Mantyl.dev

Client handovers that prove themselves.

One command turns your repo and coding-agent history into a verified passport your client can re-run themselves. Built for teams shipping AI-assisted work.

See a real passport

On a phone right now? Star the repo and it waits in your GitHub account.

Free forever · no account · your code never leaves your machine · open source
Mantyl CLI · ~/mantylSelf-run
mantyl scan .
▸repository indexed18 modules · monorepo
▸agent history ingestedclaude code · 20 decisions
mantyl verify
✓5/5 checks reproducedclean docker sandbox
⚠env undocumentedANTHROPIC_API_KEY
mantyl generate
▸passport writtendigest 1c26942a…
mantyl receive
✓independently reproducedno divergence · exit 0
✓MANTYL VERIFIEDsigned · policy default@1
MTL.01 / The handover, twice

The zip arrives. The knowledge doesn’t have to disappear with it.

On the left, what the recipient of an agentic build gets today: a repository, a README the agent wrote, and optimism. On the right, the same project delivered with a passport.

The handover today
!“rate limiting enabled”no way to check
~works on the machine it was built onsetup
!why Redis was droppedlost with the session
!a file edited after deliveryundetected

The code runs. The story of how and why it runs left with the closed context window, and the client finds out slowly.

With a passport
+every claim labelled with its evidenceagent · repo · verified
+setup executed in a clean sandboxreproduced
+decisions recovered from sessions, datedrecorded
+any post-delivery change named by filereceive

The recipient re-runs the checks on their own machine before accepting. Both sides know exactly what changed hands.

MTL.03 / The passport

Not a wall of generated docs. A document someone signs.

Architecture, setup, decisions, risks, unfinished work and verification results. Every claim is labelled with its source, every section linked to evidence, ending in acceptance rather than optimism.

Mantyl · Project passportSigned · e4f2a91
Projectbooking-app
Issued20 Jul 2026
BuilderR. Okafor · Studio North
RecipientHarbour & Co
Claims verified34 / 41
Unknowns6 surfaced
01Architecture & services✓
02Setup & environment, reproduced from clean clone✓
03Decisions & abandoned approaches (8)✓
04Risk register & unknowns (6)⚠
05Verification log: build, tests, types✓
06Acceptance record→
P<MANTYL<<BOOKING<APP<<STUDIO<NORTH<<<<<<<<<E4F2A91C7<<34OF41VERIFIED<<ACCEPTED<<<<<<<<4
Provenance, line by line

Reads like a review, not a promise

Verified, repository-backed and agent-only claims are kept apart, and unknowns are findings, not footnotes. Visible uncertainty is safer than manufactured confidence.

+build reproduced from a clean cloneverified
+42 tests passed, 0 failed, 3 skippedverified
~postgres 16 via docker-compose, no managed backuprepo
~sessions moved from Redis to JWT, why undocumentedrepo
!“rate limiting enabled”, no middleware in repoagent only
!payment refund path, not tested, no coverageunknown
Setup that survives you

Install, run, deploy: reproduced

Environment, dependencies and run steps verified from a clean machine, not copied from a README that was true three weeks ago.

Decisions

The why, extracted from history

Key decisions and abandoned approaches recovered from your agent sessions and recorded with dates and links before they vanish.

Acceptance

A record both sides can stand on

The recipient acknowledges what was delivered, verified and left outstanding. You keep a defensible record of the transfer.

Read a real one first: the passport Mantyl generated for itself, live and hosted. Then the annotated example for booking-app with all eight sections, including the check that failed.

MTL.05 / Mantyl Verified

Your word, independently countersigned.

A free passport is your evidence, honestly labelled. Mantyl Verified removes the last doubt: neutral infrastructure re-executes every recorded check from scratch and signs the result, the way a buyer trusts a surveyor over the builder. The outcome is a clean sign-off: the delivery is accepted on evidence, not assurances, and the final invoice has nothing left to argue about.

  • Every check re-executed independently on infrastructure nobody’s laptop holds, under a public verification policy.
  • The signed mark on your hosted passport, re-verified cryptographically on every render, checkable offline.
  • The compliance export pack included: EU AI Act provenance record, CycloneDX AIBOM and procurement answers, generated from the same evidence.
  • £29, one-time, per project. Less than an hour of your rate, billable to the project, with a 14-day no-questions money-back guarantee.
How Verified works14-day money-back · no subscription · no seats
Accreditation · e4f2a91
Mantyl Verified
Projectbooking-app
Checks executed6 · 1 failed, stated
Claims verified34 / 41
Issued20 Jul 2026 · clean machine

Self-attested says trust me. Independently attested says check for yourself. The mark is revoked if the evidence behind it can’t be reproduced.

MTL.07 / Pricing

Free tool. £29 when proof changes hands.

No subscription. No seats. Pay when a delivery needs an independent signature, nothing when it doesn’t. Less than an hour of your rate, billable to the project.

Live now

CLI

Free forever. No account, no credit card.

