fix(compat): take the basename of the whole ps comm path

scripts/lib/compat.sh

@@ -110,7 +110,14 @@ compat_get_comm() {
       fi
       ;;
     *)
-      ps -o comm= -p "$pid" 2>/dev/null | xargs basename 2>/dev/null
+      # `ps -o comm=` prints the executable path on macOS. Piping it through
+      # `xargs basename` splits that path on whitespace (and eats quotes), so a
+      # binary under e.g. "~/Library/Application Support/..." resolves to
+      # "Application". Take the basename of the whole string instead.
+      local _comm
+      _comm=$(ps -o comm= -p "$pid" 2>/dev/null) || return 1
+      [ -n "$_comm" ] || return 1
+      basename -- "$_comm" 2>/dev/null
       ;;
   esac
 }

tests/test_compat_posix.bats

@@ -0,0 +1,117 @@
+#!/usr/bin/env bats
+
+# Tests for compat_get_comm's POSIX (non-MSYS) branch.
+#
+# `ps -o comm=` prints the full executable path on macOS. The previous
+# implementation piped that through `xargs basename`, which word-splits on
+# whitespace and interprets quotes, so any agent installed under a path
+# containing a space -- e.g. the Claude Code desktop app, which always lives
+# under "~/Library/Application Support/Claude/..." -- resolved to "Application"
+# instead of "claude". agmsg_pid_is_agent then never matched, agmsg_agent_pid
+# fell back to a bare session id, and every actas lock was GC'd as stale.
+
+load test_helper
+
+skip_if_msys() {
+  case "$(uname -s)" in
+    MINGW*|MSYS*|CYGWIN*) skip "POSIX-only test (the msys branch is covered by test_compat.bats)" ;;
+  esac
+}
+
+setup() {
+  setup_test_env
+  skip_if_msys
+
+  # shellcheck disable=SC1090
+  source "$SCRIPTS/lib/compat.sh"
+}
+
+teardown() {
+  [ -n "${_PROC_PID:-}" ] && kill "$_PROC_PID" 2>/dev/null
+  [ -n "${_PROC_PID:-}" ] && wait "$_PROC_PID" 2>/dev/null
+  teardown_test_env
+}
+
+# Put a stub `ps` first on PATH that prints $1 as the comm field.
+_stub_ps_printing() {
+  local out="$1" dir="$TEST_SKILL_DIR/psstub"
+  mkdir -p "$dir"
+  {
+    printf '#!/usr/bin/env bash\n'
+    printf 'printf "%%s\\n" %q\n' "$out"
+  } > "$dir/ps"
+  chmod +x "$dir/ps"
+  PATH="$dir:$PATH"
+}
+
+# ── stubbed ps: deterministic on every POSIX platform ────────────────────
+
+@test "compat_get_comm returns the binary name when ps reports a path containing spaces" {
+  _stub_ps_printing "/Users/u/Library/Application Support/Claude/claude-code/2.1.227/claude.app/Contents/MacOS/claude"
+
+  run compat_get_comm 4242
+  [ "$status" -eq 0 ]
+  [ "$output" = "claude" ]
+}
+
+@test "compat_get_comm returns the binary name when ps reports a path containing a quote" {
+  _stub_ps_printing "/opt/it's here/claude"
+
+  run compat_get_comm 4242
+  [ "$status" -eq 0 ]
+  [ "$output" = "claude" ]
+}
+
+@test "compat_get_comm is unchanged for a path without spaces" {
+  _stub_ps_printing "/usr/local/bin/claude"
+
+  run compat_get_comm 4242
+  [ "$status" -eq 0 ]
+  [ "$output" = "claude" ]
+}
+
+@test "compat_get_comm fails for a pid ps knows nothing about" {
+  local dir="$TEST_SKILL_DIR/psstub"
+  mkdir -p "$dir"
+  printf '#!/usr/bin/env bash\nexit 1\n' > "$dir/ps"
+  chmod +x "$dir/ps"
+  PATH="$dir:$PATH"
+
+  run compat_get_comm 4242
+  [ "$status" -ne 0 ]
+  [ -z "$output" ]
+}
+
+# ── contract drift guard: the real ps, a real process ────────────────────
+#
+# The stub above asserts what we believe `ps` does. This test checks that
+# belief against the real `ps` on this machine, and skips where the platform
+# reports a bare comm (Linux) rather than a path -- there the split is
+# unreachable and the stub does not describe local reality.
+
+@test "compat_get_comm matches the real ps for a binary under a space-containing path" {
+  local dir="$TEST_SKILL_DIR/Application Support/bin" sleep_bin
+  sleep_bin=$(command -v sleep) || skip "no sleep on PATH"
+  mkdir -p "$dir"
+  # A symlink, not a copy: macOS kills a copied system binary for an invalid
+  # code signature (SIGKILL/137), and ps then reports nothing at all.
+  ln -s "$sleep_bin" "$dir/claude" || skip "cannot symlink into the test tree"
+
+  "$dir/claude" 30 3>&- &
+  _PROC_PID=$!
+  sleep 0.5
+
+  local raw
+  raw=$(ps -o comm= -p "$_PROC_PID" 2>/dev/null || true)
+  case "$raw" in
+    */*) ;;
+    *) skip "this platform's ps reports a bare comm ([$raw]); the space-splitting path is unreachable here" ;;
+  esac
+
+  # The real ps hands us a path with a space -- the premise of the stub above.
+  [[ "$raw" == *"Application Support"* ]]
+
+  run compat_get_comm "$_PROC_PID"
+  [ "$status" -eq 0 ]
+  [ "$output" = "claude" ]
+}