Portfolio Build
When contracts, milestones, invoices and payments are spread across separate tools, ownership and payment state drift out of sync.
This system keeps project award, contract execution, milestone tracking and payment recording inside one controlled flow.
Contract and payment flow enforcing proposal selection, milestone tracking and invoice consistency
Build Focus
Shows how contract state, milestones, and payments remain consistent across project execution.
This is a portfolio build used to show architecture, workflow behavior, interface decisions, and product reasoning without presenting it as a client-owned system.
System Behavior
Execution starts only from an accepted proposal, creating a contract
Milestones and invoices are created only within a valid contract context
Each invoice allows a single payment record, preventing duplicate payments
Payments are recorded only for valid unpaid invoices
Execution and financial state remain consistent across contracts, milestones, and invoices
01
Without a system like this, teams manage proposals, accepted vendors, contract state, milestone progress, invoices and payment confirmation across email, chat, spreadsheets and external payment dashboards. Ownership becomes blurry, payment can drift away from delivered work and the business loses confidence in what was agreed, what is due and what has already been paid.
02
The core flow is operational rather than social: customer creates a project, freelancers submit proposals, one proposal becomes the contract, work can be split into milestones, invoices are issued and payment is recorded through Stripe-backed checkout and webhook handling. State is represented through status enums and one-to-one relationships that tie the project, proposal, contract, invoice and payment models together.
Exists to stop contract execution and payment tracking from being reconstructed later from scattered tools.
03
Project creation is blocked unless the customer context is valid, required categorization exists and the deadline is not in the past. Proposal submission is blocked unless the project exists, is open and the freelancer has not already proposed. Accepting a proposal creates the contract and moves the project into execution. Milestones cannot be added to completed or cancelled contracts, invoice creation verifies contract ownership and payment creation is blocked when the invoice is already paid or already has a payment record.
04
Correctness is maintained through transactional service methods, one-to-one mappings that enforce key uniqueness relationships, status propagation across project, contract, milestone, invoice and payment state, role-scoped list access, webhook signature verification and rate limiting. The important point is that commercial agreement, work execution and financial recording do not live in unrelated tools.
05
The business gets a controlled pipeline from opportunity to cash collection. The system eliminates most manual reconciliation around which proposal won, whether a contract already exists, whether a milestone belongs to the contract being billed and whether an invoice has already been paid. Financial state becomes more predictable because payment updates are attached to the same operational chain that defines execution.
Resulting Impact
Project award, execution and payment move through a single controlled pipeline
Ownership remains clear at every stage instead of being reconstructed later
Contracts, milestones and invoices stay aligned without manual reconciliation
The business can verify what was agreed, delivered and paid from one place
Technology Stack
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Describe the workflow, users, records, permissions, and integrations that need to stay reliable.