Digital Signature Workspace (ttdttd)

A synchronous, invite-based digital signature workspace. Workspace owners can upload PDFs, assign signature placeholders to invited members, and automatically merge signatures into a flattened PDF once all parties approve.

Architecture

┌─────────────┐     ┌─────────────┐     ┌──────────┐
│  Frontend   │────▶│   Backend   │────▶│ PostgreSQL│
│  React+Vite │◀────│  Go + Gin   │◀────│           │
└─────────────┘     └──────┬──────┘     └──────────┘
                           │
                      ┌────▼────┐
                      │ AWS S3  │
                      │ (files) │
                      └─────────┘

Tech Stack

• Frontend: React 19, TypeScript, Vite, react-pdf, Zustand
• Backend: Go 1.26, Gin, sqlx, pdfcpu
• Database: PostgreSQL 16
• Storage: AWS S3
• Testing: Ginkgo BDD

Quick Start

Prerequisites

• Go 1.26+
• Node.js 20+
• PostgreSQL 16
• AWS S3 bucket (or use LocalStack for local dev)

Backend

cd backend
cp .env.example .env
# Edit .env with your database and S3 credentials

# Run migrations (auto-run on startup)
go mod tidy
go run main.go

Server starts on :8080.

Frontend

cd frontend
npm install
npm run dev

App starts on http://localhost:3000 with API proxy to :8080.

Docker Compose

docker-compose up

Starts PostgreSQL, backend, and frontend.

API Reference

Auth & Users

Method	Endpoint	Description
POST	/auth/login	SSO login, returns JWT
GET	/users/me	Get user profile
PUT	/users/me/signature	Upload signature PNG

Workspaces

Method	Endpoint	Description
POST	/workspaces	Create workspace
GET	/workspaces	List user's workspaces
GET	/workspaces/:id	Get workspace details
POST	/workspaces/:id/invites	Generate invite token

Invites

Method	Endpoint	Description
POST	/invites/:token/accept	Accept invite (requires signature)

Documents

Method	Endpoint	Description
POST	/workspaces/:id/documents	Upload PDF
GET	/workspaces/:id/documents/:docId	Get document + placeholders
POST	/workspaces/:id/documents/:docId/placeholders	Create signature box
DELETE	/workspaces/:id/documents/:docId/placeholders/:phId	Remove placeholder
POST	/workspaces/:id/documents/:docId/sign	Approve & sign
POST	/workspaces/:id/documents/:docId/complete	Finalize document

Workflow

1. Owner creates a workspace and invites signers
2. Signers accept invites (must upload signature first)
3. Owner uploads a PDF and places signature boxes on it
4. Signers review the document and click "Approve & Sign"
5. Owner clicks "Complete Document" when all have signed
6. System merges all signatures into a flattened PDF

Constraints

• No async queues — all operations are synchronous
• No OCR — manual placeholder placement only
• Every user must upload a signature before interacting with documents
• Metadata in PostgreSQL, binaries in S3
• Standard JSON error format: {"error": "message", "code": 400}