VS Code 1.134 lets one window drive agent sessions running in another

The 19 August 2026 VS Code release adds Agent Host integration: sessions can be connected across multiple VS Code windows over the Agent Host Protocol, powered by the Copilot SDK. Alongside it, a side-by-side chat layout groups related chats and subagent chats into a grid for comparison by dragging conversations together, a prompt timeline marks which prompts in a long agent session modified files and how many lines each changed, Find in Chat searches whole conversation histories with case and regex support, and the integrated browser can be set as the default editor for local HTML files.

What it means The prompt timeline and cross-window session hosting are the first-class answer to the thing that actually breaks a long agent run — nobody can tell which prompt made which edit. Reviewing an agent session is becoming a supported workflow rather than a scroll.