SnoopWpfCLI

Playwright-CLI for WPF -- Inspect and interact with running WPF applications from the command line.

Features

list-processes -- Discover running WPF processes on the system
ping -- Inject the inspector DLL and verify communication
get-tree -- Retrieve the full visual tree of a WPF window (JSON or human-readable tree)
get-subtree -- Retrieve a subtree rooted at a specific element
get-element -- Get detailed information about a single element
find-element -- Search elements by name, text content, or AutomationId
invoke -- Execute UI Automation actions (click buttons, set text, toggle checkboxes, etc.)
wait -- Wait for an element to appear, disappear, or change state
list-windows -- List all windows in a WPF application
get-datacontext -- Read ViewModel properties bound to an element
screenshot -- Capture a screenshot of the WPF window (save to file or output as base64)
assert -- Assert element existence, text content, or DataContext property values

Prerequisites

.NET 10.0 SDK (or later)
Windows 10 / 11

Installation

git clone --recursive https://github.com/diva-osaka/diva-SnoopWpfCLI.git
cd diva-SnoopWpfCLI
dotnet publish src/App/App.csproj -c Release -o ./publish

The ./publish folder contains snoopwpfcli.exe and all required DLLs. Add this folder to your PATH to use snoopwpfcli from anywhere.

The --recursive flag is required to fetch the SnoopWPF submodule used for DLL injection.

Quick Start

This walkthrough uses the included TestApp to demonstrate the full workflow.

1. Build and launch the TestApp

dotnet build tests/TestApp/TestApp.csproj
dotnet run --project tests/TestApp/TestApp.csproj

The TestApp window opens with tabs for Basic Controls, Selection Controls, Nested Structure, and Template Test.

2. List WPF processes

dotnet run --project src/App/App.csproj -- list-processes

{
  "success": true,
  "count": 1,
  "processes": [
    {
      "processId": 12345,
      "processName": "TestApp",
      "mainWindowTitle": "SnoopWpfCLI Test App",
      "isWpfApplication": true,
      "hasMainWindow": true
    }
  ]
}

Note the processId value -- you will use it for all subsequent commands.

3. Ping (inject the inspector DLL)

dotnet run --project src/App/App.csproj -- ping --pid 12345

{
  "success": true,
  "processId": 12345,
  "message": "Ping successful",
  "wasAlreadyInjected": false
}

4. Get the full visual tree (JSON)

dotnet run --project src/App/App.csproj -- get-tree --pid 12345

The response contains the entire visual tree as a nested JSON structure inside visualTreeJson:

{
  "success": true,
  "processId": 12345,
  "processName": "TestApp",
  "windowTitle": "SnoopWpfCLI Test App",
  "visualTreeJson": "{ ... nested visual tree ... }"
}

5. Get the visual tree (human-readable tree)

dotnet run --project src/App/App.csproj -- get-tree --pid 12345 --format tree

Window "SnoopWpfCLI Test App"
└─ Grid
   ├─ Border
   │  └─ StackPanel
   │     ├─ TextBlock "SnoopWpfCLI Test Application"  [HeaderTitle]
   │     └─ TextBlock  [ProcessInfoText]
   ├─ TabControl
   │  ├─ TabItem "Basic Controls"  [BasicControlsTab]
   │  │  └─ ScrollViewer
   │  │     └─ StackPanel
   │  │        ├─ GroupBox "Text Input"
   │  │        │  ├─ TextBox  [InputTextBox]
   │  │        │  └─ TextBox  [MirrorTextBox]
   │  │        ├─ GroupBox "Buttons"
   │  │        │  ├─ Button "Click Me"  [CountButton]
   │  │        │  └─ Button "Custom Template Button"  [CustomStyledButton]
   │  │        ├─ GroupBox "Toggle Controls"
   │  │        │  ├─ CheckBox "Bound CheckBox"  [BoundCheckBox]
   │  │        │  ├─ CheckBox "Three-State CheckBox"  [ThreeStateCheckBox]
   │  │        │  └─ ToggleButton "Toggle Button"  [TestToggleButton]
   │  │        └─ GroupBox "Range Controls"
   │  │           ├─ Slider  [TestSlider]
   │  │           └─ ProgressBar  [TestProgressBar]
   │  ├─ TabItem "Selection Controls"  [SelectionTab]
   │  ├─ TabItem "Nested Structure"  [NestedTab]
   │  └─ TabItem "Template Test"  [TemplateTab]
   └─ StatusBar
      └─ TextBlock  [StatusText]

