Migrate SDK HTTP stack to httpx2

[goncalossilva]

Replace httpx with httpx2 to improve maintenance and supply chain posture.

httpx2 is a fork of httpx 0.28.1 with essentially the same public API, now under active Pydantic stewardship. Pydantic explicitly says (see the top of the README) it took over because httpx had seen limited activity and a critical-path HTTP library needs timely security updates.

httpx is not archived, and the author is promising a from-scratch rewrite, but they're working in private and with no ETA in sight. Plus, the maintainer closed access to issues and discussions around February 2026. Overall, a terrible look and a supply chain risk, even if httpx works well today.

Changes

• replace the direct httpx runtime dependency with httpx2>=2.0.0,<3
• migrate sync, async, authentication, response, timeout, and public injected-client types to httpx2
• route the existing RESPX-backed tests through the maintained pytest-httpx2 plugin
• update the lockfile, README, API docs, and changelog

Compatibility

This is a breaking change for callers that pass an httpx.Client or httpx.AsyncClient or catch httpx exceptions: httpx and httpx2 expose distinct classes, so those objects and exception handlers must move to httpx2 too.

That said, we have yet to officially release any version with httpx, so there is no breaking change per se. The first release with true async support would just use httpx2.

In other words, no compatibility issues—we should ship a new major soon.

[doistbot]

This PR updates Migrate SDK HTTP stack to httpx2. No issues were flagged in the reviewed diff.

_{Share Feedback • Review Logs}

[doistbot]

This PR updates Migrate SDK HTTP stack to httpx2. No issues were flagged in the reviewed diff.

_{Share Feedback • Review Logs}

[PotHix]

Looks reasonable to me. The fact that it's under pydantic now is a plus 👍

[Copilot]

🔵 Needs a closer look

It changes a core dependency and the HTTP/test stack end-to-end, and correctness depends on external package/API compatibility that can’t be fully verified from the diff alone.

Pull request overview

This PR migrates the SDK’s HTTP layer from httpx to httpx2, updating both the public injected-client types and the test harness so the codebase depends on the actively maintained fork.

Changes:

• Swapped runtime dependency from httpx>=0.28.1,<1 to httpx2>=2.0.0,<3 and refreshed the lockfile.
• Updated sync/async client injection points, request helpers, and raised-exception documentation to reference httpx2 types.
• Routed RESPX-backed tests through the pytest-httpx2 plugin and updated docs/changelog to match.

File summaries

File	Description
uv.lock	Updates resolved dependency graph to include httpx2/httpcore2 and adds pytest-httpx2 to dev dependencies.
todoist_api_python/authentication.py	Switches optional injected clients and managed client factories to httpx2 sync/async clients.
todoist_api_python/api.py	Migrates the sync API client’s injected-client type and docstrings to httpx2.
todoist_api_python/api_async.py	Migrates the async API client’s injected-client type and docstrings to httpx2.
todoist_api_python/_core/http_requests.py	Moves request helpers and TIMEOUT configuration to httpx2 types.
tests/test_http_requests.py	Updates request-helper tests to use httpx2 and catch httpx2.HTTPStatusError.
tests/conftest.py	Adds a respx_mock fixture that aliases the pytest-httpx2 provided mock fixture.
README.md	Updates migration guidance to reference httpx2 client types and exceptions.
pyproject.toml	Replaces httpx dependency with httpx2 and adds pytest-httpx2 to dev dependencies.
docs/index.md	Updates documentation to reference httpx2.AsyncClient.
CHANGELOG.md	Documents the breaking change and updates httpx references to httpx2.

Review details

• Files reviewed: 10/11 changed files
• Comments generated: 0
• Review effort level: Lite

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