refactor: extract unpack_target helper for TSV parsing (#113)

Replace 10 instances of echo|cut TSV unpacking from resolve_target()
output with a single unpack_target() function using IFS-based read
splitting. Eliminates ~30 subshell forks per invocation.

Author: helizaga

bin/gtr

@@ -371,9 +371,8 @@ cmd_create() {
       # Check if folder_name would resolve to main repo (collision with current branch)
       local resolve_result
       if resolve_result=$(resolve_target "$folder_name" "$repo_root" "$base_dir" "$prefix" 2>/dev/null); then
-        local is_main
-        is_main=$(printf "%s" "$resolve_result" | cut -f1)
-        if [ "$is_main" = "1" ]; then
+        unpack_target "$resolve_result"
+        if [ "$_ctx_is_main" = "1" ]; then
           # Collision: folder name matches current branch, use branch name instead
           next_steps_id="$branch_name"
         else
@@ -440,9 +439,8 @@ cmd_remove() {
     # Resolve target branch
     local target is_main worktree_path branch_name
     target=$(resolve_target "$identifier" "$repo_root" "$base_dir" "$prefix") || continue
-    is_main=$(echo "$target" | cut -f1)
-    worktree_path=$(echo "$target" | cut -f2)
-    branch_name=$(echo "$target" | cut -f3)
+    unpack_target "$target"
+    is_main="$_ctx_is_main" worktree_path="$_ctx_worktree_path" branch_name="$_ctx_branch"
 
     # Cannot remove main repository
     if [ "$is_main" = "1" ]; then
@@ -536,9 +534,8 @@ cmd_rename() {
   # Resolve old worktree
   local target is_main old_path old_branch
   target=$(resolve_target "$old_identifier" "$repo_root" "$base_dir" "$prefix") || exit 1
-  is_main=$(echo "$target" | cut -f1)
-  old_path=$(echo "$target" | cut -f2)
-  old_branch=$(echo "$target" | cut -f3)
+  unpack_target "$target"
+  is_main="$_ctx_is_main" old_path="$_ctx_worktree_path" old_branch="$_ctx_branch"
 
   # Cannot rename main repository
   if [ "$is_main" = "1" ]; then
@@ -622,9 +619,8 @@ cmd_go() {
   # Resolve target branch
   local target is_main worktree_path branch
   target=$(resolve_target "$identifier" "$repo_root" "$base_dir" "$prefix") || exit 1
-  is_main=$(echo "$target" | cut -f1)
-  worktree_path=$(echo "$target" | cut -f2)
-  branch=$(echo "$target" | cut -f3)
+  unpack_target "$target"
+  is_main="$_ctx_is_main" worktree_path="$_ctx_worktree_path" branch="$_ctx_branch"
 
   # Human messages to stderr so stdout can be used in command substitution
   if [ "$is_main" = "1" ]; then
@@ -680,9 +676,8 @@ cmd_run() {
   # Resolve target branch
   local target is_main worktree_path branch
   target=$(resolve_target "$identifier" "$repo_root" "$base_dir" "$prefix") || exit 1
-  is_main=$(echo "$target" | cut -f1)
-  worktree_path=$(echo "$target" | cut -f2)
-  branch=$(echo "$target" | cut -f3)
+  unpack_target "$target"
+  is_main="$_ctx_is_main" worktree_path="$_ctx_worktree_path" branch="$_ctx_branch"
 
   # Human messages to stderr (like cmd_go)
   if [ "$is_main" = "1" ]; then
@@ -757,7 +752,8 @@ cmd_copy() {
   # Resolve source path
   local src_target src_path
   src_target=$(resolve_target "$source" "$repo_root" "$base_dir" "$prefix") || exit 1
-  src_path=$(echo "$src_target" | cut -f2)
+  unpack_target "$src_target"
+  src_path="$_ctx_worktree_path"
 
   # Get patterns (flag > config)
   if [ -z "$patterns" ]; then
@@ -798,8 +794,8 @@ cmd_copy() {
   for target_id in $targets; do
     local dst_target dst_path dst_branch
     dst_target=$(resolve_target "$target_id" "$repo_root" "$base_dir" "$prefix") || continue
-    dst_path=$(echo "$dst_target" | cut -f2)
-    dst_branch=$(echo "$dst_target" | cut -f3)
+    unpack_target "$dst_target"
+    dst_path="$_ctx_worktree_path" dst_branch="$_ctx_branch"
 
     # Skip if source == destination
     [ "$src_path" = "$dst_path" ] && continue
@@ -860,8 +856,8 @@ cmd_editor() {
   # Resolve target branch
   local target worktree_path branch
   target=$(resolve_target "$identifier" "$repo_root" "$base_dir" "$prefix") || exit 1
-  worktree_path=$(echo "$target" | cut -f2)
-  branch=$(echo "$target" | cut -f3)
+  unpack_target "$target"
+  worktree_path="$_ctx_worktree_path" branch="$_ctx_branch"
 
   if [ "$editor" = "none" ]; then
     # Just open in GUI file browser
@@ -934,8 +930,8 @@ cmd_ai() {
   # Resolve target branch
   local target worktree_path branch
   target=$(resolve_target "$identifier" "$repo_root" "$base_dir" "$prefix") || exit 1
-  worktree_path=$(echo "$target" | cut -f2)
-  branch=$(echo "$target" | cut -f3)
+  unpack_target "$target"
+  worktree_path="$_ctx_worktree_path" branch="$_ctx_branch"
 
   log_step "Starting $ai_tool for: $branch"
   echo "Directory: $worktree_path"

lib/core.sh

@@ -271,6 +271,15 @@ resolve_target() {
   return 1
 }
 
+# Unpack TSV output from resolve_target into globals.
+# Sets: _ctx_is_main, _ctx_worktree_path, _ctx_branch
+# Usage: unpack_target "$target_string"
+unpack_target() {
+  local IFS=$'\t'
+  # shellcheck disable=SC2162
+  read _ctx_is_main _ctx_worktree_path _ctx_branch <<< "$1"
+}
+
 # Create a new git worktree
 # Usage: create_worktree base_dir prefix branch_name from_ref track_mode [skip_fetch] [force] [custom_name] [folder_override]
 # track_mode: auto, remote, local, or none