request_flow.tuned.d2

direction: down

title: Request Flow with Audit Trail (tuned) {
  near: top-center
  shape: text
  style.font-size: 22
  style.bold: true
}

# rank_groups force each audit row onto the same rank as the service
# step that writes it. Without this, dot minimises edge length and
# parks the audit nodes at whatever rank the edges happen to allow,
# which is rarely the one that reads correctly.
vars: {
  d2-config: {
    data: {
      graphviz: |
        {
          "rank_groups": [
            ["flow.service.receive",  "flow.audit.log_in"],
            ["flow.service.validate", "flow.audit.log_decision"],
            ["flow.service.respond",  "flow.audit.log_out"]
          ]
        }
      |
    }
  }
}

flow: "" {
  direction: right
  style.fill: transparent
  style.stroke: transparent

  service: Primary Service {
    direction: down
    style.fill: "#eef6ff"
    style.stroke: "#6699cc"

    receive: RECEIVE REQUEST {style.fill: "#ddeeff"}
    auth: AUTHENTICATE {style.fill: "#ddeeff"}
    rate_limit: RATE-LIMIT CHECK {style.fill: "#ddeeff"}
    validate: VALIDATE PAYLOAD {style.fill: "#ddeeff"}
    process: PROCESS {style.fill: "#FFD700"; style.bold: true}
    serialize: SERIALIZE RESPONSE {style.fill: "#ddeeff"}
    respond: RESPOND {style.fill: "#90EE90"; style.bold: true}

    receive -> auth
    auth -> rate_limit
    rate_limit -> validate
    validate -> process
    process -> serialize
    serialize -> respond
  }

  audit: Audit Trail {
    direction: down
    style.fill: "#fdf5e6"
    style.stroke: "#d4a017"

    log_in: LOG INBOUND {style.fill: "#ffeebb"}
    log_decision: LOG DECISION {style.fill: "#ffeebb"}
    log_out: LOG OUTBOUND {style.fill: "#ffeebb"}

    log_in -> log_decision
    log_decision -> log_out
  }
}

flow.service.receive -> flow.audit.log_in: write
flow.service.validate -> flow.audit.log_decision: write
flow.service.respond -> flow.audit.log_out: write