# BilHej / Bilhälsning.se — Requirements Document

> **Note:** This file is loaded by OpenCode via `AGENTS.md` as an external
> instruction source. It is referenced by `opencode.json` instructions.

> **Version:** 0.1.0 (Draft)
> **Date:** April 2026
> **Status:** Pre-development

---

## 1. Executive Summary

BilHej (Bilhälsning.se) is a web platform that allows Swedish residents to contact the owner of a vehicle by entering a registration number, composing a message, and having a physical letter printed and mailed. The platform acts as a trusted intermediary — the user never sees the recipient's name or address. Revenue comes from charging users per letter, with a hybrid subscription + pay-as-you-go model.

---

## 2. Project Vision

A driver sees a car parked on the street. They want to:
- Compliment the owner on their well-kept Volvo 240
- Express interest in buying the car
- Let the owner know their tire is flat or lights were left on
- Give feedback about driving behavior or a honking incident

They visit Bilhälsning.se on their phone, enter the plate, write a short message, pay 49 SEK — and a physical letter arrives in the owner's mailbox 1–3 days later. The sender remains anonymous unless they choose to include their contact details in the letter body.

---

## 3. Target Users

- **Sender:** Swedish resident, 18+, with email and a payment method
- **Recipient:** Swedish vehicle owner (never directly interacts with the platform)

---

## 4. Data Flow & Privacy Design

```
Sender                    BilHej                       Third Parties
──────                    ──────                       ─────────────
Enters plate ──────────→ Plate number stored
Composes letter ───────→ Letter content stored
Pays (Stripe/Swish) ───→ Payment recorded
                         │
                         ├─→ Transportstyrelsen: owner address lookup
                         │   (address used to mail envelope, then DELETED)
                         │
                         ├─→ PostNord/Strålfors: letter content + address
                         │   (print, envelope, mail, return tracking ID)
                         │
Receives confirmation ←── Tracking + order status
```

**Key principles:**
- The sender never sees the recipient's name or address
- The recipient's address is only used transiently — obtained, used for envelope addressing, then deleted
- The recipient's name is never stored by BilHej
- Letter content is stored only for order history and moderation purposes
- The letter itself serves as GDPR Art. 14 notification (informs recipient their address was accessed)

---

## 5. Functional Requirements

### F1 — User Account (Sender)

| Detail | Description |
|--------|-------------|
| Registration | Email + password |
| Login | Email + password |
| Account page | View order history, manage subscription |
| Auth method | JWT tokens (Spring Security + stateless sessions) |

**Rationale:** BankID is not required. The user never accesses personal data — BilHej
(the company) is the sole data controller querying Transportstyrelsen. Email+password
keeps the user experience simple and avoids BankID integration costs and GDPR
complexity on the user side.

### F2 — License Plate Input

| Detail | Description |
|--------|-------------|
| Input | Registration number (e.g., "ABC123") |
| Validation | Swedish plate format (3 letters + 3 digits, or 3 letters + 2 digits + 1 letter) |
| Lookup — public vehicle info | Transportstyrelsen's open vehicle data (make, model, year, color). This is publicly available and free/low-cost. |
| Lookup — owner address | Transportstyrelsen "Fråga om fordonsägare" or "Fordonsregisterkund" API. NOT shown to the sender. Used internally to address the envelope. |

**Phase 0 (hobby/manual):** The vehicle info lookup can optionally use a free/open dataset or the Transportstyrelsen SMS service for make/model. Owner address is obtained manually via the "Fråga om fordonsägare" form.

**Phase 1 (business/automated):** Direct API integration with Transportstyrelsen as a "Fordonsregisterkund" for automated owner address lookup.

