fix(git): refuse duplicate values, show list errors, Escape on Add

Review findings. With a key holding the same value twice, --fixed-value
--replace-all rewrote both and merged two rows into one, and --unset
failed on both; gitcfg now counts the matches and refuses anything but
exactly one, pointing at the editor. A file git cannot parse made list
print nothing, which the page drew as an empty config; list now prints
git's error as an error= line and the page shows it. Escape in the Add
fields clears the typed text before it leaves the page, as a row's edit
is undone first.

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

1 files changed, 19 insertions, 7 deletions

diff --git a/desktop/modules/git/gitcfg b/desktop/modules/git/gitcfg
index df955bf..a5641f7 100755
--- a/desktop/modules/git/gitcfg
+++ b/desktop/modules/git/gitcfg
@@ -13,7 +13,7 @@
 #
 # The global git config, for the drawer's git page.
 #
-#   gitcfg list                    git config --global -z --list
+#   gitcfg list                    git config --global -z --list, or error=<why>
 #   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>
@@ -39,16 +39,28 @@ g() {
     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.
+# Exactly one value equal to <value>, or refuse. --replace-all with no match
+# appends <new> and succeeds, and --unset of a missing value fails silently:
+# the file may have changed in the editor since the page read it. With two
+# equal values --replace-all merges both rows into one and --unset fails, so a
+# duplicate is left to the editor.
 has() {
-    git config --global --fixed-value --get-all -- "$1" "$2" >/dev/null \
-        || { printf '%s no longer holds that value\n' "$1"; exit 1; }
+    local n
+    n="$(git config --global -z --fixed-value --get-all -- "$1" "$2" | tr -cd '\0' | wc -c)"
+    case "$n" in
+        1) ;;
+        0) printf '%s no longer holds that value\n' "$1"; exit 1 ;;
+        *) printf '%s holds that value twice or more; use the editor\n' "$1"; exit 1 ;;
+    esac
 }
 
 case "${1:-}" in
-    list)  [[ $# -eq 1 ]] || usage; exec git config --global -z --list ;;
+    # A file git cannot parse prints nothing on stdout, which would read as
+    # an empty config, so its error comes out as one error= line instead.
+    list)  [[ $# -eq 1 ]] || usage
+           err="$(git config --global --list 2>&1 >/dev/null)" \
+               || { printf 'error=%s\n' "${err:-git config failed}"; exit 1; }
+           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" ;;