diff --git a/.dir-locals.el b/.dir-locals.el
index ce7febca851..4edcad458a4 100644
--- a/.dir-locals.el
+++ b/.dir-locals.el
@@ -27,9 +27,7 @@
                (electric-quote-comment . nil)
                (electric-quote-string . nil)
 	       (mode . bug-reference-prog)))
- (c-ts-mode . ((c-ts-mode-indent-style . gnu)
-               (indent-tabs-mode . t)
-               (mode . bug-reference-prog)))
+ (c-ts-mode . ((c-ts-mode-indent-style . gnu))) ;Inherits `c-mode' settings.
  (log-edit-mode . ((log-edit-font-lock-gnu-style . t)
                    (log-edit-setup-add-author . t)
 		   (vc-git-log-edit-summary-target-len . 50)))
diff --git a/lisp/align.el b/lisp/align.el
index fa95f24fa02..81ccc4b5e2d 100644
--- a/lisp/align.el
+++ b/lisp/align.el
@@ -181,13 +181,12 @@ align-large-region
   :type '(choice (const :tag "Align a large region silently" nil) integer)
   :group 'align)
 
-(defcustom align-c++-modes '( c++-mode c-mode java-mode
-                              c-ts-mode c++-ts-mode)
+(defcustom align-c++-modes '( c++-mode c-mode java-mode)
   "A list of modes whose syntax resembles C/C++."
   :type '(repeat symbol)
   :group 'align)
 
-(defcustom align-perl-modes '(perl-mode cperl-mode)
+(defcustom align-perl-modes '(perl-mode)
   "A list of modes where Perl syntax is to be seen."
   :type '(repeat symbol)
   :group 'align)
@@ -576,13 +575,13 @@ align-rules-list
                     "="
                     (group (zero-or-more (syntax whitespace)))))
      (group . (1 2))
-     (modes . '(conf-toml-mode toml-ts-mode lua-mode lua-ts-mode)))
+     (modes . '(conf-toml-mode lua-mode)))
 
     (double-dash-comment
      (regexp . ,(rx (group (zero-or-more (syntax whitespace)))
                     "--"
                     (zero-or-more nonl)))
-     (modes  . '(lua-mode lua-ts-mode))
+     (modes  . '(lua-mode))
      (column . comment-column)
      (valid  . ,(lambda ()
                   (save-excursion
diff --git a/lisp/cedet/semantic/symref/grep.el b/lisp/cedet/semantic/symref/grep.el
index 83e3bc36073..cc4d1546c85 100644
--- a/lisp/cedet/semantic/symref/grep.el
+++ b/lisp/cedet/semantic/symref/grep.el
@@ -44,9 +44,7 @@ semantic-symref-tool-grep
 
 (defvar semantic-symref-filepattern-alist
   '((c-mode "*.[ch]")
-    (c-ts-mode "*.[ch]")
     (c++-mode "*.[chCH]" "*.[ch]pp" "*.cc" "*.hh")
-    (c++-ts-mode "*.[chCH]" "*.[ch]pp" "*.cc" "*.hh")
     (html-mode "*.html" "*.shtml" "*.php")
     (mhtml-mode "*.html" "*.shtml" "*.php") ; FIXME: remove
                                             ; duplication of
@@ -55,12 +53,8 @@ semantic-symref-filepattern-alist
                                             ; major mode definition?
     (ruby-mode "*.r[bu]" "*.rake" "*.gemspec" "*.erb" "*.haml"
                "Rakefile" "Thorfile" "Capfile" "Guardfile" "Vagrantfile")
-    (ruby-ts-mode "*.r[bu]" "*.rake" "*.gemspec" "*.erb" "*.haml"
-                  "Rakefile" "Thorfile" "Capfile" "Guardfile" "Vagrantfile")
     (python-mode "*.py" "*.pyi" "*.pyw")
-    (python-ts-mode "*.py" "*.pyi" "*.pyw")
     (perl-mode "*.pl" "*.PL")
-    (cperl-mode "*.pl" "*.PL")
     (lisp-interaction-mode "*.el" "*.ede" ".emacs" "_emacs")
     )
   "List of major modes and file extension pattern.
diff --git a/lisp/emulation/viper.el b/lisp/emulation/viper.el
index 83fcdf89375..287292a24dc 100644
--- a/lisp/emulation/viper.el
+++ b/lisp/emulation/viper.el
@@ -388,7 +388,6 @@ viper-vi-state-mode-list
     idl-mode
 
