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Metadata
FieldValue
Canonical URIhttps://docs.aion.to/extensions/aion/middleware/1.0.0
Issueraion
Version1.0.0
ActivationThis extension is declarative. It will always be active and does not require activation.
Related ExtensionsMiddleware/Fulfills

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Overview

The Middleware extension marks an agent as a sequence middleware: it receives an A2A request from an upstream component, performs validation or transformation, and either forwards the request downstream or terminates the flow with a response. This extension is descriptive. It does not add new RPC methods or message shapes, and it does not, by itself, require client activation.

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Agent Card Declaration

{
  "capabilities": {
    "extensions": [
      {
        "uri": "https://docs.aion.to/extensions/aion/middleware/1.0.0",
        "description": "Role-based access control middleware",
        "required": false,
        "params": {
          "intent": "authz",
          "terminates": true
        }
      }
    ]
  }
}

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Parameters

NameRequiredDescription
intentoptionalShort label for purpose (e.g., authz, moderation, routing).
terminatesoptionalIndicates the middleware may return a final response without forwarding downstream.

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Behavior

  • Middleware should preserve the A2A request envelope and add or modify metadata or parts as needed.
  • Middleware may short-circuit a request by returning an error or response when policy checks fail.
  • Ordering is controlled by the agent sequence configuration, not by this extension itself.
Use Middleware Fulfills when a middleware agent can satisfy downstream required extensions on behalf of the client.