Skip to content
Calimero Calimero Docs

Registry Overview

The Calimero App Registry is the distribution layer for Calimero applications. It lets teams publish signed WebAssembly bundles, browse available apps, and install them into nodes with a repeatable verification path.

Unlike a generic package index, the registry is opinionated about bundle integrity, publisher identity, and installation-time re-verification.

What the registry actually stores

Section titled “What the registry actually stores”

A published Calimero app is distributed as an .mpk bundle:

bundle.mpk
├── manifest.json
├── app.wasm
└── abi.json        # optional
PartPurpose
manifest.jsonHuman-readable metadata plus the Ed25519 signature used for verification
app.wasmThe compiled application logic that runs inside merod
abi.jsonOptional interface metadata used by tooling and generated clients

End-to-end trust path

Section titled “End-to-end trust path”
flowchart LR
    DEV[Developer or team] --> SIGN[Sign manifest with mero-sign]
    SIGN --> PUSH[Push bundle to registry]
    PUSH --> VERIFY[Registry canonicalizes and verifies signature]
    VERIFY --> STORE[Manifest and artifact metadata stored]
    STORE --> DISCOVER[Desktop or CLI discovers app]
    DISCOVER --> INSTALL[Node installs bundle]
    INSTALL --> RECHECK[Desktop or node re-verifies signature and digest]

    classDef lime fill:#14210a,stroke:#a5ff11,color:#f5ffe0,stroke-width:2px;
    classDef cyan fill:#0b2526,stroke:#39d0c8,color:#dcfffd,stroke-width:2px;
    classDef purple fill:#221133,stroke:#c084fc,color:#f7ecff,stroke-width:2px;
    classDef orange fill:#2c1805,stroke:#ffb54d,color:#fff2d6,stroke-width:2px;

    class DEV,SIGN lime;
    class PUSH,VERIFY cyan;
    class STORE,DISCOVER purple;
    class INSTALL,RECHECK orange;

Publish flow in practice

Section titled “Publish flow in practice”
  1. Build your application to WASM.
  2. Generate or reuse an Ed25519 signing key with mero-sign.
  3. Create a bundle with the registry CLI.
  4. Sign the manifest.
  5. Push the bundle to the registry.
  6. Browse and install it from Calimero Desktop or with CLI tooling.

The existing App Directory overview covers the author workflow. This page explains the system behavior behind that workflow.

Why the signature model matters

Section titled “Why the signature model matters”

The registry README describes a strict verification path:

  1. Remove the signature field and registry-added internal fields.
  2. Canonicalize the manifest JSON into deterministic bytes.
  3. Hash those bytes.
  4. Verify the Ed25519 signature against the publisher public key.

That same idea runs again when a bundle is installed. This means the registry is not the only trust anchor. The consumer side also checks what was published.

What the registry is responsible for

Section titled “What the registry is responsible for”
CapabilityWhat it means
DiscoveryUsers can browse available apps and versions
ValidationMalformed manifests and invalid signatures are rejected
Ownership checksNew versions and edits are gated by author or organization rules
Artifact resolutionThe manifest points to the application artifact and its digest
InstallabilityDesktop and nodes can fetch, verify, and open apps consistently

What it is not

Section titled “What it is not”

The registry is not the node runtime, the auth system, or the execution environment for app logic.

  • merod runs the app.
  • The registry distributes the app.
  • Desktop provides user-facing install and launch flows.
Section titled “Recommended next reads”