     perl-mode
-    cperl-mode
     javascript-mode
     tcl-mode
     python-mode
diff --git a/lisp/files.el b/lisp/files.el
index 8b4e4394e5a..e546e9473a3 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -4414,6 +4414,12 @@ dir-locals-collect-variables
                   (funcall predicate key)
                 (or (not key)
                     (derived-mode-p key)))
+              ;; If KEY is an extra parent it may remain not loaded
+              ;; (hence with some of its mode-specific vars missing their
+              ;; `safe-local-variable' property), leading to spurious
+              ;; prompts about unsafe vars (bug#68246).
+              (if (and (symbolp key) (autoloadp (indirect-function key)))
+                  (ignore-errors (autoload-do-load (indirect-function key))))
               (let* ((alist (cdr entry))
                      (subdirs (assq 'subdirs alist)))
                 (if (or (not subdirs)
diff --git a/lisp/htmlfontify.el b/lisp/htmlfontify.el
index 6b9c623f31f..89c2bee2204 100644
--- a/lisp/htmlfontify.el
+++ b/lisp/htmlfontify.el
@@ -586,6 +586,7 @@ 'hfy-colour-vals
 (defvar hfy-cperl-mode-kludged-p nil)
 
 (defun hfy-kludge-cperl-mode ()
+  ;; FIXME: Still?
   "CPerl mode does its damnedest not to do some of its fontification when not
 in a windowing system - try to trick it..."
   (declare (obsolete nil "28.1"))
diff --git a/lisp/info-look.el b/lisp/info-look.el
index da7beafe500..cd59fdf17d7 100644
--- a/lisp/info-look.el
+++ b/lisp/info-look.el
@@ -985,9 +985,8 @@ info-complete
                                  finally return "(python)Index")))))
 
 (info-lookup-maybe-add-help
- :mode 'cperl-mode
- :regexp "[$@%][^a-zA-Z]\\|\\$\\^[A-Z]\\|[$@%]?[a-zA-Z][_a-zA-Z0-9]*"
- :other-modes '(perl-mode))
+ :mode 'perl-mode
+ :regexp "[$@%][^a-zA-Z]\\|\\$\\^[A-Z]\\|[$@%]?[a-zA-Z][_a-zA-Z0-9]*")
 
 (info-lookup-maybe-add-help
  :mode 'latex-mode
diff --git a/lisp/progmodes/c-ts-mode.el b/lisp/progmodes/c-ts-mode.el
index e5835bdb62d..461218cbb7d 100644
--- a/lisp/progmodes/c-ts-mode.el
+++ b/lisp/progmodes/c-ts-mode.el
@@ -1314,6 +1314,8 @@ c-ts-mode
                   (lambda (_pos) 'c))
       (treesit-font-lock-recompute-features '(emacs-devel)))))
 
+(derived-mode-add-parents 'c-ts-mode '(c-mode))
+
 ;;;###autoload
 (define-derived-mode c++-ts-mode c-ts-base-mode "C++"
   "Major mode for editing C++, powered by tree-sitter.
@@ -1357,6 +1359,8 @@ c++-ts-mode
       (setq-local add-log-current-defun-function
                   #'c-ts-mode--emacs-current-defun-name))))
 
+(derived-mode-add-parents 'c++-ts-mode '(c++-mode))
+
 (easy-menu-define c-ts-mode-menu (list c-ts-mode-map c++-ts-mode-map)
   "Menu for `c-ts-mode' and `c++-ts-mode'."
   '("C/C++"
diff --git a/lisp/progmodes/cmake-ts-mode.el b/lisp/progmodes/cmake-ts-mode.el
index d933e4ebb81..2a185fb0aa2 100644
--- a/lisp/progmodes/cmake-ts-mode.el
+++ b/lisp/progmodes/cmake-ts-mode.el
@@ -261,6 +261,8 @@ cmake-ts-mode
 
