SwiftPM

AXM reads Swift extension metadata from an agent-extensions.json sidecar at the package root — next to Package.swift. This is the two-way linking model applied to the Swift Package Manager ecosystem. SwiftPM has no manifest field for arbitrary metadata, so a sidecar file carries the recommendation.

Add an agent-extensions.json file at the package root with an agentExtensions array. Each entry is an extension reference (@owner/<type>/<name>):

// agent-extensions.json
{
  "$schema": "https://axm.sh/schemas/agent-extensions.schema.json",
  "agentExtensions": [{ "ref": "@examples/packs/swift-spm-tinyflags" }],
}

SwiftPM resolves packages from source checkouts, so committing agent-extensions.json beside Package.swift makes it available to consumers in their checkout.

Keep recommendations identity-only — omit versionRange. AXM resolves the reference to the newest matching extension version and pins it in the user's axm.lock. Prefer recommending a single pack so you keep one stable reference while its contents evolve.

Add a semver versionRange only when your package genuinely pairs with a bounded major line of the extension:

{
  "agentExtensions": [
    {
      "ref": "@examples/packs/swift-spm-tinyflags",
      "versionRange": "^1.0.0",
    },
  ],
}

On the extension manifest (skill.json, pack.json, subagent.json, …), add a packages array with a Swift purl. The Swift purl type is swift, and the host and path of the package's source repository form the namespace and name:

// pack.json
{
  "packages": [
    { "purl": "pkg:swift/example.com/agentxm/example-tinyflags-swift" },
  ],
}

Default to identity-only. Add a VERS versionRange with the swift scheme only when the extension depends on package APIs introduced or removed in a known range:

{
  "packages": [
    {
      "purl": "pkg:swift/example.com/agentxm/example-tinyflags-swift",
      "versionRange": "vers:swift/>=0.1.0|<1.0.0",
    },
  ],
}

When the SwiftPM package recommends an extension through the AgentXM Registry and that extension names the package as a companion via its purl, AXM derives official status for the pair — no extra flag. See Official extensions.

The swift-spm-lib and swift-spm-app directories in polyglot-examples are the working fixtures for everything above. The package publishes a TinyFlags companion pack and recommends it from the agent-extensions.json sidecar beside Package.swift; the pack and each skill declare the package's pkg:swift purl as an identity-only companion package.