Use version-aware silo status checks

[ReubenBond]

Part 6 of 7 split from #10085.

Problem:
Directory and cache validation need to treat entries as invalid only when the referenced silo is Dead, or when the silo is unknown in a snapshot newer than the entry's membership version. ShuttingDown and Stopping silos should remain valid until they are Dead.

Solution:
Add ClusterMembershipSnapshot.GetSiloStatus(silo, seenAtVersion), update LocalGrainDirectory, handoff, cached locator, and partition validation to use it, and add coverage for the version-aware semantics.

Stack:
Merge after #10090. This branch is stacked on split/pr10085-05-dead-silo-message-break; until earlier PRs merge, GitHub may show earlier stack changes. Incremental compare: ReubenBond/orleans@split/pr10085-05-dead-silo-message-break...split/pr10085-06-version-aware-status

Review focus:
Version-aware GetSiloStatus semantics, Dead-only filtering, and preserving ShuttingDown/Stopping registrations.

[Copilot]

Pull request overview

This PR updates Orleans grain-directory and locator logic to use version-aware silo status checks, treating entries as invalid only when the referenced silo is Dead (or provably stale/unknown relative to a newer membership snapshot), while keeping ShuttingDown/Stopping registrations valid until death.

Changes:

• Add ClusterMembershipSnapshot.GetSiloStatus(SiloAddress, MembershipVersion) and switch directory/cache/handoff validation to use it for dead-only filtering with version awareness.
• Rework LocalGrainDirectory membership processing to apply IClusterMembershipService snapshots and use dead-only invalidation for directory entries and cache.
• Add/extend tests to cover version-aware “unknown vs dead” semantics and terminating-but-not-dead behavior.

Show a summary per file

File	Description
test/Orleans.Runtime.Internal.Tests/LocalGrainDirectoryTests.cs	Adds unit tests for LocalGrainDirectory.IsDefunctActivation version-aware semantics.
test/Orleans.Runtime.Internal.Tests/GrainDirectoryPartitionTests.cs	Switches partition tests to IClusterMembershipService and adds coverage for terminating-but-not-dead behavior.
test/Orleans.Runtime.Internal.Tests/GrainDirectoryHandoffManagerTests.cs	Adds tests ensuring handoff transferability is dead-only and version-aware.
test/Orleans.Runtime.Internal.Tests/ClusterMembershipSnapshotTests.cs	Adds tests for GetSiloStatus(silo, seenAtVersion) semantics (unknown/older => Dead).
test/Orleans.Core.Tests/Directory/CachedGrainLocatorTests.cs	Updates wiring to include membership service and adds cache validation tests for ShuttingDown/Stopping silos.
src/Orleans.Runtime/Networking/SiloConnectionMaintainer.cs	Breaks outstanding messages to Dead silos and closes connections on death.
src/Orleans.Runtime/MembershipService/SiloStatusListenerManager.cs	Minor type change (sealed).
src/Orleans.Runtime/MembershipService/ClusterMembershipSnapshot.cs	Introduces the version-aware GetSiloStatus overload.
src/Orleans.Runtime/GrainDirectory/LocalGrainDirectoryPartition.cs	Replaces terminating-based checks with snapshot-based dead-only defunct detection.
src/Orleans.Runtime/GrainDirectory/LocalGrainDirectory.cs	Moves to snapshot-driven membership application; dead-only invalidation; refreshes membership when entries are newer than applied snapshot.
src/Orleans.Runtime/GrainDirectory/ILocalGrainDirectory.cs	Removes IsSiloInCluster from the internal interface.
src/Orleans.Runtime/GrainDirectory/GrainDirectoryPartition.Interface.cs	Uses version-aware dead detection when deciding whether an entry is dead.
src/Orleans.Runtime/GrainDirectory/GrainDirectoryHandoffManager.cs	Uses snapshot dead-only filtering for transferable registrations; changes pending-operation retry behavior.
src/Orleans.Runtime/GrainDirectory/CachedGrainLocator.cs	Changes proactive cleanup to dead-only and uses version-aware status checks for cached entries.
src/Orleans.Runtime/Catalog/Catalog.cs	Removes directory-owned silo-status-change deactivation logic (moved elsewhere).
src/api/Orleans.Runtime/Orleans.Runtime.cs	Updates generated public API surface for the new GetSiloStatus overload.

Copilot's findings

Comments suppressed due to low confidence (2)

src/Orleans.Runtime/GrainDirectory/LocalGrainDirectory.cs:677

• UnregisterAsync: the retry-delay/recheck gate uses hopCount > 1, so the first forwarded request (hopCount == 1) will forward again without delay/revalidation. This is inconsistent with LookupAsync/DeleteGrainAsync (hopCount > 0) and may reintroduce fast hop chains when directory ownership is unstable. Consider using hopCount > 0 (or otherwise aligning the hop-count semantics) so forwarded unregisters also get a stabilization delay.

            await RefreshMembershipIfNewer(address.MembershipVersion);

            // see if the owner is somewhere else (returns null if we are owner)
            var forwardAddress = this.CheckIfShouldForward(address.GrainId, hopCount, "UnregisterAsync");

            // After the first forward, we insert a retry delay and recheck owner before forwarding again
            if (hopCount > 1 && forwardAddress != null)
            {
                await Task.Delay(RETRY_DELAY);
                forwardAddress = this.CheckIfShouldForward(address.GrainId, hopCount, "UnregisterAsync");

src/Orleans.Runtime/GrainDirectory/CachedGrainLocator.cs:190

• ListenToClusterChange computes snapshot.CreateUpdate(previousSnapshot) but never updates previousSnapshot inside the loop. As a result, every iteration diffs against the initial snapshot, which can repeatedly re-process the same dead silos and grow the change set over time. Updating previousSnapshot = snapshot at the end of each loop will make the processing incremental and avoid redundant UnregisterSilos calls.

            var previousSnapshot = this.clusterMembershipService.CurrentSnapshot;

            ((ITestAccessor)this).LastMembershipVersion = previousSnapshot.Version;

            var updates = this.clusterMembershipService.MembershipUpdates.WithCancellation(this.shutdownToken.Token);
            await foreach (var snapshot in updates)
            {
                // Active filtering: detect dead silos and try to clean proactively the directory
                var changes = snapshot.CreateUpdate(previousSnapshot).Changes;
                var deadSilos = changes
                    .Where(member => member.Status == SiloStatus.Dead)
                    .Select(member => member.SiloAddress)
                    .ToList();

                if (deadSilos.Count > 0)
                {
                    var tasks = new List<Task>();
                    foreach (var directory in this.grainDirectoryResolver.Directories)
                    {
                        tasks.Add(directory.UnregisterSilos(deadSilos));
                    }
                    await Task.WhenAll(tasks).WaitAsync(this.shutdownToken.Token);
                }

                ((ITestAccessor)this).LastMembershipVersion = snapshot.Version;
            }

• Files reviewed: 16/16 changed files
• Comments generated: 2

[ReubenBond]

Closing as obsolete: the later stacked PR #10092 has already merged and its merge commit includes the #10090/#10091 changes, including the xUnit logger crash fix. Current main also includes the follow-up directory retry PRs #10094 and #10095.