6. Get a specific element

Find an element from the tree output (e.g., the CountButton with type System.Windows.Controls.Button and hashcode 56789), then query its details:

dotnet run --project src/App/App.csproj -- get-element --pid 12345 \
    --type System.Windows.Controls.Button --hash 56789

{
  "success": true,
  "processId": 12345,
  "type": "System.Windows.Controls.Button",
  "hashcode": 56789,
  "message": "Element retrieved successfully",
  "element": {
    "type": "System.Windows.Controls.Button",
    "hashcode": 56789,
    "name": "CountButton",
    "content": "Click Me",
    "automationPatterns": ["Invoke"]
  }
}

7. Invoke an action (click a button)

dotnet run --project src/App/App.csproj -- invoke --pid 12345 \
    --type System.Windows.Controls.Button --hash 56789 \
    --action Invoke_Invoke

{
  "success": true,
  "processId": 12345,
  "type": "System.Windows.Controls.Button",
  "hashcode": 56789,
  "action": "Invoke_Invoke",
  "message": "Action invoked successfully"
}

The click counter in the TestApp increments.

8. Take a screenshot

dotnet run --project src/App/App.csproj -- screenshot --pid 12345 \
    --output screenshot.png

{
  "success": true,
  "processId": 12345,
  "processName": "TestApp",
  "message": "Screenshot saved to screenshot.png",
  "windowTitle": "SnoopWpfCLI Test App",
  "width": 900,
  "height": 700,
  "filePath": "C:\\...\\screenshot.png",
  "format": "PNG"
}

Command Reference

list-processes

List running WPF processes.

snoopwpfcli list-processes [--json] [--format json|tree] [--verbose]

Option	Default	Description
`--json`	`true`	Output as JSON
`--format`	`json`	Output format: `json` or `tree`
`--verbose`	`false`	Enable verbose output

ping

Inject the inspector DLL into a WPF process and verify communication.

snoopwpfcli ping --pid <PID> [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--verbose`	No	Enable verbose output

get-tree

Retrieve the full visual tree of the target WPF window.

snoopwpfcli get-tree --pid <PID> [--window <INDEX>] [--format tree] [--detail] [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--window`	No	Window index (use `list-windows` to find)
`--format tree`	No	Output as human-readable tree instead of JSON
`--detail`	No	Show binding details for each element (tree format only)
`--verbose`	No	Enable verbose output

get-subtree

Retrieve the subtree rooted at a specific element.

snoopwpfcli get-subtree --pid <PID> (--name <NAME> | --text <TEXT> | --binding-path <PATH> | --type <TYPE> --hash <HASH>) [--format tree] [--detail] [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--name`	No	Element name (x:Name). Alternative to `--type`/`--hash`
`--text`	No	Element text/content to search for
`--binding-path`	No	Binding path to search for
`--type`	No	Fully-qualified element type (e.g. `System.Windows.Controls.Button`)
`--hash`	No	Element hashcode
`--format tree`	No	Output as human-readable tree
`--detail`	No	Show binding details for each element (tree format only)
`--verbose`	No	Enable verbose output

get-element

Get detailed information about a single element.

snoopwpfcli get-element --pid <PID> (--name <NAME> | --text <TEXT> | --type <TYPE> --hash <HASH>) [--format json|tree] [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--name`	No	Element name (x:Name). Alternative to `--type`/`--hash`
`--text`	No	Element text/content to search for. Alternative to `--name` or `--type`/`--hash`
`--type`	No	Fully-qualified element type
`--hash`	No	Element hashcode
`--format`	No	Output format: `json` or `tree`
`--verbose`	No	Enable verbose output

find-element

Search for elements by name, text content, AutomationId, or binding path.

snoopwpfcli find-element --pid <PID> [--name <NAME>] [--text <TEXT>] [--automationid <ID>] [--type <TYPE>] [--binding-path <PATH>] [--interactive-only] [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--name`	No	Element name (x:Name), exact match
`--text`	No	Text/content to search for, partial match
`--automationid`	No	AutomationId, exact match
`--type`	No	Filter by element type
`--binding-path`	No	Find elements with a binding to this property path
`--interactive-only`	No	Filter results to interactive controls only (Button, TextBox, CheckBox, etc.)
`--verbose`	No	Enable verbose output

At least one search criterion (--name, --text, --automationid, --type, or --binding-path) is required, or --interactive-only can be used alone.

invoke

Execute a UI Automation action on an element.

