PostIt — Extension

This document targets developers who want to build, debug or extend the PostIt VS Code extension.

Overview

PostIt is a minimal Webview-based VS Code extension that offers small sticky notes persisted locally using ExtensionContext.globalState. The extension exposes a status-bar command (postit.toggle) which opens a WebviewPanel beside the editor containing the note UI.

Goals:

• Very lightweight runtime and build-time configuration
• Simple local persistence (no network)
• Webview handshake to avoid race conditions

Architecture

• src/extension.ts — extension entry point, registers commands and manages the WebviewPanel lifecycle.
• src/html-template.ts — produces the Webview HTML/CSS/JS. The webview sends/receives messages via postMessage.
• media/ — static assets (icon.svg).
• tsconfig.json — TypeScript configuration (incremental build enabled, no sourcemaps for a lighter build).

Persistence:

• Key: postit.notes stored in context.globalState as an array of notes: { text: string, color: string }[].

Webview handshake:

• Webview posts { type: 'ready' } when initialized.
• Extension replies with { type: 'init', value: notes, theme }.

Message protocol (webview <-> extension)

• From webview to extension:
  • ready — webview loaded and ready for init
  • save { index, value, color } — save note at index
  • add { value, color } — add a new note
  • delete { index } — delete note (no confirmation)
  • requestDelete { index } — extension shows modal confirmation then may delete
  • changeColor { index, color } — change color
  • reorder { value: Array<{text,color}> } — reorder notes array
• From extension to webview:
  • init { value: notes, theme } — initial payload
  • added { index, value, color } — at add, extension returns the assigned index so webview can set data-index
  • theme { value } — theme changed event

Files of interest

• src/extension.ts — command registration, WebviewPanel creation (retainContextWhenHidden: false by default), message handling and globalState updates.
• src/html-template.ts — inline HTML/CSP/nonce generation and webview script.
• media/icon.svg — activity bar / fallback icon.
• tsconfig.json — lightweight settings used for faster incremental builds.
• package.json — contributes commands and configuration keys.

Build & Run (development)

1. cd into extension directory:
   • cd extension-vscode
2. Install exact dev deps from lockfile (reproducible):
   • npm ci
3. Build:
   • npm run build
4. Launch Extension Development Host
   • From root of the workspace or extension folder: code --extensionDevelopmentPath=., or press F5 in the extension VS Code debug configuration.

Useful scripts (from package.json):

• npm run build — compile TypeScript (tsc -p ./)
• npm run watch — tsc watch mode

Lint / TypeScript

• tsconfig.json is optimized for speed: incremental: true, sourceMap: false, declaration: false.
• If you enable stricter checks for development, consider toggling strict or noUnusedLocals locally.

Packaging & Publishing

• Ensure npm run build completes and out/ contains the compiled extension.
• Use vsce or @vscode/vsce to package and publish to Marketplace.

Performance notes

• retainContextWhenHidden is set to false to reduce memory usage while the Webview is hidden (trades off keeping live DOM state when hidden).
• Webview handshake avoids unnecessary re-renders and race conditions.
• tsconfig is tuned for incremental builds and minimal emitted artifacts.

Extending the extension

• To embed the full UI inside the Activity Bar view (instead of opening a floating panel), implement a WebviewViewProvider and render the same HTML. Be mindful of available height and retainContextWhenHidden semantics.

Troubleshooting

• Error "There is no data provider registered that can provide view data." — indicates a contributed view exists but no WebviewViewProvider is registered. Ensure vscode.window.registerWebviewViewProvider('viewId', provider) is called during activation if you contribute views in package.json.

Contact / Contributing

Open issues or PRs against the repository. Keep changes small and focused on low-runtime overhead.

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If you want, I can also add a DEVELOPMENT.md with step-by-step debugging scenarios and a minimal test skeleton. Want that?