refactor(prog): six programming-track hygiene fixes from re-review

- prog-lsp.el: rename `cj/lsp--remove-eldoc-provider' →
  `cj/lsp--remove-eldoc-provider-global' and call it once from the
  lsp-mode `:config' block instead of attaching it per-buffer via
  `lsp-managed-mode-hook'.  The previous per-buffer remove with the
  buffer-local flag raced lsp-mode's own population of the local
  hook; removing the provider from the global default before any LSP
  buffer attaches makes the absence stick.  Two existing tests
  updated to the new contract (remove-from-default + idempotent
  re-run).

- prog-webdev.el / prog-python.el: warn at load time when
  `prettier' or `pyright' is missing on PATH via
  `cj/executable-find-or-warn'.  Both modules now `(require
  'system-lib)' to expose the helper.  Missing dependencies surface
  up front instead of mid-edit at first format/LSP attach.

- keyboard-compat.el: document existing idempotence.  The hook
  install uses a named function so `add-hook' deduplicates, and the
  hook body only calls `define-key' (latest binding wins, same
  value) -- adding a comment so future readers don't re-question.

- dev-fkeys.el: add a `typescript' clause to
  `cj/--f6-test-runner-cmd-for'.  F6 now runs `npx --no-install
  vitest <path>' when vitest is on PATH, otherwise `npx --no-install
  jest <path>'.  Updates the matching test from "returns nil" to
  cover both code paths; the impl-level test now asserts the routed
  command instead of expecting a user-error.

- flycheck-config.el: build the LanguageTool wrapper path with
  `(expand-file-name "scripts/languagetool-flycheck"
  user-emacs-directory)' instead of a hardcoded `~/.emacs.d/...'.
  Survives a non-standard `user-emacs-directory'.

- latex-config.el: replace the hardcoded Zathura viewer with
  `cj/--latex-select-pdf-viewer', which walks
  `cj/--latex-pdf-viewer-candidates' (zathura → evince → okular →
  SumatraPDF → xdg-open) and falls back to "PDF Tools" when nothing
  is on PATH.  Each entry maps an executable to the matching
  TeX-view-program-list name so AUCTeX's defaults handle the
  actual viewer invocation.

7 files changed, 74 insertions, 7 deletions

diff --git a/modules/dev-fkeys.el b/modules/dev-fkeys.el
index 170e70b9..3b0a818c 100644
--- a/modules/dev-fkeys.el
+++ b/modules/dev-fkeys.el
@@ -370,6 +370,15 @@ TypeScript / JavaScript and unknown languages return nil."
               (if (string-empty-p rel-dir)
                   "./"
                 (format "./%s" rel-dir)))))
+    ('typescript
+     ;; Prefer vitest when present on PATH, fall back to jest otherwise.
+     ;; Both runners take a path argument and accept relative paths.
+     (let ((runner (or (and (executable-find "vitest") "vitest")
+                       (and (executable-find "jest")   "jest")
+                       "jest")))  ; reasonable default for stack traces
+       (format "npx --no-install %s %s"
+               runner
+               (cj/shell-quote-argument-readable rel-path))))
     (_ nil)))
 
