summarize_recent_events and wait_for_event embed each
event's payload as JSON with $type sentinels for
NativePointer, BigInt, Date, typed arrays, Map, Set, and
friends. Tracer events decode into named fields with
caller and backtrace pre-symbolicated.
Add read_event(event_id) for the full uncapped payload.
SymbolicateResult collapses to one struct with optional
offset and source. Agent symbolicate returns objects with
a numeric offset field.
