Implement comprehensive chat session telemetry with GDPR compliance

[Copilot]

This PR implements comprehensive telemetry tracking for chat session lifecycle events in VS Code, providing valuable insights into session usage patterns while maintaining strict GDPR compliance.

Overview

Prior to this implementation, VS Code's chat functionality had limited telemetry coverage for session management operations. This made it difficult to understand:

• How users interact with chat sessions over time
• Session restoration success rates and performance
• Storage efficiency and session persistence health
• User engagement patterns across different chat locations

Implementation

New Telemetry Events

1. chatSessionCreated - Tracks when chat sessions are created or restored

• Captures session location (Chat panel, inline editor, etc.)
• Distinguishes between new sessions and restored sessions
• Tracks initial state (empty vs. with history)

2. chatSessionDisposed - Tracks when sessions are cleared or disposed

• Measures session duration for engagement analysis
• Counts requests and responses for usage metrics
• Categorizes disposal reasons (user-initiated clear, error, etc.)

3. chatSessionRestored - Tracks session restoration from persistent storage

• Monitors restoration success rates for reliability insights
• Measures session age to understand persistence patterns
• Captures error codes for failure analysis

4. chatSessionPersisted - Tracks session storage operations

• Monitors storage success rates and performance
• Tracks session data size for storage optimization
• Provides error tracking for storage reliability

GDPR Compliance

All telemetry events follow VS Code's strict GDPR requirements:

• Data Classification: Uses SystemMetaData classification for non-personal system information
• Purpose Attribution: Properly categorizes data as FeatureInsight (usage patterns) or PerformanceAndHealth (diagnostics)
• Field Documentation: Every field includes clear comments explaining what data is collected and why
• Measurement Flags: Numeric values are properly marked with isMeasurement: true for analytics
• Owner Attribution: All events are properly attributed to the responsible team member

Privacy Protection

The implementation ensures zero collection of sensitive data:

• ❌ No user conversation content or messages
• ❌ No file paths or personal identifiers
• ❌ No usernames, emails, or personal information
• ✅ Only anonymous session IDs for correlation
• ✅ Aggregate usage metrics and performance data

Integration Points

• ChatServiceTelemetry: Extended with 4 new telemetry methods with full type safety
• ChatService: Integrated telemetry calls into session lifecycle methods (_startSession, getOrRestoreSession, clearSession)
• ChatSessionStore: Added persistence telemetry in the writeSession method with size tracking
• Comprehensive Testing: Full test coverage in chatSessionTelemetry.test.ts validates event emission and data structure

Benefits

This telemetry will enable the team to:

• Optimize Performance: Track session restoration times and storage efficiency
• Improve Reliability: Monitor error rates in session operations
• Enhance UX: Understand user engagement patterns across different chat contexts
• Guide Development: Make data-driven decisions about session management features

Testing

The implementation includes comprehensive test coverage that validates:

• Correct telemetry event emission for all lifecycle events
• GDPR-compliant data structures with proper classifications
• No sensitive data leakage in any telemetry events
• Proper error handling and edge case coverage

All tests follow VS Code's existing testing patterns and integrate with the current test infrastructure.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• electronjs.org
  • Triggering command: node-gyp (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Created from VS Code via the GitHub Pull Request extension.

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