Emacs 31.0.90 pretest highlights tree-sitter defaults and an editable xref workflow

Category: Dev tools
Status: developing
Sources: emacs-devel announcement, Rahul Juliato write-up, discussion
Summary: The first Emacs 31 pretest, 31.0.90, was announced on the emacs-devel list in June 2026. A practitioner write-up that reached the HN front page on 2026-06-18 details the changes being daily-driven: treesit-enabled-modes set to t switches the major modes that have a tree-sitter variant over to it; treesit-auto-install-grammar offers to fetch and build a missing grammar instead of erroring; grammar sources for languages such as TypeScript, TSX, Rust, TOML, YAML, and Dockerfile now live inside the modes; and a new command xref-export-to-grep, bound to E in xref buffers, gives an editable grep-and-dired-style workflow. This is a pretest, not a final release.
Why it matters: The tree-sitter defaults reduce per-language configuration for Emacs users and continue the editor's move toward built-in incremental parsing.