The creator's locked table (2026-10-17) gives the Chat scene its own rules in
the 9:16 tier: RECT ONLY - the circle option is not offered - and a size that
is either the normal small tile or ENLARGED to fill one whole 607x540 area
(top or bottom). Unit 1 shipped the per-scene placement; this unit is the Chat
scene's own variant of it.
The rule lives on the MODEL, not on the button:
- Models/SceneElement.cs: ClipShape and ToggleClipShape() are now virtual.
- Models/WebcamSceneConfig.cs: VerticalShapeLocked (set per scene by the VM)
OVERRIDES the ClipShape property, so no writer can slip a circle in - the
toggle, the Shape button and the placement swap all go through it. The lock
is cleared BEFORE the 16:9 layout comes back, so the desktop shape returns.
- ViewModels/MainViewModel.Webcam.cs: CanToggleClipShape (the circle is NOT
offered in the vertical Chat layout - the Shape button disappears, it is not
merely greyed out), IsChatSceneCamera, ResizeWebcamInVerticalTier.
- Models/VerticalCameraLayout.cs: FillsArea (the "enlarged" state, derived -
no new column) and SizeFor - the Chat camera's TWO sizes, the tile or the
whole area, whichever is nearer the requested width, so the resize handle
has two detents instead of any size in between.
- An enlarged camera FILLS the area its centre is in (top or bottom), so
dragging it up/down swaps the areas.
- The Chat camera is auto-tiled like the Live one when the vertical tier is
picked - otherwise the vertical chat stream has no camera at all.
- Controls/PreviewPane.xaml.cs: the resize routes through the VM; the drag
assigns, lets the model clamp into the band, then snaps (so the enlarged
camera can be dragged from the top area to the bottom one).
Test: ytLive.Tests/VerticalChatCameraLayoutTests.cs - the ONE Good Dog test for
the unit: the vertical tier is picked -> the Chat camera comes into the band as
a small RECT tile -> the circle option is not offered and cannot be set even on
the model -> dragged up and enlarged it fills the TOP area exactly -> back to
16:9 the desktop layout is restored exactly and the circle option is offered
again. 430/430 tests pass, 0 warnings.
Research (the creator's table is the established practice, not our invention):
- Streamlabs' vertical guide: "splitting the screen in half horizontally,
placing the camera feed in the top half and the main content on the bottom
(or vice versa) may be the bet", and a just-chatting vertical wants the
camera "to take up most of the screen"
(streamlabs.com/content-hub/post/overlays-vertical-and-horizontal-streaming)
- Bloopbot's vertical overlay docs describe the same per-layer model we use at
scene granularity: "move or resize a layer on Vertical and it stops being
Auto-placed. It keeps the place you gave it, and the horizontal layout is not
touched" (bloopbot.com/docs/vertical-overlays-twitch-dual-format) - our
swap-at-tier-change, stored per scene.
- Landmine recorded: "about the bottom 560 px of the vertical video can be
covered by Twitch's chat and player controls on phones" (Bloopbot) - the Chat
camera's enlarged BOTTOM area may be half-hidden by the platform chrome;
TASK 53's safe-zone work decides that.
Memory in the same commit: ai.md (the Chat rules, the shape lock, the tests),
TASKS.md + TASKS/task-57-vertical-camera-layout.md (TASK 57 complete), HANDOFF.md,
MyMistakes.md (3 recipes: lock the model property not the UI button; two detents
for a discrete size set; the edit tool cannot match an oldString with an em
dash), Models/ViewModels/Controls index rows.
The vertical tier is a centred band crop of the SAME 1920x1080 master (band x
656.25, w 607.5, h 1080), so the 16:9 camera placement (x~1408) falls outside the
cropped window and the creator is simply not in the vertical stream. Each scene
now keeps its own vertical position, size and shape; switching back to 16:9
restores the desktop layout exactly (the creator's locked table, 2026-10-17).
Geometry only - NO render-path change. The preview and the compositor both read
the element's own X/Y/W/H + ClipShape, so the tier switch swaps the LIVE geometry:
- Models/VerticalCameraLayout.cs (new): the pure math - the band, its two 607x540
areas, the six spots (top/bottom x left/centre/right), the 32px inset and the
270x152 default tile (480x270 in the 1080x1920 output) in the bottom-right spot,
the corner the 16:9 default webcam uses.
