feat(git): gitcfg, global git config through git itself

list, set, add and unset over git config --global. --fixed-value lets a
write touch one value of a multi-valued key. set and unset check the old
value is still there first: --replace-all with no match appends and exits
0, and the file may have changed in an editor since the page read it.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/desktop/modules/git/gitcfg b/desktop/modules/git/gitcfg
new file mode 100755
index 0000000..df955bf
--- /dev/null
+++ b/desktop/modules/git/gitcfg
@@ -0,0 +1,56 @@
+#!/bin/bash
+#
+# Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# The global git config, for the drawer's git page.
+#
+#   gitcfg list                    git config --global -z --list
+#   gitcfg set <key> <old> <new>   replace the one value equal to <old>
+#   gitcfg add <key> <value>       add a value
+#   gitcfg unset <key> <value>     remove the one value equal to <value>
+#
+# Every write goes through git config, so the file keeps its comments, layout
+# and quoting. --fixed-value makes a value a literal rather than a regex, so a
+# write touches one value of a multi-valued key, and the `--` before the key
+# keeps a leading dash an argument rather than an option.
+#
+# A write prints nothing on success. On failure it prints the reason on
+# stdout, for the page, and exits 1.
+
+set -u
+
+usage() {
+    printf 'usage: %s list | set <key> <old> <new> | add <key> <value> | unset <key> <value>\n' \
+           "${0##*/}" >&2
+    exit 2
+}
+
+g() {
+    local err
+    err="$(git config --global "$@" 2>&1)" || { printf '%s\n' "${err:-git config failed}"; exit 1; }
+}
+
+# --replace-all with no value equal to <old> appends <new> and succeeds, and
+# --unset of a missing value fails silently, so both check first: the file
+# may have changed in the editor since the page read it.
+has() {
+    git config --global --fixed-value --get-all -- "$1" "$2" >/dev/null \
+        || { printf '%s no longer holds that value\n' "$1"; exit 1; }
+}
+
+case "${1:-}" in
+    list)  [[ $# -eq 1 ]] || usage; exec git config --global -z --list ;;
+    set)   [[ $# -eq 4 ]] || usage; has "$2" "$3"; g --fixed-value --replace-all -- "$2" "$4" "$3" ;;
+    add)   [[ $# -eq 3 ]] || usage; g --add -- "$2" "$3" ;;
+    unset) [[ $# -eq 3 ]] || usage; has "$2" "$3"; g --fixed-value --unset -- "$2" "$3" ;;
+    *)     usage ;;
+esac