From fdb6e5db4cf31813c60a131bf4194c4982a2379a Mon Sep 17 00:00:00 2001
From: BruceChen <hi@brucec.cn>
Date: Sun, 12 Apr 2026 19:00:42 +0800
Subject: [PATCH] tools: harden session helper and tests

---
 tools/mcc-env.sh      | 11 ++++++++++-
 tools/test-mcc-env.sh | 13 +++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/tools/mcc-env.sh b/tools/mcc-env.sh
index 490bf10b..505b0ea3 100644
--- a/tools/mcc-env.sh
+++ b/tools/mcc-env.sh
@@ -26,7 +26,16 @@ _mcc_servers_root() {
 }
 
 _mcc_current_worktree_name() {
-  git -C "$MCC_REPO_ROOT" rev-parse --show-toplevel 2>/dev/null | xargs basename
+  local worktree_root
+  if ! worktree_root="$(git -C "$MCC_REPO_ROOT" rev-parse --show-toplevel 2>/dev/null)"; then
+    return 0
+  fi
+
+  if [[ -z "$worktree_root" ]]; then
+    return 0
+  fi
+
+  basename "$worktree_root"
 }
 
 _mcc_resolve_session() {
diff --git a/tools/test-mcc-env.sh b/tools/test-mcc-env.sh
index 73278e1f..6fb9957d 100755
--- a/tools/test-mcc-env.sh
+++ b/tools/test-mcc-env.sh
@@ -43,6 +43,19 @@ assert_eq "${TMPDIR:-/tmp}/mcc-debug/demo-branch" "$(_mcc_session_root "demo-bra
 assert_eq "mcc-demo-branch" "$(_mcc_tmux_session_name "demo-branch")" "tmux session name"
 
 MCC_BUILD_MODE=tmpfs
+
+original_repo_root="$MCC_REPO_ROOT"
+fallback_root="$REPO_ROOT/nonexistent-worktree"
+MCC_REPO_ROOT="$fallback_root"
+
+fallback_session="$(_mcc_resolve_session)"
+assert_eq "$(basename "$fallback_root")" "$fallback_session" "session fallback without git"
+
+fallback_build_root="$(_mcc_build_root)"
+assert_regex "^(/dev/shm|/tmp)/mcc-build/$(basename "$fallback_root")\$" "$fallback_build_root" "tmpfs build root fallback"
+
+MCC_REPO_ROOT="$original_repo_root"
+
 build_root="$(_mcc_build_root)"
 assert_regex '^(/dev/shm|/tmp)/mcc-build/.+$' "$build_root" "tmpfs build root"