feat(zsh): enrich pacopt with reverse-optdep info

Promote pacopt from a plain alias to a function. In addition to listing
packages that remain installed solely as someone's optional dependency,
each package is now annotated with its parent(s) and the upstream
reason text from the parent's Optional Deps field.

Implementation is pacman-only (no expac): one awk pass over 'pacman -Qi'
builds a reverse index of every (parent, optdep, reason) edge in the
local DB, then per leaf package the index is filtered for matching deps.

1 files changed, 35 insertions, 1 deletions

diff --git a/dot_config/zsh/dot_zshrc b/dot_config/zsh/dot_zshrc
index 99f67f3..2eea559 100644
--- a/dot_config/zsh/dot_zshrc
+++ b/dot_config/zsh/dot_zshrc
@@ -239,7 +239,41 @@ alias gimme='sudo chown $USER:$(id -gn $USER)'
 alias pacdiff='sudo pacdiff'
 
 # Pacman
-alias pacopt='comm -13 <(pacman -Qqdt | sort) <(pacman -Qqdtt | sort)'
+# List packages installed only because they are someone's *optional* dep
+# (no package strictly requires them), and for each one show the parent
+# package(s) that list it as an Optional Dep along with the upstream reason.
+pacopt() {
+	local -a leaves
+	leaves=( ${(f)"$(comm -13 <(pacman -Qqdt | sort) <(pacman -Qqdtt | sort))"} )
+	(( ${#leaves[@]} )) || return 0
+	# One pass over `pacman -Qi`: emit "dep<TAB>parent<TAB>reason" lines
+	# for every (parent, optional-dep) edge in the local DB.
+	local index
+	index=$(pacman -Qi 2>/dev/null | awk '
+		function emit(line, parent,    n, dep, reason) {
+			sub(/^ +/, "", line); sub(/ \[installed\]$/, "", line)
+			n = index(line, ":")
+			if (n) { dep = substr(line, 1, n-1); reason = substr(line, n+2); sub(/^ +/, "", reason) }
+			else   { dep = line; reason = "" }
+			print dep "\t" parent "\t" reason
+		}
+		/^Name +:/          { name=$3; in_od=0; next }
+		/^Optional Deps +:/ {
+			sub(/^[^:]*: */, "")
+			if ($0 == "None") { in_od=0; next }
+			in_od=1; emit($0, name); next
+		}
+		/^[A-Z][a-z]+[a-zA-Z ]*: / { in_od=0; next }
+		in_od && NF        { emit($0, name) }
+	')
+	local p
+	for p in "${leaves[@]}"; do
+		print -P -- "%B${p}%b"
+		print -r -- "$index" | awk -F'\t' -v p="$p" '
+			$1 == p { printf "  ← %s%s\n", $2, ($3 ? ": " $3 : "") }
+		'
+	done
+}
 
 # Git
 alias g='git'