Publish native hosted preview textures through XCUI compositor

docs/plan/XCUI_Phase_Status_2026-04-05.md

@@ -20,6 +20,8 @@ Old `editor` replacement is explicitly out of scope for this phase.
   - `NativeWindowUICompositor` is now buildable alongside the legacy ImGui compositor
   - `Application` now defaults to a native XCUI host path instead of creating the ImGui shell by default
   - the native default path now drives `XCUIDemoRuntime` and `XCUILayoutLabRuntime` directly, composes their `UIDrawData`, and submits one swapchain packet through the native compositor
+  - the native compositor now publishes hosted-preview textures as SRV-backed `UITextureRegistration` / `UITextureHandle` values instead of relying on ImGui-only descriptor semantics
+  - the native shell now begins the hosted-preview queue/registry lifecycle each frame, queues native preview frames, drains them during the native render pass, and consumes published hosted-surface images directly in panel cards with live/warming placeholder states
   - the old ImGui shell path remains present as an explicit compatibility host instead of the default host
   - `XCUIInputBridge.h` no longer drags `imgui.h` through the public XCUI input seam
 - Old `editor` replacement remains deferred; all active execution still stays inside XCUI shared code and `new_editor`.
@@ -70,7 +72,7 @@ Current gap:
 ### 3. Editor Layer
 
 - `new_editor` remains the isolated XCUI sandbox.
-- Native hosted preview is working as `RHI offscreen surface -> hosted surface image present` through the current shell adapter path.
+- Native hosted preview is now working end-to-end as `RHI offscreen surface -> SRV-backed publication -> hosted surface image present` through the native shell path.
 - Hosted preview surface descriptors now stay on XCUI-owned value types (`UITextureHandle`, `UIPoint`, `UIRect`) instead of exposing ImGui texture/UV types through the generic preview contract.
 - Shared `UI::UIDrawData` image commands now carry explicit `uvMin` / `uvMax` source-rect semantics, and the native panel canvas host preserves those UVs when it records hosted surface-image preview commands.
 - `XCUI Demo` remains the long-lived effect and behavior testbed.
@@ -108,13 +110,14 @@ Current gap:
   - drives both sandbox runtimes directly from Win32/XCUI input snapshots instead of routing through ImGui panel hosts
   - composes one native `UIDrawData` packet and submits it through `NativeWindowUICompositor`
 - `NativeXCUIPanelCanvasHost` now backs that direct shell path as an externally driven canvas/session host for native cards instead of assuming an ImGui child-window model, and it now emits native `Image` draw commands for hosted surface-image previews while preserving per-surface UVs.
+- `NativeWindowUICompositor` now creates and frees SRV-backed texture registrations for hosted preview surfaces, so native publication no longer depends on ImGui descriptor handles.
+- `Application` now runs the hosted-preview lifecycle in both legacy and native frame paths, treats published textures as XCUI-owned `UITextureHandle` state, queues native preview frames from `BuildNativeShellDrawData(...)`, and drains them during native rendering before shell chrome overlays.
 - `XCUIInputBridge.h` no longer includes `imgui.h`, so the public XCUI input bridge seam is now host-neutral at the header boundary.
 - `XCNewEditor` builds successfully to `build/new_editor/bin/Debug/XCNewEditor.exe`.
 
 Current gap:
 
