LightSession for ChatGPT v0.4.2

Changelog

v0.4.2 (Critical Bug Fix)

• Fixed (Chrome): Removed dangerous DOM selector that was deleting message input areas on new chat pages
• Fixed (Chrome): Added safety check to prevent trimming on empty/new chat pages
• Fixed (Chrome): New chat pages now preserve message input area and limit messages
• Note: This fixes a critical issue where users couldn't start new conversations

v0.4.1 (Chrome Bug Fixes & Stability)

• Fixed (Chrome): Extension toggle now properly disables all trimming operations
• Fixed (Chrome): Auto-trim toggle correctly stops automatic trimming
• Fixed (Chrome): Ctrl+Shift+2 manual trim now works regardless of auto-trim setting
• Fixed (Chrome): Empty spaces and leftover elements removed after trimming
• Improved (Chrome): Settings synchronization between popup, content script, and page script
• Improved (Chrome): Better handling of manual vs automatic trimming logic
• Firefox: Version updated to 0.4.1 for consistency (no functional changes - experimental support)

v0.4.0 (Previous Release)

• Initial stable release with core features

Platform Status:

• ✅ Chrome: Fully functional and stable
• 🚧 Firefox: Under development - may have issues

LightSession is a lightweight browser extension that improves ChatGPT UI performance by trimming long conversations at render time. It keeps only the last N messages in the DOM while preserving the full conversation on OpenAI servers. Reloading the page restores the full history.

Features

• DOM-only trimming of ChatGPT conversation payloads
• No flicker — React never sees untrimmed data
• Configurable message limit (1–100)
• Auto Trim Toggle - enable/disable automatic trimming
• Dark Mode - popup theme matching system preference
• Keyboard Shortcuts - Ctrl+Shift+L (toggle), Ctrl+Shift+T (trim), Ctrl+Shift+P (popup)
• Onboarding & Update Pages - user-friendly welcome and update notifications
• Firefox Data Collection Consent - AMO compliant privacy settings
• Optional status indicator
• Ultra Lean Mode (CSS-only reduction of animations)
• 100% local — no telemetry, no external requests

What it does not do

• Does not reset sessions or clear cookies
• Does not automate prompts or scrape data
• Does not send telemetry or external requests
• Does not modify server-side conversation history

How it works

1. A page script runs in the page context at document_start and patches window.fetch.
2. When ChatGPT returns conversation JSON (/backend-api/conversation), LightSession trims the mapping to the last N messages.
3. The trimmed payload is returned as a new Response, so React only renders the trimmed DOM.

Only the UI is affected. The full conversation remains on the server and reappears after a reload.

Message counting rules

• A message = contiguous nodes with the same role
• Consecutive assistant nodes count as one message
• system, tool, and thinking roles are ignored

Why message count instead of tokens?

• Performance: counting roles and adjacency is cheap and avoids extra parsing.
• Simplicity: message boundaries are stable in the payload.
• Safety: tokenization is model-dependent and risks unexpected variance.

Configure via CustomEvent

The content script listens for a lightsession:settings event in the page context. This is primarily for advanced users and developers.

window.dispatchEvent(
  new CustomEvent("lightsession:settings", {
    detail: {
      enabled: true,
      keepLastN: 30
    }
  })
);

• enabled: enable/disable trimming
• keepLastN: number of messages to keep (1–100)

Test Automation

A userscript is provided to automatically test DOM trimming:

1. Open scripts/lightsession-auto-test.user.js.
2. Copy the entire script.
3. Open ChatGPT, paste into DevTools console and press Enter.
4. The script will:
   • Detect the conversation container.
   • Run tests for keepLastN = [1, 3, 5].
   • Trim DOM and verify results.
   • Print a summary table.

Manual test:

LightSessionAutoTestHelpers.runTest(5);

All tests should show ✅ PASS.

Build

Prerequisites

• Node.js 18.0+ and npm
• Operating System: Windows, macOS, or Linux
• Required packages: esbuild 0.21.5+, TypeScript 5.9.3+

Installation

# Install Node.js from https://nodejs.org/ (version 18.0 or higher)
# Verify installation:
node --version
npm --version

# Clone and install dependencies:
git clone <repository-url>
cd lightsession
npm install

Important: The project includes a comprehensive .gitignore file that excludes:

• node_modules/ - Dependencies
• dist/ - Build outputs
• IDE files and OS-specific files
• Extension packages (.zip, .crx, .xpi)

This ensures a clean repository and prevents unnecessary file tracking.