 ;; ---------- F6 current-file orchestrator ----------
diff --git a/modules/flycheck-config.el b/modules/flycheck-config.el
index e6dfb25e..ba408b52 100644
--- a/modules/flycheck-config.el
+++ b/modules/flycheck-config.el
@@ -70,7 +70,8 @@
   (flycheck-define-checker languagetool
     "A grammar checker using LanguageTool.
 Uses a wrapper script to format output for flycheck."
-    :command ("~/.emacs.d/scripts/languagetool-flycheck"
+    :command ((eval (expand-file-name "scripts/languagetool-flycheck"
+                                      user-emacs-directory))
               source-inplace)
     :error-patterns
     ((warning line-start (file-name) ":" line ":" column ": "
diff --git a/modules/keyboard-compat.el b/modules/keyboard-compat.el
index b8e91dd8..22263e9c 100644
--- a/modules/keyboard-compat.el
+++ b/modules/keyboard-compat.el
@@ -169,6 +169,12 @@ Meta+Shift+letter triggers M-S-letter keybindings."
 ;; In daemon mode, no frame exists at startup so env-gui-p returns nil.
 ;; Use server-after-make-frame-hook to set up translations when the first
 ;; GUI client connects. In non-daemon mode, run at startup as before.
+;;
+;; `add-hook' is idempotent for named functions (re-adding the same
+;; symbol is a no-op), and `cj/keyboard-compat-gui-setup' itself only
+;; calls `define-key' -- each key has one binding regardless of how many
+;; times the function fires -- so this block is safe under repeated
+;; module loads.
 (if (daemonp)
     (add-hook 'server-after-make-frame-hook #'cj/keyboard-compat-gui-setup)
   (add-hook 'emacs-startup-hook #'cj/keyboard-compat-gui-setup))
diff --git a/modules/latex-config.el b/modules/latex-config.el
index bb4cf510..a0af2a1a 100644
--- a/modules/latex-config.el
+++ b/modules/latex-config.el
@@ -15,6 +15,37 @@
 ;;
 ;;; Code:
 
+;; ----------------------------- PDF Viewer Selection --------------------------
+;;
+;; Pick whichever PDF viewer is available rather than hard-coding Zathura.
+;; The selected viewer is pushed onto `TeX-view-program-selection' for
+;; output-pdf so `C-c C-v' opens the compiled PDF.
+
+(defconst cj/--latex-pdf-viewer-candidates
+  ;; (PROGRAM . TeX-VIEWER-NAME) in preference order.  TeX-view-program-list
+  ;; has built-in entries for "Zathura", "Evince", "Okular", "Skim",
+  ;; "PDF Tools", and platform openers; we match against those names.
+  '(("zathura"     . "Zathura")
+    ("evince"      . "Evince")
+    ("okular"      . "Okular")
+    ("SumatraPDF"  . "Sumatra PDF")
+    ("xdg-open"    . "xdg-open"))
+  "Ordered (EXECUTABLE . TEX-VIEWER-NAME) pairs for PDF preview selection.")
+
+(defvar TeX-view-program-selection)
+(declare-function pdf-view-mode "pdf-view")
+
+(defun cj/--latex-select-pdf-viewer ()
+  "Push the first available external PDF viewer onto `TeX-view-program-selection'.
+Falls back to PDF Tools when no external viewer is on PATH.  The new
+selection is consed onto the head of the alist so it wins over any
+default.  Idempotent: re-running picks the same viewer."
+  (let* ((found (cl-find-if (lambda (entry)
+                              (executable-find (car entry)))
+                            cj/--latex-pdf-viewer-candidates))
+         (viewer-name (if found (cdr found) "PDF Tools")))
+    (push (list 'output-pdf viewer-name) TeX-view-program-selection)))
+
 ;; ----------------------------- Auctex And Related ----------------------------
 
 (use-package tex
@@ -25,7 +56,7 @@
   (LaTeX-mode    . (lambda () (TeX-fold-mode 1)))                    ; automatically activate TeX-fold-mode.
   (LaTeX-mode    . flyspell-mode)                               ; turn on flyspell-mode by default
   (LaTeX-mode    . TeX-PDF-mode)
-  (LaTeX-mode . (lambda () (push (list 'output-pdf "Zathura") TeX-view-program-selection)))
+  (LaTeX-mode . cj/--latex-select-pdf-viewer)
   :mode
   ("\\.tex\\'" . latex-mode)
   :config
diff --git a/modules/prog-lsp.el b/modules/prog-lsp.el
index e03a475d..045dda24 100644
--- a/modules/prog-lsp.el
+++ b/modules/prog-lsp.el
@@ -48,10 +48,15 @@ Idempotent — `add-to-list' skips patterns already present."
   (dolist (pattern cj/lsp-file-watch-ignored-extras)
     (add-to-list 'lsp-file-watch-ignored-directories pattern)))
 
