fix: standardize event buffer defaults

[dustinbyrne]

💡 Motivation and Context

The .NET SDK currently buffers 1,000 events, flushes after 20 events or 30 seconds, and caps batch requests at 100 events. Increase the queue to 10,000 events and standardize the flush threshold, maximum batch size, and flush interval at 100 events, 100 events, and 5 seconds respectively. These defaults align with the Python, Ruby, and Rails server-side SDKs, as summarized in the server-side SDK event buffer defaults comparison.

Related changes: Node.js SDK, Java server SDK, and PHP SDK.

💚 How did you test it?

• dotnet restore --locked-mode
• bin/fmt --check
• dotnet build --configuration Release --no-restore --nologo
• dotnet test tests/UnitTests/UnitTests.csproj --configuration Release --no-build --nologo --framework net8.0 (945 passed, 2 skipped)
• dotnet test tests/UnitTests.AspNetCore/UnitTests.AspNetCore.csproj --configuration Release --no-build --nologo --framework net8.0 (49 passed)
• dotnet test tests/PostHog.AI.Tests/PostHog.AI.Tests.csproj --configuration Release --no-build --nologo --framework net8.0 (19 passed)

The legacy netcoreapp3.1 test target could not run locally because this arm64 machine does not have the required x64 .NET host; CI will cover that target.

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran pnpm changeset to generate a changeset file

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Implemented with the Pi coding agent as part of a human-directed server-side SDK standardization. Updated PostHogOptions, its XML documentation, configuration/default assertions, and a patch changeset for the core PostHog package. The existing 100-event maximum batch size already matched the target and remains unchanged.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "chore: standardize event buffer defaults" | Re-trigger Greptile}

[github-actions]

posthog-dotnet Compliance Report

Date: 2026-07-16 14:21:11 UTC
Duration: 4420ms

✅ All Tests Passed!

17/17 tests passed

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Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	246ms
Request Payload.Flags Request Uses V2 Query Param	✅	130ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	111ms
Request Payload.Flags Request Omits Authorization Header	✅	110ms
Request Payload.Token In Flags Body Matches Init	✅	111ms
Request Payload.Groups Round Trip	✅	113ms
Request Payload.Groups Default To Empty Object	✅	110ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	109ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	110ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	111ms
Request Lifecycle.No Flags Request On Init Alone	✅	4ms
Request Lifecycle.No Flags Request On Normal Capture	✅	115ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	214ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	115ms
Retry Behavior.Retries Flags On 502	✅	1117ms
Retry Behavior.Retries Flags On 504	✅	1114ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	213ms