editors syntax highlighting ...

- emacs syntax: add tree-sitter major mode for SiSU spine markup
  New file sisu-spine-ts-mode.el is a sibling of the existing regex
  mode, backed by Emacs 29+'s built-in treesit.el and the
  tree-sitter-sisu grammar. It replaces the long font-lock keyword list
  with treesit-font-lock-rules grouped into eight features (comment,
  header, heading, block, inline, note, link, index, misc) so users
  can dial verbosity via treesit-font-lock-level. It also wires up:
  - treesit-simple-imenu-settings for a heading outline,
  - treesit-thing-settings for sentence / paragraph motions,
  - treesit-defun-type-regexp so C-M-a / C-M-e jump heading-to-heading,
  - a sisu-spine-ts-install-grammar command that registers
    treesit-language-source-alist and runs
    treesit-install-language-grammar so users can install the parser
    from inside Emacs without leaving the editor.

- the original sisu-spine-mode.el is unchanged and supported for
  Emacs < 29 and for users who prefer regex highlighting.

- nvim drop-in: point parser fetch at tools/tree-sitter-sisu
  sundry/editor-syntax-etc/nvim/
  The nvim-treesitter install_info now fetches the parser from
  https://git.sisudoc.org/projects/tree-sitter-sisu which can be cloned
  via git://git.sisudoc.org/tools/tree-sitter-sisu The fetched paths:
    files = { "src/parser.c", "src/scanner.c" }
  submission of the sisu parser to nvim-treesitter's parsers.lua should
  be a near-trivial one-liner.

- the original vim regex highlighter remains as before
  - sundry/editor-syntax-etc/vim/syntax/sisu-spine.vim
  - sundry/editor-syntax-etc/vim/templates/{sst,ssm,ssi}.tpl
    new skeleton templates for the three SiSU markup file types
    sets up the YAML header (title, creator, date, rights, classify,
    identfier)

- .gitignore - whitelist the new files

(assisted by Claude-Code)

2 files changed, 317 insertions, 3 deletions

diff --git a/sundry/editor-syntax-etc/emacs/sisu-spine-mode-autoloads.el b/sundry/editor-syntax-etc/emacs/sisu-spine-mode-autoloads.el
index 4cc6332..098a28c 100644
--- a/sundry/editor-syntax-etc/emacs/sisu-spine-mode-autoloads.el
+++ b/sundry/editor-syntax-etc/emacs/sisu-spine-mode-autoloads.el
@@ -1,10 +1,28 @@
 (add-to-list 'load-path (or (file-name-directory #$) (car load-path)))
+;; Regex / font-lock major mode.  Fallback for Emacs < 29 and for users
+;; who have not installed the tree-sitter-sisu parser.
 (autoload 'sisu-spine-mode "sisu-spine-mode" "\
 Major mode for editing SiSU (spine) markup files.
 SiSU (https://www.sisudoc.org/) document structuring, publishing
 and search.
 
