Add agent skill for lvt tool usage

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: asklar

.github/copilot/skills/lvt.md

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+# Skill: Inspect Windows application UI with lvt
+
+## When to use
+
+Use `lvt` whenever you need to understand the visual content or structure of a running Windows application. Common scenarios:
+
+- **UI verification** — confirm that a UI change was applied correctly (e.g. a button label changed, a dialog appeared)
+- **Finding UI elements** — locate a specific control, menu item, or text field in an app's visual tree
+- **Screenshot capture** — take an annotated screenshot of an app with element IDs overlaid
+- **Framework detection** — determine which UI frameworks an app uses (Win32, ComCtl, XAML, WinUI 3)
+- **Automated UI interaction planning** — get element IDs and bounds to plan mouse clicks or keyboard input
+
+## Prerequisites
+
+`lvt.exe` must be built and available. The default build output location is `build/lvt.exe` in the repository root.
+
+## Usage
+
+### Target an application
+
+You must specify exactly one target. Pick the most convenient option:
+
+```powershell
+# By process name (most common — omit .exe extension if you like)
+lvt --name notepad
+
+# By window title substring
+lvt --title "Untitled - Notepad"
+
+# By PID
+lvt --pid 1234
+
+# By HWND (hex)
+lvt --hwnd 0x1A0B3C
+```
+
+### Get the visual tree
+
+```powershell
+# JSON output (default) — best for programmatic parsing
+lvt --name notepad
+
+# XML output — more compact, easier to read
+lvt --name notepad --format xml
+
+# Write to a file instead of stdout
+lvt --name notepad --output tree.json
+```
+
+### Capture a screenshot
+
+```powershell
+# Screenshot only (no tree output)
+lvt --name notepad --screenshot out.png
+
+# Screenshot + tree output together
+lvt --name notepad --screenshot out.png --dump
+```
+
+Screenshots are annotated with element IDs (e0, e1, …) overlaid on each element, making it easy to correlate visual positions with tree nodes.
+
+### Scope to a subtree
+
+When the full tree is too large, scope to a specific element:
+
+```powershell
+# Only show element e5 and its descendants, up to 3 levels deep
+lvt --name myapp --element e5 --depth 3
+```
+
+### Detect frameworks only
+
+```powershell
+lvt --name notepad --frameworks
+```
+
+## Interpreting the output
+
+### Element IDs
+
+Every element gets a stable ID like `e0`, `e1`, `e2`, etc., assigned in depth-first order. These IDs are consistent within a single invocation — use them to:
+
+- Reference specific elements in follow-up commands (`--element e5`)
+- Correlate screenshot annotations with tree nodes
+- Identify click targets by combining element ID with its `bounds`
+
+### Key element properties
+
+| Property | Description |
+|----------|-------------|
+| `id` | Stable element ID (e.g. `e0`) |
+| `type` | Element type name (e.g. `Window`, `Button`, `TextBlock`) |
+| `framework` | Which framework owns this element (`win32`, `comctl`, `xaml`, `winui3`) |
+| `className` | Win32 window class name (Win32/ComCtl elements) |
+| `text` | Visible text content or window title |
+| `bounds` | Screen-relative bounding rectangle `{x, y, width, height}` |
+| `children` | Nested child elements |
+
+### JSON example
+
+```json
+{
+  "target": { "hwnd": "0x001A0B3C", "pid": 12345, "processName": "Notepad.exe" },
+  "frameworks": ["win32", "winui3"],
+  "root": {
+    "id": "e0",
+    "type": "Window",
+    "framework": "win32",
+    "className": "Notepad",
+    "text": "Untitled - Notepad",
+    "bounds": { "x": 100, "y": 100, "width": 800, "height": 600 },
+    "children": [ ... ]
+  }
+}
+```
+
+### XML example
+
+```xml
+<LiveVisualTree hwnd="0x001A0B3C" pid="12345" process="Notepad.exe" frameworks="win32,winui3">
+  <Window id="e0" framework="win32" className="Notepad" text="Untitled - Notepad" bounds="100,100,800,600">
+    <ContentPresenter id="e1" framework="winui3" bounds="108,140,784,552" />
+  </Window>
+</LiveVisualTree>
+```
+
+## Recommended workflow
+
+1. **Start the target app** if it isn't already running
+2. **Run `lvt --name <app> --format xml`** to get a quick overview of the UI tree
+3. **Take a screenshot** with `lvt --name <app> --screenshot ui.png` to see the visual layout with element IDs
+4. **Drill into a subtree** with `--element <id> --depth <n>` if the tree is large
+5. **Use element IDs and bounds** to plan any UI interactions (clicks, keyboard input)
+
+## Tips
+
+- Use `--format xml` for human-readable output and `--format json` for programmatic parsing
+- If the tree is very large, use `--depth` to limit traversal depth first, then drill deeper with `--element`
+- Element IDs change between invocations if the UI structure changes — always re-query before acting on stale IDs
+- The tool requires no special permissions beyond being able to read the target process (same user session)
+- For XAML/WinUI 3 apps, lvt injects a helper DLL into the target — this is safe and non-destructive but means `lvt_tap.dll` must be next to `lvt.exe`