The cycle-aware burst tracking re-gate reset the measurement burst at the
top of renderMessages(), but the added block pushed the session-load
loading-placeholder guard past the 1400-char window asserted by
test_renderMessages_preserves_loading_placeholder_for_session_switch, and
the standalone renderMessages harness in test_anchor_fallback_ownership.py
lacked the new _resetMessageVirtualMeasurementBurst dependency. Compact the
reset (identical behavior: every unmarked external render starts a fresh
burst before any early return or rAF coalescing) and add the helper stub to
the harness. CI test shard 2 is green again.
webtecnica
b1ea6141b3