- Models/WebcamSceneConfig.cs: the vertical placement lives in seven additive
columns (VerticalX/Y/Width/Height/ClipShape/RectWidth/RectHeight; NULL = "this
scene has no vertical placement yet"). The 16:9 layout stays in the old columns
and is parked in the transient Landscape* fields while the vertical tier is
live; Begin/EndVerticalLayout + CommitLiveLayoutToVertical do the swap. The
X/Y/W/H overrides clamp every write into the band - outside it the camera is
invisible in the vertical output.
- Models/SceneElement.cs: X/Y/Width/Height became virtual so the derived element
constrains every writer (drag, resize handle, typed fields) in ONE choke point
instead of three writers each re-implementing the rule.
- ViewModels/MainViewModel.Webcam.cs + .Streaming.cs: IsVerticalTier/VerticalBand,
ResolveVerticalCameraLayout(s) (the tier swap), MoveWebcamInVerticalTier /
SnapWebcamInVerticalTier (the six-spot snap, by the tile's centre),
EnsureVerticalCameraLayout; ApplyStreamQuality is the tier-change hook. The
Live scene gets its small tile automatically on the first vertical switch (the
vertical stream would otherwise have no camera at all); the other scenes keep
their 16:9 placement until the creator drags them into the band.
- Controls/PreviewPane.xaml.cs: the drag/resize route through the VM snap under
the vertical tier instead of free-floating over the master.
Controls/LeftPanel.xaml: the webcam properties gained a Geometry section
(X/Y/W/H) for the manual entry the creator asked for, bound to the LIVE
placement, gated on the VM's IsWebcamSelected (NOT SelectedElement.IsWebcam -
the TASK 51 test finds that panel by binding text and would match twice).
- The store: seven guarded ADD COLUMNs, the INSERT/SELECT extended, and the
X/Y/W/H/ClipShape columns stay the 16:9 layout - while the vertical tier is
live the save writes the parked values there and the live ones into Vertical*.
Test: ytLive.Tests/VerticalWebcamLayoutTests.cs - the ONE Good Dog test. The
vertical tier brings the Live camera INTO the band as a small tile; dragging it to
the top-right lands it top-right inside the band; back to 16:9 the desktop layout
is restored exactly (1408/778/480x270); both placements survive a save + reload.
Full suite 429/429, 0 warnings. LayerReorderPersistenceTests.RealMouseDrag fails
ALONE on a clean tree in this environment - pre-existing flake, proven by stashing
this work, not a regression.
Derivative work: OBS has no built-in per-aspect-ratio layout storage - the
maintainers' answer is "create a second scene and add the scene you want to send
as source" (obsproject.com/forum/threads/161307) - and Streamyard's dual-aspect
guide says the same ("no built-in way to store separate layouts per aspect ratio",
so you rely on manual workarounds and plugins):
https://streamyard.com/blog/dual-aspect-ratio-streaming-tool
Our per-scene, per-tier stored placement, resolved on the tier change, is the
step past both.
Memory in the same commit: ai.md (new section), TASKS.md + TASKS/task-57-*.md
(Unit 1 shipped, Unit 2 = the Chat scene still open), HANDOFF.md, MyMistakes.md
(the per-tier geometry-swap recipe, the binding-text panel trap, the store's
webcam-identity rule) and the Models/Services/ViewModels/Controls index rows.
Creator refinement: 'offered iff there's not one already configured & attainable'.
CanAddWebcam now requires IsWebcamAttainable = identity present AND a RUNNING
session (CameraManager.IsRunning) — an identity whose camera was unplugged or
whose lock keeps failing leaves the row greyed with reason 'No webcam is
currently available…', and it un-greys the moment a session is live. Gate
re-raised at every attainability flip: staging, removal, startup lock success,
first frame, camera failure, identity swap.
Root cause the old test surfaced: the startup pass skipped acquiring when the
loaded identity's configs already held the session, so there was no independent
app base ref — removing the last placement dropped RefCount to 0 and killed the
session. The single-camera branch now ALWAYS acquires (a running session just
bumps), laying the app-wide base hold so the default outlives the scenes.
Good Dog: WebcamMenuGateTests second fact — identity loaded, session can't start
→ row NOT offered + 'No webcam is currently available…' tooltip. Positive fact
waits for WebcamStartupValidationTask to make the IsRunning read deterministic.
