OpenCode is a coding agent that runs where you already work rather than in a separate chat window. The same session can be driven from a terminal, an editor extension, or a desktop client, and it keeps context across all three.
Cursor forked VS Code rather than extending it, which let it change the editing model itself. Multi-file edits, codebase-wide context, and a tab completion that predicts the next edit rather than the next token are the result.
Copilot put model assisted completion in front of a very large number of developers first, and inline suggestion in the editor remains the interaction most people mean by AI coding.