 \(fn)" t nil)
-(add-to-list 'auto-mode-alist '("\\.sst\\'" . sisu-spine-mode))
-(add-to-list 'auto-mode-alist '("\\.ssm\\'" . sisu-spine-mode))
-(add-to-list 'auto-mode-alist '("\\.ssi\\'" . sisu-spine-mode))
+
+;; Tree-sitter major mode (Emacs 29+).  When the parser is installed it
+;; is selected by `auto-mode-alist'; otherwise the regex mode is used.
+(autoload 'sisu-spine-ts-mode "sisu-spine-ts-mode" "\
+Tree-sitter major mode for editing SiSU (spine) markup files.
+
+\(fn)" t nil)
+(autoload 'sisu-spine-ts-install-grammar "sisu-spine-ts-mode" "\
+Install the tree-sitter-sisu grammar for `sisu-spine-ts-mode'.
+\(fn)" t nil)
+(defun sisu-spine-auto-mode ()
+  "Choose `sisu-spine-ts-mode' if the parser is installed, else fall back."
+  (if (and (fboundp 'treesit-ready-p) (treesit-ready-p 'sisu t))
+    (sisu-spine-ts-mode)
+  (sisu-spine-mode)))
+
+(add-to-list 'auto-mode-alist '("\\.sst\\'" . sisu-spine-auto-mode))
+(add-to-list 'auto-mode-alist '("\\.ssm\\'" . sisu-spine-auto-mode))
+(add-to-list 'auto-mode-alist '("\\.ssi\\'" . sisu-spine-auto-mode))
diff --git a/sundry/editor-syntax-etc/emacs/sisu-spine-ts-mode.el b/sundry/editor-syntax-etc/emacs/sisu-spine-ts-mode.el
new file mode 100644
index 0000000..ef59d14
--- /dev/null
+++ b/sundry/editor-syntax-etc/emacs/sisu-spine-ts-mode.el
@@ -0,0 +1,296 @@
+;;; sisu-spine-ts-mode.el --- Tree-sitter major mode for SiSU spine markup -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2026  Free Software Foundation, Inc.
+
+;; Author: Ralph Amissah <ralph.amissah@gmail.com>
+;; Maintainer: Ralph Amissah <ralph.amissah@gmail.com>
+;; Keywords: text, syntax, processes, tools
+;; Version:   1.0.0
+;; URL: https://git.sisudoc.org/projects/sisudoc-spine/tree/sundry/editor-syntax-etc/emacs/sisu-spine-ts-mode.el
+;;      https://sisudoc.org/
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3, or (at your option)
+;; any later version.
+
+;;; Commentary:
+
+;; Tree-sitter-backed major mode for SiSU spine markup (.sst / .ssm /
+;; .ssi).  Sibling to `sisu-spine-mode' (regex / font-lock); requires
+;; Emacs 29 or newer with `treesit' built in and the tree-sitter-sisu
+;; parser installed.
+;;
+;; To install the parser inside Emacs:
+;;
+;;   M-x sisu-spine-ts-install-grammar RET
+;;
+;; or, equivalently:
+;;
+;;   (add-to-list 'treesit-language-source-alist
+;;     '(sisu "https://git.sisudoc.org/projects"
+;;            :source-dir "tree-sitter-sisu/src"))
+;;   M-x treesit-install-language-grammar RET sisu RET
+;;
+;; The mode is auto-enabled for .sst / .ssm / .ssi files when the parser
+;; is available.  When it is not, `sisu-spine-mode' (the regex variant)
+;; remains available as a fallback.
+
+;;; Code:
+
+(require 'treesit nil t)
+
+(defgroup sisu-spine-ts nil
+  "Tree-sitter mode for SiSU spine markup."
+  :group 'text
+  :prefix "sisu-spine-ts-")
+
+;; ---------------------------------------------------------------------
+;; Faces (mirror the structural categories the highlights.scm assigns)
+;; ---------------------------------------------------------------------
+
+(defface sisu-spine-ts-heading-1-face
+  '((t (:inherit outline-1 :weight bold)))
+  "Face for :A~ headings."
+  :group 'sisu-spine-ts)
+
+(defface sisu-spine-ts-heading-2-face
+  '((t (:inherit outline-2 :weight bold)))
+  "Face for :B~ headings."
+  :group 'sisu-spine-ts)
+
+(defface sisu-spine-ts-heading-3-face
+  '((t (:inherit outline-3 :weight bold)))
+  "Face for :C~ / :D~ headings."
+  :group 'sisu-spine-ts)
+
+(defface sisu-spine-ts-heading-segment-face
+  '((t (:inherit outline-4)))
+  "Face for 1~ / 2~ / 3~ segment headings."
+  :group 'sisu-spine-ts)
+
+(defface sisu-spine-ts-block-delimiter-face
+  '((t (:inherit font-lock-keyword-face)))
+  "Face for block opening/closing delimiters."
+  :group 'sisu-spine-ts)
+
+(defface sisu-spine-ts-raw-content-face
+  '((t (:inherit font-lock-string-face)))
+  "Face for raw block content (code, table, etc.)."
+  :group 'sisu-spine-ts)
+
+(defface sisu-spine-ts-footnote-face
+  '((t (:inherit font-lock-doc-face)))
+  "Face for footnote and editor-note bodies."
+  :group 'sisu-spine-ts)
+
+(defface sisu-spine-ts-link-face
