SpendFlow

Business

Original Idea

Budget Approval Workflow A web app that routes spend requests through policy rules with a full audit trail.

Product Requirements Document (PRD): SpendFlow

1. Executive Summary

SpendFlow is a next-generation budget approval and spend management platform designed for mid-to-large enterprises. By 2026 standards, it leverages automated, configuration-driven workflow engines to route financial requests through complex policy rules with 100% accountability. The system provides a tamper-evident audit trail using cryptographic hash chains, ensuring compliance with SOC2 and financial regulations while significantly reducing the manual overhead of traditional procurement processes.

2. Problem Statement

Organizations currently face significant financial leakage due to:

  • Manual Bottlenecks: Requests getting lost in email chains or Slack messages.
  • Shadow Spend: Difficulty enforcing spending policies before the money is actually spent.
  • Audit Deficiencies: Lack of an immutable, searchable record of who approved what and why.
  • Data Entry Fatigue: Manual entry of receipt data leading to human error and employee frustration.

3. Goals & Success Metrics

  • Efficiency: Reduce the average time from request submission to final approval by 60%.
  • Compliance: Maintain a 0% failure rate in internal and external financial audits regarding spend authorization.
  • Accuracy: Achieve 95%+ accuracy in automated receipt data extraction using Intelligent Document Processing.
  • User Adoption: Target a Net Promoter Score (NPS) of 70+ by providing a seamless, "headless" form experience.

4. User Personas

| Persona | Goal | Pain Point | | :--- | :--- | :--- | | Employee (Requester) | Quickly request funds for tools or travel. | Confusing forms and slow response times. | | Dept Manager (Approver) | Review and approve requests within budget limits. | High volume of notifications and lack of context. | | Finance Admin | Define global spend policies and monitor budget health. | Maintaining complex routing logic and manual ERP syncing. | | Internal Auditor | Verify compliance and investigate suspicious activity. | Reconstructing the history of a request across multiple systems. |

5. User Stories

  • As an employee, I want to upload a receipt and have it auto-filled so that I don't have to manually type in transaction details.
  • As a manager, I want to receive a real-time notification on my device so that I can approve requests on-the-go without logging into a full desktop suite.
  • As a Finance Admin, I want to create a rule that routes all hardware requests over $5,000 to the CTO so that we maintain executive oversight on large CapEx.
  • As an auditor, I want to see a Merkle-proofed audit log of all decisions so that I can verify no records were altered after the fact.

6. Functional Requirements

6.1 Request Submission & OCR

  • Dynamic Form Engine: Support for department-specific JSON-driven schemas (via SurveyJS).
  • IDP (Intelligent Document Processing): OCR extraction using Amazon Textract with AWS Bedrock (Claude 3.5) refinement to map receipt data to internal entities.

6.2 Automated Routing Engine

  • DAG-Based Workflows: Requests move through a Directed Acyclic Graph based on department, amount, and category.
  • Conditional Logic: Integration with json-rules-engine to allow non-technical admins to modify routing thresholds.
  • SLA & Escalation: Automatic re-routing to a delegate if a request remains idle for >24 hours.

6.3 Audit & Compliance

  • Tamper-Evident Ledger: Every state change must record a cryptographic hash of the current record plus the previous record's hash.
  • Snapshotting: Store a JSON snapshot of the policy rules active at the exact moment an approval was granted.

6.4 Dashboard & Reporting

  • Real-time Tracking: Live status updates via AWS AppSync Events.
  • Budget Variance: Visual reporting on "Actual vs. Budgeted" spend per department.

7. Technical Requirements

7.1 Tech Stack (2026 Standards)

  • Frontend: React v19.2.3 (utilizing React Compiler and Activity API), Tailwind CSS v4.1.18 (Oxide engine, CSS-first config).
  • Backend: Node.js v24.13.0 (LTS), Express v5.2.1 (native Promise support).
  • Database: PostgreSQL 18 (utilizing io_method = io_uring for async I/O and native UUIDv7).
  • Auth: Auth0 (utilizing Passkeys for phishing-resistant MFA and Auth0 Actions for RBAC).
  • Communication: AWS AppSync (WebSockets/Subscriptions) and Amazon SES (BIMI/DMARC compliant).

7.2 Integrations

  • ERP: Bi-directional sync with NetSuite (OAuth 2.0 JWT) and QuickBooks Online.
  • SSO: Okta/Azure AD via Auth0.
  • Collaboration: Slack/MS Teams notifications via EventBridge.

