feat: auto-relink skill symlinks on prefix config change (#578)

New bin/gstack-relink creates prefixed (gstack-*) or flat symlinks
based on skill_prefix config. gstack-config auto-triggers relink
when skill_prefix changes. Setup guards against recursive calls
with GSTACK_SETUP_RUNNING env var.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bin/gstack-config

@@ -41,6 +41,11 @@ case "${1:-}" in
     else
       echo "${KEY}: ${VALUE}" >> "$CONFIG_FILE"
     fi
+    # Auto-relink skills when prefix setting changes (skip during setup to avoid recursive call)
+    if [ "$KEY" = "skill_prefix" ] && [ -z "${GSTACK_SETUP_RUNNING:-}" ]; then
+      GSTACK_RELINK="$(dirname "$0")/gstack-relink"
+      [ -x "$GSTACK_RELINK" ] && "$GSTACK_RELINK" || true
+    fi
     ;;
   list)
     cat "$CONFIG_FILE" 2>/dev/null || true

bin/gstack-relink

@@ -0,0 +1,64 @@
+#!/usr/bin/env bash
+# gstack-relink — re-create skill symlinks based on skill_prefix config
+#
+# Usage:
+#   gstack-relink
+#
+# Env overrides (for testing):
+#   GSTACK_STATE_DIR   — override ~/.gstack state directory
+#   GSTACK_INSTALL_DIR — override gstack install directory
+#   GSTACK_SKILLS_DIR  — override target skills directory
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+GSTACK_CONFIG="${SCRIPT_DIR}/gstack-config"
+
+# Detect install dir
+INSTALL_DIR="${GSTACK_INSTALL_DIR:-}"
+if [ -z "$INSTALL_DIR" ]; then
+  if [ -d "$HOME/.claude/skills/gstack" ]; then
+    INSTALL_DIR="$HOME/.claude/skills/gstack"
+  elif [ -d "${SCRIPT_DIR}/.." ] && [ -f "${SCRIPT_DIR}/../setup" ]; then
+    INSTALL_DIR="$(cd "${SCRIPT_DIR}/.." && pwd)"
+  fi
+fi
+
+if [ -z "$INSTALL_DIR" ] || [ ! -d "$INSTALL_DIR" ]; then
+  echo "Error: gstack install directory not found." >&2
+  echo "Run: cd ~/.claude/skills/gstack && ./setup" >&2
+  exit 1
+fi
+
+# Detect target skills dir
+SKILLS_DIR="${GSTACK_SKILLS_DIR:-$(dirname "$INSTALL_DIR")}"
+[ -d "$SKILLS_DIR" ] || mkdir -p "$SKILLS_DIR"
+
+# Read prefix setting
+PREFIX=$("$GSTACK_CONFIG" get skill_prefix 2>/dev/null || echo "false")
+
+# Discover skills (directories with SKILL.md, excluding meta dirs)
+SKILL_COUNT=0
+for skill_dir in "$INSTALL_DIR"/*/; do
+  [ -d "$skill_dir" ] || continue
+  skill=$(basename "$skill_dir")
+  # Skip non-skill directories
+  case "$skill" in bin|browse|design|docs|extension|lib|node_modules|scripts|test|.git|.github) continue ;; esac
+  [ -f "$skill_dir/SKILL.md" ] || continue
+
+  if [ "$PREFIX" = "true" ]; then
+    # Create gstack-* symlink, remove flat if exists
+    ln -sfn "$INSTALL_DIR/$skill" "$SKILLS_DIR/gstack-$skill"
+    [ -L "$SKILLS_DIR/$skill" ] && rm -f "$SKILLS_DIR/$skill"
+  else
+    # Create flat symlink, remove gstack-* if exists
+    ln -sfn "$INSTALL_DIR/$skill" "$SKILLS_DIR/$skill"
+    [ -L "$SKILLS_DIR/gstack-$skill" ] && rm -f "$SKILLS_DIR/gstack-$skill"
+  fi
+  SKILL_COUNT=$((SKILL_COUNT + 1))
+done
+
+if [ "$PREFIX" = "true" ]; then
+  echo "Relinked $SKILL_COUNT skills as gstack-*"
+else
+  echo "Relinked $SKILL_COUNT skills as flat names"
+fi

setup

@@ -44,6 +44,7 @@ esac
 # ─── Resolve skill prefix preference ─────────────────────────
 # Priority: CLI flag > saved config > interactive prompt (or flat default for non-TTY)
 GSTACK_CONFIG="$SOURCE_GSTACK_DIR/bin/gstack-config"
+export GSTACK_SETUP_RUNNING=1  # Prevent gstack-config post-set hook from triggering relink mid-setup
 if [ "$SKILL_PREFIX_FLAG" -eq 0 ]; then
   _saved_prefix="$("$GSTACK_CONFIG" get skill_prefix 2>/dev/null || true)"
   if [ "$_saved_prefix" = "true" ]; then