Comprehensive guide for writing correct, secure, and idiomatic Cadence smart contract code on the Flow blockchain. Covers language fundamentals (resources, contracts, transactions, interfaces, accounts, references, imports), access control and entitlements, capabilities, pre/post conditions, security best practices (including checks-effects-interactions, trust-boundary validation, and bounded loops), anti-patterns to avoid, proven design patterns, style and readability rules, and numeric precision with checked arithmetic.
TRIGGER when: writing or debugging Cadence code, asking about Cadence syntax, access(self), access(all), entitlements, resources, move operator (<-), capabilities, references, pre/post conditions, storage paths, optional binding, if let, guard let, force-unwrap, string templates, UFix128, Fix128, fixed-point precision, overflow, checks-effects-interactions, reentrancy, "how do I write cadence", "cadence error", "compile error in .cdc", "what does access(self) mean", "how do resources work",
Guide for writing, running, and debugging unit tests for Cadence smart contracts using the built-in Cadence Testing Framework and `flow test`. Covers test file structure (_test.cdc, setup/beforeEach/tearDown), assertions and matchers, blockchain emulation (accounts, deployments, events, time manipulation), coverage reports, CI integration, and testing patterns.
TRIGGER when: writing Cadence unit tests, debugging failing tests, using Test.assert / Test.expect / Test.assertEqual / Test.expectFailure, matchers (Test.equal, Test.beGreaterThan, etc.), Test.createAccount / Test.deployContract / Test.executeTransaction / Test.executeScript in tests, Test.moveTime, Test.eventsOfType in tests, Test.reset, `flow test`, `flow test --cover`, coverage reports, `_test.cdc`, "how do I test this contract", "test is flaky", "mock a capability in a test".
DO NOT TRIGGER when: writing contract or transaction code itself (use cadence-lang), generating new contracts/transactions from scratch (use cadence-scaffold), auditing non-t
Guide for developing NFT and Fungible Token contracts on the Flow blockchain using Cadence. Covers NonFungibleToken and FungibleToken interface conformance, MetadataViews integration for marketplace compatibility, collection patterns, minting, standard paths, event emission, and modular NFT architectures for complex traits and evolution.
TRIGGER when: building NFT contracts, FT token contracts, implementing NonFungibleToken or FungibleToken interfaces, working with MetadataViews, creating collections, minting tokens, "create an NFT", "build a token contract", "mint NFT", "NFT collection", "fungible token vault", "royalties", "MetadataViews.Display", "NonFungibleToken.Collection", "token standards", "FungibleToken.Vault".
DO NOT TRIGGER when: asking about general Cadence syntax or patterns (use cadence-lang), setting up flow.json or deploying (use flow-project-setup), auditing code (use cadence-audit).