8. Data Model

8.1 Core Entities

  • User: (UUIDv7) id, email, role_id, department_id, mfa_enabled (boolean).
  • SpendRequest: (UUIDv7) id, requester_id, amount (numeric), currency, status (enum), metadata (jsonb), current_step_id.
  • AuditTrail: (UUIDv7) id, request_id, user_id, action, prev_hash, current_hash, timestamp.
  • WorkflowDefinition: (UUIDv7) id, version (semver), rules_json (jsonb), is_active.
  • Department: (UUIDv7) id, name, total_budget, remaining_budget.

9. API Specification (Sample Endpoints)

POST /api/v1/requests

  • Description: Submits a new spend request.
  • Request Body: 
    {
  "amount": 1250.00,
  "category": "Software",
  "justification": "Annual SaaS renewal",
  "attachments": ["s3_url_1"]
}
  • Response: 201 Created with request_id and initial routing_status.

PATCH /api/v1/approvals/{requestId}

  • Description: Approves or rejects a request.
  • Header: Idempotency-Key: <unique_string>
  • Request Body: 
    {
  "action": "APPROVE",
  "comments": "Budget verified."
}

10. UI/UX Requirements

  • Mobile-First Approvals: The approval interface must be optimized for one-handed mobile use (large buttons, gesture-based swipes).
  • Headless Forms: Use SurveyJS to render forms dynamically. If a user selects "Travel," the form should instantly morph to include "Flight Number" and "Hotel Info" without page reloads.
  • Accessibility: WCAG 2.1 AA compliance; high-contrast modes and keyboard navigation for all tables.

11. Non-Functional Requirements

  • Performance: All dashboard queries must resolve in <200ms using PostgreSQL Columnar extensions for budget aggregations.
  • Security: AES-256 encryption at rest; TLS 1.3 in transit; SOC2 Type II compliance readiness.
  • Availability: 99.99% uptime utilizing AWS Multi-AZ deployment.
  • Scalability: Support up to 50,000 concurrent users and 1 million historical audit entries without degradation.

12. Out of Scope

  • Payroll Processing: SpendFlow handles business expenses, not employee salaries.
  • Direct Payment Fulfillment: The app routes approvals; payments are triggered in the ERP (NetSuite/QuickBooks).
  • Cryptocurrency Support: Only fiat currencies are supported in Phase 1.

13. Risks & Mitigations

| Risk | Mitigation | | :--- | :--- | | Auth0 Rules Deprecation | All logic must be built using Auth0 Actions from day one. | | API Rate Limiting (ERP) | Implement BullMQ for job queuing with exponential backoff and circuit breakers. | | Database Bloat | Use PostgreSQL 18 Declarative Partitioning to archive audit logs older than 2 years to S3. |

14. Implementation Tasks

Phase 1: Foundation & Environment Setup

  • [ ] Initialize Node.js v24.13.0 project with Express v5.2.1
  • [ ] Configure React v19.2.3 with Tailwind CSS v4.1.18 (Oxide engine)
  • [ ] Set up PostgreSQL 18 with io_uring and UUIDv7 extensions
  • [ ] Configure Auth0 Tenant with Passkey/WebAuthn support and Auth0 Actions

Phase 2: Workflow & Core API

  • [ ] Implement json-rules-engine for dynamic routing logic
  • [ ] Create workflow_definitions and workflow_instances schemas
  • [ ] Build the DAG routing service (Node.js) to calculate next-approver steps
  • [ ] Implement Idempotency layer for all PATCH/POST approval endpoints

Phase 3: Intelligent Data Ingestion

  • [ ] Integrate AWS Textract AnalyzeExpense API for receipt scanning
  • [ ] Build AWS Bedrock wrapper to refine OCR JSON into SpendFlow CDM (Canonical Data Model)
  • [ ] Implement SurveyJS dynamic form renderer on the frontend

Phase 4: Audit & Real-time Alerts

  • [ ] Build PostgreSQL trigger-based audit log with SHA-256 hash chaining
  • [ ] Setup AWS AppSync Events for real-time dashboard notifications
  • [ ] Configure Amazon SES with SQS FIFO queues for approval email delivery

Phase 5: ERP Integration & Reporting

  • [ ] Implement NetSuite OAuth 2.0 (JWT) integration module
  • [ ] Create PostgreSQL Columnar views for real-time budget variance reporting
  • [ ] Perform SOC2 compliance dry-run and penetration testing