Project Blueprint: Citadel

Document Version: 1.0 Status: Proposed

1. Vision & Mission

Project Name:Citadel

Vision: To be the command and control layer for the AI-powered enterprise—an indomitable runtime that forges chaotic agentic processes into disciplined, resilient, and effective digital legions.

Mission: To provide an unshakeable, OTP-powered fortress for stateful AI agents. Citadel imposes order on the chaos of distributed systems, guaranteeing the lifecycle, state integrity, and operational resilience of every agent under its command. It is the architectural high ground from which reliable AI applications are built and governed.

2. The Problem: The Unruly Frontier of Agentic AI

The AI frontier is a lawless territory. Developers are creating powerful agents, but they are deploying them into the wild as scattered, fragile scripts. This approach is untenable for production systems, leading to critical vulnerabilities:

Citadel is the answer. It is not merely a framework; it is the fortified infrastructure that transforms this unruly frontier into a disciplined, strategic asset.

3. Core Concepts & Fortress Architecture

Citadel is a complete, clustered OTP application designed for strategic dominance. It provides the architectural foundation and command structure for an entire population of AI agents.

The Core Architectural Primitives:

Diagram: Citadel Cluster Command Structure

graph TD
    subgraph "External Network"
        LB[Load Balancer / Gateway]
    end

    subgraph "The Citadel (Distributed BEAM Cluster)"
        direction LR
        NodeA["Citadel Node A (Bastion)"]
        NodeB["Citadel Node B (Bastion)"]
        NodeC["Citadel Node C (Bastion)"]
        
        subgraph NodeA
            PhoenixEndpoint[Phoenix Endpoint]
            GarrisonA[Garrison Supervisor]
            Sentinel1[Sentinel Process 1]
            Sentinel4[Sentinel Process 4]
        end
        
        subgraph NodeB
            GarrisonB[Garrison Supervisor]
            Sentinel2[Sentinel Process 2]
            Sentinel5[Sentinel Process 5]
        end

        subgraph NodeC
            GarrisonC[Garrison Supervisor]
            Sentinel3[Sentinel Process 3]
            Sentinel6[Sentinel Process 6]
        end
    end
    
    LB --> PhoenixEndpoint
    PhoenixEndpoint -->|Issues Command via Registry| Sentinel3
    Sentinel3 -->|Coordinates with| Sentinel5
    
    linkStyle 2 stroke-width:2px,stroke:red,stroke-dasharray: 5 5;
    linkStyle 3 stroke-width:2px,stroke:blue,stroke-dasharray: 5 5;

    %% Horde's internal command & control network (gossip protocol)
    GarrisonA <--> GarrisonB
    GarrisonB <--> GarrisonC
    GarrisonA <--> GarrisonC

4. Ecosystem Integration: The Citadel.Sentinel Protocol

To enforce discipline and streamline development, Citadel defines a formal behaviour: the Sentinel Protocol. Developers implement this protocol to forge their agent's logic, ensuring it integrates seamlessly into the Citadel's command structure.

# lib/my_app/sentinels/analyst_sentinel.ex

defmodule MyApp.Sentinels.AnalystSentinel do
  @behaviour Citadel.Sentinel

  alias AITrace.Context

  # A Sentinel&#39;s state represents its memory and current orders.
  defstruct [:id, :mission_objective, :intel, :memory]

  @impl Citadel.Sentinel
  def init(mission_briefing) do
    state = %__MODULE__{id: mission_briefing.id, mission_objective: mission_briefing.objective}
    {:ok, state}
  end

  # `handle_command` is the Sentinel&#39;s core operational loop.
  @impl Citadel.Sentinel
  def handle_command(command, state, %Context{} = ctx) do
    # Every command is executed within a fully traced operational theatre.
    
    # 1. Strategic Core (`DSPex`): Determine the next action.
    {:ok, decision, new_ctx} = AITrace.span ctx, "sentinel.strategize" do
      DSPex.execute(MyStrategyModule, %{command: command, intel: state.intel}, context: ctx)
    end
    
    # 2. Rules of Engagement (`Altar`): Execute the action via the command wrapper.
    {:ok, action_report, _final_ctx} = AITrace.span new_ctx, "sentinel.action" do
      Citadel.Arsenal.execute(decision.tool_call, context: new_ctx)
    end
    
    # 3. Update internal state and report back.
    new_state = update_intel(state, action_report)
    report = format_report(action_report)
    {:report, report, new_state}
  end
end

How the Ecosystem Serves the Citadel:

5. Key Features

Citadel is the definitive answer for developers who are serious about moving beyond AI prototypes. It is the architectural foundation required to build, command, and conquer with large-scale, production-grade AI agent systems.