428b8db024
P8-8: replace the remaining wall-clock sleep-then-assert instances outside Communication.Tests' Medium-wave sweep with the same row-40 house pattern — continuous polling (AssertHoldsFor) for ABSENCE assertions instead of a single end-of-window sample, which cannot distinguish "stayed quiet throughout" from "hadn't happened yet when the one sample landed" and cannot catch a value that flips wrong and back before that sample. - DataConnectionActorBatchTests: QualityCounters_ArePushedOnTransitionOnly_AndCoalesced (:206/:214 class) converted to AssertHoldsFor; ResolutionProbes_BackOff... (:181/:184, a genuine real-time backoff-RATE assertion, not a sync-primitive stand-in) converted to AssertRoundsWithinWindow, which enforces the ceiling continuously (fails fast on a no-backoff regression) while the floor still necessarily waits out the window. - SiteAlarmLiveCacheServiceTests (:452-454, :470-472): converted to the project's own AssertHoldsFor (mirrors SiteAlarmAggregatorActorTests', same assembly). - StoreAndForwardServiceTests (:891-892): async AssertHoldsForAsync variant (the class runs on the async test thread). - KpiHistoryRecorderActorTests (:1043-1049): two skip-path FoldCount==0 absence checks converted. Each helper is a private per-file copy, matching the Medium-wave T17 precedent (SiteAlarmAggregatorActorTests.AssertHoldsFor) rather than a shared TestSupport utility. Proof of the mechanism: a standalone (non-repo) harness run 100 trials of a real background thread flipping a boolean true then back to false inside a 300ms window — Thread.Sleep(300)+one sample missed the violation 100/100 times (false pass), continuous 20ms polling caught it 100/100 times. Most of the actual conversions here guard monotonic counters (their single-sample variant would eventually see the final value too), so each converted test carries an inline honesty note on what specifically the conversion buys for that assertion (fail-fast vs. true flip-back detection). P8-9: ScadaBridgeTelemetryTests.EmitHelpers_DoNotThrow called SetQueueDepthProvider(() => 5) against the process-global row-32 provider slot with no clear and no [Collection] — a landmine for any future same-process reader of scadabridge.store_and_forward.queue.depth. Fixed with compare-and-clear in a finally via the existing (production, untouched) ClearQueueDepthProvider. Searched this assembly and the whole test tree for a second same-process reader that asserts on the value: none exists today (MetricsEndpointTests scrapes /metrics but only asserts on the response shape, and the only value-asserting test, QueueDepthGaugeTests, lives in StoreAndForward.Tests — a separate test-host process the leak cannot reach), so no [Collection] was added; the test's doc comment records the search and flags it for re-check if that changes. Test-only change, zero production edits. Full suites green: DCL.Tests 342/342, Communication.Tests 729/729, StoreAndForward.Tests 135/135, KpiHistory.Tests 54/54, Host.Tests 522/522. Each converted test additionally looped 20x in isolation with zero flakes.