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'cmake-ts-mode '(cmake-mode))
+
 (if (treesit-ready-p 'cmake)
     (add-to-list 'auto-mode-alist
                  '("\\(?:CMakeLists\\.txt\\|\\.cmake\\)\\'" . cmake-ts-mode)))
diff --git a/lisp/progmodes/cperl-mode.el b/lisp/progmodes/cperl-mode.el
index 9f7f29b8182..2496100c21c 100644
--- a/lisp/progmodes/cperl-mode.el
+++ b/lisp/progmodes/cperl-mode.el
@@ -1922,6 +1922,8 @@ cperl-mode
   ;; Setup Flymake
   (add-hook 'flymake-diagnostic-functions #'perl-flymake nil t))
 
+(derived-mode-add-parents 'cperl-mode '(perl-mode))
+
 (defun cperl--set-file-style ()
   (when cperl-file-style
     (cperl-set-style cperl-file-style)))
diff --git a/lisp/progmodes/csharp-mode.el b/lisp/progmodes/csharp-mode.el
index 7bf57bcbe21..18114d08528 100644
--- a/lisp/progmodes/csharp-mode.el
+++ b/lisp/progmodes/csharp-mode.el
@@ -998,6 +998,8 @@ csharp-ts-mode
 
   (add-to-list 'auto-mode-alist '("\\.cs\\'" . csharp-ts-mode)))
 
+(derived-mode-add-parents 'csharp-ts-mode '(csharp-mode))
+
 (provide 'csharp-mode)
 
 ;;; csharp-mode.el ends here
diff --git a/lisp/progmodes/dockerfile-ts-mode.el b/lisp/progmodes/dockerfile-ts-mode.el
index 334f3064d98..618082cfe7a 100644
--- a/lisp/progmodes/dockerfile-ts-mode.el
+++ b/lisp/progmodes/dockerfile-ts-mode.el
@@ -190,6 +190,8 @@ dockerfile-ts-mode
 
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'dockerfile-ts-mode '(dockerfile-mode))
+
 (if (treesit-ready-p 'dockerfile)
     (add-to-list 'auto-mode-alist
                  ;; NOTE: We can't use `rx' here, as it breaks bootstrap.
diff --git a/lisp/progmodes/eglot.el b/lisp/progmodes/eglot.el
index ba2cc72a6b4..7007e71713b 100644
--- a/lisp/progmodes/eglot.el
+++ b/lisp/progmodes/eglot.el
@@ -226,90 +226,101 @@ eglot-alternatives
                       when probe return (cons probe args)
                       finally (funcall err)))))))
 
