fix: guard EnterWorktree core.bare parent checkout

skills/using-git-worktrees/SKILL.md

@@ -50,10 +50,25 @@ Honor any existing declared preference without asking. If the user declines cons
 
 ### 1a. Native Worktree Tools (preferred)
 
-The user has asked for an isolated workspace (Step 0 consent). Do you already have a way to create a worktree? It might be a tool with a name like `EnterWorktree`, `WorktreeCreate`, a `/worktree` command, or a `--worktree` flag. If you do, use it and skip to Step 2.
+The user has asked for an isolated workspace (Step 0 consent). Do you already have a way to create a worktree? It might be a tool with a name like `EnterWorktree`, `WorktreeCreate`, a `/worktree` command, or a `--worktree` flag. If you do, use it, run any post-native sanity check below, and skip to Step 2.
 
 Native tools handle directory placement, branch creation, and cleanup automatically. Using `git worktree add` when you have a native tool creates phantom state your harness can't see or manage.
 
+**Known issue (Claude Code):** `EnterWorktree` can trigger an upstream Claude Code bug that writes `core.bare=true` into the parent checkout's shared git config. This is not a Superpowers bug, and the native preference still applies. Record the parent checkout before calling the native tool:
+
+```bash
+PARENT_REPO_ROOT=$(git rev-parse --show-toplevel)
+```
+
+After the native tool returns, verify the parent checkout. If `core.bare` flipped to `true`, repair it immediately and tell the user what happened:
+
+```bash
+if [ "$(git -C "$PARENT_REPO_ROOT" config --get core.bare 2>/dev/null)" = "true" ]; then
+  git -C "$PARENT_REPO_ROOT" config --unset core.bare
+  echo "Repaired parent checkout: unset unexpected core.bare=true after native worktree creation."
+fi
+```
+
 Only proceed to Step 1b if you have no native worktree tool available.
 
 ### 1b. Git Worktree Fallback

tests/claude-code/README.md

@@ -122,6 +122,13 @@ RED-GREEN-REFACTOR validation for the using-git-worktrees skill (~5 minutes):
 - PRESSURE: same as GREEN under urgency framing with pre-existing `.worktrees/`
 - Drill scenario `worktree-creation-under-pressure.yaml` covers the PRESSURE phase only
 
+#### test-enterworktree-core-bare-guard.sh
+Static regression test for the using-git-worktrees Step 1a Claude Code guard:
+- Records the parent checkout before native tool use
+- Checks the parent checkout's `core.bare` after native tool use
+- Repairs unexpected `core.bare=true` with `git -C "$PARENT_REPO_ROOT" config --unset core.bare`
+- Preserves native worktree preference and does not tell agents to avoid `EnterWorktree`
+
 ## Adding New Tests
 
 1. Create new test file: `test-<skill-name>.sh`

tests/claude-code/run-skill-tests.sh

@@ -57,6 +57,7 @@ while [[ $# -gt 0 ]]; do
             echo "  --help, -h           Show this help"
             echo ""
             echo "Tests:"
+            echo "  test-enterworktree-core-bare-guard.sh  Test EnterWorktree parent core.bare guard"
             echo "  test-subagent-driven-development.sh  Test skill loading and requirements"
             echo ""
             echo "Integration Tests (use --integration):"
@@ -73,6 +74,7 @@ done
 
 # List of skill tests to run (fast unit tests)
 tests=(
+    "test-enterworktree-core-bare-guard.sh"
     "test-worktree-path-policy.sh"
     "test-subagent-driven-development.sh"
 )

tests/claude-code/test-enterworktree-core-bare-guard.sh

@@ -0,0 +1,64 @@
+#!/usr/bin/env bash
+# Regression check: using-git-worktrees should guard against the known Claude
+# Code EnterWorktree parent-checkout core.bare failure mode.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+USING_SKILL="$REPO_ROOT/skills/using-git-worktrees/SKILL.md"
+
+failures=0
+
+assert_contains() {
+    local file="$1"
+    local pattern="$2"
+    local label="$3"
+
+    if grep -Fq "$pattern" "$file"; then
+        echo "  [PASS] $label"
+    else
+        echo "  [FAIL] $label"
+        echo "    Expected to find: $pattern"
+        echo "    In file: $file"
+        failures=$((failures + 1))
+    fi
+}
+
+assert_not_contains() {
+    local file="$1"
+    local pattern="$2"
+    local label="$3"
+
+    if grep -Fq "$pattern" "$file"; then
+        echo "  [FAIL] $label"
+        echo "    Did not expect to find: $pattern"
+        echo "    In file: $file"
+        failures=$((failures + 1))
+    else
+        echo "  [PASS] $label"
+    fi
+}
+
+echo "=== EnterWorktree core.bare Guard Test ==="
+echo ""
+
+assert_contains "$USING_SKILL" "Known issue (Claude Code)" "Step 1a names the known Claude Code issue"
+assert_contains "$USING_SKILL" "EnterWorktree" "Step 1a names EnterWorktree"
+assert_contains "$USING_SKILL" "core.bare" "Step 1a names core.bare"
+assert_contains "$USING_SKILL" 'PARENT_REPO_ROOT=$(git rev-parse --show-toplevel)' "Step 1a records the parent checkout root"
+assert_contains "$USING_SKILL" 'git -C "$PARENT_REPO_ROOT" config --get core.bare' "Step 1a checks parent checkout core.bare"
+assert_contains "$USING_SKILL" 'git -C "$PARENT_REPO_ROOT" config --unset core.bare' "Step 1a repairs parent checkout core.bare"
+assert_contains "$USING_SKILL" "Native tools handle directory placement, branch creation, and cleanup automatically." "Step 1a still preserves native tool preference"
+assert_not_contains "$USING_SKILL" "avoid native tools" "Step 1a does not tell agents to avoid native tools"
+assert_not_contains "$USING_SKILL" "skip EnterWorktree" "Step 1a does not tell agents to skip EnterWorktree"
+
+echo ""
+
+if [ "$failures" -gt 0 ]; then
+    echo "STATUS: FAILED ($failures failures)"
+    exit 1
+fi
+
+echo "STATUS: PASSED"