Change default large-payload threshold to 256 KiB (mirror .NET)

[torosent]

Summary

Mirrors the .NET SDK default change (microsoft/durabletask-dotnet#755) in the Python SDK: lowers the default large-payload externalization threshold LargePayloadStorageOptions.threshold_bytes from 900,000 to 262,144 bytes (256 KiB). The store.py docstring already states the Python default should match the .NET SDK default.

Behavioral change

Intentional behavioral change (not source/binary breaking): payloads larger than 256 KiB are now externalized to blob storage by default (previously 900,000 bytes). Callers who want the old behavior can set threshold_bytes=900_000 explicitly.

Changes

• durabletask/payload/store.py — default threshold_bytes 900_000 → 262_144; updated docstring.
• tests/durabletask/test_large_payload.py — test_default_options now asserts 262_144.
• examples/large_payload/app.py — sample threshold set to 262_144 (256 KiB, the default); bumped the "large" demo input 10_000 → 50_000 (~342 KB) so it still exceeds the new threshold and externalizes. The small input stays inline.
• examples/large_payload/README.md, docs/features.md, docs/supported-patterns.md — updated the documented default (900 KB → 256 KiB) and the sample's payload figure.
• tests/durabletask/test_large_payload_e2e.py, tests/durabletask-azuremanaged/test_dts_large_payload_e2e.py — corrected the "production default" comment (kept the 1 KB fast-test value).
• CHANGELOG.md — Unreleased entry.

Verification

• pytest tests/durabletask/test_large_payload.py → 28 passed locally (Python 3.13).
• Confirmed LargePayloadStorageOptions().threshold_bytes == 262144.

[Copilot]

Pull request overview

Aligns the Durable Task Python SDK’s large-payload externalization default threshold with the .NET SDK by lowering LargePayloadStorageOptions.threshold_bytes to 256 KiB, and updates tests/docs/examples/changelog to reflect the new default behavior.

Changes:

• Lowered the default externalization threshold from 900,000 bytes to 262,144 bytes (256 KiB).
• Updated unit tests (including e2e comments) and documentation to reflect the new default.
• Adjusted the large-payload example so the “large” path still exceeds the new threshold.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
durabletask/payload/store.py	Updates LargePayloadStorageOptions.threshold_bytes default and its docstring to 256 KiB.
tests/durabletask/test_large_payload.py	Updates default-threshold assertion in the blob payload store defaults test.
tests/durabletask/test_large_payload_e2e.py	Updates comment describing the production default threshold value.
tests/durabletask-azuremanaged/test_dts_large_payload_e2e.py	Updates comment describing the production default threshold value.
examples/large_payload/app.py	Sets example threshold to 256 KiB and increases demo “large” input so it still externalizes.
examples/large_payload/README.md	Updates example narrative + options table to the new default threshold and new demo payload size.
docs/features.md	Updates large-payload externalization docs and sample config defaults to 256 KiB.
docs/supported-patterns.md	Updates the described default threshold for the externalization example.
CHANGELOG.md	Adds an Unreleased “CHANGED” entry documenting the new default threshold and behavior impact.