Extract brush UI operation planning

docs/modernization/debt.md

@@ -40,6 +40,7 @@ agent or engineer to remove them without reconstructing context from chat.
 | DEBT-0020 | Open | Modernization | Document resize dialog state and selected-resolution planning now consume pure `pp_app_core` through `NodeDialogResize`, `App::dialog_resize`, and `pano_cli plan-document-resize`, but live resize execution still calls legacy `Canvas::resize` and clears legacy `ActionManager` history directly | Preserve existing layer/frame GPU resize behavior while the document model and canvas execution boundary are extracted incrementally | `pp_app_core_document_resize_tests`; `pano_cli plan-document-resize --current-resolution 2048 --selected-resolution-index 4`; `ctest --preset desktop-fast --build-config Debug` | Document resize execution is owned by a document/app boundary with legacy `Canvas` acting only as an adapter or removed entirely |
 | DEBT-0021 | Open | Modernization | Layer rename and layer panel operation planning now consume pure `pp_app_core` through `App::dialog_layer_rename`, `App::init_sidebar` layer callbacks, `pano_cli plan-layer-rename`, and `pano_cli plan-layer-operation`, but live execution still mutates legacy `Canvas` layer state, `NodeLayer`/`NodePanelLayer`, and `ActionManager` undo entries directly | Preserve existing UI/canvas behavior while document layer commands and undo history are extracted incrementally | `pp_app_core_document_layer_tests`; `pano_cli plan-layer-rename --old-name Base --new-name Paint`; `pano_cli plan-layer-operation --kind add --layer-count 2 --index 1 --name Paint`; `ctest --preset desktop-fast --build-config Debug` | Layer command execution is owned by the document/app command boundary with legacy `Canvas`/UI nodes acting only as adapters or removed entirely |
 | DEBT-0022 | Open | Modernization | Animation panel frame command planning now consumes pure `pp_app_core` through `NodePanelAnimation` and `pano_cli plan-animation-operation`, and `pp_legacy_ui_core` temporarily links `pp_app_core`, but live execution still mutates legacy `Canvas`/`Layer` frame state and animation playback state directly | Preserve existing animation panel behavior while timeline/frame commands move toward the document/app command boundary | `pp_app_core_document_animation_tests`; `pano_cli plan-animation-operation --kind add --frame-count 2 --current-frame 0`; `pano_cli plan-animation-operation --kind next --total-duration 5 --current-frame 4`; `ctest --preset desktop-fast --build-config Debug` | Animation frame/timeline execution is owned by the document/app command boundary with legacy `Canvas`/`Layer`/UI nodes acting only as adapters or removed entirely |
+| DEBT-0023 | Open | Modernization | Brush/color/preset UI planning now consumes pure `pp_app_core` through `App::init_sidebar`, restored/docked floating-panel callbacks, and `pano_cli plan-brush-operation`, but live execution still mutates legacy `Brush`, calls legacy brush texture loading, and refreshes legacy quick/stroke/color widgets directly | Preserve existing brush UI behavior while brush commands move toward a brush/app command boundary and asset-managed texture selection | `pp_app_core_brush_ui_tests`; `pano_cli plan-brush-operation --kind color --r 0.25 --g 0.5 --b 0.75 --a 1`; `pano_cli plan-brush-operation --kind pattern --path data/patterns/noise.png --thumb data/patterns/thumbs/noise.png`; `ctest --preset desktop-fast --build-config Debug` | Brush color/texture/preset execution is owned by a brush/app command boundary with legacy `Brush`/UI nodes acting only as adapters or removed entirely |
 
 ## Closed Debt
 

docs/modernization/roadmap.md

@@ -494,6 +494,10 @@ UI layer execution continue.
 frame add, duplicate, remove, duration adjustment, timeline moves, timeline
 goto/next/previous, and onion-size updates used by the live animation panel
 before legacy `Canvas`/`Layer` frame execution continues.
+`pano_cli plan-brush-operation` exposes app-core planning for brush color
+changes, tip/pattern/dual texture changes, preset brush replacement, and stroke
+settings refreshes used by the live brush, quick, color, and floating panel
+callbacks before legacy `Brush` mutation and resource loading continue.
 `pp_platform_api` now owns a headless `PlatformServices` interface for
 startup storage path preparation, clipboard text, cursor visibility,
 virtual-keyboard visibility, UI-thread lifecycle hooks, render-context
@@ -1123,6 +1127,15 @@ Results:
   `pano_cli_plan_animation_operation_next_wrap_smoke`, and
   `pano_cli_plan_animation_operation_rejects_remove_last_frame` passed and
   expose live animation-panel planning as JSON automation.
+- `pp_app_core_brush_ui_tests` passed, covering brush color channel validation,
+  invalid color rejection, texture-path validation, preset-brush availability,
+  preserve-current-color intent, and stroke-settings refresh intent.
+- `pano_cli_plan_brush_operation_color_smoke`,
+  `pano_cli_plan_brush_operation_texture_smoke`,
+  `pano_cli_plan_brush_operation_preset_smoke`,
+  `pano_cli_plan_brush_operation_rejects_bad_color`, and
+  `pano_cli_plan_brush_operation_rejects_empty_texture` passed and expose live
+  brush/color/preset UI planning as JSON automation.
 - `pp_app_core_document_sharing_tests` passed, covering saved-path gating before
   platform share execution.
 - `pano_cli_plan_share_file_unsaved_smoke` and