Mantyl is the handover layer for agentic development. It reads your repository and your coding agent’s session history, executes real verification in a sandbox, and produces a project passport that a recipient can independently check. Everything runs on your machine and nothing is uploaded unless you explicitly publish.
Mantyl ships as a single npm package. You need Node 20.12 or newer. Docker Desktop is optional but recommended because it powers the verification sandbox.
Run these four commands from the root of a project you want to hand over. Each one is useful on its own and none of them talks to a server.
Artefacts land in the .mantyl directory. The canonical contract is passport.json, stamped with a digest that binds it to the exact commit and file contents it describes.passport.html is the same content as a readable report.
Every statement in a passport carries a truth status and a source reference. The repository is evidence. Executed checks are evidence. What an agent said it did is recorded as exactly that, a report, and when the repository contradicts it the passport says so plainly. The full vocabulary is on the truth model page.
Session transcripts pass through fail-closed secret redaction before they are stored or analysed. If you enable the optional LLM analysis, it sees redacted excerpts only and everything it writes is permanently marked as inference.
Mantyl currently reads Claude Code session stores, with more agentic coding tools planned. From the transcripts it extracts claims, which are statements about work done, and decisions, which are choices made along the way. Your own recorded words become creator confirmed entries, because the person who made the call said so on the record.