Docs same commit (ai.md gate + base-lock, TASKS.md, HANDOFF.md incl. proven
pre-existing audio flake). 305 tests (304 pass + known flake), 0 warnings.
Chat's camera no longer greys Web Cam in Live (per-scene max, not app-wide);
TASK 26 superseded by creator directive (app-level resource model). Add Webcam
now places the existing app default without the picker; the picker runs only
for the initial selection. Removing the last placement keeps the identity
(_webcam never nulled) so Add stays offered. Startup pass adopts a solo camera
as the app default, so a clean layout offers the layer in Live/Chat at once.
Dynamic WebcamAddToolTip names the why (incl. the 'graduated to OBS' line).
Good Dog: WebcamMenuGateTests rewritten (real app + temp DB + camera seams) —
identity in Chat does not gray Live; Add in Live places same wc-1 no picker;
scene-with-placement stays gray; identity survives both removals (DB row 1).
WebcamStartupResourceTests single-lock fact asserts CanAddWebcam after adoption.
Docs same commit (ai.md supersession, TASKS.md, HANDOFF.md). 304/304, 0 warnings.
The creator couldn't add a webcam to Live (grayed app-wide) and nothing in the
app explained why. Ground truth from the live DB: one Webcam identity AND one
WebcamSceneConfig in the Chat scene — so the gray was the single-identity rule
working, but the reason was unobservable. This slice makes the webcam a
resource the app validates and locks, mirroring how OBS reserves its devices.
At startup we enumerate the OS once (ValidateWebcamResourceStartupAsync, fired
after LoadLayout, stored as WebcamStartupValidationTask for tests to await):
- 0 webcams -> app runs on, layer inactive, no alarm
- exactly 1 -> attempt CameraManager.AcquireAsync as an app-wide lock; on
failure show a persistent red alert at the bottom of the Layers panel
(WebcamLockAlert + Retry) that re-polls every 5s and clears itself the
moment the camera locks, or on any first real frame
- >=2 -> deliberately no auto-lock; camera selection belongs to the App
Settings dialog (gear) — next slice
CameraManager.IsRunning(deviceId) tells the pass a session already exists
(started OR still starting) so loaded identity configs count as the lock and
the pass never double-acquires. Test seams mirror LayoutPathOverride:
CameraEnumeratorOverride / CameraFrameSourceFactoryOverride so the startup
probe never touches real hardware under test.
Good Dog test: WebcamStartupResourceTests x3 — single-cam locked + app runs on,
zero-cams no-alarm/no-lock, lock-fails -> red alert -> Retry -> clears. Full
suite 304/304, build 0 warnings, scope-check passed.
Docs in-commit: TASKS Open items + ai.md Webcam section + HANDOFF rewrite.
Also corrects the record: 'NVIDIA Broadcast opens the webcam exclusively' was a
suspect-list claim (CameraConflictProbe reads process names only, no handles)
— not restated as fact.
- Add ElementKind (Static/Dynamic) to SceneElement base; Source/WebcamSceneConfig classify
- Services/SceneGraph.cs: owns the Scenes collection (ViewModel's Scenes delegates to it),
the element mutation surface (Add/Insert/Remove/Move, each invalidating the bake), and the
queries that were scattered LINQ (GetBackground/GetWebcam/GetChatBoxes/GetSplitPoint/IsStatic)
- SceneCompositor: split-aware BakeStaticBase + CompositeLayers + Render(.., staticBase, split);
builds/caches the static base below the split point in source-rect space
- FramePump: optional SceneGraph -> optimized bake+composite path; falls back to full render
- MainViewModel: routes element mutations through the graph; invalidates the bake on static
layout/opacity/visibility/useDefaultBackground changes and after background heal/Ensure
- Integration test SceneGraphTests.BakedStaticBase_WithDynamicLayer_CompositesCorrectly
Derivative survey (mandated): tried before writing — OBS does per-source opacity/visibility
caching and static-scene baking; this mirrors OBS's 'cached static source' optimization.
3 documented defensive deviations from the spec (ChatOverlayLayer stays decoupled;
background helpers stay VM-static for direct testability; full facade peel deferred post-1.0)
in TASKS.md + ai.md. Scope check passed; clean build 0 warnings.
gramps