Module 3: Your First Contribution

1Fork Bitcoin Core

• Go to github.com/bitcoin/bitcoin
• Click "Fork" in the top right
• This creates your own copy of Bitcoin Core

2Clone Your Fork

# Clone your fork (replace YOUR_USERNAME)
git clone https://github.com/YOUR_USERNAME/bitcoin.git
cd bitcoin

# Add upstream remote (official Bitcoin repo)
git remote add upstream https://github.com/bitcoin/bitcoin.git

# Verify remotes
git remote -v
# origin    -> your fork
# upstream  -> bitcoin/bitcoin

3Install Dependencies

# macOS
brew install automake libtool boost pkg-config libevent

# Ubuntu/Debian
sudo apt-get update
sudo apt-get install build-essential libtool autotools-dev automake \
  pkg-config bsdmainutils python3 libssl-dev libevent-dev \
  libboost-dev libsqlite3-dev

# Check you have required tools
python3 --version  # Should be 3.7+
git --version      # Should be 2.0+

4Build Bitcoin Core

# Generate build files
./autogen.sh

# Configure (adjust for your system)
./configure --without-gui --with-incompatible-bdb

# Build (use all CPU cores)
make -j$(nproc)  # Linux
make -j$(sysctl -n hw.ncpu)  # macOS

# This will take 10-30 minutes on first build

5Run Tests to Verify

# Run unit tests
make check

# Run a quick functional test
test/functional/wallet_basic.py

# If these pass, your environment is ready!

1Sync with Latest Master

# Fetch latest changes
git fetch upstream

# Update your local master
git checkout master
git merge upstream/master

# Push to your fork
git push origin master

2Create Feature Branch

# Create descriptive branch name
git checkout -b fix-wallet-backup-test

# Good branch names:
# - add-rpc-example-to-docs
# - test-wallet-restore
# - fix-typo-developer-notes
# - refactor-net-logging

# Bad branch names:
# - fix
# - changes
# - my-branch

3Make Your Changes

Follow the coding standards in doc/developer-notes.md:

• Use consistent formatting
• Write clear variable names
• Add comments for complex logic
• Keep changes focused (one issue per PR)

4Test Your Changes

# Rebuild
make -j$(nproc)

# Run affected tests
make check
test/functional/test_runner.py

# Run linter
test/lint/lint-all.sh

# Test manually if needed
./src/bitcoind -regtest
./src/bitcoin-cli -regtest [your command]

5Commit with Good Message

# Stage your changes
git add [files]

# Write descriptive commit message
git commit

# Commit message format:
# component: Short description (max 50 chars)
#
# Longer explanation of what changed and why.
# Wrap at 72 characters.
#
# Fixes #12345

Example good commit message:

test: Add coverage for wallet backup restoration

Adds functional test that verifies wallet can be restored
from backup file. Tests both with and without encryption.

This increases test coverage for wallet backup functionality
and catches potential regressions in backup/restore flow.

6Push and Create PR

# Push to your fork
git push origin fix-wallet-backup-test

# Go to GitHub - you'll see "Compare & pull request" button
# Or manually: github.com/bitcoin/bitcoin/compare/master...YOUR_USERNAME:fix-wallet-backup-test

✅ Good Response Examples:

// When accepting feedback:
"Good catch! I'll update to use std::optional here."

// When explaining your approach:
"I chose this approach because X, but I can see the benefit
of your suggestion. Let me try that and see if it's clearer."

// When disagreeing respectfully:
"I see your point about performance. However, in this case
I think readability is more important because [reason].
What do you think?"

// Asking for clarification:
"Could you elaborate on the edge case you mentioned?
I want to make sure I understand the concern."

❌ Bad Response Examples:

// Defensive:
"That's how I always do it and it works fine."

// Dismissive:
"This is just a small change, it doesn't matter."

// Demanding:
"Can someone review this? It's been 2 days."

// Vague:
"Fixed."  (without explanation)