/// Processes a loan application through parallel credit and compliance sub-graphs then branches on the underwriting decision.
///
/// Validates the application, then runs creditAssessment and complianceCheck sub-graphs
/// concurrently. Both results are fed into underwriting, and the graph branches to generate
/// either an approval letter or a rejection notice based on the outcome.
///
/// Key DSL concepts demonstrated:
///   subgraph("name")     — each sub-graph embeds a full pipeline; its final node's output is the result
///   depends_on = [a, b]  — underwritingDecision fans in from both parallel sub-graphs
///   branch on <expr>     — exactly one of generateApprovalLetter or generateRejectionNotice executes
///   timeout = Ns         — each sub-graph is independently time-boxed to 30 s
///
/// Context variables:
///   ctx.applicationId   — unique identifier of the loan application
///   ctx.applicantName   — full name of the applicant
///   ctx.requestedAmount — principal amount requested
///   ctx.termMonths      — loan duration in months
///   ctx.employerId      — applicant's employer identifier used in the credit assessment sub-graph
graph loanApprovalSubgraph {

  /// Receives and validates the incoming loan application
  node receiveApplication : ReceiveApplicationOperator {
    input {
      applicationId   = ctx.applicationId
      applicantName   = ctx.applicantName
      requestedAmount = ctx.requestedAmount
      termMonths      = ctx.termMonths
      employerId      = ctx.employerId
    }
    timeout = 3s
  }

  /// Runs credit assessment sub-graph: creditQuery → incomeVerification → debtRatioCalc → riskScoring
  node creditAssessment : subgraph("credit-assessment") {
    depends_on = [receiveApplication]
    input {
      applicationId   = receiveApplication.output.applicationId
      applicantName   = receiveApplication.output.applicantName
      requestedAmount = receiveApplication.output.requestedAmount
      employerId      = receiveApplication.output.employerId
    }
    timeout = 30s
  }

  /// Runs compliance check sub-graph: amlScreening → kycVerification → sanctionListCheck → complianceDetermination
  node complianceCheck : subgraph("compliance-check") {
    depends_on = [receiveApplication]
    input {
      applicationId = receiveApplication.output.applicationId
      applicantName = receiveApplication.output.applicantName
    }
    timeout = 30s
  }

  /// Makes underwriting decision based on credit and compliance sub-graph results
  node underwritingDecision : UnderwritingDecisionOperator {
    depends_on = [creditAssessment, complianceCheck]
    input {
      applicationId = receiveApplication.output.applicationId
      credit        = creditAssessment.output.riskScoring
      compliance    = complianceCheck.output.complianceDetermination
    }
  }

  /// Generates approval letter for approved loans
  node generateApprovalLetter : GenerateApprovalLetterOperator {
    depends_on = [underwritingDecision]
    input {
      applicationId   = underwritingDecision.output.applicationId
      applicantName   = ctx.applicantName
      requestedAmount = ctx.requestedAmount
      approvedRate    = underwritingDecision.output.approvedRate
      termMonths      = ctx.termMonths
    }
  }

  /// Generates rejection notice for declined loans
  node generateRejectionNotice : GenerateRejectionNoticeOperator {
    depends_on = [underwritingDecision]
    input {
      applicationId = underwritingDecision.output.applicationId
      applicantName = ctx.applicantName
      reason        = underwritingDecision.output.reason
    }
  }

  /// Routes to approval letter or rejection notice; exactly one branch executes, others are skipped
  branch on underwritingDecision.output.decision {
    "approved" -> generateApprovalLetter
    otherwise  -> generateRejectionNotice
  }
}