Initial commit: Crypto address tracker for Romanian tax calculations

- Bitcoin and Ethereum address tracking
- Identifies first purchase from exchanges
- Interactive CLI mode with historical price lookup links
- Test suite with public addresses
- Documentation for Claude Code

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+A Python tool that tracks Bitcoin and Ethereum addresses to identify the first cryptocurrency purchase - essential for Romanian crypto tax calculations. The tool analyzes blockchain transactions backward in time to find when crypto was first acquired from an exchange.
+
+## Architecture
+
+**Single-file application** ([crypto_tracker.py](crypto_tracker.py)) with one main class:
+
+- `CryptoTracker`: Core class handling both BTC and ETH tracking
+  - `track_bitcoin_address()`: Uses blockchain.info API (no API key required)
+  - `track_ethereum_address()`: Uses Etherscan API (optional API key)
+  - `_check_exchange()`: Matches addresses against known exchange wallets
+  - `_display_bitcoin_results()` / `_display_ethereum_results()`: Formatted output
+  - `main()`: Interactive CLI entry point
+
+**Data flow**: User address → API fetch → Parse transactions (oldest first) → Identify exchange sources → Display first purchase with date/amount/hash
+
+## Development Commands
+
+### Run interactive mode
+```bash
+python crypto_tracker.py
+```
+
+### Run tests (with public addresses)
+```bash
+python test_tracker.py
+```
+
+### Install dependencies
+```bash
+pip install -r requirements.txt
+# or simply:
+pip install requests
+```
+
+## Key Implementation Details
+
+**Bitcoin tracking**:
+- Uses blockchain.info free API (`https://blockchain.info/rawaddr/{address}`)
+- Hardcoded list of known exchange addresses in `known_exchanges` dict
+- Processes transactions in reverse chronological order to find oldest first
+- Converts satoshi to BTC (÷ 100,000,000)
+
+**Ethereum tracking**:
+- Uses Etherscan API (`https://api.etherscan.io/api`)
+- Free tier: 5 requests/second without API key
+- Converts wei to ETH (÷ 10^18)
+- Manual verification required for exchange detection (Etherscan address tags)
+
+**Exchange detection**:
+- Bitcoin: Direct address matching against `known_exchanges` dictionary
+- Ethereum: Flagged for manual review (addresses should be checked on Etherscan for exchange tags)
+
+## Extending the Codebase
+
+**Adding new exchanges**: Update `known_exchanges` dict in `__init__()` with exchange name as key and list of known wallet addresses as value.
+
+**Adding new blockchains**: Follow the pattern of `track_bitcoin_address()` / `track_ethereum_address()` - create new method, fetch transactions via blockchain API, parse chronologically, identify exchange markers.
+
+**Testing**: [test_tracker.py](test_tracker.py) uses public addresses (Genesis block for BTC, Ethereum Foundation for ETH) to verify API connectivity and parsing logic.
+
+## Important Constraints
+
+- **Read-only operation**: No private keys, no transactions sent
+- **Rate limits**: Ethereum API limited to 5 req/sec without key
+- **Exchange detection limitations**: Only major exchanges in Bitcoin; Ethereum requires manual verification
+- **Not for privacy coins**: Only supports transparent blockchain analysis