### F3 — Letter Composer

| Detail | Description |
|--------|-------------|
| Template selection | Choose a pre-written template or "Fritt meddelande" |
| Text editor | Textarea with character limit (e.g., 1000 chars) |
| Preview | Rendered preview showing exactly what the recipient will see (A4 page) |
| Sender identity | Optional: include name/email/phone in letter body. Default: anonymous |
| Language | Swedish (expandable to English later) |

### F4 — Letter Templates

| # | Template name | Purpose | Legal risk |
|---|---------------|---------|------------|
| 1 | **Komplimang** | Compliment on the car | Low |
| 2 | **Jag vill köpa din bil** | Purchase interest inquiry | Low |
| 3 | **Tips / servicebehov** | Heads-up about flat tire, lights, etc. | Low |
| 4 | **Synpunkter på körbeteende** | Feedback about driving behavior | **Medium** |
| 5 | **Tuta / frustration** | Honking incident follow-up (worded diplomatically) | **Medium** |
| 6 | **Fritt meddelande** | Free text, sender's own words and responsibility | Low (user liability) |

Templates 4 and 5 should always include clear disclaimers and respectful wording.
If legal counsel advises against them, merge them into "Fritt meddelande" where
the user assumes full responsibility for content.

### F5 — Payment Wall

| Detail | Description |
|--------|-------------|
| Triggers | After letter is composed and sender clicks "Send" |
| Before payment | Sender sees: plate number, vehicle info (if available), letter preview |
| After payment | Letter is queued for processing and dispatch |
| Payment provider | Stripe (cards + Swish) |
| Price tiers | See Section 10 |

### F6 — Letter Sending & Tracking

| Detail | Description |
|--------|-------------|
| Phase 0 (manual) | Owner address obtained via Transportstyrelsen form → manual print + envelope + PostNord "Digitalt frimärke" (22 SEK, no tracking) or Varubrev (22 SEK, tracked) → manual status update |
| Phase 1 (automated) | PostNord "Skicka Direkt" API or Strålfors API → print + envelope + mail + automatic tracking |
| Tracking (automated) | PostNord returns shipment ID → poll for status (CREATED → IN_TRANSIT → DELIVERED) |
| Tracking (manual) | Varubrev shipment ID entered manually |
| User-facing status | "Skickat", "På väg", "Levererat" |

### F7 — Order History

| Detail | Description |
|--------|-------------|
| Access | Authenticated users only |
| Contents | Date, plate number, template used, status, tracking link (if available) |
| Letter content | Stored for sender's reference |
| No PII | Recipient address/name NEVER shown, NEVER stored after sending |

### F8 — Admin Panel

| Detail | Description |
|--------|-------------|
| Access | Internal only (admin credentials) |
| Template management | Create/edit/disable letter templates |
| Order overview | View all orders, statuses, revenue |
| Moderation queue | Review "Fritt meddelande" content if flagged |
| Blocklist | Manage opt-out list (recipients who don't want letters) |
| Revenue dashboard | Stripe integration for transaction overview |

---

## 6. Non-Functional Requirements

| ID | Requirement | Detail |
|----|-------------|--------|
| N1 | Responsive design | Mobile-first. Most users will be on a phone, standing next to a car. |
| N2 | Page load time | <2 seconds on 4G mobile |
| N3 | Security | HTTPS, password hashing (bcrypt), JWT expiration, input sanitization |
| N4 | Privacy | Address deleted after PostNord dispatch. No PII logs. |
| N5 | Availability | Phase 0: best-effort (home server). Phase 1: 99.5% uptime |
| N6 | Localization | Swedish UI (expandable to English) |
| N7 | Audit log | Every address lookup logged with plate, timestamp, purpose. Required by Transportstyrelsen for API users. |

---

## 7. Technical Architecture

### Stack

| Layer | Technology |
|-------|-----------|
| Frontend | Vue.js 3 (Composition API), Vite, Pinia state management, Vue Router |
| Backend API | Java 21, Spring Boot 4, Spring Security (JWT), Spring Data JPA |
| Database | PostgreSQL 16 |
| Deployment | Docker, Docker Compose |
| Hosting (Phase 0) | Home server via dynamic DNS or static IP, Let's Encrypt SSL |
| Hosting (Phase 1) | Swedish VPS provider (Binero, FS Data, Elastx) |
| Payment | Stripe (Checkout / Payment Intents) — supports Swish + cards |
| Mail API (Phase 1) | PostNord "Skicka Direkt" or Strålfors Document Delivery API |

