Android Home Task

Create a new private repo and invite: @mario-deblock.

AI-Assisted Development

At Deblock we value effective use of AI tooling. For this task, we encourage you to use Claude Code (or any AI assistant) as part of your workflow. We provide the folder .claude/ with useful ready made assets, but you can translate those into codex or gemini too.

What we score:

• We will review your git history to assess progress and workflow. We score descriptive commits that reflect meaningful, incremental pieces of work. Bonus if we see the provided /commit under .claude/commands (or one of your own) used as you progress through the implementation. The commit history shows your structure when building a feature, and we pay attention to it.
• We have included a .claude/rules/architecture.md file in this repo describing the architecture and coding standards we follow at Deblock. You can feed this to your AI assistant for context, or simply use it as a manual reference: what matters is the outcome.
• We score positively if the architecture described in that file is followed.
• See .claude/rules files.
• We pay the most attention to the graph.

Tech Stack

• UI using Compose
• Single Activity with Compose - Navigation (no fragments) MVVM
• Dependency injection with Dagger or Hilt
• Repository pattern
• 100% Kotlin
• Coroutines
• Flow

Some easy steps to kick start your project:

1. Android Studio -> New project → Empty Activity (Compose)
2. Configuration file language: Kotlin DSL
3. Unit test with MOCKK
4. UI test with Espresso
5. Networking with Retrofit
6. Jetpack libs

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Requirements

Design

🎨 => Figma file to follow colors, spacing, icons, etc here

Features

A Deblock user has a crypto wallet containing multiple assets (e.g. ETH, BTC, USDT). Assume the current user has the following balances:

• ETH: 0.051
• BTC: 0.051
• USDT: 230

The task consists of a Buy Crypto flow with two steps: Set Amount and Set Limit.

---

Step 1 — Set Amount

Screen: "Set amount" — subtitle: "Your {asset} purchase" (e.g. "Your BTC purchase")

• The subtitle dynamically reflects the currently selected asset (e.g. selecting ETH changes it to "Your ETH purchase").
• As a user I see a numeric input field to enter the amount I want to spend in fiat (e.g. EUR).
• As a user I can select which crypto asset to buy by tapping a dropdown (e.g. "BTC"). This opens a "Choose asset" modal.
• The "Choose asset" modal displays a list of available assets with their current balances (e.g. ETH 0.051, BTC 0.051, USDT 230). Each currency shows the current conversion to EUR value below the amount. See Data points section to obtain values from a free API.
• A custom numeric keypad is displayed at the bottom for amount entry.
• The "Next" button is disabled when the amount is 0 or empty, and becomes enabled once a valid amount is entered (e.g. €50).
• Tapping "Next" navigates to the Set Limit screen.

---

Step 2 — Set Limit

Screen: "Set limit" — subtitle: "Current Price: € {currentPrice}"

• As a user I see the current market price of the selected asset displayed in the subtitle (e.g. "Current Price: € 1,460").
• As a user I see a fiat input field to set my desired limit price (the price at which I want to buy).
• Below the input, a helper text reads: "is the price you will buy at".
• A price chart is displayed showing recent price history for the selected asset.
• The chart includes a draggable horizontal line (slider) that allows the user to visually set the limit price. Dragging the slider updates the input field and vice versa.
• When a limit price is set, a percentage badge is shown indicating the difference from the current price (e.g. "+0.86%").
• The "Confirm {amount} limit" button at the bottom reflects the entered limit price (e.g. "Confirm 1,200 limit"). It is disabled when the limit is 0 and enabled once a valid limit price is entered.

---

Step 3 — Order Summary

Screen: Order summary

• After confirming the limit, the user is taken to a summary screen.
• The screen displays the purchase amount from Step 1 (e.g. 50 €) and the limit price from Step 2 (e.g. 1,200 €).
• Additional order details are listed (asset, amounts, limit price).
• This screen serves as a final review before the user confirms the order.

---

Data Points

You will need to consume 2 data points:

1. Exchange rate (crypto to EUR)
2. Price chart data

1. Obtaining Exchange Rate

For the exchange rate, you can consume any free API. Here is a working example:

Request

https://api.coingecko.com/api/v3/simple/price?ids=bitcoin&vs_currencies=eur

Response

{
  "bitcoin": {
    "eur": 1460.0
  }
}

You can replace bitcoin with ethereum and vs_currencies accepts usd, eur and gbp.

2. Price Chart Data

For the price chart, you can use a free API to obtain historical price data. Here is a working example:

Request

https://api.coingecko.com/api/v3/coins/bitcoin/market_chart?vs_currency=eur&days=30

Response

{
  "prices": [
    [1648684800000, 1420.5],
    [1648771200000, 1435.2],
    ...
  ]
}

Each entry is a [timestamp, price] pair.

What we look for

• Be pixel perfect
• Clean code (networking, UI, simplicity)
• Interactive chart with draggable limit line
• Use of AI, without the AI slop :)