LaTeX

(use-package auctex
  :defer t
  :straight (:build t)
  :hook (tex-mode . lsp-deferred)
  :hook (latex-mode . lsp-deferred)
  :init
  (setq TeX-command-default   (if (executable-find "latexmk") "LatexMk" "LaTeX")
        TeX-engine            (if (executable-find "xetex")   'xetex    'default)
        TeX-auto-save                     t
        TeX-parse-self                    t
        TeX-syntactic-comment             t
        TeX-auto-local                    ".auctex-auto"
        TeX-style-local                   ".auctex-style"
        TeX-source-correlate-mode         t
        TeX-source-correlate-method       'synctex
        TeX-source-correlate-start-server nil
        TeX-electric-sub-and-superscript  t
        TeX-fill-break-at-separators      nil
        TeX-save-query                    t)
  :config
  (setq font-latex-match-reference-keywords
        '(;; BibLaTeX.
          ("printbibliography" "[{") ("addbibresource" "[{")
          ;; Standard commands.
          ("cite" "[{")       ("citep" "[{")
          ("citet" "[{")      ("Cite" "[{")
          ("parencite" "[{")  ("Parencite" "[{")
          ("footcite" "[{")   ("footcitetext" "[{")
          ;; Style-specific commands.
          ("textcite" "[{")   ("Textcite" "[{")
          ("smartcite" "[{")  ("Smartcite" "[{")
          ("cite*" "[{")      ("parencite*" "[{")
          ("supercite" "[{")
          ;; Qualified citation lists.
          ("cites" "[{")      ("Cites" "[{")
          ("parencites" "[{") ("Parencites" "[{")
          ("footcites" "[{")  ("footcitetexts" "[{")
          ("smartcites" "[{") ("Smartcites" "[{")
          ("textcites" "[{")  ("Textcites" "[{")
          ("supercites" "[{")
          ;; Style-independent commands.
          ("autocite" "[{")   ("Autocite" "[{")
          ("autocite*" "[{")  ("Autocite*" "[{")
          ("autocites" "[{")  ("Autocites" "[{")
          ;; Text commands.
          ("citeauthor" "[{") ("Citeauthor" "[{")
          ("citetitle" "[{")  ("citetitle*" "[{")
          ("citeyear" "[{")   ("citedate" "[{")
          ("citeurl" "[{")
          ;; Special commands.
          ("fullcite" "[{")
          ;; Cleveref.
          ("cref" "{")          ("Cref" "{")
          ("cpageref" "{")      ("Cpageref" "{")
          ("cpagerefrange" "{") ("Cpagerefrange" "{")
          ("crefrange" "{")     ("Crefrange" "{")
          ("labelcref" "{")))

  (setq font-latex-match-textual-keywords
        '(;; BibLaTeX brackets.
          ("parentext" "{") ("brackettext" "{")
          ("hybridblockquote" "[{")
          ;; Auxiliary commands.
          ("textelp" "{")   ("textelp*" "{")
          ("textins" "{")   ("textins*" "{")
          ;; Subcaption.
          ("subcaption" "[{")))

  (setq font-latex-match-variable-keywords
        '(;; Amsmath.
          ("numberwithin" "{")
          ;; Enumitem.
          ("setlist" "[{")     ("setlist*" "[{")
          ("newlist" "{")      ("renewlist" "{")
          ("setlistdepth" "{") ("restartlist" "{")
          ("crefname" "{")))
  (setq TeX-master t)
  (setcar (cdr (assoc "Check" TeX-command-list)) "chktex -v6 -H %s")
  (add-hook 'TeX-mode-hook (lambda ()
                             (setq ispell-parser          'tex
                                   fill-nobreak-predicate (cons #'texmathp fill-nobreak-predicate))))
  (add-hook 'TeX-mode-hook #'visual-line-mode)
  (add-hook 'TeX-update-style-hook #'rainbow-delimiters-mode)
  :general
  (phundrak/major-leader-key
    :packages 'lsp-mode
    :keymaps  '(latex-mode-map LaTeX-mode-map)
   "l"  '(:keymap lsp-command-map :which-key "lsp"))
  (phundrak/major-leader-key
    :packages 'auctex
    :keymaps  '(latex-mode-map LaTeX-mode-map)
    "v" '(TeX-view            :which-key "View")
    "c" '(TeX-command-run-all :which-key "Compile")
    "m" '(TeX-command-master  :which-key "Run a command")))

From Doom Emacs’ configuration:

