feat: ArbitusPolicy CRD — Kubernetes-native per-agent policy management

[nfvelten]

Migrated from nfvelten/arbitus#133

Summary

Per-agent policies as first-class Kubernetes objects, managed via kubectl and compatible with GitOps workflows (Flux, ArgoCD).

apiVersion: arbitus.dev/v1alpha1
kind: ArbitusPolicy
metadata:
  name: cursor-policy
  namespace: ai-agents
spec:
  agent: cursor
  allowedTools: [read_file, "list_*"]
  deniedTools: [delete_file]
  rateLimit: 30
  rules:
    blockPatterns: ["password", "api_key"]
    filterMode: block
    blockPromptInjection: true

Benefits over ConfigMap approach

• Per-policy RBAC (K8s admins control who can create/edit agent policies)
• Status subresource (controller reports active tools, last-applied, validation errors)
• Works naturally with GitOps and policy-as-code workflows

Implementation via kube-rs

#[derive(CustomResource, Serialize, Deserialize, Clone, JsonSchema)]
#[kube(group = "arbitus.dev", version = "v1alpha1", kind = "ArbitusPolicy", namespaced)]
pub struct ArbitusSpec {
    pub agent: String,
    pub allowed_tools: Option<Vec<String>>,
    pub rate_limit: Option<u32>,
    pub rules: Option<PolicyRules>,
}

Prerequisites

• #132 (ConfigMap watcher) — establishes the kube-rs dependency and live-config infrastructure

References

• FEATURE_ADOPTION_FEASIBILITY.md §3 (Tier 3)