### Architecture Diagram

```
┌──────────────────────────────────────────┐
│                Internet                   │
│                                           │
│  ┌──────────────┐     ┌───────────────┐  │
│  │  User Phone  │     │  User Desktop  │  │
│  └──────┬───────┘     └───────┬───────┘  │
└─────────┼─────────────────────┼──────────┘
          │    HTTPS            │
┌─────────▼─────────────────────▼──────────┐
│          Nginx (reverse proxy)            │
│          Let's Encrypt SSL                │
└──────────────────┬───────────────────────┘
                   │
┌──────────────────▼───────────────────────┐
│          Vue.js 3 SPA (Vite)              │
│           Port: 3000 (dev)                │
│           Served as static files          │
└──────────────────┬───────────────────────┘
                   │ REST API calls
┌──────────────────▼───────────────────────┐
│          Spring Boot 4 (Java 21)          │
│           Port: 8080                      │
│  ┌────────────┐  ┌────────────────────┐  │
│  │  Spring    │  │  Service Layer     │  │
│  │  Security  │  │  - LetterService    │  │
│  │  (JWT)     │  │  - LookupService    │  │
│  │            │  │  - MailService      │  │
│  │            │  │  - PaymentService   │  │
│  └────────────┘  └────────┬───────────┘  │
│                           │               │
│              ┌────────────▼───────────┐   │
│              │  PostgreSQL 16         │   │
│              │  Port: 5432            │   │
│              └────────────────────────┘   │
└──────────────────┬───────────────────────┘
                   │
    ┌──────────────┼──────────────┐
    ▼              ▼              ▼
┌────────┐  ┌──────────┐  ┌──────────┐
│ Trans- │  │ PostNord │  │ Stripe   │
│ port-  │  │ /        │  │ (cards + │
│ styrel │  │ Strålfors│  │ Swish)   │
│ sen    │  │ API      │  │          │
└────────┘  └──────────┘  └──────────┘
```

### Database Schema (Core Tables)

```
users
  id            UUID PK
  email         VARCHAR(255) UNIQUE NOT NULL
  password_hash VARCHAR(255) NOT NULL
  created_at    TIMESTAMP
  subscription  ENUM('none', 'basic', 'pro')

orders
  id            UUID PK
  user_id       UUID FK → users
  plate         VARCHAR(10) NOT NULL
  template      VARCHAR(50)
  letter_text   TEXT NOT NULL
  status        ENUM('pending_payment','paid','lookup_started','sent','delivered','failed')
  amount_paid   DECIMAL(10,2)
  tracking_id   VARCHAR(100)
  created_at    TIMESTAMP
  updated_at    TIMESTAMP

templates
  id            UUID PK
  name          VARCHAR(100)
  body_template TEXT
  is_active     BOOLEAN

blocklist
  id            UUID PK
  plate         VARCHAR(10) UNIQUE
  reason        VARCHAR(255)
  created_at    TIMESTAMP

audit_log
  id            UUID PK
  plate         VARCHAR(10)
  action        VARCHAR(50)
  timestamp     TIMESTAMP
  ip_address    VARCHAR(45)
```

---

## 8. API Integrations

### 8.1 Transportstyrelsen

| Aspect | Phase 0 (Hobby) | Phase 1 (Business) |
|--------|----------------|-------------------|
| Method | "Fråga om fordonsägare" form (manual) | "Fordonsregisterkund" API (automated) |
| What you get | Owner name + address | Owner name + address (programmatic) |
| Cost | ~10–15 SEK per request | ~3–5 SEK per query (estimated) |
| Turnaround | Days (manual processing) | Seconds (API) |
| Setup | None (open to individuals) | Formal application + agreement required |
| Name/address stored by BilHej | No (deleted after envelope is addressed) | No (deleted after envelope is addressed) |

**Open questions for Transportstyrelsen:**
- Can a small business / enskild firma get API access, or do they require a minimum volume?
- What is the actual per-query cost?
- What are the formal GDPR/data processing agreement requirements?
- How does the "Fordonsregisterkund" API handle address-update frequency (dagsaktuella uppgifter)?

**Email template for Transportstyrelsen:**
> Hej,
> Jag planerar att starta en tjänst där privatpersoner kan skicka brev till fordonsägare
> via registreringsnummer. Tjänsten fungerar så att avsändaren aldrig ser mottagarens
> adress — det är endast vi som mellanhand som hanterar adressen för att posta brevet,
> varefter adressen raderas.
> Jag undrar:
> 1. Kan vi som mindre företag få tillgång till ägaruppgifter via ert API
>    (Fordonsregisterkund)?
> 2. Vad kostar det per uppslag?
> 3. Vilka krav ställer ni gällande GDPR och personuppgiftshantering?
> 4. Finns det någon minimivolym?
> Tack på förhand.

