Qt Devtools Runtime Eval

Qt Runtime Eval

When to use this skill

Use the bridge when AT-SPI cannot give you what you need:

• Internal widget properties -- AT-SPI shows the label text but you need QComboBox.currentData(), QCheckBox.isChecked(), or a custom property.
• Calling Qt methods directly -- trigger a slot, toggle visibility, resize a widget, call repaint().
• Running multi-step logic inside the app -- iterate over model rows, collect data from multiple widgets in one call, run assertions on internal state.
• Reading model data -- row counts, cell values, selection state from QAbstractItemModel subclasses.
• Anything AT-SPI roles/names/text cannot express -- style sheets, font metrics, palette colors, custom Q_PROPERTY values.

For normal widget clicking, typing, and tree inspection, use qt-devtools-app-interaction. The bridge is the power tool -- reach for it when the standard inspect-interact-verify loop is insufficient.

Setup

Two methods. Choose based on your Python version.

App-installed (any Python version)

Add to your app after QApplication is created:

from qt_ai_dev_tools.bridge import start
start()

Set the env var to enable (bridge is a no-op without it):

export QT_AI_DEV_TOOLS_BRIDGE=1

Auto-inject (Python 3.14+ only)

No code changes needed. Inject into a running process:

qt-ai-dev-tools bridge inject --pid <PID>

Uses sys.remote_exec -- only available in Python 3.14+.

Commands

Eval

# Eval expression, return result
qt-ai-dev-tools eval "expression"

# Exec statement, return captured stdout
qt-ai-dev-tools eval "statement"

# Return result as structured JSON
qt-ai-dev-tools eval --json "code"

# Eval from file
qt-ai-dev-tools eval --file script.py

# Eval from stdin
qt-ai-dev-tools eval --file - < script.py

# Target specific app by PID
qt-ai-dev-tools eval --pid PID "code"

# Set execution timeout (default 30s)
qt-ai-dev-tools eval --timeout 60 "long_running_code()"

Expressions return their value. Statements (assignments, loops, print()) return None as result but captured stdout is printed.

Bridge management

# List active bridge sockets
qt-ai-dev-tools bridge status

# List as JSON
qt-ai-dev-tools bridge status --json

# Inject into running Python 3.14+ app
qt-ai-dev-tools bridge inject --pid PID

Pre-populated namespace

Every eval session has these names available without imports:

Recipes

Read a widget property

qt-ai-dev-tools eval "widgets['status_label'].text()"

Find all buttons

qt-ai-dev-tools eval "findall(QPushButton)"

Click via Qt API (bypasses xdotool)

qt-ai-dev-tools eval "widgets['save_btn'].click()"

Read combo box internal data

qt-ai-dev-tools eval "widgets['country'].currentData()"

Multi-line with stdout capture

qt-ai-dev-tools eval "for btn in findall(QPushButton): print(btn.text())"

Check if widget is enabled

qt-ai-dev-tools eval "widgets['save_btn'].isEnabled()"

Access model data

qt-ai-dev-tools eval "widgets['table'].model().rowCount()"

Get window title

qt-ai-dev-tools eval "app.activeWindow().windowTitle()"

Limitations

• Modal dialogs block the bridge. While a modal dialog is open (QFileDialog, QMessageBox, etc.), the bridge cannot respond because the Qt event loop is blocked by the modal. Use AT-SPI and xdotool for dialog interaction (see qt-devtools-form-and-input skill).
• Statements return None. Assignments, loops, and print() calls return None as their result value. Use print() to produce output -- stdout is captured and returned.
• Bridge must be active. Either bridge.start() must be called in the app code with QT_AI_DEV_TOOLS_BRIDGE=1 set, or bridge inject must be used on a Python 3.14+ process.

Troubleshooting

"No bridge socket found" -- The app is not running, bridge.start() was not called, or QT_AI_DEV_TOOLS_BRIDGE=1 is not set. Verify the app is running: qt-ai-dev-tools apps. For inject method: requires Python 3.14+.

"Connection refused" / "Broken pipe" -- The app crashed or was killed. Check the PID is alive: kill -0 <pid>. Delete stale sockets: rm /tmp/qt-ai-dev-tools-bridge-<pid>.sock.

NameError -- The name is not in the pre-populated namespace. Check spelling. Inspect available names on a widget: qt-ai-dev-tools eval "dir(widgets['name'])".

AttributeError -- Wrong method name on the widget. Inspect available methods: qt-ai-dev-tools eval "dir(widgets['name'])".

Bridge inject fails -- Requires Python 3.14+ (sys.remote_exec). For older Python, use the app-installed method (add bridge.start() to app code).

Related skills

• qt-devtools-setup -- install qt-ai-dev-tools, configure VM, verify environment
• qt-devtools-app-interaction -- inspect widgets, click, type, verify results via AT-SPI (the core workflow loop)
• qt-devtools-form-and-input -- clipboard and file dialog automation
• qt-devtools-desktop-integration -- system tray, notifications, and audio