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Plugins

Plugins are Arbiter's service adapters. A plugin connects Arbiter to one service area, such as SMTP or IMAP, and defines the capability and operations that agents can discover and use.

Installing a plugin makes its capability available to the server. Configuration still decides which accounts and policies are active, so installing a plugin does not by itself grant an agent access to an upstream service.

What Plugins Provide​

A service plugin is responsible for the service-specific parts of Arbiter:

  • account and policy config schemas
  • bootstrap examples for new accounts and policies
  • operation names, descriptions, and input schemas
  • runtime behavior for calling the upstream service
  • service-specific policy checks
  • management of service-specific writable state, when needed

For example, the SMTP plugin owns smtp:send_email and the policy controls that decide whether a message can be sent. The IMAP plugin owns folder and message operations, plus the policy controls that decide which folders and message actions are allowed.

What Operators Configure​

Operators decide how installed plugins are exposed by configuring:

  • accounts: connection settings, credential references, display metadata, and the policy selected for that account
  • policies: service-specific guardrails for one or more accounts
  • activation: which account and policy files are included in the composed server config

Bootstrap creates a matching policy for each new account, but accounts refer to policies by name. Multiple accounts can share the same policy when that matches the deployment model.

From Plugin To Operation​

At startup, Arbiter discovers installed service plugins, registers their config schemas, composes the active deployment config, validates it, and then exposes operations for configured accounts.

Agents see the resulting capability and operation surface. They do not provide transport settings, credentials, folder access, recipient policy, or other deployment-owned controls in operation arguments.

For the file layout and activation model, see Configuration Model. For plugin authoring, see Writing Plugins.