 - The default shell host is now native, but the legacy ImGui shell and panel path still exists as a compatibility host and is still compiled into `new_editor`.
-- Hosted-preview offscreen surface publication is still not wired for the native compositor path because descriptor-backed texture registration is still ImGui-host-centric today.
 - The native shell currently proves direct runtime composition, but its shell chrome is still a bespoke `Application`-side layout rather than a fully shared XCUI-authored editor shell document.
 - Editor-specialized widgets are still incomplete at the shared-module level: the authored prototypes exist, but virtualization, multi-selection/focus traversal, toolbar/menu chrome, menu interaction widgets, and icon-atlas widgets are not yet extracted into reusable XCUI modules.
 - The default native path still depends on ImGui font-atlas internals through `XCUIStandaloneTextAtlasProvider`, so text rendering is not yet cleanly de-ImGuiized even though the shell/panel composition path is native by default.
@@ -130,9 +133,9 @@ Current gap:
 - `new_editor_xcui_rhi_render_backend_tests`: `5/5`
 - `new_editor_xcui_hosted_preview_presenter_tests`: `20/20`
 - `new_editor_imgui_window_ui_compositor_tests`: `7/7`
-- `new_editor_native_window_ui_compositor_tests`: `5/5`
+- `new_editor_native_window_ui_compositor_tests`: `8/8`
 - `new_editor_xcui_editor_command_router_tests`: `5/5`
-- `new_editor_application_shell_command_bindings_tests`: `6/6`
+- `new_editor_application_shell_command_bindings_tests`: `8/8`
 - `new_editor_xcui_shell_chrome_state_tests`: `11/11`
 - `new_editor_xcui_panel_canvas_host_tests`: `4/4`
 - `new_editor_imgui_xcui_panel_canvas_host_tests`: `1/1`
@@ -250,6 +253,12 @@ Current gap:
   - generic preview frame submission no longer carries an ImGui draw-list pointer
   - the ImGui presenter now resolves inline draw targets through an explicit ImGui-only binding seam
   - panel/runtime callers still preserve the same legacy and native-preview behavior
+- Native hosted-preview publication is now wired through the default shell path:
+  - `NativeWindowUICompositor` publishes hosted preview textures as SRV-backed XCUI registrations and frees them through the compositor seam
+  - `Application::BeginHostedPreviewFrameLifecycle(...)` now resets queue/registry state for both legacy and native frame paths
+  - hosted-preview surface readiness now keys on published texture availability instead of ImGui-style descriptor validity
+  - `BuildNativeShellDrawData(...)` now queues native preview frames for `XCUI Demo` / `LayoutLab`, while shell cards consume the previously published hosted-surface image with warming/live placeholder text
+  - native compositor and shell-command tests now cover the new publication / lifecycle guards
 - `LayoutLab` now resolves editor collection widget taxonomy and metrics through shared `UIEditorCollectionPrimitives` helpers instead of duplicating the same tag and metric rules inside the sandbox runtime.
 - `LayoutLab` runtime now consumes shared keyboard-navigation semantics for list/tree/property traversal, while the remaining panel-level key mapping is tracked as an editor-host integration gap rather than a runtime gap.
 - `LayoutLab` panel now maps concrete arrow/home/end keys into the shared navigation model, with dedicated panel-level coverage proving that the sandbox UI can actually drive the runtime navigation seam end-to-end.
@@ -270,6 +279,6 @@ Current gap:
 
 1. Expand runtime/game-layer ownership from the current `SceneRuntime` UI context into scene-declared HUD/menu bootstrapping, draw submission, and higher-level runtime UI policies.
 2. Promote the current editor-facing widget prototypes out of authored `LayoutLab` content and into reusable XCUI widget/runtime modules, then continue with toolbar/menu chrome, shell-state adoption, virtualization, and broader focus/multi-selection behavior.
-3. Finish native compositor texture registration and hosted-preview surface publication so the native path no longer depends on ImGui-centric descriptor registration.
-4. Strip the remaining default-path ImGui seams down to compatibility-only code, starting with the standalone text/font-atlas path and then the remaining hosted-preview fallback layers.
+3. Strip the remaining default-path ImGui seams down to compatibility-only code, starting with the standalone text/font-atlas path and then the remaining hosted-preview fallback layers.
+4. Promote the native shell chrome and card layout out of bespoke `Application` code into a shared XCUI/editor-layer shell model or authored shell document.
 5. Continue phased validation, commit, push, and plan refresh after each stable batch.