The test asserted msg_count == 0 on a process-global broadcast channel
(TRANSITION_TX is a single OnceLock<Sender> shared across the test
binary), so any concurrent test calling apply_transition could land
events in our receiver between the drain and the post-reconcile check.
Observed failure: 3 stray transitions from parallel tests.
Drop the strict count check. The real "never floods" invariant is
captured by the Lagged check alone: 1000 seeded items must not overflow
the 256-slot channel, which can only hold if the reconcile path
bypasses the broadcast (AC4). The sibling test
`reconcile_pass_scales_to_1000_items_without_lagged_divergence` already
uses this Lagged-only pattern.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
TimmyandClaude Opus 4.7
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