Pygame Live Preview

Run Python/Pygame projects with fast restart-based hot reload, runtime diagnostics, and traceback-driven error feedback.

What This Extension Is

Pygame Live Preview is a VS Code development extension for Python game projects. It focuses on rapid local iteration:

• edit code
• save file
• see result quickly

It supports standard pygame, pygame-ce, and custom wrappers that use the same runtime surface, with optional adapter hooks for richer telemetry.

What It Offers

• Managed run/restart workflow from inside VS Code.
• Auto reload on save with guardrails against reload storms.
• Error panel with parsed traceback and source links.
• Debug panel for runtime health metrics.
• Optional in-editor preview surface with input routing.
• Health check + dependency guidance for common setup failures.

Features (v1)

• Start/Stop/Restart preview commands.
• Reload on file save with debounce.
• Output channel for stdout/stderr and warnings.
• Error panel with traceback and clickable file/line frames.
• Debug panel with:
  • uptime
  • restart count
  • CPU%
  • memory
  • last reload cause
  • optional FPS and frame time (from adapter)
• Project config via .pygame-preview.json.

Features (v2 foundations)

• Experimental in-editor preview surface panel (adapter-driven frame stream).
• Setup wizard command to scaffold/update .pygame-preview.json.
• Dependency Doctor command to scan imports and check missing modules in the selected interpreter.
• Debug panel timeline for lifecycle/warning/error events.
• Experimental embedded capture path for pygame apps (bootstrap capture, no project rewrite required).
• Adapter template generator command for custom metrics/hooks.
• src-layout import support (e.g. src/core, src/ui) for bootstrap runner.

Features (v4)

• Preview panel input routing:
  • keyboard events
  • mouse move/click
  • wheel events
• Performance controls:
  • previewFrameIntervalMs
  • previewMaxWidth
  • adaptive capture scaling under load
• Reload intelligence:
  • soft-reload strategy for asset/config changes
  • full restart fallback for code changes

Features (v5)

• Surface mode control:
  • native (no embedded frame capture, native window only)
  • mirror (native window + in-editor mirrored preview)
  • embedded (panel-first mode, native window hidden where supported)
• Faster embedded frame transport:
  • binary frame file transport (rgb24) instead of JSON base64 payload churn
  • sequence-based frame polling to avoid redundant frame decode work
• Input parity improvements in preview panel:
  • key repeat/modifier forwarding
  • mouse movement deltas and click count
  • input capture indicator in panel UI

Features (v6)

• Faster preview transport path:
  • local socket frame stream from game bootstrap to extension host
  • file transport fallback when socket stream is unavailable
• Latest-frame-only rendering:
  • stale frames are dropped under load
  • panel always renders the newest received frame

Features (v7)

• Embedded mode hardening:
  • reports surfaceModeRequested vs surfaceModeActual
  • explicit fallback reason when embedded window hiding is unsupported/fails
• Input parity upgrades:
  • pointer-lock aware mouse routing for relative movement
  • blur-safe key release to reduce stuck-key issues
  • text-input forwarding for UI/chat/name-entry flows
  • gamepad state forwarding as custom preview events (pygame.USEREVENT)
  • embedded input state overrides for pygame.key.get_pressed() and pygame.mouse.get_pos()/get_pressed()/get_rel()

Features (v8)

• Panel-first beta controls:
  • panelOnlyMode (best effort) to prefer embedded panel runtime
  • explicit panel-only status/fallback reporting
• Transport and rendering upgrades:
  • previewTransport (hybrid / socket / file)
  • binary RGB frame bytes forwarded to webview (avoids base64 decode on socket path)
  • dropped-frame counter (latest-frame strategy visibility)
• Input system upgrades:
  • deterministic capture/idle/paused focus model in panel
  • IME composition end forwarding
  • optional adapter input hook (on_preview_input)
• In-panel perf HUD v2:
  • live mini-graph for FPS and frame-time trends
  • dropped frame + input latency stats
• Compatibility upgrades:
  • sourceRoots config for src-layout/monorepo import roots
  • bootstrap auto-discovers common monorepo roots (packages/*/src, apps/*/src, services/*/src)
• Adapter SDK v1 workflow:
  • typed adapter template (TypedDict hook signatures)
  • Validate Adapter command for signature/import checks
• Playback tooling:
  • record input sessions to .pygame-preview-runtime/input-session-*.jsonl
  • replay recorded sessions at 1x/2x/4x

Features (v9)

• Inspector workflow:
  • Toggle Inspector Panel command
  • Refresh Inspector Snapshot command
  • optional auto-refresh via inspectorAutoRefreshMs
  • adapter hooks: get_scene_snapshot() / get_inspector_snapshot()
• Diagnostics export:
  • Export Bug Report Bundle command
  • writes .pygame-preview-runtime/bug-report-*.json
• Runtime control upgrades:
  • audio controls from preview panel (mute/volume input events)
  • cursor controls from preview panel (visibility/lock input events)
  • drop events from preview panel to pygame user events
  • gamepad normalization presets (raw / generic / xbox)
• Capture/perf controls:
  • performanceMode and previewBandwidthKbps propagate to bootstrap capture logic
  • panelOnlyStrict for strict embedded-only startup behavior
• Optional telemetry:
  • telemetryOptIn includes runner counters in metrics payload

Features (v10)

• Panel runtime GA path:
  • stable surfaceMode: "panel" alias for panel-first execution
  • automatic mapping to embedded runtime with explicit fallback diagnostics
• Recovery and safety:
  • Start Preview (Safe Mode) command
  • startup crash guard (startupGuardMaxRestarts, startupGuardWindowMs)
  • one-click recovery actions on runtime error (safe mode / dependency doctor / open config)
• Input/runtime diagnostics:
  • deterministic input clock option (inputDeterministic, inputDeterministicStepMs)
  • preview input sequence metadata
  • input-to-present latency metric in panel/debug HUD
  • dropped-frame cause counters
• Inspector v2:
  • snapshot diff indicator
  • pinned watch paths
  • optional source jump buttons from adapter-provided source hints
• Low-latency tuning:
  • lowLatencyMode for tighter polling/capture pacing

Features (v11 hardening)

• Reload stability and storm protection:
  • configurable burst guard (reloadBurstMax, reloadBurstWindowMs)
  • configurable reload floor (reloadMinimumIntervalMs)
  • temporary per-file suppression for runaway self-updating files
  • clearer reload telemetry in Output and debug timeline
• Dependency helper UX hardening:
  • configurable prompt cooldown and post-install mute windows
  • deduplicated dependency prompts per module-set/interpreter session
  • reduced prompt spam during repeated runtime failures
• Diagnostics polish:
  • improved traceback parsing for non-standard/colon-style Python errors
  • better summary extraction for argparse/syntax errors
  • safer error panel rendering and improved relative-path file linking
• Adapter validation v1 hardening:
  • dedicated validator script with workspace/source-root path resolution
  • expanded hook signature checks (inspect, checkpoint hooks)
  • structured errors/warnings/details output for actionable fixes
• Test/quality improvements:
  • extra runner protocol tests (reload lifecycle)
  • sample integration tests (pygame, pygame-ce, custom framework)
  • CI matrix for extension tests and runner protocol/integration smoke

Features (v12 quality bundle)

• First-run health-check flow:
  • one-time prompt before first preview launch in a workspace
  • checks entry resolution, interpreter resolution, missing modules, and adapter validation
  • quick-fix actions (Open Config, Setup Wizard, Dependency Doctor, module install shortcut)
• New quality presets:
  • qualityPreset: "quality" | "balanced" | "performance"
  • applies a consistent tuning profile for preview fidelity/latency/overhead
• Bug report sharing polish:
  • exported bundle now supports Copy Summary for issue reports
• CI + tests expansion:
  • input mapping unit tests (including function keys)
  • protocol matrix keeps core runner behavior covered across platforms

Features (v13 performance + reliability)

• Lower-latency panel streaming and runtime overhead reductions:
  • latest-frame worker pipeline
  • improved socket transport with delta-rect packet envelopes
  • adaptive transport/capture tuning visibility in panel diagnostics
• Frame trace and bottleneck diagnostics:
  • richer drop-cause counters
  • improved transport telemetry for debugging stutter and lag
• Socket transport reliability hardening:
  • fixed dedup-state advancement on failed socket sends in socket-only mode
  • prevents stale/frozen preview cases when delivery fails transiently

