I got tired of asking coding agents “are you sure?”, so I built a local evidence checker

I built Plumbref because I kept running into the same loop with coding agents

They would give a confident answer about a repo, and then I’d have to ask:

• “Are you sure?”


• “Did you check the other path?”


• “What about downstream consumers?”


• “Is this actually only used there?”

The issue wasn’t that the agent couldn’t read code. The issue was that the answer didn’t always come with a clear verification trail

Plumbref is a local-first MCP server that helps a coding agent check repo answers before giving them back

It lets the agent:

• break an answer into claims


• search the repository


• read bounded source snippets


• check for contradictions


• classify claims as supported, too_broad, uncertain, contradicted, not_found, or not_verifiable

Plumbref runs locally:

• no hosted service


• no repo upload


• no database


• no vector store


• no model API key

Right now it includes an MCP server, a CLI, Markdown/JSON reports, ripgrep-based repo search, bounded snippets, broad-claim detection, and built-in templates for flow explanations, field migrations, change impact, downstream consumers, and external integrations

It’s still early, but I’ve been dogfooding it on its own repo and I’d like feedback from people using coding agents on real codebases

Repo: https://github.com/ftaboadac/plumbref