snoopwpfcli invoke --pid <PID> (--name <NAME> | --text <TEXT> | --binding-path <PATH> | --type <TYPE> --hash <HASH>) --action <ACTION> [--params <JSON>] [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--name`	No	Element name (x:Name). Alternative to `--type`/`--hash`
`--text`	No	Element text/content to search for
`--binding-path`	No	Binding path to search for
`--type`	No	Fully-qualified element type
`--hash`	No	Element hashcode
`--action`	Yes	Automation peer action name
`--params`	No	Additional parameters as JSON string
`--verbose`	No	Enable verbose output

Supported actions:

Action	Description
`Invoke_Invoke`	Click a button
`Value_Get`	Get the current text value
`Value_Set`	Set a text value (requires `--params '{"value":"..."}'`)
`Toggle_Toggle`	Toggle a checkbox or toggle button
`Toggle_Status`	Get the current toggle state
`SelectionItem_Select`	Select an item
`SelectionItem_AddToSelection`	Add to current selection
`SelectionItem_RemoveFromSelection`	Remove from selection
`SelectionItem_Status`	Get selection state
`ExpandCollapse_Expand`	Expand a node
`ExpandCollapse_Collapse`	Collapse a node
`ExpandCollapse_Toggle`	Toggle expand/collapse
`ExpandCollapse_Status`	Get expand/collapse state
`RangeValue_Get`	Get the current range value
`RangeValue_Set`	Set a range value (requires `--params '{"value":...}'`)
`Scroll_Status`	Get scroll position
`Scroll_Scroll`	Scroll by amount
`Scroll_SetPosition`	Set absolute scroll position
`Selection_GetItems`	List items in ComboBox/ListBox (index, text, isSelected)
`ButtonBase_Click`	Fire Click event on ButtonBase derivatives (RadioButton, ToggleButton)
`ExecuteCommand`	Execute the ICommand bound to the element

wait

Wait for an element to appear, disappear, or change state.

snoopwpfcli wait --pid <PID> [--name <NAME>] [--text <TEXT>] [--automationid <ID>] [--type <TYPE>] [--until <CONDITION>] [--timeout <MS>] [--interval <MS>] [--interactive-only] [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--name`	No	Element name (x:Name) to wait for
`--text`	No	Text/content to wait for (partial match)
`--automationid`	No	AutomationId to wait for
`--type`	No	Element type name to filter by
`--until`	No	Wait condition: `found` (default), `gone`, `enabled`, `disabled`
`--timeout`	No	Timeout in milliseconds (default: 30000)
`--interval`	No	Polling interval in milliseconds (default: 500)
`--interactive-only`	No	Filter results to interactive controls only (Button, TextBox, CheckBox, etc.)
`--verbose`	No	Enable verbose output

list-windows

List all windows in a WPF application.

snoopwpfcli list-windows --pid <PID> [--format json|tree] [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--format`	No	Output format: `json` or `tree`
`--verbose`	No	Enable verbose output

get-datacontext

Read ViewModel properties bound to an element's DataContext.

snoopwpfcli get-datacontext --pid <PID> (--name <NAME> | --text <TEXT> | --binding-path <PATH> | --type <TYPE> --hash <HASH>) [--property <NAME>] [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--name`	No	Element name (x:Name). Alternative to `--type`/`--hash`
`--text`	No	Element text/content to search for
`--binding-path`	No	Binding path to search for
`--type`	No	Fully-qualified element type
`--hash`	No	Element hashcode
`--property`	No	Return only a specific property
`--verbose`	No	Enable verbose output

screenshot

Capture a screenshot of the WPF window.

snoopwpfcli screenshot --pid <PID> [--window <INDEX>] [--output <PATH>] [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--window`	No	Window index (use `list-windows` to find)
`--output`	No	Save as PNG file. If omitted, outputs base64 JSON.
`--verbose`	No	Enable verbose output

assert

Assert element existence, text content, or DataContext property values. Useful for automated UI testing.

snoopwpfcli assert --pid <PID> [--name <NAME>] [--text <TEXT>] [--automationid <ID>] [--binding-path <PATH>] [--type <TYPE>] [--hash <HASH>] [--exists] [--property <NAME>] [--expected <VALUE>] [--format json|tree] [--verbose]

Option	Required	Description
`--pid`	Yes	Target process ID
`--name`	No	Element name (x:Name)
`--text`	No	Element text/content to search for (partial match) and/or assert (exact match)
`--automationid`	No	AutomationId to search for
`--binding-path`	No	Binding path to search for
`--type`	No	Element type name
`--hash`	No	Element hashcode (use with `--type`)
`--exists`	No	Assert that the element exists
`--property`	No	DataContext property name to assert on
`--expected`	No	Expected value for `--property` assertion
`--format`	No	Output format: `json` or `tree`
`--verbose`	No	Enable verbose output

Assertion modes (--exists, --text, --property) are mutually exclusive.

