diff --git a/HANDOFF.md b/HANDOFF.md
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@@ -1,91 +1,31 @@
 # HANDOFF — Session State
 
 ## Branch
-`main` — clean, last push `8951141` (TASK 10 shipped). TRAX meter fix pushed `e06bfa4`.
-All Control Surface UX work is **uncommitted** — build passes 0 warnings/0 errors.
-
-## ⚠️ IN FLIGHT: repo-wide Backdrop→Background rename (multi-session)
-Models already renamed (`Source.IsBackground`, `Scene.HasBackground`/`CustomBackgroundPath`,
-`SceneCatalog.HasBackground`, `Source` enum `Background`). Status per file:
-- ✅ `ViewModels/MainViewModel.cs` — full case-sensitive rename done; compiles clean.
-- ✅ `MainWindow.xaml.cs` + `MainWindow.xaml` — renamed; full solution builds 0 warnings/0 errors.
-- ✅ `Services/Compositor/SceneCompositor.cs` — CS0128 duplicate locals fixed.
-- ⏳ `Services/LayoutStore.cs` — C# members renamed, but DB column strings
-  (`HasBackdrop`/`IsBackdrop`) are **schema** and intentionally still say Backdrop:
-  renaming them needs a real migration (new user_version) touching every existing DB.
-  The V5-backfill unit test's raw CREATE TABLE must keep `IsBackdrop` to match —
-  blanket-renaming it breaks `V5_Database_Backfill_Removes_NonLive_Backgrounds`
-  (verified: migration can't see flags, Live source loses `IsBackground`).
-- ✅ `ytLive.Tests` — all 5 files blanket-renamed (class/method/var/comment names +
-  C# property accesses); `BackdropTests.cs` → `BackgroundTests.cs`. Tests: 207/208 pass;
-  the only red is pre-existing `AudioPipelineTests.Mix_HonorsProviderGains_AndGameMute_KillsTheLoopback`
-  (unrelated gain-math assert at AudioPipelineTests.cs:373, zero backdrop occurrences).
-- Pending elsewhere: leftover "backdrop" doc comments (`Source.cs`, `SceneCatalog.cs`,
-  `ScreenCaptureManager.cs`, `ScreenCaptureFrameSource.cs`, `MainWindow.xaml:769`),
-  asset files + csproj (`Assets/*-backdrop.jpg` — pack-URI strings in MainViewModel now say
-  `-background.jpg` so default-scene seeding silently no-ops until assets+csproj are renamed).
+`main` — clean at `4b9a8e5` (Control Surface UX: pill toggle, background rename, per-scene properties).
 
 ## What shipped this session
 
-1. **TASK 10 — Polar billing + Velopack auto-updates (steps 1–7)** — full license key activation flow
-2. **TRAX meter double-attenuation fix** — removed redundant slider multiplication
+1. **TASK 10 — Polar billing + Velopack auto-updates (steps 1–7)**
+2. **TRAX meter double-attenuation fix**
 3. **LAN infrastructure documented** — all servers in `ai.md` + `CREDENTIALS.md`
-4. **llamavault NFS/SMB diagnosis** — zombie SMB session from power outage, fixed by killing stale PID
+4. **llamavault NFS/SMB diagnosis**
+5. **Control Surface UX** — all 10 phases complete (StagedScene/LiveScene, thumbnails, edit gating, transitions, brand rename)
+6. **Sliding pill toggle** — green ON (#22c55e) / red OFF (#ef4444), replaces checkbox
+7. **Backdrop → Background** — full C# rename, SQL column rename with migration, asset files renamed, `Source.IsBackground` `new` → `override` fix, legacy "Backdrop" display name migration
+8. **Geometry mismatch error** — red text when custom background aspect ratio >5% off 16:9
+9. **Per-scene background properties** — pill toggle + custom path persist per-scene via Settings table
 
