WebResearcher — the core agentic research loop:
- Tool-use loop: Claude decides when to search (Tavily) and fetch (httpx)
- Budget enforcement: stops at max_iterations or token_budget
- Synthesis step: separate LLM call produces structured ResearchResult JSON
- Fallback: valid ResearchResult even when synthesis JSON is unparseable
- Full trace logging at every step (start, search, fetch, synthesis, complete)
- Populates all contract fields: raw_excerpt, categorized gaps,
discovery_events, confidence_factors, cost_metadata with model_id
9 tests: complete research loop, budget exhaustion, synthesis failure
fallback, trace file creation, fetch_url tool integration, search
result formatting.
Refs: archeious/marchwarden#1
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>