Module event_msg 

EventMsg-out API in crates/protocol (issue #5261).

Mirrors crates/tui/src/core/events::Event but as a serializable protocol. The TUI’s rx_event / Event channel, the app-server’s SSE stream, and the CLI’s stream-json output all speak this one type so headless and TUI observe byte-identical event shapes for the same Op.

Structs

EventEnvelope

Envelope that carries an EventMsg over the wire / channel with a monotonic seq so consumers can detect drops. Mirrors the existing RuntimeEventEnvelope but typed to EventMsg.

Enums

EventMsg

One event emitted by the core engine to every consumer (TUI, CLI, app-server, tests). This is the EventMsg-out half of the Op-in / EventMsg-out contract. It is a straight projection of the existing internal Event variants (streaming deltas, tool lifecycle, turn lifecycle, approvals) plus the thread/session ids that ThreadId / SessionId now make explicit.