-## Active work: Control Surface UX (TASK 19/23 merged) — ALL PHASES COMPLETE
-
-**Design philosophy:** Director's control surface, not an editor. Five scene monitors above one central live monitor. Click thumbnail = transition (live) or stage (offline). Edit mode only when offline. Live/Recording = read-only. Right-click + drag locked when live.
-
-### Phases completed (ALL)
-1. ✅ **Phase 1:** `StagedScene`/`LiveScene` split + `IsEditMode` in MainViewModel
-2. ✅ **Phase 2:** Left panel two-state (edit: layers+props, live: chat)
-3. ✅ **Phase 3:** Right panel eliminated
-4. ✅ **Phase 4:** Thumbnail strip above center monitor + `Scene.Snapshot` + placeholder snapshots
-5. ✅ **Phase 5:** Edit-mode gating (drag/resize/context menus blocked when live)
-6. ✅ **Phase 6:** `TransitionService.cs` (Cut/Fade/Move) + `SceneCompositor.BlendFrames()`
-7. ✅ **Phase 7:** `FramePump` integrated with `TransitionService`
-8. ✅ **Phase 8:** Thumbnail click → `TransitionToScene()` wiring
-9. ✅ **Phase 9:** Brand rename "ytLlive" → "LlamaCasty" (user-visible strings)
-10. ✅ **Phase 10:** `LayoutStore.SaveTransitionSettings()` / `LoadTransitionSettings()`
-
-### Key decisions
-- **Mode is implicit:** offline = edit, live/recording = read-only. No toggle button.
-- **Left panel = one panel, two states:** offline → LAYERS + PROPERTIES; live → YouTube Live Chat (entire panel replaced, never coexists)
-- **No (=>) transition button:** clicking a thumbnail directly triggers the transition
-- **Thumbnail glow:** active scene gets brand-red `#e94560` border via `IsStaged` data trigger
-- **Right panel eliminated:** chat moved to left panel (live mode only)
-- **5 thumbnails above center monitor**, 120px height, uniform grid. Placeholder colored boxes until compositor snapshots added.
-- **Transitions:** Cut + Fade + Move (v1). Go Live always = Cut. Duration persisted to Settings table.
-- **Brand rename:** "ytLlive" → "LlamaCasty" across all XAML, VM strings, service strings. File paths (`%APPDATA%\ytLlive\`) intentionally NOT renamed.
-
-### Architecture changes
-- `ActiveScene` → split into `StagedScene` (central monitor, editable) + `LiveScene` (encoder output, read-only)
-- `IsEditMode` = derived property: `StreamStatus == StreamStatus.Offline`
-- `TransitionService` — transition state machine with Start/Tick/BlendFrame
-- `SceneCompositor.BlendFrames()` — crossfade between two VideoFrames
-- `Scene.Snapshot` + `Scene.IsStaged` — thumbnail image and staged indicator
-- `FramePump` — now accepts `TransitionService` + `fromSceneProvider`, blends during transitions
-
-### Files changed
-- `ViewModels/MainViewModel.cs` — StagedScene/LiveScene split, IsEditMode, TransitionToScene, snapshots, brand rename, transition persistence
-- `MainWindow.xaml` — 2-col layout, thumbnail strip, left panel two-state, right panel deleted, brand rename
-- `MainWindow.xaml.cs` — Thumbnail click, edit-mode gating, context menu gating, dead code cleanup
-- `Models/Scene.cs` — Snapshot, IsStaged properties
-- `Services/Compositor/SceneCompositor.cs` — BlendFrames() static method
-- `Services/Encoder/FramePump.cs` — transition support in render loop
-- `Services/TransitionService.cs` — **new** — Cut/Fade/Move transition engine
-- `Services/LayoutStore.cs` — SaveTransitionSettings/LoadTransitionSettings/UpsertSetting
-
-### What still needs testing
-- Runtime visual testing (need Windows display to run)
-- Actual transition animation quality (Fade + Move)
-- Thumbnail generation from real scene compositor (currently placeholder colors)
-- Drag-reorder of thumbnails (not yet implemented)
+## Background properties (fully shipped)
+- `Scene.UseDefaultBackground` (bool, default true) + `Scene.CustomBackgroundPath` (string?)
+- Persisted as `BackgroundUseDefault_{sceneId}` / `BackgroundPath_{sceneId}` in Settings table
+- Pill toggle ON → loads default asset from DB; OFF → loads custom file path
+- Custom path preserved when toggled back ON (not cleared)
+- Geometry mismatch: aspect ratio check ±5% of 16:9, shows expected 1920×1080
 
 ## Build
 ```bash
 taskkill.exe /F /IM ytLive.exe  # if running
-"/mnt/c/Program Files/dotnet/dotnet.exe" build "C:\Users\gramp\Documents\Code\projects\ytLive\ytLive.csproj" --no-restore
+"/mnt/c/Program Files/dotnet/dotnet.exe" build "C:\Users\gramp\Documents\Code\projects\ytLive\ytLive.csproj"
 ```
 **0 warnings, 0 errors.**
 
@@ -102,11 +42,10 @@ taskkill.exe /F /IM ytLive.exe  # if running
 | Key prefix | `LCYT-` |
 
 ## Next steps
-1. **Visual testing** — run on Windows display, verify layout, transitions, thumbnail strip
+1. **Visual testing** — run on Windows display, verify pill toggle, background properties per-scene
 2. **Thumbnail drag-reorder** — reorder scenes via drag on thumbnail strip
 3. **Real snapshot generation** — replace placeholder colors with compositor-rendered thumbnails
 4. **Transition dropdown UI** — add XAML control to pick transition type + duration
-5. **Commit** — all this work needs to be committed once visually verified
 
 ## v1 vision
 > A streaming tool that's intuitive and ready to go out-the-gate with nothing held back.