Context

Part of #685 (Wave 1, P0). Reference (self): common_system is the docs/structure reference but lacks fuzz.

Problem

• no dedicated fuzz/ for result/event_bus/circular_buffer/config parser
• README advertises 80%+ coverage while codecov floor is 40% -> honesty gap

Acceptance Criteria

• dedicated fuzz/ harness + corpus + weekly fuzzing workflow
• coverage gate floor raised to match measured value, or README figures corrected to match gate

Notes

Weekly fuzzing workflow touches .github/workflows/ -> requires workflow token scope.

Derived from the 2026-05-30 multi-agent cross-system level-matching analysis (workflow wf_0a968699-e07). Reference systems: documentation=common_system, code-structure=monitoring_system, tests/examples=container_system.