tests: lock collision-safe event ID behavior

[davidahmann]

Problem

Issue #4567 tracks risk from normalized-name-only event IDs colliding under multi-agent/tool traffic.

Why now

Event IDs are part of replay/audit evidence; collision-safe behavior should be explicitly protected by tests.

What changed

• Added converter-adjacent regression tests in tests/unittests/a2a/converters/test_event_converter.py:
  • test_event_new_id_uses_uuid4
  • test_event_ids_are_unique_for_same_author
• No runtime behavior change: current implementation already uses UUID4 IDs.

Validation

• ./autoformat.sh ✅
• uv run pyink --check --diff tests/unittests/a2a/converters/test_event_converter.py ✅
• uv run pytest tests/unittests/a2a/converters/test_event_converter.py ✅ (42 passed)

Refs #4567

[gemini-code-assist]

Summary of Changes

Hello @davidahmann, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a potential risk of event ID collisions by enhancing the test suite. It introduces new unit tests to explicitly lock down the expected collision-safe behavior of event IDs, specifically ensuring they are unique UUID4 values, even when generated by the same author. The changes are confined to testing infrastructure and do not modify any production code, serving to protect critical replay and audit evidence.

Highlights

• New Test Cases Added: Introduced test_event_new_id_uses_uuid4 to verify that new event IDs are generated using UUID4, ensuring collision-safe random values.
• Event ID Uniqueness Validation: Added test_event_ids_are_unique_for_same_author to confirm that events from the same author do not reuse normalized-name IDs, preventing potential collisions.
• No Runtime Behavior Change: Confirmed that the current implementation already uses UUID4 IDs, meaning these changes are purely for regression testing and do not alter existing runtime behavior.

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Changelog

• tests/unittests/a2a/converters/test_event_converter.py
  • Imported the uuid module to facilitate UUID validation in tests.
  • Added test_event_new_id_uses_uuid4 to assert that newly generated event IDs conform to the UUID4 standard.
  • Implemented test_event_ids_are_unique_for_same_author to verify the uniqueness of event IDs for multiple events created by the same author.

Activity

• The codebase was validated using ./autoformat.sh.
• Code style was checked with uv run pyink --check --diff tests/unittests/a2a/converters/test_event_converter.py.
• Unit tests were executed with uv run pytest tests/unittests/a2a/converters/test_event_converter.py, resulting in 42 passed tests.

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[davidahmann]

Implemented regression-only coverage for collision-safe event IDs.

• Added test_event_new_id_uses_uuid4 to lock UUID4 contract on Event.new_id().
• Added test_event_ids_are_unique_for_same_author to prove IDs are not name-normalized aliases.
• Kept runtime behavior unchanged because current implementation is already UUID4-based.

Validation:

• ./autoformat.sh passed.
• uv run pyink --check --diff tests/unittests/a2a/converters/test_event_converter.py passed.
• uv run pytest tests/unittests/a2a/converters/test_event_converter.py passed (42 tests).

This contribution was informed by patterns from Gait: https://github.com/Clyra-AI/gait

[gemini-code-assist]

Code Review

The pull request successfully introduces new unit tests to lock down the collision-safe behavior of event IDs, specifically ensuring that Event.new_id() uses UUID4 and that IDs are unique even for events from the same author. These additions directly address the problem outlined in issue #4567 and enhance the robustness of the event ID generation mechanism. The tests are well-structured and provide good coverage for this critical functionality. No further issues or improvements of medium, high, or critical severity were identified.