Client Project Hub with Invoice & Milestone Tracking

Problem and target customer

Why this exists

Customer problem

Freelancers and small agencies manage client projects across email, spreadsheets, and generic task tools. Milestone approvals, deliverable handoffs, and invoicing are disconnected, causing delayed payments, excessive client follow-up emails, and no audit trail of what was approved and when.

Who pays

Freelancers and small agencies managing 3 to 15 concurrent client projects with milestone-based billing and deliverable approval cycles.

Business model

Monthly subscription with a paid workspace tier based on number of active projects and invoiced milestones per month.

Editorial note

Freelancers and small agencies lose billable hours coordinating project status across email threads, spreadsheets, and generic task tools. A dedicated client project hub consolidates milestone tracking, approval workflows, and invoicing into one workspace.

The MVP focuses on a single workflow: move milestones through a kanban board, submit them for client approval via email, and auto-generate invoices upon approval. This eliminates manual invoice creation and reduces the back-and-forth emails that delay payments.

Scope discipline matters. Time tracking, calendar sync, and LLM-generated summaries are excluded from the first version. The core value is the connection between milestone approval and invoice generation, not feature breadth.

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What do you need next?

Evaluate the operating tradeoffs quickly, or inspect how to build the MVP.

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Compare the three operating paths at the default workload before opening the full calculator.

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Review MVP scope, workflow, states, data rules, architecture, and acceptance criteria.

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Evaluation preview

What would it take to run?

Directional infrastructure estimates for the current 1,000 generated outputs assumption. Open the full calculator when you are ready to change it.

Open full cost and deployment

ManagedSelected

$25-$65/ month

Managed app hosting, database, backups, and basic observability for the ai-generation workflow.

Lowest operating effort

Lean self-hosted

$8-$28/ month

One small VPS running the app, database, media volume, and backup job.

Lowest baseline cost

More control

$45-$125/ month

Separate app, data, storage, and worker capacity for cleaner operations.

Most separation and control

Build blueprint

Build the first paid use case

Product goal

Who it serves and what it must change

Target user: Freelancers and small agencies managing 3 to 15 concurrent client projects with milestone-based billing and deliverable approval cycles
Problem: Project status, deliverable approvals, and invoicing are scattered across email, spreadsheets, and generic tools, causing delayed payments and excessive client follow-up emails with no audit trail
Measurable outcome: Reduce client follow-up emails by 60% and cut invoice generation time from 15 minutes to under 2 minutes per milestone

MVP scope

What ships now and what waits

Included

Kanban board with five milestone status columns and drag-and-drop
Milestone approval workflow with tokenized client email links
Invoice auto-generation from approved milestones with Stripe payment tracking
Activity log with filterable audit trail of all status transitions
Multi-project workspace dashboard with invoice payment summary

Excluded

LLM-powered project summaries or content generation
Calendar sync and scheduling integration
Time tracking and timesheet entry
Multi-currency and tax calculation engine
Client self-service portal for project creation

UX and user flow

Screens, actions, and states

Project Kanban Board

Main dashboard showing all projects with milestone cards organized by status column

drag milestone cards between status columnsfilter milestones by projectview milestone count and revenue per status

Milestone Detail

Drill-down view of a single milestone with deliverable description, approval status, revision history, and linked invoice

edit milestone detailssubmit for client approvalview linked invoicereview revision history

Invoice Manager

List of all invoices with payment status, linked milestone, amount, and send or retry actions

generate invoice from approved milestonesend invoice email to clientview payment statusretry failed delivery

Activity Log

Chronological audit trail of all approvals, rejections, status changes, and invoice events

filter by projectfilter by event typefilter by date rangeexport log as CSV

Primary flow

Create project and define milestones with deliverable descriptions, due dates, and billing amounts
Drag milestones through kanban columns as work progresses from Draft to In Progress
Submit milestone for client approval triggering a tokenized email link
Auto-generate invoice upon milestone approval and send to client
Record Stripe payment confirmation, mark invoice Paid, and close milestone with activity log entry

Loading, empty, and error states

Draft
In Progress
Pending Approval
Approved
Revisions Requested
Completed
Invoiced
Paid

Core entity outline

Entities and business rules

Workspace

Top-level container for a freelancer or agency with owner and billing tier

Fields: id, name, owner_user_id, plan_tier, created_at
Relations: has many Projects, has many Users

Project

Client engagement containing milestones and associated invoices

Fields: id, workspace_id, client_name, client_email, title, status, created_at
Relations: belongs to Workspace, has many Milestones, has many Invoices