+  '((t (:inherit link)))
+  "Face for link text and target URLs."
+  :group 'sisu-spine-ts)
+
+(defface sisu-spine-ts-book-index-face
+  '((t (:inherit font-lock-preprocessor-face)))
+  "Face for book-index entries (={...})."
+  :group 'sisu-spine-ts)
+
+(defface sisu-spine-ts-marker-face
+  '((t (:inherit font-lock-builtin-face)))
+  "Face for inline-formatting delimiters and other punctuation markers."
+  :group 'sisu-spine-ts)
+
+;; ---------------------------------------------------------------------
+;; Font-lock rules
+;; ---------------------------------------------------------------------
+
+(defvar sisu-spine-ts--font-lock-settings
+  (when (fboundp 'treesit-font-lock-rules)
+    (treesit-font-lock-rules
+     :language 'sisu
+     :feature 'comment
+     '((version_comment) @font-lock-doc-face
+       (header_comment)  @font-lock-comment-face
+       (body_comment)    @font-lock-comment-face)
+
+     :language 'sisu
+     :feature 'header
+     '((header_field key: (header_key)   @font-lock-keyword-face)
+       (header_field value: (header_value) @font-lock-string-face)
+       (header_continuation) @font-lock-string-face)
+
+     :language 'sisu
+     :feature 'heading
+     '(((heading_part marker: (part_marker) @m
+                       content: (heading_content) @sisu-spine-ts-heading-1-face)
+        (:match "^:A~$" @m))
+       ((heading_part marker: (part_marker) @m
+                       content: (heading_content) @sisu-spine-ts-heading-2-face)
+        (:match "^:B~$" @m))
+       ((heading_part marker: (part_marker) @m
+                       content: (heading_content) @sisu-spine-ts-heading-3-face)
+        (:match "^:[CD]~$" @m))
+       (heading_part marker: (part_marker) @sisu-spine-ts-marker-face)
+       (heading_segment marker: (segment_marker) @sisu-spine-ts-marker-face
+                        content: (heading_content) @sisu-spine-ts-heading-segment-face)
+       (segment_name) @font-lock-function-name-face
+       (suppress_marker) @sisu-spine-ts-marker-face)
+
+     :language 'sisu
+     :feature 'block
+     '((block_open)  @sisu-spine-ts-block-delimiter-face
+       (block_close) @sisu-spine-ts-block-delimiter-face
+       (raw_content) @sisu-spine-ts-raw-content-face
+       (table_spec)  @sisu-spine-ts-block-delimiter-face)
+
+     :language 'sisu
+     :feature 'inline
+     '((emphasis)         @italic
+       (bold)             @bold
+       (italic)           @italic
+       (underline)        @underline
+       (citation_mark)    @font-lock-string-face
+       (superscript)      @font-lock-type-face
+       (subscript)        @font-lock-type-face
+       (inserted)         @underline
+       (strikethrough)    @shadow
+       (monospace_inline) @font-lock-constant-face)
+
+     :language 'sisu
+     :feature 'note
+     '((footnote)         @sisu-spine-ts-footnote-face
+       (footnote_marker)  @sisu-spine-ts-marker-face
+       (editor_note)      @sisu-spine-ts-footnote-face)
+
+     :language 'sisu
+     :feature 'link
+     '((link text: (link_text) @sisu-spine-ts-link-face)
+       (link target: (url) @sisu-spine-ts-link-face)
+       (link target: (anchor_ref) @sisu-spine-ts-link-face)
+       (link target: (collection_path) @sisu-spine-ts-link-face)
+       (image spec: (image_spec) @sisu-spine-ts-link-face)
+       (auto_footnote_marker) @sisu-spine-ts-marker-face
+       (inline_anchor) @font-lock-function-name-face
+       (anchor_name)   @font-lock-function-name-face)
+
+     :language 'sisu
+     :feature 'index
+     '((book_index)    @sisu-spine-ts-book-index-face
+       (index_content) @font-lock-string-face)
+
+     :language 'sisu
+     :feature 'misc
+     '((paragraph_prefix) @sisu-spine-ts-marker-face
+       (page_break)       @sisu-spine-ts-marker-face
+       (horizontal_rule)  @sisu-spine-ts-marker-face
+       (line_break)       @sisu-spine-ts-marker-face
+       (ocn_suppress)        @font-lock-comment-face
+       (ocn_suppress_open)   @font-lock-comment-face
+       (ocn_suppress_close)  @font-lock-comment-face
+       (composite_include) @font-lock-preprocessor-face
+       (include_path)      @font-lock-string-face)))
