A2A Skills Extension

The AGBoss skills extension — https://agboss.dev/a2a/skills/v1

A data-only extension of A2A v1.0 (spec §4.6): the JSON Schemas of an AGBoss agent's skills — what A2A's AgentSkill has no field for — and the skill a message runs. (#808 the server, #809 the client; to be mirrored at agboss.dev.)

Declaration — the Agent Card

{
  "uri": "https://agboss.dev/a2a/skills/v1",
  "required": false,
  "params": {
    "skills": {
      "<skill id>": {
        "input": { "type": "object", "properties": {} },
        "schemaHash": "<64 hex>",
        "outputs": { "<finish name>": { "type": "object" } }
      }
    }
  }
}

• A skill's id is the exported @WorkflowStart's name; input its input DTO's JSON Schema (null for a text start), outputs one schema per finish it can end at, schemaHash the input's hash — what agboss check --federation compares.
• A client with DTOs compares them with these before anything is sent ([a2a.schema-mismatch]).

In a message — message.metadata[uri].skill

The skill the message runs: optional when the agent serves one, else required (-32602 a2a.skill-required; an unknown one a2a.unknown-skill). A completed task's artifact names its finish in artifact.metadata[uri].finish.

See A2A for the framework's side.