Synthadoc: Routing at Scale, Quality Gates, and the Knowledge Backend Pattern

When we shipped v0.1.0, Synthadoc did one thing well: it turned raw sources into a structured wiki that got smarter with every ingest. v0.2.0 made that wiki searchable with hybrid BM25 + vector retrieval. v0.3.0 opened up the source types - YouTube transcripts, web search fan-out, CLI provider integration so your existing Claude Code or Opencode subscription could power the whole thing. But a pattern kept surfacing in user feedback. Once a wiki crossed a few hundred pages, three problems appeare