### 8.2 PostNord / Strålfors

| Service | Description | Cost (est.) | Tracking |
|---------|-------------|------------|----------|
| PostNord "Digitalt frimärke" | Buy postage digitally, print and mail yourself | 22 SEK (50g letter) | No |
| PostNord Varubrev 1:a klass | Tracked letter, postage only | ~22 SEK (50g) | Yes (basic) |
| PostNord "Skicka Direkt" API | Print + envelope + mail, fully automated | ~12–18 SEK total (estimated) | Yes |
| Strålfors Document Delivery API | Print + envelope + mail, enterprise grade | ~8–15 SEK total (estimated) | Yes (webhook) |

PostNord API access is free. You only pay for postage/services.

**Open questions for PostNord:**
- What is the actual price for "Skicka Direkt" (print + mail) for a single-page A4 letter?
- Is there a minimum volume?
- Can we get a business account as an enskild firma?

### 8.3 Stripe

| Detail | Description |
|--------|-------------|
| Products | Stripe Checkout, Payment Intents |
| Payment methods | Cards (Visa, Mastercard) + Swish |
| Fees | ~1.5% + 2 SEK per transaction |
| Subscription support | Stripe Billing for recurring subscriptions (Phase 1) |

---

## 9. User Flow

```
  Sender visits Bilhälsning.se
         │
         ▼
  ┌──────────────┐
  │ Enter plate   │  "ABC 123"
  │ number        │
  └──────┬───────┘
         │
         ▼
  ┌──────────────┐
  │ Vehicle info  │  "Volvo V70, 2009, Silver"
  │ displayed     │  (public data, free)
  └──────┬───────┘
         │
         ▼
  ┌──────────────┐
  │ Choose        │  Template dropdown or free text
  │ template      │
  └──────┬───────┘
         │
         ▼
  ┌──────────────┐
  │ Compose/edit  │  Text editor + preview
  │ letter        │
  └──────┬───────┘
         │
         ▼
  ┌──────────────┐
  │ Preview +     │  "Så här ser brevet ut"
  │ confirm       │  Total: 49 SEK
  └──────┬───────┘
         │
         ▼
  ┌──────────────┐
  │ Log in /      │  Email + password
  │ Register      │  (or skip: guest checkout)
  └──────┬───────┘
         │
         ▼
  ┌──────────────┐
  │ Pay via       │  Stripe Checkout
  │ Stripe/Swish  │  (card or Swish)
  └──────┬───────┘
         │
         ▼
  ┌──────────────┐
  │ Confirmation  │  "Ditt brev är på väg!"
  │ + tracking    │  Estimated delivery: 2–4 days
  └──────────────┘
```

**Behind the scenes (after payment):**
```
  BilHej backend → Transportstyrelsen lookup (owner address)
                  → PostNord/Strålfors API (print + mail)
                  → Address deleted from BilHej
                  → Order status updated
                  → Tracking webhook/callback → status updated
```

---

## 10. Business Model & Pricing

### Cost Analysis (per letter)

| Cost item | Phase 0 (manual) | Phase 1 (automated) |
|-----------|-----------------|--------------------|
| Transportstyrelsen address lookup | 10–15 SEK | 3–5 SEK |
| PostNord postage / print+mail | 22 SEK (postage only) | 12–18 SEK |
| Stripe processing (~1.5% + 2 SEK) | ~3 SEK | ~3 SEK |
| Envelope, paper, printer (manual) | ~5 SEK | 0 SEK (included) |
| **Total cost per letter** | **~40–45 SEK** | **~18–26 SEK** |

### Pricing Tiers

| Tier | Monthly price | Letters included | Extra letters | Est. margin (Phase 1) |
|------|--------------|-----------------|---------------|----------------------|
| Pay-as-you-go | — | 0 | 49 SEK | 23–31 SEK |
| Basic | 99 SEK/mån | 3 | 39 SEK | 13–21 SEK |
| Pro | 199 SEK/mån | 10 | 29 SEK | 3–11 SEK |