£0 FOREVER

  • Local-first CLI, unlimited projects
  • Scan, verify, generate, receive and accept
  • Publish passports to shareable links, free during alpha
  • Compliance exports: EU AI Act provenance, AIBOM, procurement answers
  • Open passport.json format, fail-closed secret redaction
Install from npm

Mantyl Verified

When the handover needs independent proof.

£29 ONE-TIME · PER PROJECT

  • Every recorded check re-executed on neutral infrastructure
  • Ed25519-signed accreditation under a public policy
  • The mark on your hosted passport, re-verified every render
  • Checkable offline by anyone, forever
  • Failed run with honest findings: one free re-run within 14 days
How Verified works

14-day no-questions money-back guarantee

No paywall stands between you and a finished handover, and passport.json stays open so the ecosystem can build on the format. Full terms on the pricing page.

MTL.08 / Principles

Local-first. Nothing leaves until you approve it.

Local analysis

The CLI runs where the project lives

Raw code and transcripts are processed locally by default, behind fail-closed secret redaction. Nothing needs to leave your machine to get a passport.

No telemetry

The CLI never phones home

No usage tracking, no crash reporting, no analytics in the tool itself. That is a product promise, not a settings default, and the CLI's source is public so you never have to take it on faith.

Approved publishing

Automation drafts. You publish.

The owner decides what a recipient sees. Sensitive history and wrong inferences never go out blindly.

Honest labels

Failed checks stay visible

No magic quality scores and no hidden failures. We never tidy a passport to make it look healthier. Visible uncertainty is the product working.

Documentation describes software. Agent memory continues it. Observability explains it.Mantyl transfers responsibility for it.

MTL.09 / Questions builders ask

Fair challenges. Straight answers.

Isn't this just generated documentation?

Documentation describes software; Mantyl transfers responsibility for it. The difference is provenance and verification. Every claim is labelled as agent reported, repository confirmed or verified by execution, checks actually run in a sandbox, and the recipient can independently recheck everything with one command. Documentation that merely repeats what an agent said is exactly the problem.

Couldn't I just prompt my agent to write a handover doc?

A prompt produces prose from one session's memory. Mantyl ingests history across sessions, inspects the repository directly, runs deterministic checks, detects contradictions between what was said and what exists, and records the decisions that shaped the project. The value is the evidence chain, not the text.

What's free and what's paid?

The CLI is free forever with no account: scanning, executed checks, passport generation, publishing to a shareable link (free while Mantyl is in alpha) and the compliance export pack all cost nothing. Mantyl Verified is the one paid thing: £29, one-time, per project, buys an independent re-execution of your recorded checks on neutral infrastructure and a signed accreditation on the passport. Every purchase carries a 14-day no-questions money-back guarantee, and there is no subscription, ever, until Agency arrives.

Can Mantyl run in CI?

Yes, and that changes what a passport is: one workflow step (or npx mantyl ci anywhere) executes the checks in the runner's Docker and regenerates the passport on every push, so the evidence accumulates for the life of the project instead of proving one moment. Exit codes gate the job honestly: 4 when checks fail, 5 when no sandbox exists, and skipped never masquerades as passed. At handover points the passport can be sealed as a DSSE attestation, the same format GitHub's own artifact attestations use, and your README badge dates its evidence so stale proof looks stale. The action and the CI docs are at mantyl.dev/docs/ci.

My code and transcripts are sensitive. What leaves my machine?

Nothing, unless you publish. The CLI is local first: scanning, verification and reports all happen where the project lives, and transcripts pass through fail-closed secret redaction before anything is stored. Publishing uploads the passport document you approved and nothing else, never your source code.

Is Mantyl open source?

The CLI is, fully. Everything that runs on your machine, including the secret redaction, the sandbox and the session-store adapters, is MIT licensed at github.com/jopli11/mantyl-cli, so you can audit exactly what a tool reading your private transcripts actually does. The hosted passport service and the Mantyl Verified signing infrastructure stay server-side, which is precisely what makes an independent signature worth something: it comes from a key nobody's laptop holds.

We only hand projects over a few times a year.

Then the free CLI already covers you. Generate a passport at each delivery, publish it if the client wants a link, and pay nothing. When a delivery deserves independent proof, one Verified credit covers that one project, which is exactly how often handovers actually happen. No subscription to justify.

Which agents and stacks are supported?

Agents: Claude Code first, with Cursor and OpenAI Codex support in beta. Mantyl reads their local session stores the same way, with the same redaction, so claims and decisions flow from any of the three. Stacks: Node and TypeScript projects get the full executed-check treatment, and Python joined in beta with 0.6.0 (uv, poetry, pipenv or pip installs, then pytest, ruff and mypy when your project declares them). Narrow integrations produce deep output, and more of each follow as they reach the same standard.

MTL.10 / Get Mantyl

Cleared for handover.

The CLI is free and local first. There is no account and nothing leaves your machine unless you say so. Install it, run it on a real project, and the next delivery you make carries proof instead of promises.

Read the quickstart
Free CLI · No account · Local first · MIT licence