `NdiPInvokeSenderHandle` deriving from the abstract Phase A handles, owning the unmanaged pointers.
3. **NdiInteropPInvoke:** the production `INdiInterop` implementation. Initializes NDI on construction; destroys on dispose. Marshals between native and managed frame structs. Allocates managed pixel buffers and copies; frees the native frame immediately.
4. **NdiVersion:** a constants class exposing the version string the engine probe compares against.
5. **ManagedNearestNeighborFrameScaler:** managed BGRA scaler with `Pillarbox`, `Letterbox`, `Stretch` aspect modes. Fully unit-tested.
6. **TeamsISO.Console:** a small console host. Constructs `IsoController` against `NdiInteropPInvoke` + `ManagedNearestNeighborFrameScaler`, prints participant updates, listens for `q\n` to quit. Useful for headless validation.
7. **Wire-up tests:** integration scaffold uses `RuntimeInformation.IsOSPlatform(OSPlatform.Windows)` to skip cleanly on non-Windows. Add a smoke integration test that constructs the interop and probes the version.
8. **Wrap-up:** tag `phase-b-2-complete`.

## What this phase intentionally does NOT include

- libyuv-backed scaler (deferred to v1.5 per spec — managed scaler is functionally complete).
- Actual integration test suite running against an NDI Test Pattern source. Those tests need the NDI runtime; they're authored here but stay tagged `requires=ndi` and skip in the Linux CI.
- Audio handling (passthrough video only in this phase; audio support added later if v1.0 needs it before ship).

## Self-review

Spec coverage: §4 NdiReceiver/NdiSender/IsoController already done in B-1; this phase fills in the actual NDI SDK calls under `INdiInterop`. §6 startup preflight via `NdiVersion` + the existing `NdiRuntimeProbe`. §8 console smoke runner is a Phase B-2 deliverable for first end-to-end Windows validation before WPF.
