# TASK 16 — Kill infinity display (no-game backdrop fallback)

> Catalog: [`TASKS.md`](../TASKS.md) — status and requirements live here.


**Goal:** when no full-screen game is detected, show a static branded placeholder instead of
capturing the primary display (which causes the infinity mirror effect).

### Status: ✅ Shipped

**Changes:**
1. `ResolveAutoCaptureKey()` returns `null` when no full-screen game is detected (was: primary monitor)
2. `ReacquireScreenCaptures()` — clears stale `CaptureKey` when `auto == null` (handles DB upgrades);
   skips `AcquireAsync` when no keys are set
3. `SeedLiveBackdropAsset()` — sets `AssetId` on the backdrop element itself (NOT a Background source);
   called from `ReacquireScreenCaptures()` after `EnsureBackdrop()` guarantees the element exists
4. `Source.DisplaySource` falls back to `_imageSource` when `VideoImageSource` is null for live captures
5. `Assets/live-backdrop.jpg` — user-provided image, added as `<Resource>` in csproj
6. `ResolveOutputFrame()` in compositor — `Source { IsLiveCapture: true, CaptureKey: not null }` already skips null keys; fallback pattern `Source { AssetId: not null }` picks up the static image

**Rendering flow:**
| Scenario | Preview | Compositor |
|---|---|---|
| Game detected | Live capture (opaque, covers static asset on backdrop) | `ScreenCaptureManager.GetLatestFrame` |
| No game | Static image via `DisplaySource` → `_imageSource` on backdrop | `StaticPixelCache.Get(assetId)` |
| Manual capture pick | Live capture | Live frame |