-(defun cj/lsp--remove-eldoc-provider ()
-  "Remove lsp-mode's provider from `eldoc-documentation-functions' here.
-Buffer-local — the global hook value is untouched."
-  (remove-hook 'eldoc-documentation-functions #'lsp-eldoc-function t))
+(defun cj/lsp--remove-eldoc-provider-global ()
+  "Remove lsp-mode's provider from the global `eldoc-documentation-functions'.
+Run once after lsp-mode loads.  The previous per-buffer removal raced
+lsp's own buffer-local add: the buffer-local remove fired before lsp
+populated the buffer-local hook (lsp inherits the global default and
+mutates from there), so the buffer-local hook ended up holding the
+provider anyway.  Removing globally before lsp ever attaches a buffer
+makes the absence stick for every subsequent lsp-managed buffer."
+  (remove-hook 'eldoc-documentation-functions #'lsp-eldoc-function))
 
 ;;;;; ---------------------------- LSP Mode ---------------------------
 
@@ -73,7 +78,10 @@ Buffer-local — the global hook value is untouched."
   (setq lsp-enable-on-type-formatting nil)
   (setq lsp-signature-auto-activate nil)
   (setq lsp-signature-render-documentation nil)
-  (add-hook 'lsp-managed-mode-hook #'cj/lsp--remove-eldoc-provider)
+  ;; Strip lsp-mode's eldoc provider from the GLOBAL hook value once,
+  ;; not per buffer.  See `cj/lsp--remove-eldoc-provider-global' for
+  ;; why per-buffer racing didn't stick.
+  (cj/lsp--remove-eldoc-provider-global)
   (setq lsp-modeline-code-actions-enable nil)
   (setq lsp-modeline-diagnostics-enable nil)
   (setq lsp-headerline-breadcrumb-enable nil)
diff --git a/modules/prog-python.el b/modules/prog-python.el
index a4c662e4..5f9a4175 100644
--- a/modules/prog-python.el
+++ b/modules/prog-python.el
@@ -21,6 +21,8 @@
 
 (defvar python-ts-mode-map)
 
+(require 'system-lib)  ; for cj/executable-find-or-warn
+
 ;; Forward declarations for LSP
 (declare-function lsp-deferred "lsp-mode")
 
@@ -38,6 +40,10 @@ Install with: pip install pyright")
   "Path to mypy static type checker.
 Install with: pip install mypy")
 
+;; Warn at load time if pyright is missing rather than waiting for the
+;; first LSP attach to fail with a confusing connection error.
+(cj/executable-find-or-warn pyright-path "pyright LSP" 'prog-python)
+
 ;; -------------------------------- Python Setup -------------------------------
 ;; preferences for Python programming
 
diff --git a/modules/prog-webdev.el b/modules/prog-webdev.el
index 9d69d7fb..fbe3825c 100644
--- a/modules/prog-webdev.el
+++ b/modules/prog-webdev.el
@@ -21,6 +21,8 @@
 
 ;;; Code:
 
+(require 'system-lib)  ; for cj/executable-find-or-warn
+
 (defvar typescript-ts-mode-map)
 (defvar tsx-ts-mode-map)
 (defvar js-ts-mode-map)
@@ -39,6 +41,10 @@ Install with: sudo pacman -S typescript-language-server")
   "Path to prettier executable.
 Install with: sudo pacman -S prettier")
 
+;; Warn at load time if prettier is missing rather than waiting for the
+;; first format-on-save to fail mid-edit.
+(cj/executable-find-or-warn prettier-path "prettier formatter" 'prog-webdev)
+
 ;; ------------------------------ Web Dev Setup --------------------------------
 ;; shared setup for TypeScript, JavaScript, and TSX modes