catalog / commerce

Checkout

Turn a cart into a paid order without losing the customer or double-charging them.

19 capabilities 2 sections reference specification

Build against it

# give your agent the catalog — no account, no install
claude mcp add provespec -- npx -y provespec-mcp

# then, from any agent session
spec_get(slug: "checkout")                → the capability tree
spec_checklist(slug: "checkout")          → the questions to answer
spec_grade(slug: "checkout", grades: [...])  → parity % + the gap list

# or just fetch it
curl https://provespec.com/catalog/checkout/spec.json

Grade every capability below as yes · partial · no · na, with a file reference as evidence. Whatever you leave ungraded counts as missing — the gap list is the work queue.

Or just paste this to your agent

Use the ProveSpec MCP server. Fetch the "checkout" spec with
spec_get, then walk spec_checklist and grade this repository against it —
one verdict per capability, each with a file reference as the note.
Call spec_grade with the results and give me the gap list as the plan.

If the server is not registered, add it first:
  claude mcp add provespec -- npx -y provespec-mcp

The specification

AI 16

Flow

✓ Guest checkout without forced account creation
✓ Steps resumable after abandonment

Address

✓ Validation and normalisation with a manual override
✓ Separate billing and shipping addresses

Shipping

✓ Methods with price and delivery estimate

Payment

✓ Card, wallet and redirect-based methods
✓ Card data never touches the server tokenised by the processor
✓ 3-D Secure and other step-up challenges handled
✓ Authorise then capture, or capture directly — stated

Integrity

✓ Idempotency key prevents double charging the double-submit case
✓ Prices re-validated server-side before charging never trust the client total
✓ Order created only after payment confirmation or explicitly reconciled

Failure

✓ Declines explained without leaking card detail
✓ Retry does not create a second order

After

✓ Confirmation page and email with order number
✓ Webhook or callback reconciles asynchronous payments

UI 3

Form

✓ One column, minimal fields, correct input types numeric keypad for card
✓ Inline validation with recoverable errors

Trust

✓ Total visible at every step no surprise at the last click

Open in Parity → Download spec.json All 102 specs