---
title: Agent Harness Architecture
---

%% Theme configuration
%% Uses Mermaid's dark foundation so titles and labels remain readable.
%% Edge labels use a medium charcoal rather than near-black.
%%{init: {
    "theme": "dark",
    "themeVariables": {
        "textColor": "#e6edf3",
        "titleColor": "#e6edf3",
        "lineColor": "#9ca3af",
        "edgeLabelBackground": "#242424"
    }
}}%%

graph TD
    User("User Prompt") --> RAG

    subgraph Harness["Agent Harness"]
        RAG("Context Retrieval<br/>Search · Grep · RAG") --> CW

        subgraph Loop["Agent ReAct Loop"]
            CW("Context Window")
            LLM("LLM / Model")
            TE("Tool Execution")

            CW -->|"1 · Context + History"| LLM
            LLM -->|"2a · Tool Call"| TE
            TE -->|"3 · Observation"| CW
        end

        TE --> WorkSpace[("Workspace / File System")]
    end

    %% Lengthened arrow keeps final output visually separated
    LLM ---->|"2b · Final Response"| FinalAnswer("Final Output to User")
    WorkSpace ~~~ FinalAnswer

    %% Theme: Carbon Glow v2.1
    %% Dark charcoal surfaces with restrained semantic neon accents.
    %% Subtle tinted fills add depth while preserving the README's dark card aesthetic.
    %% Brighter typography keeps labels readable against GitHub's dark background.

    %% Node styles
    %% Green = entry / successful completion
    classDef input fill:#142018,stroke:#39d353,color:#f0f0f0,stroke-width:1.5px
    classDef output fill:#142018,stroke:#39d353,color:#f0f0f0,stroke-width:1.5px

    %% Blue = context / active information state
    classDef context fill:#141c24,stroke:#58a6ff,color:#f0f0f0,stroke-width:1.5px

    %% Purple = model / intelligence
    classDef model fill:#1d1726,stroke:#a371f7,color:#f0f0f0,stroke-width:1.5px

    %% Amber = tool execution / action
    classDef tool fill:#211a0d,stroke:#f0a000,color:#f0f0f0,stroke-width:1.5px

    %% Gray = retrieval / infrastructure / persistence
    classDef retrieval fill:#1c1c1c,stroke:#8b949e,color:#e0e0e0,stroke-width:1px
    classDef storage fill:#181818,stroke:#8b949e,color:#e0e0e0,stroke-width:1px

    %% Apply node styles
    class User input
    class RAG retrieval
    class CW context
    class LLM model
    class TE tool
    class WorkSpace storage
    class FinalAnswer output

    %% Connector styles
    %% Brighter silver keeps arrows clearly visible without becoming dominant
    linkStyle default stroke:#9ca3af,stroke-width:1.15px

    %% Container styles
    %% Outer harness uses a brighter dashed architectural boundary
    style Harness fill:#1c1c1c08,stroke:#8b949e,stroke-width:1.25px,stroke-dasharray:5 5

    %% Inner ReAct loop is subtle but remains clearly visible
    style Loop fill:#1c1c1c05,stroke:#666666,stroke-width:1px