Milestone

Deliverable unit with approval workflow and billing amount

Fields: id, project_id, title, description, due_date, status, amount, approved_at, approval_token
Relations: belongs to Project, has one Invoice

Invoice

Billing record generated from an approved milestone with Stripe payment tracking

Fields: id, project_id, milestone_id, amount, currency, status, stripe_payment_id, sent_at, paid_at
Relations: belongs to Project, belongs to Milestone

ActivityLog

Audit trail entry for every status transition, approval, rejection, and invoice event

Fields: id, workspace_id, project_id, milestone_id, event_type, actor, description, created_at
Relations: belongs to Workspace, belongs to Project

Business rules

Invoice can only be generated when milestone status is Approved
Milestone cannot transition to Completed until linked invoice status is Paid
Revisions Requested resets milestone to In Progress and logs the revision request with reason
Activity log entry is mandatory for every milestone status transition
Client email is required before a milestone can be submitted for approval

Architecture and data flow

Components, integrations, and controls

Kanban Frontend

Renders project board with drag-and-drop milestone cards and handles status update calls to the backend API

Approval API

Processes milestone state transitions, validates business rules, and persists activity log entries

Invoice Service

Generates invoice records from approved milestones and syncs payment status with Stripe

Notification Service

Sends transactional emails for approval requests, revision notifications, and invoice delivery

Integrations

Resend: transactional email for client approval links and invoice notifications
Stripe: payment processing with webhook for invoice payment confirmation
Supabase: relational database with row-level security for workspace-scoped data access

Data flow

User drags milestone to Pending Approval: Approval API validates and triggers Notification Service to email client with tokenized link
Client approves milestone via tokenized link: Approval API transitions status to Approved and Invoice Service generates linked invoice
Stripe webhook confirms payment: Invoice Service marks invoice Paid, Approval API transitions milestone to Completed, Activity Log records event

Failure handling

Email delivery failure: retry 3 times with exponential backoff and log failure to ActivityLog
Stripe webhook timeout: queue webhook event for retry and mark invoice as Pending Confirmation
Database transaction failure on state transition: rollback all changes and return error to user with retry guidance

Security

Workspace-scoped data access: users can only read and modify projects within their workspace
Client approval links use expiring tokens valid for 30 days
Stripe webhook endpoints verify webhook signatures before processing

Rate limits

Email notifications: max 50 per workspace per hour
Invoice generation: max 20 per workspace per hour
Stripe webhook processing: max 100 concurrent requests per workspace

Deliverables and acceptance

Definition of done for the MVP

Deliverables

Kanban board with drag-and-drop milestone management across five status columns
Milestone approval workflow with tokenized client email links
Automated invoice generation from approved milestones with Stripe payment tracking
Activity log with filterable audit trail by project, event type, and date
Workspace dashboard with multi-project overview and invoice payment summary

Acceptance criteria

User can create a project with at least 3 milestones and drag them across 5 status columns with each transition logged
Submitting a milestone for approval sends a tokenized email link to the client that expires after 30 days
Approving a milestone through the client link automatically generates an invoice linked to that milestone with the correct amount
Stripe payment confirmation webhook updates invoice status to Paid and milestone status to Completed within 5 seconds
Every status transition, approval, rejection, and invoice event creates a visible ActivityLog entry filterable by project and event type

Recommended stack

Enough technology for the first version

Frontend

Lovable

Visual builder for the kanban board interface with drag-and-drop milestone cards and invoice summary sidebar without custom frontend code.

Database

Supabase

Relational storage for projects, milestones, invoices, and activity logs with row-level security for workspace isolation.

Automation

Make

Webhook glue connecting Stripe payment confirmations to invoice status updates and triggering email notifications on approval events.

Backend Hosting

Railway

Hosts the approval state machine API and invoice generation service with persistent environment variables for Stripe and Resend keys.

Transactional Email

Resend

Sends tokenized client approval links and invoice delivery emails with delivery tracking and retry logic.

Why this is sufficient

Lovable renders the kanban interface without custom frontend engineering. Supabase enforces relational integrity between milestones and invoices with workspace-scoped access. Make bridges Stripe webhooks and email triggers without writing glue code. Railway hosts the approval state machine and invoice generation endpoints. Resend handles client-facing transactional email with reliable delivery.

Not required for the MVP

LLM API for content generation or summariesCalendar API for scheduling or due date syncObject storage for large file hostingCustom mobile applicationMulti-tenant white-label branding

Next stepTurn the blueprint into an execution plan

Copy the build prompt, model the operating cost, and choose where to deploy.