### Example Economics (Phase 1, Pro subscriber sending 15 letters/month)

```
Revenue:         199 (subscription) + 5 × 29 (extra letters) = 344 SEK
Costs:           15 × ~22 SEK = 330 SEK
Gross margin:    14 SEK
(Low margin on Pro — designed for high-volume users, profit on Basic/Pay-as-you-go)
```

---

## 11. Legal & Compliance

### 11.1 GDPR Applicability

| Question | Answer |
|----------|--------|
| Does GDPR apply to a hobby project? | Technically yes if you process personal data of others. **However**, Art. 2(2)(c) exempts "purely personal or household activity." A paid public-facing website is **not** exempt. In practice, enforcement risk at small scale is low, but you should be aware. |
| Does GDPR apply to a registered company? | Yes, unequivocally. |
| Is a license plate personal data? | Yes (it directly identifies a vehicle owner). |
| Is an address personal data? | Yes. |
| What if we only process address transiently? | Data minimization is a GDPR principle (Art. 5(1)(c)). Transient processing with immediate deletion is a strong compliance posture. |
| Do we need to inform the recipient? | Yes, GDPR Art. 14 requires informing the data subject. The letter itself can serve this purpose — include a footer like: _"Detta brev skickades via BilHej.se. Din adress hämtades från Transportstyrelsens fordonsregister och har raderats efter utskick. För frågor: kontakt@bilhej.se"_ |

### 11.2 Transportstyrelsen Access

| For individuals | "Fråga om fordonsägare" form — open to anyone with a stated reason. ~10–15 SEK. |
| For businesses | "Fordonsregisterkund" API — requires formal application, stated purpose, data processing agreement. Price not public. |

### 11.3 Blocklist / Right to Object

Under GDPR Art. 21, data subjects have the right to object to processing. BilHej must provide:
- An email/contact form where a recipient can say "don't send me letters"
- A blocklist (per plate) that prevents future letters to that vehicle
- A clear note in the letter footer with opt-out instructions

### 11.4 Recommended Legal Steps

1. **Before launch (Phase 0):** Read Transportstyrelsen's terms for "Fråga om fordonsägare." Include GDPR Art. 14 notice in letter footer. Set up blocklist. Keep address deletion strict.
2. **Before Phase 1:** Consult a Swedish IT-jurist. Register company. Formal data processing agreement with Transportstyrelsen. Appoint DPO if needed. Draft privacy policy and terms of service.

### 11.5 Company vs Private Individual

If the website makes money, you are conducting economic activity. The Swedish Tax Agency (Skatteverket) will consider this a business regardless of formal registration. You can:
- Register as **enskild firma** (sole trader) — simplest, personal tax number, unlimited liability
- Register as **aktiebolag (AB)** — limited liability, requires 25,000 SEK share capital, more administration
- Not register at all (Phase 0) — only viable at very small scale. VAT (moms) becomes an issue above 80,000 SEK/year.

For Phase 0 with manual processing, staying unregistered is workable. If revenue approaches 80,000 SEK/year or if you want automated API access, incorporation will be necessary.

---

## 12. Development Phases

### Phase 0 — MVP (Hobby/Manual)

| Feature | Description |
|---------|-------------|
| Vue.js landing page | Plate input, letter composer, template selection |
| Email+password auth | User registration and login |
| Stripe integration | One-time payments only (no subscriptions) |
| Letter queue | Backend stores orders in DB, admin manually processes |
| Order history | Users see past orders and status |
| Admin panel | Mark orders as processed, enter tracking IDs manually |
| No API integrations (yet) | Address lookup done manually by you |
| Home server deployment | Docker Compose, dynamic DNS, Let's Encrypt |

**Timeline:** ~4–6 weeks (1 person, part-time)
**Cost:** ~0 SEK (excluding subscriptions/services)

### Phase 1 — Automated

| Feature | Description |
|---------|-------------|
| Transportstyrelsen API integration | Automated owner address lookup |
| PostNord/Strålfors API integration | Automated print + mail + tracking |
| Subscription management | Stripe Billing, recurring payments |
| Automatic tracking | Webhook callbacks from PostNord |
| Blocklist system | Opt-out management |
| Moderation queue | Review flagged free-text letters |
| Company registration + legal | Formal agreements, privacy policy, terms |
| Production hosting | Swedish VPS |

