feat: Add VSCode extension for live coding in Python

[TaliesinYang]

Summary

• Adds a new VSCode extension that brings live coding support to VS Code, addressing the long-standing request in VSCode support #218
• Includes a fix for Python 3.14 compatibility (tk.PhotoImage mock in mock_turtle.py)
• Bundled space_tracer — works out of the box without pip install

Features

Feature	Status
Split view (source left, trace right)	✅
Auto text/canvas detection	✅
Turtle graphics (Webview Canvas)	✅
Matplotlib charts	✅
Scroll sync (PyCharm-style leader/follower)	✅
File switching auto re-trace	✅
Custom turtle icon in editor title bar	✅
Keyboard shortcuts (Cmd+Shift+L / K)	✅
CodeLens quick start	✅
Status bar with mode indicator	✅
Error display (red status bar)	✅
Stop closes output panel	✅
Auto-save other documents before trace	✅
Configurable: Python path, debounce, canvas size, driver, traced module, stdin, ms limit	✅
E2E tests (@vscode/test-electron)	✅

Architecture

Follows the same pattern as the Sublime and Emacs plugins:

1. Launch space_tracer as a subprocess via stdin/stdout
2. Parse output (text trace + canvas commands)
3. Display in split editor (Virtual Document) + Webview (canvas)

Key files:

• vscode/src/extension.ts — session management, commands, scroll sync
• vscode/src/tracerManager.ts — subprocess lifecycle, debounce, Python detection
• vscode/src/canvasPanel.ts — Webview Canvas rendering (turtle/matplotlib)
• vscode/src/canvasParser.ts — canvas command parser (ported from html/src/SampleAnalyst.js)

Test plan

• npm run compile — zero errors
• npm test — E2E tests pass (extension activation, split view, trace output, file switching)
• Manual test: basic Python trace
• Manual test: turtle graphics (blue square, star, flag)
• Manual test: matplotlib chart
• Manual test: syntax error display
• Manual test: scroll synchronization
• Manual test: file switching auto re-trace
• Manual test: stop restores single panel
• Tested on code-server + VSCode Remote SSH

Screenshots

Tested via code-server with Playwright automation.

Closes #218

🤖 Generated with Claude Code

[donkirkby]

This is a great start! I see you got both modes working.

Are you interested in continuing, or shall I take it from here?

Next steps:

• Tie the live coding mode to a single file. It shouldn't start running a file without the user starting live mode for that file. I wouldn't want them to accidentally run something destructive.
• Separate code visualization from canvas mode. Sometimes you want to see variable values for visual code.
• Fix the GitHub actions. It may not be related to your changes, but the build broke.
• Extract common code from browser and VSCode versions.
• Figure out how to publish in the marketplace.

Let me know if any of those interest you, otherwise I'll merge your changes and create new issues for myself.

Thanks again for coming to the sprint!