Build Instructions

1. Install dependencies:

npm install

2. Development build (with debug logs):

npm run build:dev

3. Production build (clean, no debug logs):

npm run build

Firefox Testing (Development Version)

Note: Firefox support is currently under development and may have issues.

1. Build Firefox version:

npm run build:firefox

2. Load in Firefox:

   • Open Firefox
   • Go to about:debugging
   • Click "Load Temporary Add-on"
   • Select dist/firefox/ directory
   • Test on https://chat.openai.com or https://chatgpt.com

3. Known Issues:

   • Some features may not work as expected
   • Debug logging may be enabled by default
   • Performance may vary compared to Chrome version

For production use, Chrome is recommended at this time.

Chrome Testing

1. Build Chrome version:

npm run build:chrome

2. Load in Chrome:
   • Open Chrome
   • Go to chrome://extensions/
   • Enable "Developer mode"
   • Click "Load unpacked"
   • Select dist/chrome/ directory
   • Test on https://chat.openai.com or https://chatgpt.com

Keyboard Shortcuts

• Ctrl+Shift+L - Toggle extension on/off
• Ctrl+Shift+1 - Open settings popup
• Ctrl+Shift+2 - Trim messages now

Note: Shortcuts work on any ChatGPT page in both Chrome and Firefox.

2. Build for all platforms:

npm run build

3. Build for specific platform:

npm run build:chrome    # Chrome Web Store
npm run build:firefox   # Firefox AMO

Build Process

The build process uses esbuild to:

• Compile TypeScript to JavaScript
• Bundle multiple files into single outputs
• Minify and optimize code
• Generate platform-specific manifests

Build Script Details

• esbuild.config.mjs - Main build configuration
• TypeScript compiler - Type checking and compilation
• Node.js 18.0+ - Runtime environment
• npm - Package manager and dependency resolution

Build Output

• dist/chrome/ - Chrome Web Store ready package
• dist/firefox/ - Firefox AMO ready package

Development

npm run typecheck      # Check TypeScript types
npm run test:lightsession  # Run automated tests

TypeScript Development

The project uses TypeScript for type safety and better development experience:

# Type checking without building
npx tsc --noEmit

# Development build with type checking
npm run build:dev

# Watch mode for development (if available)
npm run dev

Common Issues:

• Identifier conflicts: If you see "Definitions of the following identifiers conflict" errors, make sure to import from shared modules:

  import { __DEV__, debugLog } from "./shared/debug";
  import { excludedRoles, type ConversationNode, type ConversationPayload } from "./shared/types";

Troubleshooting

• Build fails: Check for TypeScript errors with npx tsc --noEmit
• Permission errors: Remove dist/firefox/background.zip if build fails with EPERM error
• Extension not loading: Check browser console for errors and ensure manifest is valid
• Firefox issues:
  • Firefox support is experimental - some features may not work
  • Check about:debugging console for Firefox-specific errors
  • Content script injection may behave differently than Chrome
  • Use Chrome for stable functionality while Firefox is in development

Source Code Structure

• src/ - TypeScript source files (not minified, not bundled)
  • src/shared/ - Shared utilities and types
    • debug.ts - Debug logging utilities (__DEV__, debugLog)
    • types.ts - Common types (ConversationNode, ConversationPayload, excludedRoles)
    • settings.ts - Settings management
    • extension-api.ts - Extension API abstraction
    • dom.ts - DOM utilities
  • src/popup/ - Extension popup UI
  • src/views/ - Extension views (installed, updated pages)
  • src/background.ts - Background script
  • src/content-script.ts - Content script (Firefox + Chrome coordination)
  • src/page-script.ts - Page script (Chrome fetch interception)
• dist/ - Built/compiled files (for distribution only)
• manifest.chrome.json - Chrome-specific manifest
• manifest.firefox.json - Firefox-specific manifest

Security & privacy

• No analytics or telemetry
• No external network requests
• Domain-scoped to chat.openai.com and chatgpt.com

Notes

• This is a UI optimization only.

License

MIT