**Timeline:** ~6–10 weeks (1 person, full-time)
**Cost:** API fees, legal consultation (~10,000–30,000 SEK), VPS (~100 SEK/mån)

### Phase 2 — Growth

| Feature | Description |
|---------|-------------|
| Advanced templates | Rich text, optional images (car photo) |
| Analytics dashboard | Revenue, letter volume, user retention |
| Referral system | "Refer a friend, get a free letter" |
| English language support | UI and template localization |
| Mobile app (PWA) | Progressive Web App for app-like experience |
| Partner integrations | Dealerships, insurance companies, etc. |

---

## 13. Risks & Mitigations

| Risk | Severity | Mitigation |
|------|----------|------------|
| Transportstyrelsen denies API access | High | Phase 0 manual fallback works with form requests. SMS service as partial alternative. Investigate alternative data sources (fordonsfraga.se, biluppgifter.se). |
| High per-letter costs kill margins | Medium | Start with pay-as-you-go at 49 SEK (margin exists even at Phase 0 costs). Move to subscription+automation to reduce cost base. |
| Recipient complaints / negative PR | Medium | Polite, respectful templates. Clear opt-out in every letter. Blocklist system. Avoid "Tuta" template unless diplomatically worded. |
| GDPR complaint to IMY | Low (Phase 0) / Medium (Phase 1) | Address deletion, no name storage, Art. 14 notice in letter, blocklist. Legal review before Phase 1. |
| Home server downtime | Low | Phase 0 is best-effort. Not critical for low volume. |
| Stripe account closure (reputation risk) | Medium | Ensure terms of service compliance. Have backup payment method. |
| Competition | Low | No known competitor offers this exact service (physical letter via plate lookup). Car.info / biluppgifter.se show vehicle info but don't facilitate contact. |

---

## 14. Open Questions

| # | Question | Owner | Priority |
|---|----------|-------|----------|
| Q1 | What is Transportstyrelsen's actual per-query price for "Fordonsregisterkund" API? | To investigate | High |
| Q2 | Can we use "Fråga om fordonsägare" form for multiple requests as a commercial service? | To investigate | High |
| Q3 | What is PostNord "Skicka Direkt" API pricing for print-and-mail? | To investigate | High |
| Q4 | Does the SMS service give enough info to derive or supplement address data? | To investigate | Medium |
| Q5 | What are the exact legal requirements for API access — company registration? DPO? | To investigate | High |
| Q6 | Should we include the sender's name by default or default to anonymous? | Product decision | Low |
| Q7 | Should "Fritt meddelande" be moderated (reviewed before dispatch) or sent as-is? | Product decision | Medium |
| Q8 | Should we charge VAT (moms) from day one or only above 80,000 SEK? | Tax question | Medium |

---

## 15. Tech Stack Summary

```
Frontend:   Vue.js 3, Vite, Pinia, Vue Router
Backend:    Java 21, Spring Boot 4, Spring Security (JWT), JPA/Hibernate
Database:   PostgreSQL 16
Deploy:     Docker, Docker Compose, Nginx reverse proxy
Hosting:    Home server (Phase 0) → Swedish VPS (Phase 1)
Payments:   Stripe (cards + Swish)
Mail:       Manual (Phase 0) → PostNord API / Strålfors API (Phase 1)
Vehicle:    Manual form (Phase 0) → Transportstyrelsen API (Phase 1)
SSL:        Let's Encrypt (Certbot)
CI/CD:      GitHub Actions (optional)
```

---

## 16. Next Actions

1. **Email Transportstyrelsen** — Ask about API access, pricing, requirements
2. **Email PostNord** — Ask about "Skicka Direkt" print-and-mail pricing
3. **Set up development environment** — Docker Compose with Vue.js + Spring Boot + PostgreSQL
4. **Build plate input + vehicle info display** — First frontend component
5. **Build letter composer + template system** — Core user interaction
6. **Integrate Stripe Checkout** — One-time 49 SEK payment
7. **Build admin panel** — Order management, manual status updates
8. **Deploy to home server** — Docker Compose, Nginx, Let's Encrypt
9. **Test with one real letter** — End-to-end: plate → compose → pay → manual lookup → mail → track
10. **Decide: incorporate or stay manual** — Based on demand

---

*End of Requirements Document*