feat(config-toggle): add scope-specific variable reader helper

functions/__config_toggle_get_val.fish

@@ -0,0 +1,50 @@
+# Copyright (C) 2026 Rootiest
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+# SYNOPSIS
+#   __config_toggle_get_val <varname> <scope>
+#
+# DESCRIPTION
+#   Returns the current value of a named variable in the specified scope by
+#   parsing `set --show` output. Outputs "on", "off", or "DEFAULT" (when
+#   the variable is not set in that scope). Scope "session" maps to "global"
+#   in fish's internal terminology.
+#
+# ARGUMENTS
+#   varname  Variable name without $ prefix
+#   scope    "universal" or "session"
+#
+# RETURNS
+#   0  Always; prints "on", "off", or "DEFAULT" to stdout
+#
+# EXAMPLE
+#   set result (__config_toggle_get_val __fish_config_op_aliases universal)
+#   # result == "on" | "off" | "DEFAULT"
+function __config_toggle_get_val
+    set -l varname $argv[1]
+    set -l scope $argv[2]
+
+    set -l scope_kw $scope
+    if test $scope = session
+        set scope_kw global
+    end
+
+    set -l found 0
+    for line in (set --show $varname 2>/dev/null)
+        if string match -q "*$scope_kw scope*" $line
+            set found 1
+            continue
+        end
+        if test $found -eq 1
+            set found 0
+            set -l val (string replace -r '^\$[^\[]+\[1\]: \|(.+)\|$' '$1' $line 2>/dev/null)
+            if test -n "$val" -a "$val" != $line
+                echo $val
+                return 0
+            end
+        end
+    end
+
+    echo DEFAULT
+    return 0
+end