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RegulusPolicyPlugin

In one sentence

Enforces declarative policy guards on every ADK agent invocation: purpose binding, consent, GDPR Art. 22 safeguards, Consumer Duty outcomes, vulnerable-customer routing.

Who does it apply to?

Any agent under any Regulus profile. The plugin is profile-aware — it reads ComplianceProfile.controls() and activates whichever guards the profile declares.

The two-minute explainer

Policy guards are the first control point in the request lifecycle: before the model is called, before any tool fires, the policy decider gets to say "allow," "block," or "require confirmation."

The decision is driven by the active profile's ControlBindings. If the profile says purpose-binding is required (GDPR / UK GDPR), the plugin refuses any call missing a purposeCode. If the profile says automated-decisions-safeguards is required (GDPR Art. 22, AI Act Art. 14), the plugin routes flagged calls through ADK's ToolConfirmation HITL flow before the model is consulted. If the profile says vulnerable-customer-handling is required (FCA Consumer Duty FG22/5 §4), flagged customers get the same HITL treatment.

The plugin is pure ADK — BasePlugin + BeforeModelCallback + BeforeToolCallback. No Spring, no AOP.

What it actually requires of an engineer

To use the plugin, you need to:

  • Activate at least one profile with regulus.compliance.profiles: [...].
  • Pass an invocation context that includes the fields the active guards consume (purposeCode, vulnerable_customer, automated_legal_effect, etc.). The Spring starter wires this from request headers; bare-Java callers populate PolicyContext themselves.

What Regulus does for you

  • Maps each profile's ControlBinding to a runtime check (in DefaultPolicyEngine).
  • Emits structured PolicyDecision outputs: Allow, Block, RequireConfirmation.
  • Surfaces clause citations on every block so the audit trail and the developer console both know which clause failed.
  • Composes profiles correctly: a request that violates any active profile's binding is blocked, with the offending clause cited.

Saves you ~

  • ~2 engineer-weeks for a YAML-driven policy engine that compiles.
  • ~1 engineer-week to wire ToolConfirmation correctly into ADK's HITL flow.
  • ~1 engineer-week to keep citations in sync with regulation updates.

Net: ~4 engineer-weeks.

Code: minimal

RegulusPolicyPlugin policy = RegulusPolicyPlugin.fromProfile(
    ComplianceProfiles.byId("uk-gdpr"));
App app = App.builder("my-agent", rootAgent).plugin(policy).build();

Code: production

With the Spring starter:

regulus:
  compliance:
    profiles: [uk-gdpr, fca-sysc]

The plugin auto-configures and consumes the composite profile.

To customise the decider (e.g. add bespoke guards for a tenant):

PolicyDecider decider = context -> {
    if ("forbidden-tool".equals(context.targetId()) && "tool".equals(context.targetKind())) {
        return new PolicyDecision.Block("tool_blocked",
            "This tool is disabled for the tenant", "tenant-policy");
    }
    return DefaultPolicyEngine.evaluate(profile, context);
};
RegulusPolicyPlugin custom = RegulusPolicyPlugin.withDecider(profile, decider);

How to verify

  • Send a request without purpose_code under the gdpr profile → block with citation Art. 5(1)(b).
  • Send a request with automated_legal_effect=true → RequireConfirmation with citation Art. 22.
  • Send a request with vulnerable_customer=true under fca-sysc → RequireConfirmation with citation FG22/5 §4.

What an auditor will ask

  1. "Show me a policy block." Pull an audit event with result=block.
  2. "Why this clause?" The event's clause_citation field.
  3. "How is the HITL approver chosen?" Operational — your runbook + ADK ToolConfirmation configuration.

What this doesn't cover

  • Policy authoring DSL. YAML / Kotlin DSL parsers live in regulus-ai-dsl-yaml and regulus-ai-dsl-kotlin and feed RegulusPolicyPlugin.withDecider.
  • Tenant-bespoke guards. Implement a PolicyDecider.
  • The actual ToolConfirmation runtime. That's ADK's primitive — we return RequireConfirmation; ADK does the user-prompt + resume.

Citations