Examples:

# Assert element exists
snoopwpfcli assert --pid 12345 --name StatusText --exists

# Assert element text equals a value
snoopwpfcli assert --pid 12345 --name StatusText --text "Success"

# Assert DataContext property value
snoopwpfcli assert --pid 12345 --type MyApp.MainWindow --hash 99999 \
    --property HasUnsavedChanges --expected true

Output

All JSON results (both success and error) are written to stdout. The exit code indicates success (0) or failure (non-zero). stderr is reserved for diagnostic output (--verbose).

This means you can always parse stdout regardless of the outcome:

snoopwpfcli find-element --pid 12345 --name MyButton | jq '.matchCount'

Exit Codes

Code	Meaning
0	Success
1	General error
2	Process not found
3	Injection failed
4	Timeout

Architecture

SnoopWpfCLI uses DLL injection and Named Pipes to communicate with target WPF processes.

                          Named Pipe (IPC)
  +-----------+          +------------------+          +------------------+
  |           |  inject  |                  |  query/  |                  |
  |  CLI App  | -------> | WpfInspector.dll | <------> |  Target WPF App  |
  |           |          | (injected DLL)   |  respond |  (e.g. TestApp)  |
  +-----------+          +------------------+          +------------------+
       |
       v
  System.CommandLine         Snoop.InjectorLauncher
  (CLI framework)            (from snoopwpf submodule)

The CLI uses Snoop.InjectorLauncher (from the snoopwpf submodule) to inject WpfInspector.dll into the target process.
Once injected, the DLL starts a Named Pipe server inside the target process.
The CLI communicates with the injected DLL over Named Pipes to query the visual tree, invoke actions, and capture screenshots.

Development

Build

dotnet build src/SnoopWpfCLI.slnx

Run

dotnet run --project src/App/App.csproj --framework net10.0-windows -- <command> [options]

Run Tests

dotnet test src/App.Tests/App.Tests.csproj

Project Structure

SnoopWpfCLI/
├── snoopwpf/                    # Git submodule (SnoopWPF injector)
├── src/
│   ├── App/                     # CLI application
│   │   ├── Commands/            # Subcommand definitions (System.CommandLine)
│   │   ├── Services/            # InjectionService, WpfProcessService
│   │   ├── Models/              # Data models
│   │   └── Formatters/          # Output formatters (JSON / tree)
│   ├── WpfInspector/            # Injected DLL (visual tree inspection)
│   └── App.Tests/               # Unit tests (xUnit)
├── tests/
│   └── TestApp/                 # Sample WPF app for testing
└── docs/
    ├── plans/                   # Design documents
    ├── specs/                   # Specifications
    └── references/              # Reference materials

License

This project is licensed under the MIT License.

This project uses and depends on the following open-source projects:

SnoopWPF -- Licensed under Ms-PL (Microsoft Public License). Used as a Git submodule for DLL injection into WPF processes.
SnoopWpfMcp -- Licensed under MIT License. The architecture and implementation of this CLI were heavily inspired by this project.

Acknowledgements

SnoopWPF -- The WPF inspection tool that provides the DLL injection foundation
SnoopWpfMcp -- The MCP server implementation that this CLI's architecture is heavily based on

Name		Name	Last commit message	Last commit date
Latest commit History 40 Commits
.claude		.claude
docs		docs
snoopwpf @ 4f1b852		snoopwpf @ 4f1b852
src		src
tests/TestApp		tests/TestApp
.gitignore		.gitignore
.gitmodules		.gitmodules
CLAUDE.md		CLAUDE.md
LICENSE		LICENSE
README.ja.md		README.ja.md
README.md		README.md
snoopwpfcli.skill		snoopwpfcli.skill

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SnoopWpfCLI

Features

Prerequisites

Installation

Quick Start

1. Build and launch the TestApp

2. List WPF processes

3. Ping (inject the inspector DLL)

4. Get the full visual tree (JSON)

5. Get the visual tree (human-readable tree)

6. Get a specific element

7. Invoke an action (click a button)

8. Take a screenshot

Command Reference

list-processes

ping

get-tree

get-subtree

get-element

find-element

invoke

wait

list-windows

get-datacontext

screenshot

assert

Output

Exit Codes

Architecture

Development

Build

Run

Run Tests

Project Structure

License

Acknowledgements

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