-(defvar eglot-server-programs `(((rust-ts-mode rust-mode) . ("rust-analyzer"))
-                                ((cmake-mode cmake-ts-mode) . ("cmake-language-server"))
-                                (vimrc-mode . ("vim-language-server" "--stdio"))
-                                ((python-mode python-ts-mode)
-                                 . ,(eglot-alternatives
-                                     '("pylsp" "pyls" ("pyright-langserver" "--stdio") "jedi-language-server" "ruff-lsp")))
-                                ((js-json-mode json-mode json-ts-mode)
-                                 . ,(eglot-alternatives '(("vscode-json-language-server" "--stdio")
-                                                          ("vscode-json-languageserver" "--stdio")
-                                                          ("json-languageserver" "--stdio"))))
-                                (((js-mode :language-id "javascript")
-                                  (js-ts-mode :language-id "javascript")
-                                  (tsx-ts-mode :language-id "typescriptreact")
-                                  (typescript-ts-mode :language-id "typescript")
-                                  (typescript-mode :language-id "typescript"))
-                                 . ("typescript-language-server" "--stdio"))
-                                ((bash-ts-mode sh-mode) . ("bash-language-server" "start"))
-                                ((php-mode phps-mode)
-                                 . ,(eglot-alternatives
-                                     '(("phpactor" "language-server")
-                                       ("php" "vendor/felixfbecker/language-server/bin/php-language-server.php"))))
-                                ((c-mode c-ts-mode c++-mode c++-ts-mode objc-mode)
-                                 . ,(eglot-alternatives
-                                     '("clangd" "ccls")))
-                                (((caml-mode :language-id "ocaml")
-                                  (tuareg-mode :language-id "ocaml") reason-mode)
-                                 . ("ocamllsp"))
-                                ((ruby-mode ruby-ts-mode)
-                                 . ("solargraph" "socket" "--port" :autoport))
-                                (haskell-mode
-                                 . ("haskell-language-server-wrapper" "--lsp"))
-                                (elm-mode . ("elm-language-server"))
-                                (mint-mode . ("mint" "ls"))
-                                (kotlin-mode . ("kotlin-language-server"))
-                                ((go-mode go-dot-mod-mode go-dot-work-mode go-ts-mode go-mod-ts-mode)
-                                 . ("gopls"))
-                                ((R-mode ess-r-mode) . ("R" "--slave" "-e"
-                                                        "languageserver::run()"))
-                                ((java-mode java-ts-mode) . ("jdtls"))
-                                ((dart-mode dart-ts-mode)
-                                 . ("dart" "language-server"
-                                    "--client-id" "emacs.eglot-dart"))
-                                ((elixir-mode elixir-ts-mode heex-ts-mode)
-                                 . ,(if (and (fboundp 'w32-shell-dos-semantics)
-                                             (w32-shell-dos-semantics))
-                                        '("language_server.bat")
-                                      (eglot-alternatives
-                                       '("language_server.sh" "start_lexical.sh"))))
-                                (ada-mode . ("ada_language_server"))
-                                (scala-mode . ,(eglot-alternatives
-                                                '("metals" "metals-emacs")))
-                                (racket-mode . ("racket" "-l" "racket-langserver"))
-                                ((tex-mode context-mode texinfo-mode bibtex-mode)
-                                 . ,(eglot-alternatives '("digestif" "texlab")))
-                                (erlang-mode . ("erlang_ls" "--transport" "stdio"))
-                                ((yaml-ts-mode yaml-mode) . ("yaml-language-server" "--stdio"))
-                                (nix-mode . ,(eglot-alternatives '("nil" "rnix-lsp" "nixd")))
-                                (nickel-mode . ("nls"))
-                                (gdscript-mode . ("localhost" 6008))
-                                ((fortran-mode f90-mode) . ("fortls"))
-                                (futhark-mode . ("futhark" "lsp"))
-                                ((lua-mode lua-ts-mode) . ,(eglot-alternatives
-                                                            '("lua-language-server" "lua-lsp")))
-                                (zig-mode . ("zls"))
-                                ((css-mode css-ts-mode)
-                                 . ,(eglot-alternatives '(("vscode-css-language-server" "--stdio")
-                                                          ("css-languageserver" "--stdio"))))
-                                (html-mode . ,(eglot-alternatives '(("vscode-html-language-server" "--stdio") ("html-languageserver" "--stdio"))))
-                                ((dockerfile-mode dockerfile-ts-mode) . ("docker-langserver" "--stdio"))
-                                ((clojure-mode clojurescript-mode clojurec-mode clojure-ts-mode)
-                                 . ("clojure-lsp"))
-                                ((csharp-mode csharp-ts-mode)
-                                 . ,(eglot-alternatives
-                                     '(("omnisharp" "-lsp")
-                                       ("csharp-ls"))))
-                                (purescript-mode . ("purescript-language-server" "--stdio"))
