[sorenqh]

The Python emitter drops nullability from required model properties and collection element types. For example, string | null becomes str, and (Child | null)[] becomes list[Child], so generated type annotations contradict the API contract.

Preserve nullability in SDK model and TypedDict annotations, including nested lists and dictionaries, while keeping required constructor arguments required. Keep collection-element nullability separate from the containing field so required unwrapped XML lists still deserialize missing items as empty lists. Preserve delimited-array decoding when nullable elements introduce an Optional wrapper.

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Approved automatically for a Dependabot update.

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🔵 Needs a closer look

Shared generated-SDK deserialization changes need confirmed regression-test results and final human review; execution was not verified here.

No open issues 🎉

What changed in this PR

Fixes the Python emitter so SDK model and TypedDict annotations preserve nullable properties and collection elements without making required constructor arguments optional.

Changes:

• Carries element nullability through the emitter and Python annotation generation, including nested collections.
• Keeps collection-element nullability separate from XML field optionality and preserves delimited-array decoding.
• Adds regression tests and a changelog entry.

File	Description
packages/​http-client-python/​tests/​unit/​test_nullable_properties.py	Tests nullable annotations and constructor requiredness.
packages/​http-client-python/​tests/​unit/​test_nullable_collections.py	Tests collection annotations, imports, nesting, and forward references.
packages/​http-client-python/​tests/​unit/​test_nullable_collection_deserialization.py	Tests XML defaults, nullable items, and delimited decoding.
packages/​http-client-python/​generator/​pygen/​codegen/​templates/​model_base.py.jinja2	Separates field optionality from element nullability during decoding.
packages/​http-client-python/​generator/​pygen/​codegen/​models/​property.py	Preserves property nullability in annotations and imports.
packages/​http-client-python/​generator/​pygen/​codegen/​models/​list_type.py	Adds nullable list-element annotations and documentation.
packages/​http-client-python/​generator/​pygen/​codegen/​models/​dictionary_type.py	Adds nullable dictionary-value annotations and documentation.
packages/​http-client-python/​emitter/​test/​nullable-collections.test.ts	Tests nested nullability and shared-type isolation.
packages/​http-client-python/​emitter/​src/​types.ts	Emits collection-element nullability metadata.
.chronus/​changes/​python-nullable-type-annotations-2026-10-24.md	Documents the annotation fix.

_{Review effort: Balanced}

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