Lean reference that assumes Claude's competence — no padding explaining what Braintree, TypeScript, or testing are; tables and code carry the weight and every section earns its tokens.

Provides fully executable TypeScript (init, sale, settle, refund, webhook parse, Drop-in), exact PAN and amount tables, concrete env-var names, and a copy-paste CI yaml block.

Multi-step chains are sequenced with explicit checkpoints — sale → submitForSettlement → gateway.testing.settle → expect 'settled', and the refund prerequisite ('Refunds can only happen after settlement') is stated — plus webhook signature validation and an anti-patterns table for error recovery.

Single self-contained file with clean section headers, clearly signaled one-level-deep external doc links and named companion catalogs, and no nested references — appropriate for this focused reference skill with no bundle files.

Lists multiple concrete capabilities — 'Drop-in / Hosted Fields client-side patterns', 'Transaction lifecycle (submitted_for_settlement → settled)', 'specific PANs trigger specific errors', and 'webhook verification (Braintree Webhook Parser)' — rather than vague language.

Explicitly answers what ('Wraps Braintree sandbox testing patterns...') and when ('Use when testing Braintree-integrated code.'), satisfying both halves with an explicit trigger clause.

Covers natural terms a developer would say when needing this skill ('Braintree', 'sandbox testing', 'Drop-in / Hosted Fields', 'webhook', 'test cards'), matching the good-coverage anchor; the internal jargon (PANs, state names) sits alongside, not in place of, these natural triggers.

Occupies a clear niche — Braintree sandbox testing — with a distinct, name-scoped trigger, making it unlikely to fire for the generic or sibling (stripe/adyen/paypal) skills despite Braintree being PayPal-owned.