+  "Tree-sitter font-lock rules for `sisu-spine-ts-mode'.")
+
+;; ---------------------------------------------------------------------
+;; Imenu / navigation / things
+;; ---------------------------------------------------------------------
+
+(defvar sisu-spine-ts--imenu-settings
+  '(("Part headings"
+     "\\`heading_part\\'"
+     nil
+     sisu-spine-ts--imenu-name-part)
+    ("Segment headings"
+     "\\`heading_segment\\'"
+     nil
+     sisu-spine-ts--imenu-name-segment))
+  "`treesit-simple-imenu-settings' for `sisu-spine-ts-mode'.")
+
+(defun sisu-spine-ts--imenu-name-part (node)
+  "Return display name for a heading_part NODE."
+  (let ((c (treesit-node-child-by-field-name node "content"))
+        (m (treesit-node-child-by-field-name node "marker")))
+    (concat (and m (treesit-node-text m t)) " "
+            (and c (treesit-node-text c t)))))
+
+(defun sisu-spine-ts--imenu-name-segment (node)
+  "Return display name for a heading_segment NODE."
+  (let ((c (treesit-node-child-by-field-name node "content"))
+        (m (treesit-node-child-by-field-name node "marker")))
+    (concat (and m (treesit-node-text m t)) " "
+            (and c (treesit-node-text c t)))))
+
+(defvar sisu-spine-ts--thing-settings
+  '((sisu
+     (defun "\\`heading_\\(part\\|segment\\)\\'")
+     (sentence "\\`paragraph\\'")
+     (text "\\`\\(text\\|raw_content\\|heading_content\\)\\'")))
+  "`treesit-thing-settings' for `sisu-spine-ts-mode'.")
+
+;; ---------------------------------------------------------------------
+;; Grammar install helper
+;; ---------------------------------------------------------------------
+
+;;;###autoload
+(defun sisu-spine-ts-install-grammar ()
+  "Register and install the tree-sitter-sisu grammar.
+Convenience wrapper around `treesit-install-language-grammar' with the
+upstream URL and source directory pre-filled."
+  (interactive)
+  (unless (boundp 'treesit-language-source-alist)
+    (user-error "treesit not available; Emacs 29+ required"))
+  (add-to-list 'treesit-language-source-alist
+               '(sisu "https://git.sisudoc.org/projects"
+                      :source-dir "tree-sitter-sisu/src"))
+  (treesit-install-language-grammar 'sisu))
+
+;; ---------------------------------------------------------------------
+;; Major mode
+;; ---------------------------------------------------------------------
+
+;;;###autoload
+(define-derived-mode sisu-spine-ts-mode text-mode "SiSU-Spine[ts]"
+  "Major mode for SiSU spine markup, backed by tree-sitter."
+  (unless (and (fboundp 'treesit-ready-p) (treesit-ready-p 'sisu))
+    (user-error
+     "tree-sitter-sisu parser not installed; run M-x sisu-spine-ts-install-grammar"))
+  (treesit-parser-create 'sisu)
+
+  ;; Comments
+  (setq-local comment-start "% "
+              comment-end   ""
+              comment-start-skip "%[ \t]+")
+
+  ;; Font-lock
+  (setq-local treesit-font-lock-settings sisu-spine-ts--font-lock-settings)
+  (setq-local treesit-font-lock-feature-list
+              '((comment header heading)
+                (block inline note link index)
+                (misc)
+                ()))
+
+  ;; Imenu / navigation
+  (setq-local treesit-simple-imenu-settings sisu-spine-ts--imenu-settings)
+  (setq-local treesit-thing-settings sisu-spine-ts--thing-settings)
+  (setq-local treesit-defun-type-regexp "\\`heading_\\(part\\|segment\\)\\'")
+  (setq-local treesit-defun-name-function
+              (lambda (node)
+                (let ((c (treesit-node-child-by-field-name node "content")))
+                  (and c (treesit-node-text c t)))))
+
+  (treesit-major-mode-setup))
+
+;;;###autoload
+(when (fboundp 'treesit-ready-p)
+  (dolist (ext '("\\.sst\\'" "\\.ssm\\'" "\\.ssi\\'"))
+    ;; Prefer the ts mode iff the parser is installed; otherwise fall
+    ;; back to `sisu-spine-mode'.
+    (add-to-list 'auto-mode-alist
+                 (cons ext
+                       (lambda ()
+                         (if (treesit-ready-p 'sisu t)
+                             (sisu-spine-ts-mode)
+                           (sisu-spine-mode)))))))
+
+(provide 'sisu-spine-ts-mode)
+
+;;; sisu-spine-ts-mode.el ends here