-                                ((perl-mode cperl-mode) . ("perl" "-MPerl::LanguageServer" "-e" "Perl::LanguageServer::run"))
-                                (markdown-mode
-                                 . ,(eglot-alternatives
-                                     '(("marksman" "server")
-                                       ("vscode-markdown-language-server" "--stdio"))))
-                                (graphviz-dot-mode . ("dot-language-server" "--stdio"))
-                                (terraform-mode . ("terraform-ls" "serve"))
-                                ((uiua-ts-mode uiua-mode) . ("uiua" "lsp")))
+(defvar eglot-server-programs
+  ;; FIXME: Maybe this info should be distributed into the major modes
+  ;; themselves where they could set a buffer-local `eglot-server-program'
+  ;; instead of keeping this database centralized.
+  ;; FIXME: With `derived-mode-add-parents' in Emacs≥30, some of
+  ;; those entries can be simplified, but we keep them for when
+  ;; `eglot.el' is installed via GNU ELPA in an older Emacs.
+  `(((rust-ts-mode rust-mode) . ("rust-analyzer"))
+    ((cmake-mode cmake-ts-mode) . ("cmake-language-server"))
+    (vimrc-mode . ("vim-language-server" "--stdio"))
+    ((python-mode python-ts-mode)
+     . ,(eglot-alternatives
+         '("pylsp" "pyls" ("pyright-langserver" "--stdio")
+           "jedi-language-server" "ruff-lsp")))
+    ((js-json-mode json-mode json-ts-mode)
+     . ,(eglot-alternatives '(("vscode-json-language-server" "--stdio")
+                              ("vscode-json-languageserver" "--stdio")
+                              ("json-languageserver" "--stdio"))))
+    (((js-mode :language-id "javascript")
+      (js-ts-mode :language-id "javascript")
+      (tsx-ts-mode :language-id "typescriptreact")
+      (typescript-ts-mode :language-id "typescript")
+      (typescript-mode :language-id "typescript"))
+     . ("typescript-language-server" "--stdio"))
+    ((bash-ts-mode sh-mode) . ("bash-language-server" "start"))
+    ((php-mode phps-mode)
+     . ,(eglot-alternatives
+         '(("phpactor" "language-server")
+           ("php" "vendor/felixfbecker/language-server/bin/php-language-server.php"))))
+    ((c-mode c-ts-mode c++-mode c++-ts-mode objc-mode)
+     . ,(eglot-alternatives
+         '("clangd" "ccls")))
+    (((caml-mode :language-id "ocaml")
+      (tuareg-mode :language-id "ocaml") reason-mode)
+     . ("ocamllsp"))
+    ((ruby-mode ruby-ts-mode)
+     . ("solargraph" "socket" "--port" :autoport))
+    (haskell-mode
+     . ("haskell-language-server-wrapper" "--lsp"))
+    (elm-mode . ("elm-language-server"))
+    (mint-mode . ("mint" "ls"))
+    (kotlin-mode . ("kotlin-language-server"))
+    ((go-mode go-dot-mod-mode go-dot-work-mode go-ts-mode go-mod-ts-mode)
+     . ("gopls"))
+    ((R-mode ess-r-mode) . ("R" "--slave" "-e"
+                            "languageserver::run()"))
+    ((java-mode java-ts-mode) . ("jdtls"))
+    ((dart-mode dart-ts-mode)
+     . ("dart" "language-server"
+        "--client-id" "emacs.eglot-dart"))
+    ((elixir-mode elixir-ts-mode heex-ts-mode)
+     . ,(if (and (fboundp 'w32-shell-dos-semantics)
+                 (w32-shell-dos-semantics))
+            '("language_server.bat")
+          (eglot-alternatives
+           '("language_server.sh" "start_lexical.sh"))))
+    (ada-mode . ("ada_language_server"))
+    (scala-mode . ,(eglot-alternatives
+                    '("metals" "metals-emacs")))
+    (racket-mode . ("racket" "-l" "racket-langserver"))
+    ((tex-mode context-mode texinfo-mode bibtex-mode)
+     . ,(eglot-alternatives '("digestif" "texlab")))
+    (erlang-mode . ("erlang_ls" "--transport" "stdio"))
+    ((yaml-ts-mode yaml-mode) . ("yaml-language-server" "--stdio"))
+    (nix-mode . ,(eglot-alternatives '("nil" "rnix-lsp" "nixd")))
+    (nickel-mode . ("nls"))
+    (gdscript-mode . ("localhost" 6008))
+    ((fortran-mode f90-mode) . ("fortls"))
+    (futhark-mode . ("futhark" "lsp"))
+    ((lua-mode lua-ts-mode) . ,(eglot-alternatives
+                                '("lua-language-server" "lua-lsp")))
+    (zig-mode . ("zls"))
+    ((css-mode css-ts-mode)
+     . ,(eglot-alternatives '(("vscode-css-language-server" "--stdio")
+                              ("css-languageserver" "--stdio"))))
+    (html-mode . ,(eglot-alternatives
+                   '(("vscode-html-language-server" "--stdio")
+                     ("html-languageserver" "--stdio"))))
+    ((dockerfile-mode dockerfile-ts-mode) . ("docker-langserver" "--stdio"))
+    ((clojure-mode clojurescript-mode clojurec-mode clojure-ts-mode)
+     . ("clojure-lsp"))
+    ((csharp-mode csharp-ts-mode)
+     . ,(eglot-alternatives
+         '(("omnisharp" "-lsp")
+           ("csharp-ls"))))
+    (purescript-mode . ("purescript-language-server" "--stdio"))
+    ((perl-mode cperl-mode)
+     . ("perl" "-MPerl::LanguageServer" "-e" "Perl::LanguageServer::run"))
+    (markdown-mode
+     . ,(eglot-alternatives
+         '(("marksman" "server")
+           ("vscode-markdown-language-server" "--stdio"))))
+    (graphviz-dot-mode . ("dot-language-server" "--stdio"))
+    (terraform-mode . ("terraform-ls" "serve"))
+    ((uiua-ts-mode uiua-mode) . ("uiua" "lsp")))
   "How the command `eglot' guesses the server to start.
 An association list of (MAJOR-MODE . CONTACT) pairs.  MAJOR-MODE
 identifies the buffers that are to be managed by a specific
diff --git a/lisp/progmodes/elixir-ts-mode.el b/lisp/progmodes/elixir-ts-mode.el
index b493195eedd..9a819f5df0c 100644
--- a/lisp/progmodes/elixir-ts-mode.el
+++ b/lisp/progmodes/elixir-ts-mode.el
@@ -745,6 +745,8 @@ elixir-ts-mode
     (treesit-major-mode-setup)
     (setq-local syntax-propertize-function #'elixir-ts--syntax-propertize)))
 
