Add mypy type checking to CI/CD

[fangnx]

What

Enforces mypy type checking in the CI/CD pipeline to improve code maintainability of the repo

Checklist

• Contains customer facing changes? Including API/behavior changes
• Did you add sufficient unit test and/or integration test coverage for this PR?
  • If not, please explain why it is not required

References

JIRA: https://confluentinc.atlassian.net/browse/DGS-22076

Test & Review

Open questions / Follow-ups

[confluent-cla-assistant]

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[Copilot]

Pull Request Overview

This PR integrates mypy type checking into the CI pipeline to enforce static type checking across the codebase. The changes add mypy as a new test environment and provide multiple ways to run type checks during development and CI.

Key changes:

• Adds mypy as a new tox test environment with required type stub dependencies
• Integrates mypy checking into the CI verification script
• Includes type checking artifacts (py.typed marker and cimpl.pyi stub file) in the source distribution

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
tox.ini	Adds mypy test environment with type-checking dependencies and command configuration
tools/source-package-verification.sh	Integrates mypy type checking into the CI verification workflow for Linux x64 builds
Makefile	Adds mypy target for convenient local type checking execution
MANIFEST.in	Includes type checking marker file and stub file in source distribution

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[Copilot]

The mypy command should include the --strict or explicit configuration flags (e.g., --disallow-untyped-defs, --warn-return-any) to ensure consistent type checking behavior. Without explicit flags, mypy's behavior depends on project configuration files which may not be present, leading to inconsistent results across environments.

Suggested change

	commands = mypy src/confluent_kafka
	commands = mypy --strict src/confluent_kafka

[fangnx]

We already have config in pyproject.toml

[Copilot]

The mypy invocation should match the configuration used in tox.ini. Consider using tox -e mypy instead of calling mypy directly to ensure consistency between local development and CI environments.

Suggested change

	mypy src/confluent_kafka
	tox -e mypy

[sonarqube-confluent]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube