fix(ui): drawers close on any click outside the rail — TEST was the missing third

Creator: 'when the test slide-out is active, then any click off the div should
close the div — this behaviour applies to all tabs, not just TEST.'

MainWindow.Window_PreviewMouseLeftButtonDown already closed the Stream Settings
and YPP drawers on any click outside TextPullOutHost, but its close list skipped
TestSession — so the TEST drawer never dismissed on an outside click.

Fix: run TestSession.CloseDrawerCommand in the same outside-click branch.
All three drawers share the rail host, so the containment check is unchanged.

Good Dog: ONE integration test — the existing TestStream window section now
raises a window-root PreviewMouseLeftButtonDown (source = window => outside the
rail; deterministic, no OS mouse) and asserts the TEST and Stream Settings
drawers both close. Gate: clean build 0 warnings, full vstest 318/318.

TASKS/task-46-drawer-click-outside-close.md

@@ -0,0 +1,37 @@
+# TASK 46 — Drawers: any click outside the rail closes the open drawer (TEST included)
+
+> Catalog: [`TASKS.md`](../TASKS.md). Status: ✅ **SHIPPED 2026-09-25**.
+
+## Provenance
+
+- **2026-09-25, creator:** "when the test slide-out is active, then any click off the
+  div should close the div — this behaviour applies to all tabs, not just TEST."
+
+## Diagnosis
+
+The right-rail slides (Stream Settings / YPP / TEST; `TextPullOutHost` in
+`Controls/PreviewPane.xaml`) already close on any click outside the rail for Stream
+Settings + YPP — `MainWindow.Window_PreviewMouseLeftButtonDown` closes
+`BroadcastForm` and `Ypp` when `IsClickInsideDrawer` is false. The handler simply
+**omitted `TestSession`**, so the TEST drawer never dismissed on an outside click.
+The XAML comment mentioned "both" — stale once a third drawer landed.
+
+## What shipped
+
+- `MainWindow.xaml.cs` — the outside-click close now also runs
+  `TestSession.CloseDrawerCommand` when the TEST drawer is open (matching the other
+  two; all three share `TextPullOutHost`, so the containment check is unchanged).
+- `Controls/PreviewPane.xaml` — comment corrected ("the rail … whichever is open").
+- `ytLive.Tests/TestStreamTests.cs` — section-2 window test now opens TEST and Stream
+  Settings, raises a window-root `PreviewMouseLeftButtonDown` (sourced on the window,
+  i.e. outside the rail — deterministic, no OS mouse input, immune to the fullscreen
+  mouse-steal flake), and asserts each closes.
+- Docs: `ai.md` (Test Stream section), `TASKS.md` (row 46), `HANDOFF.md` rewritten.
+
+## Validation (Good Dog: ONE integration test)
+
+`TestStream_DockTooling_And_ThreeWayDrawerExclusivity` — extended section 2, no new
+tests: the raised outside-click asserts TEST (the fixed drawer) AND Stream Settings
+(the pre-existing behavior) both close.
+
+**Gate: clean build 0 warnings; full vstest (captured in HANDOFF).**