+(derived-mode-add-parents 'elixir-ts-mode '(elixir-mode))
+
 (if (treesit-ready-p 'elixir)
     (progn
       (add-to-list 'auto-mode-alist '("\\.elixir\\'" . elixir-ts-mode))
diff --git a/lisp/progmodes/go-ts-mode.el b/lisp/progmodes/go-ts-mode.el
index 65adc1c55ea..e16459cd975 100644
--- a/lisp/progmodes/go-ts-mode.el
+++ b/lisp/progmodes/go-ts-mode.el
@@ -261,6 +261,8 @@ go-ts-mode
 
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'go-ts-mode '(go-mode))
+
 (if (treesit-ready-p 'go)
     (add-to-list 'auto-mode-alist '("\\.go\\'" . go-ts-mode)))
 
@@ -437,6 +439,9 @@ go-mod-ts-mode
 
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'go-mode-ts-mode '(go-mod-mode))
+
+
 (if (treesit-ready-p 'gomod)
     (add-to-list 'auto-mode-alist '("/go\\.mod\\'" . go-mod-ts-mode)))
 
diff --git a/lisp/progmodes/gud.el b/lisp/progmodes/gud.el
index be6357f4139..8b911918e86 100644
--- a/lisp/progmodes/gud.el
+++ b/lisp/progmodes/gud.el
@@ -3673,6 +3673,9 @@ gud-tooltip-mode
 (defcustom gud-tooltip-modes '( gud-mode c-mode c++-mode fortran-mode
 				python-mode c-ts-mode c++-ts-mode
                                 python-ts-mode)
+  ;; FIXME: Currently the check is made via
+  ;; `(memq major-mode gud-tooltip-modes)' so it doesn't pay attention
+  ;; to the mode hierarchy.
   "List of modes for which to enable GUD tooltips."
   :type '(repeat (symbol :tag "Major mode"))
   :group 'tooltip)
diff --git a/lisp/progmodes/heex-ts-mode.el b/lisp/progmodes/heex-ts-mode.el
index 7b53a44deb2..702610bc1eb 100644
--- a/lisp/progmodes/heex-ts-mode.el
+++ b/lisp/progmodes/heex-ts-mode.el
@@ -177,6 +177,8 @@ heex-ts-mode
 
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'heex-ts-mode '(heex-mode))
+
 (if (treesit-ready-p 'heex)
     ;; Both .heex and the deprecated .leex files should work
     ;; with the tree-sitter-heex grammar.
diff --git a/lisp/progmodes/hideshow.el b/lisp/progmodes/hideshow.el
index b181b21118f..b47a505f64f 100644
--- a/lisp/progmodes/hideshow.el
+++ b/lisp/progmodes/hideshow.el
@@ -254,6 +254,9 @@ hs-isearch-open
 
