Project Overview
Build a real-time credit risk assessment platform for small and micro enterprise (SME) operating loans to address lagging scorecards, slow approvals, coarse-grained risk strategies, and rising bad debt. The platform will fuse multi-source data (transaction flows, tax invoices, operating accounts, third-party bureau, and behavioral signals), deliver millisecond-level online scoring and large-scale batch approvals, and support PD/LGD modeling and fraud detection with explainability and full compliance traceability. Target performance: PD AUC ≥ 0.82, delinquency (e.g., 30/60 DPD) recall ≥ 85% at controlled precision, and production-grade A/B testing for risk strategies and rapid product onboarding.
Problem Analysis
Solution
Architecture overview
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Ingestion and storage
- Batch and streaming ingestion from:
- Bank transaction flows and operating accounts (core banking, payment gateways).
- Tax invoice data (e.g., VAT fapiao) via secure connectors.
- Third-party bureau data via API.
- Behavioral/telemetry (online banking/app interactions, device and network metadata where consented).
- Message bus: Kafka (or Pulsar) for streaming; SFTP/HTTPS for scheduled batch.
- Data lake/warehouse: HDFS/S3-compatible object store + columnar warehouse (Parquet + Hive/Trino or cloud DW).
- Metadata and lineage: data catalog (e.g., Apache Atlas) with dataset versioning.
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Feature platform
- Offline feature store for training (e.g., Feast + lake/warehouse).
- Online feature store for serving (Redis/KeyDB or low-latency KV store).
- Point-in-time feature computation using backfill jobs (Spark/Flink) to prevent leakage.
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Modeling
- PD: Gradient-boosted trees (XGBoost/LightGBM) as primary; calibrated logistic regression challenger/scorecard for governance.
- LGD: Regression (Elastic Net or LightGBM with monotonic/shape constraints), downturn and segmentation by product/collateral.
- Fraud: Hybrid approach:
- Supervised classifier for first-pay default/early delinquency.
- Unsupervised anomaly detection (Isolation Forest) on velocity and consistency features.
- Rules engine for hard controls (KYC, blacklist, out-of-bound signals).
- Calibration and stability: Platt/Isotonic calibration, population stability monitoring.
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Serving and decisioning
- Real-time scoring microservice (Java/Spring Boot or Python/FastAPI with ONNX Runtime/treelite) with warm-loaded models, per-request SLA p99 ≤ 20–30 ms including feature fetch if precomputed.
- Batch scoring pipeline (Spark) for nightly/ intraday mass re-scoring and campaigns.
- Decision engine (Drools or similar) for strategy orchestration: cutoffs, pricing, limits, policy overrides, and A/B experiments.
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Explainability and governance
- Model explainability: SHAP for feature contribution; reason codes for adverse actions.
- Rules traceability: versioned rule sets with lineage and change history.
- Model registry and lineage (MLflow): versions, approvals, staged deployment (Dev/Staging/Prod).
- Audit trail: immutable, event-sourced decision logs stored in WORM-compliant storage.
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Security, privacy, and compliance
- Data classification tiers (L1 sensitive PII, L2 confidential financial, L3 operational).
- Encryption in transit (mTLS) and at rest (KMS-managed).
- Access control: RBAC/ABAC with just-in-time access; fine-grained data masking and tokenization for PII.
- Consent and purpose limitation; data retention aligned with regulation.
- Model risk management: documentation, validation reports, backtesting, performance monitoring.
Data layer and feature engineering
Modeling design
Serving and decision orchestration
MLOps, monitoring, and auditability
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CI/CD
- Git-based workflows; infrastructure as code (Terraform/Helm).
- Model pipeline: feature tests → training → validation gates → bias/calibration checks → registry → canary deploy.
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Registry and lineage
- MLflow Model Registry with approvals and metadata (training data snapshot, code commit, environment).
- Data and model lineage tracked in catalog; reproducibility with environment pinning.
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Observability
- Online metrics: latency, error rates, throughput, feature fetch misses.
- Model metrics: population drift (PSI), feature drift, prediction drift, calibration tracking, fraud capture vs. false positives.
- Alerting via Prometheus/Grafana; anomaly alerts to on-call.
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Decision logging
- Event-sourced immutable logs: request payload hash, features used, model version, score, decision, explanations, rule versions, operator actions.
- WORM storage retention per policy (e.g., ≥ 7 years).
Security and compliance
- Data classification and handling
- L1 Sensitive: PII, taxpayer IDs, device IDs (tokenized/masked in non-prod).
- L2 Confidential: financial and bureau data.
- L3 Operational: metadata, logs (no raw PII).
- Access control and encryption
- mTLS, TLS 1.2+; KMS-managed keys; RBAC/ABAC with least privilege; PAM for break-glass access.
