Closes out Stream B per docs/v2/implementation/phase-6-1-resilience-and-observability.md.
Core.Abstractions:
- IDriverSupervisor — process-level supervisor contract a Tier C driver's
out-of-process topology provides (Galaxy Proxy/Supervisor implements this in
a follow-up Driver.Galaxy wiring PR). Concerns: DriverInstanceId + RecycleAsync.
Tier A/B drivers don't implement this; Stream B code asserts tier == C before
ever calling it.
Core.Stability:
- MemoryRecycle — companion to MemoryTracking. On HardBreach, invokes the
supervisor IFF tier == C AND a supervisor is wired. Tier A/B HardBreach logs
a promotion-to-Tier-C recommendation and returns false. Soft/None/Warming
never triggers a recycle at any tier.
- ScheduledRecycleScheduler — Tier C opt-in periodic recycler per decision #67.
Ctor throws for Tier A/B (structural guard — scheduled recycle on an
in-process driver would kill every OPC UA session and every co-hosted
driver). TickAsync(now) advances the schedule by one interval per fire;
RequestRecycleNowAsync drives an ad-hoc recycle without shifting the cron.
- WedgeDetector — demand-aware per decision #147. Classify(state, demand, now)
returns:
* NotApplicable when driver state != Healthy
* Idle when Healthy + no pending work (bulkhead=0 && monitored=0 && historic=0)
* Healthy when Healthy + pending work + progress within threshold
* Faulted when Healthy + pending work + no progress within threshold
Threshold clamps to min 60 s. DemandSignal.HasPendingWork ORs the three counters.
The three false-wedge cases the plan calls out all stay Healthy: idle
subscription-only, slow historian backfill making progress, write-only burst
with drained bulkhead.
Tests (22 new, all pass):
- MemoryRecycleTests (7): Tier C hard-breach requests recycle; Tier A/B
hard-breach never requests; Tier C without supervisor no-ops; soft-breach
at every tier never requests; None/Warming never request.
- ScheduledRecycleSchedulerTests (6): ctor throws for A/B; zero/negative
interval throws; tick before due no-ops; tick at/after due fires once and
advances; RequestRecycleNow fires immediately without shifting schedule;
multiple fires across ticks advance one interval each.
- WedgeDetectorTests (9): threshold clamp to 60 s; unhealthy driver always
NotApplicable; idle subscription stays Idle; pending+fresh progress stays
Healthy; pending+stale progress is Faulted; MonitoredItems active but no
publish is Faulted; MonitoredItems active with fresh publish stays Healthy;
historian backfill with fresh progress stays Healthy; write-only burst with
empty bulkhead is Idle; HasPendingWork theory for any non-zero counter.
Full solution dotnet test: 989 passing (baseline 906, +83 for Phase 6.1 so far).
Pre-existing Client.CLI Subscribe flake unchanged.
Stream B complete. Next up: Stream C (health endpoints + structured logging).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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