Build and ship

Execution

Build, price, and deploy the MVP

Once the blueprint is clear, use the prompt, cost model, and deployment options to start building.

Build prompt

Copy this into a builder

lovable

Build prompt

Your build prompt is ready

Open the prompt pack whenever you are ready to take this blueprint into your builder.

Based on the blueprintReady for your builderFollow-up steps included

Cost calculator

Model the MVP operating cost

A technical run-cost estimate for the first production version. Team, acquisition, payment fees, and business COGS are excluded.

Estimated monthly total$25-$65

$13-$33 per 500 generated outputs

Generated outputs / month1,000 generated outputs

Selected pathEasiest

Pricing checkedAug 2, 2026

Cost breakdown

$25-$65 per month

Low and high values allow for usage variance and plan headroom.

Managed infrastructure

Managed app hosting, database, backups, and basic observability for the ai-generation workflow.

50K generated outputs included, then $8-$20 per 100K generated outputs

$25-$65

Transactional email

Transactional email is implied by the source workflow or feature list.

3K generated outputs included

Included

Application hosting
Relational database
Basic backups
work items, delivery signals, and cycle outcomes state
Transactional email

Not included

Paid acquisition
Founder or team time
Tax or legal review
Custom enterprise procurement

Pricing basis

The estimate combines the selected infrastructure path, required operating modules, selected optional modules, and usage above included monthly allowances. Taxes and regional uplifts are excluded.

Managed app baseline Resend pricing

Deployment options

Pick the operational tradeoff

Choose based on operating preference, not only the headline price.

EasiestRecommended

Railway

Fast Docker deployment for the app, database, worker, and preview workflow without managing a VPS.

$15-90/month before usage-heavy add-ons

Good fit

Fast setup
Low starting cost
Good preview workflow

Limitation

Usage billing needs active monitoring as traffic and jobs grow.

Open Railway

Cheapest

Vultr

Run the app, worker, and database on one small Vultr VPS with Docker Compose and explicit backups.

$8-60/month before managed add-ons

Good fit

Predictable baseline
Portable setup
Room for workers

Limitation

You own patching, backups, monitoring, and incident response.

Deploy on Vultr View the lean VPS guide

More control

DigitalOcean

Separate application, worker, data, storage, and backup responsibilities as the workload grows.

$10-120/month before managed add-ons

Good fit

Cloud VPS control
Global regions
Room for workers

Limitation

You own server setup, patching, backups, and operational monitoring.

Explore DigitalOcean View the separated cloud guide

Start building

Prototype, automate, then deploy

Recommended route

01Vibe-coding builderBuild the Kanban Board and Project Dashboard

Create the main kanban interface with five milestone status columns, drag-and-drop card movement, project detail drill-down, invoice summary sidebar, and activity log view. Wire up Supabase for data persistence and authentication.

Open Lovable 02AutomationConnect Stripe Webhooks and Email Triggers

Set up Make scenarios to listen for Stripe payment confirmation webhooks, update invoice status in Supabase, and trigger Resend email notifications when milestones are submitted for approval or invoices are sent.

Open Make 03DeployDeploy Approval API and Invoice Service

Host API endpoints for milestone state transitions, invoice generation from approved milestones, tokenized approval link validation, and activity log persistence. Connect to Supabase and Resend via environment variables.

Open Railway

Client Project Hub with Invoice & Milestone Tracking

Is this worth validating?

Build this if

Avoid this if

Validate first

Why this exists

Customer problem

Who pays

Business model

What do you need next?

What would it take to run?

Build the first paid use case

Who it serves and what it must change

What ships now and what waits

Included

Excluded

Screens, actions, and states

Primary flow

Loading, empty, and error states

Entities and business rules

Business rules

Components, integrations, and controls

Integrations

Data flow

Failure handling

Security

Rate limits

Definition of done for the MVP

Deliverables

Acceptance criteria

Enough technology for the first version

Lovable

Supabase

Make

Railway

Resend

Why this is sufficient

Not required for the MVP

Build, price, and deploy the MVP

Copy this into a builder

Your build prompt is ready

Model the MVP operating cost

Usage assumptions

$25-$65 per month

Included

Not included

Pricing basis

Pick the operational tradeoff

Railway

Good fit

Limitation

Vultr

Good fit

Limitation

DigitalOcean

Good fit

Limitation

Prototype, automate, then deploy

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