 ;;;###autoload
 (defvar hs-special-modes-alist
+  ;; FIXME: Currently the check is made via
+  ;; `(assoc major-mode hs-special-modes-alist)' so it doesn't pay attention
+  ;; to the mode hierarchy.
   (mapcar #'purecopy
   '((c-mode "{" "}" "/[*/]" nil nil)
     (c-ts-mode "{" "}" "/[*/]" nil nil)
diff --git a/lisp/progmodes/java-ts-mode.el b/lisp/progmodes/java-ts-mode.el
index 0b1ac49b99f..51e0eeef79a 100644
--- a/lisp/progmodes/java-ts-mode.el
+++ b/lisp/progmodes/java-ts-mode.el
@@ -401,6 +401,8 @@ java-ts-mode
                 ("Method" "\\`method_declaration\\'" nil nil)))
   (treesit-major-mode-setup))
 
+(derived-mode-add-parents 'java-ts-mode '(java-mode))
+
 (if (treesit-ready-p 'java)
     (add-to-list 'auto-mode-alist '("\\.java\\'" . java-ts-mode)))
 
diff --git a/lisp/progmodes/js.el b/lisp/progmodes/js.el
index 0115feb0e97..2420bdde50a 100644
--- a/lisp/progmodes/js.el
+++ b/lisp/progmodes/js.el
@@ -3898,6 +3898,8 @@ js-ts-mode
     (add-to-list 'auto-mode-alist
                  '("\\(\\.js[mx]\\|\\.har\\)\\'" . js-ts-mode))))
 
+(derived-mode-add-parents 'js-ts-mode '(js-mode))
+
 (defvar js-ts--s-p-query
   (when (treesit-available-p)
     (treesit-query-compile 'javascript
diff --git a/lisp/progmodes/json-ts-mode.el b/lisp/progmodes/json-ts-mode.el
index 32bc10bbda9..1fb96555010 100644
--- a/lisp/progmodes/json-ts-mode.el
+++ b/lisp/progmodes/json-ts-mode.el
@@ -164,6 +164,8 @@ json-ts-mode
 
   (treesit-major-mode-setup))
 
+(derived-mode-add-parents 'json-ts-mode '(json-mode))
+
 (if (treesit-ready-p 'json)
     (add-to-list 'auto-mode-alist
                  '("\\.json\\'" . json-ts-mode)))
diff --git a/lisp/progmodes/lua-ts-mode.el b/lisp/progmodes/lua-ts-mode.el
index 3b600f59521..e81f05ff3cb 100644
--- a/lisp/progmodes/lua-ts-mode.el
+++ b/lisp/progmodes/lua-ts-mode.el
@@ -757,6 +757,8 @@ lua-ts-mode
 
   (add-hook 'flymake-diagnostic-functions #'lua-ts-flymake-luacheck nil 'local))
 
+(derived-mode-add-parents 'lua-ts-mode '(lua-mode))
+
 (when (treesit-ready-p 'lua)
   (add-to-list 'auto-mode-alist '("\\.lua\\'" . lua-ts-mode)))
 
diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index 1148da11a06..94a133b0688 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -6995,6 +6995,8 @@ python-ts-mode
     (add-to-list 'auto-mode-alist '("\\.py[iw]?\\'" . python-ts-mode))
     (add-to-list 'interpreter-mode-alist '("python[0-9.]*" . python-ts-mode))))
 
+(derived-mode-add-parents 'python-ts-mode '(python-mode))
+
 ;;; Completion predicates for M-x
 ;; Commands that only make sense when editing Python code.
 (dolist (sym '(python-add-import
diff --git a/lisp/progmodes/ruby-ts-mode.el b/lisp/progmodes/ruby-ts-mode.el
index 598eaa461ff..7282d43e091 100644
--- a/lisp/progmodes/ruby-ts-mode.el
+++ b/lisp/progmodes/ruby-ts-mode.el
@@ -1196,6 +1196,8 @@ ruby-ts-mode
 
   (setq-local syntax-propertize-function #'ruby-ts--syntax-propertize))
 
+(derived-mode-add-parents 'ruby-ts-mode '(ruby-mode))
+
 (if (treesit-ready-p 'ruby)
     ;; Copied from ruby-mode.el.
     (add-to-list 'auto-mode-alist
diff --git a/lisp/progmodes/rust-ts-mode.el b/lisp/progmodes/rust-ts-mode.el
index c5fc57cc374..c67ac43e4d0 100644
--- a/lisp/progmodes/rust-ts-mode.el
+++ b/lisp/progmodes/rust-ts-mode.el
@@ -474,6 +474,8 @@ rust-ts-mode
 
