Copilot Chat v0.43.2026040301: MCP & Claude 4.6

TL;DR

• MCP Insiders mode now configurable via `githubMcpServer.channel` setting
• Claude 4.6 now uses optimized Anthropic prompts by default
• New `fetchedValue` concept and `isSystemInitiated` flag for better session tracking

New

• MCP Insiders channel setting — Control GitHub MCP Server mode via `githubMcpServer.channel` configuration for testing bleeding-edge features.
• fetchedValue concept — New abstraction for handling fetched data in chat sessions.
• isSystemInitiated flag — Track whether chat sessions were triggered by system actions versus user input.

Improved

• Claude 4.6 prompts — Optimized Anthropic prompts are now the default for Claude 4.6 models, improving response quality.
• Codebase index UI — Aligned terminology and labels across the new codebase indexing interface.
• ChatSessionCustomizationProvider — Enhanced implementation for better session customization control.
• Context keys — Updated session context keys for improved state management.
• API integration — Updated copilot-api dependency and added `event_content` payload support.

Changed

• Documentation structure — Moved `docs/prompts.md` to scoped `.instructions.md` file for better organization.

Update via: code --install-extension GitHub.Copilot-Chat or check for updates in VS Code Extensions.

Source: Copilot Chat