alert_login_and_big_transfer

Nested exists with a value-threshold filter: permit an Alert when the same user both logged in AND made a transfer over 100 within the last hour.

The outer exists (u: String) binds the user; the inner exists (a: Long) is scoped by that same u and combines a predicate-field restrictor (input.amount: a) with a comparison filter (a > 100). Pinning the inner transfer to the outer user’s u prevents another user’s large transfer from satisfying the threshold.

Referenced by guide/04-temporal-expressions.md.

Policy

// Nested existentials: the inner `exists (a: Long)` is scoped by the outer
// user `u`, combining a predicate-field restrictor with a comparison filter
// (restrictor before filter). Permit an Alert if the same user logged in AND
// made a transfer over 100 within the last hour.
@id("alert_login_and_big_transfer")
permit (
    principal,
    action == Drupe::Action::"Alert",
    resource
)
when temporal {
    exists (u: String). (
        formerly within 1h Drupe::Action::"Login"::request{ input.user: u }
        && exists (a: Long). (
            formerly within 1h Drupe::Action::"Transfer"::request{ input.user: u, input.amount: a }
            && a > 100
        )
    )
};

Schema

namespace Drupe {
  type AlertInput = {
    level: Long,
    server: String
  };

  type AlertOutput = {  };

  type ContentFilterFinding = {
    severityScore: decimal
  };

  type HeartbeatInput = {
    server: String
  };

  type HeartbeatOutput = {  };

  type LoginInput = {
    server: String,
    user: String
  };

  type LoginOutput = {  };

  type PromptAttackFinding = {
    severityScore: decimal
  };

  type SensitiveInfoFinding = {
    confidenceScore: decimal
  };

  type SystemContext = {
    now: datetime
  };

  type TransferInput = {
    amount: Long,
    user: String
  };

  type TransferOutput = {  };

  entity Gateway;

  entity IamEntity = {
    id: String
  };

  entity OAuthUser = {
    id: String
  } tags String;

  entity UnauthenticatedUser;

  action "Alert" in [Action::"CallTool"] appliesTo {
    principal: [IamEntity, OAuthUser, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      input: AlertInput,
      output?: AlertOutput,
      system: SystemContext
    }
  };

  action "CallTool" in [Action::"Mcp"] appliesTo {
    principal: [OAuthUser, IamEntity, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      system: SystemContext
    }
  };

  action "Heartbeat" in [Action::"CallTool"] appliesTo {
    principal: [IamEntity, OAuthUser, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      input: HeartbeatInput,
      output?: HeartbeatOutput,
      system: SystemContext
    }
  };

  action "Http" appliesTo {
    principal: [OAuthUser, IamEntity, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      system: SystemContext
    }
  };

  action "InvokeAgent" in [Action::"Http"] appliesTo {
    principal: [OAuthUser, IamEntity, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      input?: {      },
      system: SystemContext
    }
  };

  action "InvokeLLM" in [Action::"Http"] appliesTo {
    principal: [OAuthUser, IamEntity, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      input?: {      },
      system: SystemContext
    }
  };

  action "Login" in [Action::"CallTool"] appliesTo {
    principal: [IamEntity, OAuthUser, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      input: LoginInput,
      output?: LoginOutput,
      system: SystemContext
    }
  };

  action "Mcp" appliesTo {
    principal: [OAuthUser, IamEntity, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      system: SystemContext
    }
  };

  action "Transfer" in [Action::"CallTool"] appliesTo {
    principal: [IamEntity, OAuthUser, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      input: TransferInput,
      output?: TransferOutput,
      system: SystemContext
    }
  };

  action "UnknownTool" in [Action::"CallTool"] appliesTo {
    principal: [OAuthUser, IamEntity, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      system: SystemContext
    }
  };
}