.NET: fix: filter filesystem checkpoint index by session

[he-yufeng]

Summary

• filter FileSystemJsonCheckpointStore.RetrieveIndexAsync by the requested session id
• add a regression test that covers mixed-session indexes before and after reopening the store

Fixes #5942.

To verify

• dotnet build dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\Microsoft.Agents.AI.Workflows.UnitTests.csproj --no-restore --tl:off
• dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\bin\Debug\net10.0\Microsoft.Agents.AI.Workflows.UnitTests.exe --filter-method "*RetrieveIndexAsync_ShouldOnlyReturnCheckpointsForRequestedSessionAsync" --no-progress
• dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\bin\Debug\net10.0\Microsoft.Agents.AI.Workflows.UnitTests.exe --filter-class "Microsoft.Agents.AI.Workflows.UnitTests.FileSystemJsonCheckpointStoreTests" --no-progress
• git diff --check

Note: direct dotnet test is blocked locally by the Microsoft.Testing.Platform / .NET 10 VSTest entrypoint error, so I ran the generated test runner executable instead.

[lokitoth]

Please also include filtering by withParent

[he-yufeng]

Updated in 04e1cba to include the parent filter as well.

The filesystem index now persists the parent checkpoint id, reloads it with the index, and applies withParent in RetrieveIndexAsync. I also added coverage for both the live store and a reopened store so the persisted index path is covered.

Validation:

• dotnet build dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/Microsoft.Agents.AI.Workflows.UnitTests.csproj --no-restore
• dotnet dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/bin/Debug/net10.0/Microsoft.Agents.AI.Workflows.UnitTests.dll --filter-class Microsoft.Agents.AI.Workflows.UnitTests.FileSystemJsonCheckpointStoreTests --no-progress
• git diff --check

Note: this machine has only .NET SDK 10.0.203, so direct dotnet test hits the Microsoft.Testing.Platform/VSTest entrypoint error. I ran the generated MTP test app directly after build.

[he-yufeng]

Rebased this branch onto current upstream/main again. The withParent filtering update remains in the branch, and the PR diff is back down to the checkpoint store plus its tests.

Validation on Windows:

dotnet build dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\Microsoft.Agents.AI.Workflows.UnitTests.csproj --tl:off
# build succeeded, 0 warnings, 0 errors

dotnet .\dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\bin\Debug\net10.0\Microsoft.Agents.AI.Workflows.UnitTests.dll --filter-method "*RetrieveIndexAsync_ShouldOnlyReturnCheckpointsForRequestedSessionAsync" --no-progress
# 1 passed

dotnet .\dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\bin\Debug\net10.0\Microsoft.Agents.AI.Workflows.UnitTests.dll --filter-class "Microsoft.Agents.AI.Workflows.UnitTests.FileSystemJsonCheckpointStoreTests" --no-progress
# 8 passed

git diff --check upstream/main..HEAD

[he-yufeng]

Rebased onto the latest microsoft:main and reran the checkpoint-store checks.

Validation:

dotnet build .\dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\Microsoft.Agents.AI.Workflows.UnitTests.csproj -f net10.0 -c Debug --tl:off
# succeeded, 0 warnings, 0 errors

dotnet .\dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\bin\Debug\net10.0\Microsoft.Agents.AI.Workflows.UnitTests.dll --filter-class Microsoft.Agents.AI.Workflows.UnitTests.FileSystemJsonCheckpointStoreTests --no-progress
# 8 passed

git diff --check

dotnet test itself still hits the repo's local .NET 10 Microsoft.Testing.Platform/VSTest incompatibility, so I used the same direct MTP runner path after building.

[he-yufeng]

Rebased onto the latest microsoft:main and pushed c681aa31.

The requested withParent coverage is still included: the filesystem checkpoint index persists and reloads the parent checkpoint id, and RetrieveIndexAsync applies the parent filter together with the session filter. The tests cover both the live store and a reopened store so the persisted index path is exercised.

Current local check against fetched upstream/main:

git rev-list --left-right --count HEAD...upstream/main
# 2 0

Validation on Windows:

dotnet build .\dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\Microsoft.Agents.AI.Workflows.UnitTests.csproj -f net10.0 -c Debug --tl:off
# succeeded, 0 warnings, 0 errors

dotnet .\dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\bin\Debug\net10.0\Microsoft.Agents.AI.Workflows.UnitTests.dll --filter-class Microsoft.Agents.AI.Workflows.UnitTests.FileSystemJsonCheckpointStoreTests --no-progress
# 8 passed

dotnet format dotnet\agent-framework-dotnet.slnx --verify-no-changes --no-restore --include dotnet\src\Microsoft.Agents.AI.Workflows\Checkpointing\FileSystemJsonCheckpointStore.cs dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\FileSystemJsonCheckpointStoreTests.cs
# exit 0; workspace load warning only

git diff --check
# passed

[he-yufeng]

Rebased onto current microsoft:main and pushed fae6a6377.

Validation on Windows:

dotnet build .\dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\Microsoft.Agents.AI.Workflows.UnitTests.csproj -f net10.0 -c Debug --tl:off
# succeeded, 0 warnings, 0 errors

dotnet .\dotnet\tests\Microsoft.Agents.AI.Workflows.UnitTests\bin\Debug\net10.0\Microsoft.Agents.AI.Workflows.UnitTests.dll --filter-class Microsoft.Agents.AI.Workflows.UnitTests.FileSystemJsonCheckpointStoreTests --no-progress
# 8 passed

git diff --check upstream/main..HEAD
# passed