feat(pi): add persistent Mosaic goal controller

packages/mosaic/framework/systemd/user/test-fleet-units.sh

@@ -66,7 +66,10 @@ if command -v tmux >/dev/null 2>&1 && command -v cc >/dev/null 2>&1; then
   trap 'tmux -L "$TEST_SOCKET" kill-server >/dev/null 2>&1 || true; rm -rf "$TEST_ROOT"' EXIT
   MARKER="$TEST_ROOT/loader-marker"
   LIBRARY="$TEST_ROOT/marker.so"
+  FIXTURE_READY="$TEST_ROOT/loader-ready"
+  FIXTURE_FIFO="$TEST_ROOT/loader-block"
   HOLDER_HOME="$TEST_ROOT/holder-home"
+  mkfifo "$FIXTURE_FIFO"
   mkdir -p "$HOLDER_HOME/.config/mosaic/fleet/run"
   chmod 700 "$HOLDER_HOME/.config" "$HOLDER_HOME/.config/mosaic" \
     "$HOLDER_HOME/.config/mosaic/fleet" "$HOLDER_HOME/.config/mosaic/fleet/run"
@@ -87,7 +90,17 @@ __attribute__((constructor)) static void mark_loader(void) {
 EOF
   cc -shared -fPIC -o "$LIBRARY" "$TEST_ROOT/marker.c"
   MOSAIC_LOADER_MARKER="$MARKER" LD_PRELOAD="$LIBRARY" \
-    tmux -L "$TEST_SOCKET" new-session -d -s _holder 'sleep 60'
+    tmux -L "$TEST_SOCKET" new-session -d -s _holder \
+      "touch '$FIXTURE_READY'; read _ < '$FIXTURE_FIFO'"
+  # tmux starts the pane asynchronously. Wait until its contaminated shell has
+  # loaded the constructor and reached a builtin-only FIFO barrier before
+  # clearing the marker; otherwise that expected constructor can race with the
+  # clean holder assertion below and create a false failure.
+  for _attempt in {1..100}; do
+    [ -e "$FIXTURE_READY" ] && break
+    sleep 0.01
+  done
+  [ -e "$FIXTURE_READY" ] || fail "contaminated fixture pane did not become ready"
   [ -s "$MARKER" ] || fail "contaminated fixture did not execute loader constructor"
   server_pid=$(tmux -L "$TEST_SOCKET" display-message -p '#{pid}')
   : > "$MARKER"