Support datetime.timedelta for seconds/milliseconds duration encoding (python)

[Copilot]

Overview:

Other language emitters have fully support this feature and this feature belongs to core features in spec dashboard.

PR description

Adds support in @typespec/http-client-python for SDK users to pass datetime.timedelta for durations encoded as seconds/milliseconds (in addition to the existing ISO8601 support), and extends the encode/duration mock_api test coverage to exercise this.

Changes

Feature: timedelta support for seconds/milliseconds durations

• Emitter (emitter/src/types.ts): emitBuiltInType now emits seconds/milliseconds DurationKnownEncoding values as a duration type carrying the encode and numeric wireType, alongside the existing ISO8601 branch.
• Generator (generator/pygen/codegen/models/primitive_types.py): DurationType reads encode + wireType and produces a combined format token duration-{seconds|milliseconds}-{int|float}; ISO8601 retains the legacy duration behavior.
• Runtime serialization/deserialization (both paths):
  • model_base.py.jinja2 (DPG body model properties): added _serialize_duration plus seconds/milliseconds deserializers and the corresponding _DESERIALIZE_MAPPING_WITHFORMAT entries.
  • serialization.py.jinja2 (msrest query/header params): added serialize/deserialize methods for the seconds/milliseconds (int/float) formats, registered in the type maps.

This lets users pass datetime.timedelta and receive datetime.timedelta back for these encodings, with conversion to/from the numeric wire value handled by the runtime.

Test coverage

• Added scenario coverage across all three operation groups (query, property, header), now using datetime.timedelta input:
  • milliseconds encodings (int32, float, float64)
  • larger-unit encodings (int32/float seconds and milliseconds)
  • milliseconds arrays
• Files (sync + async, both flavors):
  • tests/mock_api/azure/test_encode_duration.py, tests/mock_api/azure/asynctests/test_encode_duration_async.py
  • tests/mock_api/unbranded/test_encode_duration.py, tests/mock_api/unbranded/asynctests/test_encode_duration_async.py
• Property assertions use the correct per-scenario models (e.g. Float64SecondsDurationProperty, Int32MillisecondsLargerUnitDurationProperty) and assert datetime.timedelta on responses.
• Changelog entry under .chronus/changes (changeKind: feature).

Example of newly-covered cases using datetime.timedelta:

client.query.int32_milliseconds_array(
    input=[datetime.timedelta(milliseconds=36000), datetime.timedelta(milliseconds=47000)]
)
client.header.float_milliseconds_larger_unit(duration=datetime.timedelta(milliseconds=210000))
result = client.property.int32_milliseconds_larger_unit(
    Int32MillisecondsLargerUnitDurationProperty(value=datetime.timedelta(milliseconds=180000))
)
assert result.value == datetime.timedelta(milliseconds=180000)

Testing

• ✅ Regenerated encode/duration for both azure and unbranded flavors; verified generated models use datetime.timedelta with the new format tokens
• ✅ mock_api suites pass against the live mock server (azure + unbranded, sync + async — 12 passing)

[msyyc]

need new feature to support the test.

[Copilot]

need new feature to support the test.

Added in a7edc4d: SDK users can now pass datetime.timedelta for seconds/milliseconds duration encodings, supported end-to-end in the emitter, generator model, and serialization/deserialization logic.

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npm i https://pkg.pr.new/@typespec/http-client-python@10947

commit: 5ee0911

[github-actions]

All changed packages have been documented.

• ✅ @typespec/http-client-python

Show changes

@typespec/http-client-python - feature ✏️

Support datetime.timedelta for duration types encoded as seconds or milliseconds. SDK users can now pass a datetime.timedelta (instead of a raw int/float) and responses are deserialized back into datetime.timedelta.

[Copilot]

Pull request overview

Adds end-to-end support in @typespec/http-client-python for duration values encoded as numeric seconds/milliseconds, allowing SDK users to pass and receive datetime.timedelta (in addition to the existing ISO8601 duration behavior).

Changes:

• Extend the Python emitter + generator model typing so duration with seconds/milliseconds encodings carries encode + numeric wireType, and maps to new combined format tokens (e.g. duration-seconds-int).
• Add runtime serialization/deserialization helpers for the new numeric duration format tokens in both the DPG model runtime (model_base.py.jinja2) and msrest runtime (serialization.py.jinja2).
• Update mock API tests (azure + unbranded, sync + async) to exercise query/property/header duration paths using datetime.timedelta for seconds/milliseconds scenarios.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/http-client-python/tests/mock_api/unbranded/test_encode_duration.py	Expands unbranded sync duration tests to use timedelta for seconds/milliseconds query/property/header scenarios.
packages/http-client-python/tests/mock_api/unbranded/asynctests/test_encode_duration_async.py	Expands unbranded async duration tests to use timedelta for seconds/milliseconds query/property/header scenarios.
packages/http-client-python/tests/mock_api/azure/test_encode_duration.py	Expands azure sync duration tests to use timedelta for seconds/milliseconds query/property/header scenarios.
packages/http-client-python/tests/mock_api/azure/asynctests/test_encode_duration_async.py	Expands azure async duration tests to use timedelta for seconds/milliseconds query/property/header scenarios.
packages/http-client-python/generator/pygen/codegen/templates/serialization.py.jinja2	Adds msrest serializer/deserializer support for `duration-*-{int
packages/http-client-python/generator/pygen/codegen/templates/model_base.py.jinja2	Adds DPG runtime serializer/deserializer support for numeric duration formats and routes timedelta serialization through format-aware logic.
packages/http-client-python/generator/pygen/codegen/models/primitive_types.py	Updates DurationType to interpret encode + wireType and emit combined format tokens for numeric duration encodings.
packages/http-client-python/emitter/src/types.ts	Emits encode + wireType metadata for duration when encoded as seconds/milliseconds.
.chronus/changes/add-python-duration-seconds-milliseconds-encode-2026-6-10-9-3-37.md	Adds a chronus feature changelog entry for the new timedelta support.

[azure-sdk-automation]

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[msyyc]

@iscai-msft / @l0lawrence / @tadelesh pls help review and code diff is in Azure/azure-sdk-for-python#47471. You may focus on the api signature change in https://github.com/Azure/azure-sdk-for-python/pull/47471/changes#diff-60dc1ef1c0ec0a97c1bd1e6ecfba30a049b2644327aa9c276be3831b24148882