charges-on-payment-intent - Update code that uses the deprecated payment_intent.charges attribute (removed in newer API versions). Must use Charge.list() or latest_charge instead.
invoice-partial-payments - Update invoice-related code to work with SDK v15.x
subscription-billing-migration - Update subscription-related code to work with SDK v15.x

SDK Versions

Before	After
stripe ~> 7.1	stripe ~> 15.0
API 2022-08-01	API 2025-03-31.basil

Prerequisites

Ruby 3.x and Bundler

Local Setup

Each problem lives in environment/<problem>/server/. To run a problem locally:

1. Configure Stripe API Keys

# Pick a problem to work on
PROBLEM=charges-on-payment-intent  # or invoice-partial-payments, subscription-billing-migration

# Create .env from the example
cp environment/$PROBLEM/server/.env.example environment/$PROBLEM/server/.env

Edit environment/$PROBLEM/server/.env and fill in your Stripe test keys:

STRIPE_SECRET_KEY=sk_test_...
STRIPE_PUBLISHABLE_KEY=pk_test_...

2. Install Dependencies and Start the Server

cd environment/$PROBLEM/server
bundle install
bundle exec ruby server.rb

The server starts on http://localhost:4242. Verify it's running:

curl http://localhost:4242/config

3. Run the Grader (should fail on the initial environment)

In a separate terminal, from the sdk-upgrades-ruby/ root:

# Copy .env so the grader can access Stripe API keys
cp environment/$PROBLEM/server/.env grader/.env

# Install grader dependencies (first time only)
cd grader
bundle install

# Run the grader RSpec tests directly against the running server
bundle exec rspec $PROBLEM/grade.rb --format documentation

Note: The RSpec tests verify endpoint behavior and may pass against the old SDK since the old API still returns compatible response shapes. The full grading gate is in grade.sh, which also checks SDK version — but grade.sh uses Docker-internal paths and is not meant for local use.

Docker Setup (run_solution.sh)

The Docker workflow tests both the unmodified environment (should fail) and the reference solution (should pass) automatically.

Option A: Using a .env file (preferred)

Create a .env file in the sdk-upgrades-ruby/ root directory:

cat > .env << 'EOF'
STRIPE_SECRET_KEY=sk_test_...
STRIPE_PUBLISHABLE_KEY=pk_test_...
EOF

Then run:

./run_solution.sh

Option B: Using environment variables

STRIPE_SECRET_KEY=sk_test_... ./run_solution.sh

Structure

sdk-upgrades-ruby/
├── environment/          # Given to AI (old SDK code)
│   ├── charges-on-payment-intent/
│   ├── invoice-partial-payments/
│   └── subscription-billing-migration/
├── grader/               # Hidden (RSpec tests)
├── solution/             # Reference (upgraded SDK code)
├── Dockerfile
├── run_inside_docker.sh
└── run_solution.sh

Grading

Each problem's grader:

Validates Stripe SDK version is 15.x
Starts the server on port 4242
Runs RSpec tests against HTTP endpoints
Returns pass/fail based on response format

Leak Detection

UUIDs are embedded in grader/solution files to detect leaks:

charges-on-payment-intent (UUID 0891efcc-7898-4eb6-9700-dd889d098897):

Grader: sdk-upgrades-ruby-charges-on-payment-intent-0891efcc-7898-4eb6-9700-dd889d098897-grader
Solution: sdk-upgrades-ruby-charges-on-payment-intent-0891efcc-7898-4eb6-9700-dd889d098897-solution

invoice-partial-payments (UUID b8f99b7e-2b4c-4f8c-82ad-7c922686de83):

Grader: sdk-upgrades-ruby-invoice-partial-payments-b8f99b7e-2b4c-4f8c-82ad-7c922686de83-grader
Solution: sdk-upgrades-ruby-invoice-partial-payments-b8f99b7e-2b4c-4f8c-82ad-7c922686de83-solution

subscription-billing-migration (UUID c3efe58e-a583-4031-83cc-bd4e49e13305):

Grader: sdk-upgrades-ruby-subscription-billing-migration-c3efe58e-a583-4031-83cc-bd4e49e13305-grader
Solution: sdk-upgrades-ruby-subscription-billing-migration-c3efe58e-a583-4031-83cc-bd4e49e13305-solution