How the Copilot coding agent harness spread from web to every Copilot surface
martinwoodward · x · 2026-09-17
Background context: the harness originated from the web coding agent powering GitHub Copilot and code review, was adopted by Copilot CLI where much of the goodness happened, and is now expanding across all Copilots. The author recommends reading stephentoub's full post, calling it denser than a master's thesis.
Related event: GitHub Rewrote Its Copilot Runtime in 800K Lines of Rust Using Copilot(10 posts)→
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