Define a stable JSON event protocol for reporters and integrations #10

Motivation

Editors, CI systems, the future web UI, and external tools need structured real-time test events. The current JSON strings are assembled ad hoc and are not defined as a versioned protocol.

Proposed work

• Define typed events for run, suite, test, hook, output, retry, and coverage lifecycle data.
• Serialize events through the standard JSON facilities with correct escaping.
• Add a protocol version and compatibility policy.
• Let JSON output, UI broadcasting, and test history share the same event model.
• Document the schema with examples.

Acceptance criteria

• All event JSON is generated from typed structures rather than string interpolation.
• Arbitrary test names and error messages are escaped correctly.
• Schema fixtures or contract tests cover every event type.
• Consumers can detect the protocol version.