- Privacy and consent
- Consent capture and purpose binding; opt-out flows; data minimization; retention and deletion SLAs.
- Regulatory alignment
- Credit risk: IFRS 9/Basel for PD/LGD/ECL.
- Local data/privacy regulations (e.g., PIPL) and regulator guidelines (e.g., CBIRC/PBoC equivalents).
- Model risk management: independent validation and periodic review.
Technology stack (reference, adjustable to enterprise standards)
- Data: Kafka, Spark/Flink, Object Store (S3-compatible), Trino/Hive, PostgreSQL.
- Feature store: Feast (offline on parquet; online on Redis).
- Modeling: Python, scikit-learn, XGBoost/LightGBM, SHAP, MLflow, ONNX Runtime/treelite.
- Serving: Spring Boot or FastAPI, Redis, gRPC/REST, Kubernetes.
- Rules/decisioning: Drools or enterprise rules engine; internal policy service.
- Observability: Prometheus, Grafana; data validation with Great Expectations.
- Security: Vault/KMS, mTLS, IAM integrated with enterprise SSO.
Implementation Plan
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Phase 0 – Discovery and design (2–3 weeks)
- Deliverables: Business/credit policy review, data contracts, target KPIs, architecture HLD, compliance plan.
- Resources: Solution architect, risk lead, data engineer, compliance officer.
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Phase 1 – Data foundation and governance (4–6 weeks)
- Build ingestion pipelines (Kafka/batch), entity resolution, data catalog, data quality checks, PII masking/tokenization.
- Deliverables: Curated base layers (bronze/silver), quality dashboards, data classification matrix.
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Phase 2 – Feature store and baseline models (6–8 weeks)
- Implement offline/online feature store; define feature views with point-in-time correctness.
- Train baseline PD and fraud models; initial LGD data prep and prototype.
- Deliverables: Feature library v1, PD v1 (AUC target validation), fraud v1, validation report, model registry entries.
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Phase 3 – Real-time scoring and batch pipelines (4–6 weeks)
- Deploy scoring microservices, online feature store, and batch scoring on Spark.
- Integrate with decision engine; implement explainability APIs and reason codes.
- Deliverables: Production-ready APIs with p99 latency certification, batch scoring jobs, decision logs.
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Phase 4 – Strategy, A/B testing, and compliance (3–4 weeks)
- Implement champion–challenger strategies, traffic allocation, and guardrails.
- Complete audit trail, model documentation, and access controls.
- Deliverables: Strategy experiments live, audit-compliant decision log, adverse action workflow.
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Phase 5 – LGD model and ECL integration (4–6 weeks)
- Finalize LGD model with downturn overlay; optional EAD enhancement if needed.
- Integrate PD/LGD into ECL calculators and risk reporting.
- Deliverables: LGD v1, ECL reports, governance approvals.
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Phase 6 – Hardening and scale-out (2–4 weeks)
- Load/performance testing (e.g., 2k–5k RPS), chaos testing, canary/rollback, runbooks.
- Deliverables: SRE playbooks, SLO dashboards, DR plan, go-live checklist.
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Ongoing – Monitoring and model lifecycle (continuous)
- Drift monitoring, scheduled re-training (e.g., monthly/quarterly), post-deployment validation, compliance reviews.
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Team and roles
- PM, solution architect, data engineers (2–3), ML engineers (2), data scientist/risk modelers (3–4), platform/DevOps engineers (2), fraud analyst (1–2), QA (1–2), compliance/security (1–2).
Risk Assessment
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Data acquisition delays or quality issues
- Mitigation: phased onboarding by source, strong DQ contracts, backfill plan, automated validation with SLAs.
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Label leakage and temporal bias
- Mitigation: strict point-in-time feature computation, time-based CV, independent validation review.
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Concept drift and macro shocks
- Mitigation: drift detectors, alert thresholds, retraining triggers, fallback scorecards/rules, stress testing.
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Latency SLO breach under peak load
- Mitigation: precompute features, Redis hot sets, autoscaling, circuit breakers, backpressure with graceful degradation to cached or rules-only decisions.
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Regulatory/model validation hurdles
- Mitigation: early engagement with validation, comprehensive model documentation, challenger models, reason codes, and calibration evidence.
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Integration risks with core systems
- Mitigation: well-defined APIs, sandbox/staging environments, contract testing, canary releases.
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Security and privacy incidents
- Mitigation: encryption everywhere, RBAC/ABAC, tokenization, regular audits, DLP scanning, secret rotation.
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Experimentation risk (A/B causing performance dip)
- Mitigation: small initial traffic, strict guardrails, sequential monitoring, fast rollback.
Expected Outcomes
This proposal delivers a production-grade, compliant, and explainable real-time credit risk platform for SME lending, aligning advanced ML with robust operations to achieve measurable gains in risk control, speed, and profitability.