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'rust-ts-mode '(rust-mode))
+
 (if (treesit-ready-p 'rust)
     (add-to-list 'auto-mode-alist '("\\.rs\\'" . rust-ts-mode)))
 
diff --git a/lisp/progmodes/sh-script.el b/lisp/progmodes/sh-script.el
index 0562415b4e5..e7e08fba1c9 100644
--- a/lisp/progmodes/sh-script.el
+++ b/lisp/progmodes/sh-script.el
@@ -1638,6 +1638,8 @@ bash-ts-mode
     (setq-local treesit-defun-type-regexp "function_definition")
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'bash-ts-mode '(sh-mode))
+
 (advice-add 'bash-ts-mode :around #'sh--redirect-bash-ts-mode
             ;; Give it lower precedence than normal advice, so other
             ;; advices take precedence over it.
diff --git a/lisp/progmodes/typescript-ts-mode.el b/lisp/progmodes/typescript-ts-mode.el
index e9c6afff440..83a3baaf5ef 100644
--- a/lisp/progmodes/typescript-ts-mode.el
+++ b/lisp/progmodes/typescript-ts-mode.el
@@ -491,6 +491,8 @@ typescript-ts-mode
 
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'typescript-ts-mode '(typescript-mode))
+
 (if (treesit-ready-p 'typescript)
     (add-to-list 'auto-mode-alist '("\\.ts\\'" . typescript-ts-mode)))
 
@@ -548,6 +550,8 @@ tsx-ts-mode
 
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'tsx-ts-mode '(tsx-mode))
+
 (defvar typescript-ts--s-p-query
   (when (treesit-available-p)
     (treesit-query-compile 'typescript
diff --git a/lisp/textmodes/css-mode.el b/lisp/textmodes/css-mode.el
index 425f3ec8a30..f5a20e0ca0e 100644
--- a/lisp/textmodes/css-mode.el
+++ b/lisp/textmodes/css-mode.el
@@ -1830,6 +1830,8 @@ css-ts-mode
 
     (add-to-list 'auto-mode-alist '("\\.css\\'" . css-ts-mode))))
 
+(derived-mode-add-parents 'css-ts-mode '(css-mode))
+
 ;;;###autoload
 (define-derived-mode css-mode css-base-mode "CSS"
   "Major mode to edit Cascading Style Sheets (CSS).
diff --git a/lisp/textmodes/html-ts-mode.el b/lisp/textmodes/html-ts-mode.el
index 301f3e8791c..bf6c1307e96 100644
--- a/lisp/textmodes/html-ts-mode.el
+++ b/lisp/textmodes/html-ts-mode.el
@@ -123,6 +123,8 @@ html-ts-mode
               '(("Element" "\\`tag_name\\'" nil nil)))
   (treesit-major-mode-setup))
 
+(derived-mode-add-parents 'html-ts-mode '(html-mode))
+
 (if (treesit-ready-p 'html)
     (add-to-list 'auto-mode-alist '("\\.html\\'" . html-ts-mode)))
 
diff --git a/lisp/textmodes/toml-ts-mode.el b/lisp/textmodes/toml-ts-mode.el
index 1ba410045f5..1b621032f8a 100644
--- a/lisp/textmodes/toml-ts-mode.el
+++ b/lisp/textmodes/toml-ts-mode.el
@@ -153,6 +153,8 @@ toml-ts-mode
 
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'toml-ts-mode '(toml-mode))
+
 (if (treesit-ready-p 'toml)
     (add-to-list 'auto-mode-alist '("\\.toml\\'" . toml-ts-mode)))
 
diff --git a/lisp/textmodes/yaml-ts-mode.el b/lisp/textmodes/yaml-ts-mode.el
index 08fe4c49733..dc702dff790 100644
--- a/lisp/textmodes/yaml-ts-mode.el
+++ b/lisp/textmodes/yaml-ts-mode.el
@@ -165,6 +165,8 @@ yaml-ts-mode
 
     (treesit-major-mode-setup)))
 
+(derived-mode-add-parents 'yaml-ts-mode '(yaml-mode))
+
 (if (treesit-ready-p 'yaml)
     (add-to-list 'auto-mode-alist '("\\.ya?ml\\'" . yaml-ts-mode)))