refactor(system-lib): extract cj/shell-quote-argument-readable from dev-fkeys

Phase 2.2 of utility-consolidation. The "quote only when shell-unsafe characters appear, otherwise leave the argument readable" pattern was trapped in dev-fkeys as `cj/--f6-shell-quote-argument' alongside its `cj/--f6-shell-safe-argument-regexp' constant. Lift both into system-lib.el under their generic names; the F6 branding hid that the same shape is useful for any generated compile/test command where the surrounding line ends up in a *compilation* buffer the user reads.

Six Normal/Boundary tests cover safe inputs that pass through unchanged (alphanumeric paths, test regexes, `FLAG=value', `host:port'), unsafe inputs that get quoted (spaces, `$', `;', `&', backticks, `*'), and the empty-string boundary.

Migrate dev-fkeys's five callers to the new name and add `(require \='system-lib)' per the Phase 2 exit criterion.

2 files changed, 24 insertions, 17 deletions

diff --git a/modules/dev-fkeys.el b/modules/dev-fkeys.el
index c9a5fc13..170e70b9 100644
--- a/modules/dev-fkeys.el
+++ b/modules/dev-fkeys.el
@@ -41,6 +41,7 @@
 ;;; Code:
 
 (require 'cl-lib)
+(require 'system-lib)
 
 (declare-function projectile-compile-project "projectile" (arg))
 (declare-function projectile-run-project "projectile" (arg))
@@ -334,18 +335,6 @@ languages fall back to the basename without extension."
 
 ;; ---------- F6 test-runner command builder ----------
 
-(defconst cj/--f6-shell-safe-argument-regexp "\\`[[:alnum:]_./=+@%:,^-]+\\'"
-  "Regexp matching shell arguments safe to interpolate unchanged.")
-
-(defun cj/--f6-shell-quote-argument (argument)
-  "Quote ARGUMENT for shell command interpolation when needed.
-Simple file paths and test regexes are returned unchanged so existing
-F6 command strings stay readable. Arguments containing whitespace or
-shell-significant characters are escaped with `shell-quote-argument'."
-  (if (string-match-p cj/--f6-shell-safe-argument-regexp argument)
-      argument
-    (shell-quote-argument argument)))
-
 (defun cj/--f6-test-runner-cmd-for (language is-test-file rel-path stem rel-dir)
   "Return shell command to run tests for the given primitives, or nil.
 LANGUAGE is the language symbol; IS-TEST-FILE is non-nil when the file
@@ -364,20 +353,20 @@ TypeScript / JavaScript and unknown languages return nil."
          ;; The project Makefile prepends `tests/' to FILE, so pass the
          ;; basename only — passing the rel-path produces `tests/tests/...'.
          (format "make test-file FILE=%s"
-                 (cj/--f6-shell-quote-argument
+                 (cj/shell-quote-argument-readable
                   (file-name-nondirectory rel-path)))
        (format "make test-name TEST=%s"
-               (cj/--f6-shell-quote-argument
+               (cj/shell-quote-argument-readable
                 (format "^test-%s-" stem)))))
     ('python
      (if is-test-file
-         (format "pytest %s" (cj/--f6-shell-quote-argument rel-path))
+         (format "pytest %s" (cj/shell-quote-argument-readable rel-path))
        (format "pytest %s"
-               (cj/--f6-shell-quote-argument
+               (cj/shell-quote-argument-readable
                 (format "tests/test_%s.py" stem)))))
     ('go
      (format "go test %s"
-             (cj/--f6-shell-quote-argument
+             (cj/shell-quote-argument-readable
               (if (string-empty-p rel-dir)
                   "./"
                 (format "./%s" rel-dir)))))
diff --git a/modules/system-lib.el b/modules/system-lib.el
index f932353f..dc1f8316 100644
--- a/modules/system-lib.el
+++ b/modules/system-lib.el
@@ -36,6 +36,24 @@ keep working."
          :warning)
         nil)))
 
+(defconst cj/shell-safe-argument-regexp "\\`[[:alnum:]_./=+@%:,^-]+\\'"
+  "Regexp matching shell arguments safe to interpolate unchanged.
+Members of this character set survive shell parsing without quoting,
+so a command line containing only these characters in each argument
+remains both safe and readable.")
+
+(defun cj/shell-quote-argument-readable (argument)
+  "Quote ARGUMENT for shell command interpolation when needed.
+
+When ARGUMENT consists only of characters in `cj/shell-safe-argument-regexp'
+it is returned unchanged so the surrounding command stays human-readable
+(useful for compile/test command lines you'll inspect in *compilation*).
+Otherwise falls back to `shell-quote-argument' so the result is safe to
+interpolate."
+  (if (string-match-p cj/shell-safe-argument-regexp argument)
+      argument
+    (shell-quote-argument argument)))
+
 (defun cj/log-silently (format-string &rest args)
   "Append formatted message (FORMAT-STRING with ARGS) to *Messages* buffer.
 This does so without echoing in the minibuffer."