Replace httpx with httpx2

[skupriienko-mailgun]

Links:

Jira

Actions:

• Core Engine Modernization (httpx2):

  • Async Engine Migration: Transitioned the asynchronous transport layer exclusively to httpx2 >=2.7.0, dropping the unmaintained httpx >=0.24.0 dependency across pyproject.toml, environment.yaml, and environment-dev.yaml.
  • Direct Core Imports: Updated mailgun.client, mailgun.endpoints, mailgun.security, and mailgun.types to interface natively with httpx2 for AsyncClient, Request, Response, Timeout, and exception classes.
  • Compatibility Layer Decommissioning: Removed mailgun/_httpx_compat.py and its runtime detection flag (HAS_HTTPX2), eliminating dynamic import branching, dual-engine shims, and obsolete tests (tests/unit/test_httpx_compat.py).
  • Security Policy Alignment: Updated SECURITY.md supported release targets to designate 1.10.x as active and deprecate < 1.10.0.

• Bug Fixes & Network Resilience:

  • Cyclic & Stagnant Cursor Guard in Streams: Hardened Endpoint.stream() and AsyncEndpoint.stream() to track prev_url, terminating the generator if Mailgun's pagination API returns duplicate or stagnant cursor tokens (next_url == prev_url) to prevent infinite iteration loops.
  • Stream Error Contract Parity: Wrapped synchronous requests.HTTPError into ApiError(exc.response) in Endpoint.stream(), matching the defensive exception contract implemented in AsyncEndpoint.stream() for httpx2.HTTPStatusError.
  • Dead Code Elimination: Removed the redundant secondary if not next_url or not items: break check in Endpoint.stream().
  • Telemetry Log Index Boundary Guard: Added an explicit items existence check in test_post_query_get_account_logs across test_integration_async.py and test_integration_sync.py to prevent IndexError: list index out of range on accounts with empty log retention windows.
  • Test Suite Error Handling & Log Format: Refactored verbose exception re-raising (raise e to raise) and corrected format string parameter alignment in test_integration_coverage.py.

• Linting, Tooling & Developer Experience (DX):

  • Ruff Formatter Conflict Resolution: Added missing-trailing-comma (COM812) to [tool.ruff.lint.ignore] in pyproject.toml to eliminate formatting rule collisions with ruff format.
  • Test Suite Rule Scoping: Configured targeted per-file-ignores for tests/** in pyproject.toml to suppress non-library false positives (such as assert, magic-value-comparison, pytest-unittest-assertion, and private test helper imports).
  • Pre-Commit Dependency Synchronization: Bumped commitizen to v4.19.2, semgrep to v1.180.0, typos to v1.51.1, check-jsonschema to 0.38.2, ruff to v0.16.10, and mypy to v2.4.0 in .pre-commit-config.yaml.
  • Codebase-Wide Formatting: Applied ruff check --fix --unsafe-fixes and ruff format across all unit, integration, fuzz, property, and regression test suites.

• Documentation & Release Preparation:

  • Release Changelog (v1.10.0): Documented the httpx2 migration, stream pagination hardening, tooling updates, and merged Dependabot PRs (build(deps): Bump the minor-and-patch group with 2 updates #68, build(deps): Bump the minor-and-patch group with 2 updates #70) in CHANGELOG.md.
  • Documentation Synchronization: Updated README.md runtime dependencies to mandate httpx2 >=2.7.0 exclusively and aligned integration test tagging metadata to httpx2-sdk.

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Verification & Testing:

1. Run the Unit Test Suite:
Validates core client lifecycle, builders, security guards, and httpx2 lazy client instantiation.

pytest tests/unit/ -v

2. Verify Stream Pagination & Endpoints:
Confirms cyclic cursor detection, type drift casting, and HTTP status handling across sync and async streams.

pytest tests/unit/test_endpoint.py tests/unit/test_pagination.py -v

3. Run the Live Integration Suite:
Executes end-to-end flows against sandbox domains verifying async/sync parity under httpx2.

pytest tests/integration/test_integration_sync.py -v
pytest tests/integration/test_integration_async.py -v

4. Execute Live Routing Meta-Tests:
Verifies URL formulation across all supported endpoints against live Mailgun servers.

pytest tests/integration/test_routing_meta_live.py -v -s

5. Performance & Concurrency Benchmarks:
Proves connection pooling throughput under httpx2.Limits(max_connections=100).

pytest tests/test_perf.py --benchmark-only

6. Static Analysis & Lint Gates:
Ensures complete Ruff, Mypy, and Pyright compliance across all library and test modules.

ruff check tests/ mailgun/
ruff format --check tests/ mailgun/
mypy mailgun/