fix(treesit): prompt before grammar installs, add explicit bootstrap

treesit-auto-install was t, so opening a file could silently trigger a network download and compiler build mid-edit. It now prompts, and cj/install-treesit-grammars is the deliberate fresh-machine bootstrap that installs everything in one command.

2 files changed, 48 insertions, 3 deletions

diff --git a/modules/prog-general.el b/modules/prog-general.el
index 15bf40c4..831f43cb 100644
--- a/modules/prog-general.el
+++ b/modules/prog-general.el
@@ -115,11 +115,14 @@ REGEXP must be a string or an rx form."
 ;; incremental language syntax parser
 ;; Using Emacs 29+ built-in treesit with treesit-auto for grammar management
 
-;; installs tree-sitter grammars if they're absent
+;; Manages tree-sitter grammars.  Install is 'prompt, never t: with t,
+;; merely opening a file could trigger a network download and a compiler
+;; build mid-edit.  Batch/test runs never load treesit-auto (no package
+;; init), so they can never install.  Fresh-machine bootstrap is the
+;; explicit `cj/install-treesit-grammars' command below.
 (use-package treesit-auto
   :custom
-  (treesit-auto-install t)
-  ;;  (treesit-auto-install 'prompt) ;; optional prompt instead of auto-install
+  (treesit-auto-install 'prompt)
   :config
   (require 'cl-lib)
   ;; Pin Go grammar to v0.19.1 for compatibility with Emacs 30.2 font-lock queries
@@ -134,6 +137,14 @@ REGEXP must be a string or an rx form."
   (treesit-auto-add-to-auto-mode-alist 'all)
   (global-treesit-auto-mode))
 
+(defun cj/install-treesit-grammars ()
+  "Install every tree-sitter grammar treesit-auto knows about.
+The deliberate bootstrap for a fresh machine, replacing the old
+silent install-on-file-open (`treesit-auto-install' t)."
+  (interactive)
+  (require 'treesit-auto)
+  (treesit-auto-install-all))
+
 ;; -------------------------------- Code Folding -------------------------------
 
 ;; BICYCLE
diff --git a/tests/test-prog-general--install-treesit-grammars.el b/tests/test-prog-general--install-treesit-grammars.el
new file mode 100644
index 00000000..62bf3920
--- /dev/null
+++ b/tests/test-prog-general--install-treesit-grammars.el
@@ -0,0 +1,34 @@
+;;; test-prog-general--install-treesit-grammars.el --- Grammar bootstrap command -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; `treesit-auto-install' is set to `prompt' so opening a file never silently
+;; downloads and builds a grammar.  `cj/install-treesit-grammars' is the
+;; explicit fresh-machine bootstrap: it loads treesit-auto and installs every
+;; grammar in one deliberate command.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'prog-general)
+
+;; Satisfy the command's (require 'treesit-auto) without the real package,
+;; which isn't available in batch runs.
+(provide 'treesit-auto)
+
+(ert-deftest test-prog-general-install-treesit-grammars-is-a-command ()
+  "Normal: the bootstrap entry point exists and is interactive."
+  (should (commandp 'cj/install-treesit-grammars)))
+
+(ert-deftest test-prog-general-install-treesit-grammars-installs-all ()
+  "Normal: the command delegates to treesit-auto-install-all."
+  (let ((called 0))
+    (cl-letf (((symbol-function 'treesit-auto-install-all)
+               (lambda (&rest _) (setq called (1+ called)))))
+      (cj/install-treesit-grammars)
+      (should (= called 1)))))
+
+(provide 'test-prog-general--install-treesit-grammars)
+;;; test-prog-general--install-treesit-grammars.el ends here