Incorporates valuable extra coverage from fullstack-engineer's PR #336:
- test_push_queued_missing_queue_id_still_parsed: queue_id is optional,
absence must not break parsing
- test_push_queued_is_distinct_from_poll_queued: both envelope shapes
parse correctly and independently, with correct delivery_mode values
Also adds push_queued_no_queue_id fixture and regression gate entry.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Bug: a2a_response.py:197 returned Queued(method=method) without passing
delivery_mode, silently defaulting to "poll" for push-mode busy-queue
responses. Callers branching on v.delivery_mode would mis-identify push-mode
responses as poll-mode, causing wrong dispatch logic.
Fix: pass delivery_mode="push" explicitly in the push-mode branch.
Tests: add push_queued_full/notify/no_method fixtures and 4 test cases
asserting delivery_mode="push" for all three envelope shapes. Also add
adversarial {"queued": "yes"} and {"queued": False} → Malformed guards.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