Commands

• Pygame Live Preview: Start Preview
• Pygame Live Preview: Start Preview (Safe Mode)
• Pygame Live Preview: Stop Preview
• Pygame Live Preview: Restart Preview
• Pygame Live Preview: Toggle Debug Panel
• Pygame Live Preview: Toggle Preview Surface
• Pygame Live Preview: Setup Project
• Pygame Live Preview: Run Health Check
• Pygame Live Preview: Dependency Doctor
• Pygame Live Preview: Setup Adapter Template
• Pygame Live Preview: Validate Adapter
• Pygame Live Preview: Start Input Recording
• Pygame Live Preview: Stop Input Recording
• Pygame Live Preview: Replay Input Session
• Pygame Live Preview: Toggle Inspector Panel
• Pygame Live Preview: Refresh Inspector Snapshot
• Pygame Live Preview: Export Bug Report Bundle

Project Config

Create .pygame-preview.json in workspace root:

{
  "entry": "main.py",
  "reloadDebounceMs": 300
}

Supported fields:

• entry: string
• pythonPath?: string
• watchInclude?: string[]
• watchExclude?: string[]
• softReloadEnabled?: boolean
• softReloadInclude?: string[]
• softReloadExclude?: string[]
• reloadDebounceMs?: number
• autoStart?: boolean
• debugPanelDefault?: boolean
• previewPanelDefault?: boolean
• previewFrameIntervalMs?: number
• previewMaxWidth?: number
• previewInputEnabled?: boolean
• panelOnlyMode?: boolean
• panelOnlyStrict?: boolean
• previewTransport?: "hybrid" | "socket" | "file"
• sourceRoots?: string[]
• gamepadPreset?: "raw" | "generic" | "xbox"
• audioInitMode?: "auto" | "always" | "off"
• audioDefaultMuted?: boolean
• audioDefaultVolume?: number (0..1)
• checkpointOnReload?: boolean
• performanceMode?: boolean
• previewBandwidthKbps?: number
• inspectorAutoRefreshMs?: number
• telemetryOptIn?: boolean
• lowLatencyMode?: boolean
• inputDeterministic?: boolean
• inputDeterministicStepMs?: number
• qualityPreset?: "quality" | "balanced" | "performance"
• startupGuardMaxRestarts?: number
• startupGuardWindowMs?: number
• reloadBurstMax?: number
• reloadBurstWindowMs?: number
• reloadMinimumIntervalMs?: number
• dependencyPromptCooldownMs?: number
• dependencyPromptMuteAfterInstallMs?: number
• surfaceMode?: "native" | "mirror" | "embedded" | "panel"
• adapterModule?: string
• reloadMode?: "restart" | "inprocess"

Unknown fields warn in output but do not block startup.

Compatibility

Compatibility targets are documented in COMPATIBILITY.md.

Entry Resolution Fallback

If entry is omitted:

1. main.py at workspace root
2. app.py at workspace root
3. first .py file containing if __name__ == "__main__":

Adapter API (optional)

When adapterModule is configured, the runner imports it from workspace root.

Optional functions:

• get_metrics() -> dict
• request_reload(payload: dict) -> bool (for experimental inprocess reload mode)
• on_preview_input(payload: dict) -> None
• get_frame() -> dict (optional advanced frame source)
• get_scene_snapshot() -> dict or get_inspector_snapshot() -> dict (for Inspector panel)
• get_checkpoint() -> dict and restore_checkpoint(payload: dict) -> None (optional experimental checkpoint flow)

Optional frame stream fields from get_metrics():

• framePngBase64: str or frameJpegBase64: str
• frameRgbBase64: str together with frameWidth: int and frameHeight: int

Adapter failures are non-fatal and logged as warnings.

Development

npm install
npm run compile

Package VSIX for install/share:

npm run package:vsix

Runner tests:

npm run test:runner

TypeScript tests:

npm test

Troubleshooting Quick Checks

1. Pick the interpreter first: Python: Select Interpreter, then confirm it in preview output.
2. If startup crashes loop: run Pygame Live Preview: Start Preview (Safe Mode).
3. If modules are missing: run Pygame Live Preview: Dependency Doctor.
4. If reload storms happen from generated files:
   • add explicit watchExclude globs
   • tune reloadBurstMax, reloadBurstWindowMs, and reloadMinimumIntervalMs
5. If panel input feels delayed:
   • enable lowLatencyMode
   • keep surfaceMode as "panel" or "embedded"
6. If adapter behavior is unclear: run Pygame Live Preview: Validate Adapter.

Samples

• samples/pygame-basic
• samples/pygame-ce-basic
• samples/custom-framework

Changelog

Current release notes are tracked in CHANGELOG.md.

License

Apache-2.0. See LICENSE.