PySide6 Engineer

Overview

Use this skill to build desktop interfaces that are technically sound with PySide6. Focus on widget architecture, signal-slot design, state management, and Qt best practices. Use the official Qt for Python docs as the primary source for APIs, examples, and tool behavior. For UI/UX review and design polish, use the ui-ux-engineer skill.

Workflow

1. Detect the project shape before coding.

• Inspect the target for existing PySide6 source: window or widget classes, .ui files, signal-slot wiring, and any GUI tests or screenshots.
• If GUI code exists, follow the existing-app path: inventory the current widgets and state flow, then make targeted, layout-preserving changes tied to a specific issue.
• If no GUI code exists, follow the greenfield path: decide the window shell and primary surface first, then build the layout and hierarchy before wiring behavior.
• Read references/project_workflow.md for the full two-path workflow: greenfield (evidence, Qt contract, implementation choices, validation) and existing-repo (inspect first, identify current design, targeted changes, prove improvement).

2. Classify the surface before coding.

• Read references/topic_index.md as the routing front door: match the user problem to a row to find the right reference guide before writing any code.
• Decide whether the work belongs in Qt Widgets or Qt Quick first, then decide whether it should use a QMainWindow, QWidget, QDialog, wizard, dock layout, or model/view surface.
• Read references/task_selection.md to classify underspecified requests by window container, state coordination model, user goal, and required states.
• Identify the primary user goal, the main workflow path, and the states that must be handled: loading, empty, valid, invalid, busy, success, and failure.
• Read references/official_qt_for_python_docs.md when you need the official entry points for installation, module lookup, tutorials, examples, or package tools.

3. Choose a structure that keeps state understandable.

• Prefer a small composition tree of widgets over a giant window class.
• Keep business logic separate from widget layout logic.
• Use signals, slots, and small controller-style helpers to avoid tightly coupling every widget to every other widget.
• Read references/pyside6_patterns.md when choosing between common widget, dialog, navigation, threading, and model/view patterns.
• Read references/signals_slots.md when designing event flow, widget coordination, worker updates, or signal boundaries.

4. Build the UI from layout and hierarchy first.

• Prefer layouts over absolute positioning.
• Keep forms short, labels explicit, and primary actions visually dominant.
• Design for resizing from the start; do not assume one fixed window size.
• Read references/model_view.md before building non-trivial tables, trees, filtering, sorting, or custom cell rendering.
• Read references/testing_and_oracles.md to drive every UI state through pytest-qt and qtbot, validate against an oracle, and capture a before-and-after screenshot grid as the proof artifact.

Implementation defaults

• Load the local-only design books first when present; see the survey in references/reference_survey.md for the topic-to-book map, validated grep terms, and the graceful-absent fallback to official Qt docs. See references/local_books.md for the reading order and Qt-UX lens per book.
• Prefer Qt Widgets for classic desktop productivity tools, forms, settings, inspectors, admin panels, and other dense business UIs.
• Use Qt Quick only when the product genuinely needs a more fluid, animated, or QML-centric surface and the request clearly points there.
• Prefer QMainWindow for multi-region applications with menus, toolbars, docks, or status bars.
• Prefer QDialog for short focused tasks that need confirmation or cancellation.
• Prefer QStackedWidget or a router/controller pattern for multi-step flows when tabs would expose too much complexity.
• Prefer Qt's model/view classes for tables, trees, and large changing datasets.
• Keep long-running work off the UI thread; use worker objects plus QThread or other Qt-safe async patterns.
• Treat stylesheets as a finishing layer, not a substitute for good widget choice and layout structure.
• Prefer official Qt tools when the task involves .ui, .qrc, or project-generation workflows instead of reinventing those steps by hand.
• Read references/designer_ui_workflow.md when .ui files, Qt Designer, or pyside6-uic are involved.
• Read references/deployment_and_packaging.md when the task includes packaging, shipping, or validating a distributable PySide6 app.

Quality bar

• Favor stable patterns over clever widget tricks.
• Favor predictable state transitions over hidden side effects.
• Do not block the event loop with expensive work, sleeps, or synchronous network/file operations in click handlers.

Output expectations

When using this skill, aim to produce:

• PySide6 code that is organized by responsibility and easy to extend.
• Explicit handling for validation, error messaging, empty states, and loading states.
• References to the relevant official Qt for Python docs when using unfamiliar APIs or package tools.