read_prev_login_success

previous with a response predicate and an output-field filter. Permit a Read only if the immediately preceding event (within 1h) was the same user’s successful Login — i.e. a Login::response whose output.result is true. Because previous looks only at timepoint i - 1, at timepoint 0 there is no predecessor, so the rule can never fire there.

The trace shows all three behaviors:

• @0 — a Read at timepoint 0: no predecessor exists, so deny (the no-verdict-at-tp0 behavior).
• @7 — a Read whose immediately preceding event (@5) is alice’s successful Login::response (output.result: true) → allow.
• @31 — a Read whose predecessor (@30) is bob’s Login::response with output.result: false; the output-field filter rejects the failed login → deny.

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

Policy

// `previous` with a response predicate and an output-field filter. Permit a
// Read only if the immediately preceding event (within 1h) was the same
// user's SUCCESSFUL Login (output.result: true). At timepoint 0 there is no
// predecessor, so the rule never fires there.
@id("read_after_prev_login_success")
permit (
    principal,
    action == Drupe::Action::"Read",
    resource
)
when temporal {
    previous within 1h Drupe::Action::"Login"::response{ input.user: context.input.user, output.result: true }
};

Schema

namespace Drupe {
  type ContentFilterFinding = {
    severityScore: decimal
  };

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

  type LoginOutput = {
    result: Bool
  };

  type PromptAttackFinding = {
    severityScore: decimal
  };

  type ReadInput = {
    document: String,
    user: String
  };

  type ReadOutput = {  };

  type SensitiveInfoFinding = {
    confidenceScore: decimal
  };

  type SystemContext = {
    now: datetime
  };

  entity Gateway;

  entity IamEntity = {
    id: String
  };

  entity OAuthUser = {
    id: String
  } tags String;

  entity UnauthenticatedUser;

  action "CallTool" in [Action::"Mcp"] appliesTo {
    principal: [OAuthUser, IamEntity, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      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 "Read" in [Action::"CallTool"] appliesTo {
    principal: [IamEntity, OAuthUser, UnauthenticatedUser],
    resource: [Gateway],
    context: {
      input: ReadInput,
      output?: ReadOutput,
      system: SystemContext
    }
  };

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

Trace

@0 scope(principal: Drupe::OAuthUser::"alice", resource: Drupe::Gateway::"gw1") request_context(input: { document: "doc0", user: "alice" }) Drupe::Action::"Read"::request(input: { document: "doc0", user: "alice" }, callerPrincipal: Drupe::OAuthUser::"alice", callerResource: Drupe::Gateway::"gw1", requestId: "r0")
@5 scope(principal: Drupe::OAuthUser::"alice", resource: Drupe::Gateway::"gw1") Drupe::Action::"Login"::response(input: { server: "s1", user: "alice" }, output: { result: true }, callerPrincipal: Drupe::OAuthUser::"alice", callerResource: Drupe::Gateway::"gw1", requestId: "l1")
@7 scope(principal: Drupe::OAuthUser::"alice", resource: Drupe::Gateway::"gw1") request_context(input: { document: "doc1", user: "alice" }) Drupe::Action::"Read"::request(input: { document: "doc1", user: "alice" }, callerPrincipal: Drupe::OAuthUser::"alice", callerResource: Drupe::Gateway::"gw1", requestId: "r1")
@30 scope(principal: Drupe::OAuthUser::"bob", resource: Drupe::Gateway::"gw1") Drupe::Action::"Login"::response(input: { server: "s1", user: "bob" }, output: { result: false }, callerPrincipal: Drupe::OAuthUser::"bob", callerResource: Drupe::Gateway::"gw1", requestId: "l2")
@31 scope(principal: Drupe::OAuthUser::"bob", resource: Drupe::Gateway::"gw1") request_context(input: { document: "doc2", user: "bob" }) Drupe::Action::"Read"::request(input: { document: "doc2", user: "bob" }, callerPrincipal: Drupe::OAuthUser::"bob", callerResource: Drupe::Gateway::"gw1", requestId: "r2")

Expected Output

@0 (time point 0): DENY
@7 (time point 1): ALLOW  [rules: 0]
@31 (time point 2): DENY