# Mileage Tracking Automation — Plan

## How it works

1. Open the web app on your phone
2. Take a photo of the odometer
3. Claude Vision API reads the number automatically
4. The km driven is calculated and saved to an Excel sheet
5. Download the sheet anytime

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## Stack

| Layer       | Technology                  |
|-------------|-----------------------------|
| Backend     | Rust + Axum                 |
| AI / OCR    | Claude API (vision)         |
| Spreadsheet | rust_xlsxwriter (Excel)     |
| Frontend    | Mobile-friendly HTML        |

---

## Excel sheet columns

| Date       | Time  | Odometer (km) | Trip (km) | Notes |
|------------|-------|---------------|-----------|-------|
| 2026-03-18 | 08:14 | 84 320        | 47        | Work  |

---

## Files to create

```
Driverthing/
├── src/
│   ├── main.rs         # Axum server + routes
│   ├── claude.rs       # Claude API vision call
│   └── excel.rs        # Excel read/write logic
├── templates/
│   └── index.html      # Mobile camera upload page
├── Cargo.toml
└── mileage_log.xlsx    # Generated, gitignored
```

---

## Flow

```
Phone camera → upload photo
    → Axum receives multipart/form-data
        → Claude Vision: "What is the odometer reading?"
            → Extract number
                → Calculate delta from last reading
                    → Append row to Excel
                        → Show confirmation on screen
```

---

## Implementation steps

1. Set up Axum server with a multipart file upload endpoint
2. Send uploaded image (base64) to Claude API with a vision prompt
3. Parse the odometer number from the response
4. Read the last recorded odometer value from the Excel file
5. Calculate the difference (km driven)
6. Append a new row (date, time, odometer, trip km, notes) to the sheet
7. Return confirmation to the browser
8. Add a download endpoint for the Excel file