fix(schemas): add missing 'executive_synthesis_skipped' to Event.type enum

[MerouaneBen]

Summary

When the Reporter's executive-synthesis LLM call raises, the graceful-fallback path emits Event(type="executive_synthesis_skipped", …) — but that string isn't in the Event.type Literal enum (schemas.py). Pydantic then raises ValidationError, which crashes the entire run at the reporter stage, after the (expensive) jury + consensus work is already done. The safety net is itself the failure.

Where

proofagent_harness/agents/reporter.py → _generate_executive_synthesis() except Exception: block calls _emit(state, Event(type="executive_synthesis_skipped", …)). The Event.type Literal in schemas.py does not list that value.

Repro

Any Harness().evaluate(...) where the harness LLM fails/refuses/times out on the exec-synthesis call. We hit it reliably with a --metrics subset + a harness model that occasionally returns malformed JSON. Instead of degrading to the deterministic summary, the process dies with:

pydantic_core.ValidationError: 1 validation error for Event
type
  Input should be 'setup_start', … , 'done' or 'error' [input_value='executive_synthesis_skipped']

Fix

Add "executive_synthesis_skipped" to the Event.type Literal. Verified locally — the run then completes on the deterministic fallback as intended.

Context

Found while running a serious hands-on evaluation of a fleet of internal agents. Genuinely useful harness — thanks for open-sourcing it.