(setq font-latex-match-reference-keywords
      '(;; BibLaTeX.
        ("printbibliography" "[{") ("addbibresource" "[{")
        ;; Standard commands.
        ("cite" "[{")       ("citep" "[{")
        ("citet" "[{")      ("Cite" "[{")
        ("parencite" "[{")  ("Parencite" "[{")
        ("footcite" "[{")   ("footcitetext" "[{")
        ;; Style-specific commands.
        ("textcite" "[{")   ("Textcite" "[{")
        ("smartcite" "[{")  ("Smartcite" "[{")
        ("cite*" "[{")      ("parencite*" "[{")
        ("supercite" "[{")
        ;; Qualified citation lists.
        ("cites" "[{")      ("Cites" "[{")
        ("parencites" "[{") ("Parencites" "[{")
        ("footcites" "[{")  ("footcitetexts" "[{")
        ("smartcites" "[{") ("Smartcites" "[{")
        ("textcites" "[{")  ("Textcites" "[{")
        ("supercites" "[{")
        ;; Style-independent commands.
        ("autocite" "[{")   ("Autocite" "[{")
        ("autocite*" "[{")  ("Autocite*" "[{")
        ("autocites" "[{")  ("Autocites" "[{")
        ;; Text commands.
        ("citeauthor" "[{") ("Citeauthor" "[{")
        ("citetitle" "[{")  ("citetitle*" "[{")
        ("citeyear" "[{")   ("citedate" "[{")
        ("citeurl" "[{")
        ;; Special commands.
        ("fullcite" "[{")
        ;; Cleveref.
        ("cref" "{")          ("Cref" "{")
        ("cpageref" "{")      ("Cpageref" "{")
        ("cpagerefrange" "{") ("Cpagerefrange" "{")
        ("crefrange" "{")     ("Crefrange" "{")
        ("labelcref" "{")))

(setq font-latex-match-textual-keywords
      '(;; BibLaTeX brackets.
        ("parentext" "{") ("brackettext" "{")
        ("hybridblockquote" "[{")
        ;; Auxiliary commands.
        ("textelp" "{")   ("textelp*" "{")
        ("textins" "{")   ("textins*" "{")
        ;; Subcaption.
        ("subcaption" "[{")))

(setq font-latex-match-variable-keywords
      '(;; Amsmath.
        ("numberwithin" "{")
        ;; Enumitem.
        ("setlist" "[{")     ("setlist*" "[{")
        ("newlist" "{")      ("renewlist" "{")
        ("setlistdepth" "{") ("restartlist" "{")
        ("crefname" "{")))

(use-package tex-mode
  :defer t
  :straight (:type built-in)
  :config
  (setq LaTeX-section-hook '(LaTeX-section-heading
                             LaTeX-section-title
                             LaTeX-section-toc
                             LaTeX-section-section
                             LaTeX-section-label)
        LaTeX-fill-break-at-separators nil
        LaTeX-item-indent              0))

(use-package preview
  :defer t
  :straight (:type built-in)
  :config
  (add-hook 'LaTeX-mode-hook #'LaTeX-preview-setup)
  (setq-default preview-scale 1.4
                preview-scale-function
                (lambda () (* (/ 10.0 (preview-document-pt)) preview-scale)))
  (setq preview-auto-cache-preamble nil)
  (phundrak/major-leader-key
    :packages 'auctex
    :keymaps '(latex-mode-map LaTeX-mode-map)
    "p" #'preview-at-point
    "P" #'preview-clearout-at-point))

(use-package cdlatex
  :defer t
  :after auctex
  :straight (:build t)
  :hook (LaTeX-mode . cdlatex-mode)
  :hook (org-mode   . org-cdlatex-mode)
  :config
  (setq cdlatex-use-dollar-to-ensure-math nil)
  :general
  (phundrak/major-leader-key
    :packages 'cdlatex
    :keymaps 'cdlatex-mode-map
    "$" nil
    "(" nil
    "{" nil
    "[" nil
    "|" nil
    "<" nil
    "^" nil
    "_" nil
    [(control return)] nil))

(use-package adaptive-wrap
  :defer t
  :after auctex
  :straight (:build t)
  :hook (LaTeX-mode . adaptative-wrap-prefix-mode)
  :init (setq-default adaptative-wrap-extra-indent 0))

(use-package auctex-latexmk
  :after auctex
  :defer t
  :straight (:build t)
  :init
  (setq auctex-latexmk-inherit-TeX-PDF-mode t)
  (add-hook 'LaTeX-mode (lambda () (setq TeX-command-default "LatexMk")))
  :config
  (auctex-latexmk-setup))

(use-package company-auctex
  :defer t
  :after (company auctex)
  :straight (:build t)
  :config
  (company-auctex-init))

(use-package company-math
  :defer t
  :straight (:build t)
  :after (company auctex)
  :config
  (defun my-latex-mode-setup ()
    (setq-local company-backends
                (append '((company-math-symbols-latex company-latex-commands))
                        company-backends)))
  (add-hook 'TeX-mode-hook #'my-latex-mode-setup))