chainlink-data-feeds-skill

# Chainlink Data Feeds Skill ## Overview Route Data Feed requests to the simplest valid path. Generate working code on first attempt when possible. Fetch documentation only when a specific gap blocks progress. ## Progressive Disclosure 1. Keep this file as the default guide. 2. Read [references/reading-price-feeds.md](references/reading-price-feeds.md) only when the user wants to read a price feed on EVM, write a consumer contract, read off-chain, look up AggregatorV3Interface, or debug a price feed integration. 3. Read [templates/starter-kit/README.md](templates/starter-kit/README.md) and the files in [templates/starter-kit](templates/starter-kit) when the user asks for a working example project, Foundry starter kit, runnable Data Feeds example, or says something like "give me a working example of a data feeds project." Use this starter-kit template instead of inventing project scaffolding. 4. Read [references/mvr-feeds.md](references/mvr-feeds.md) only when the user asks about Multiple-Variable Response feeds, bundle feeds, or BundleAggregatorProxy. 5. Read [references/svr-feeds.md](references/svr-feeds.md) only when the user asks about Smart Value Recapture, OEV recapture, or searcher onboarding. 6. Read [references/feed-types.md](references/feed-types.md) only when the user asks about feed categories, SmartData/RWA, rates/volatility, tokenized equity feeds, or needs help choosing a feed type. 7. Read [references/multi-chain.md](references/multi-chain.md) only when the user targets Solana, StarkNet, Aptos, or Tron. 8. Read [references/feed-operations.md](references/feed-operations.md) only when the user asks about L2 sequencer uptime checks, feed deprecation, contract registry, developer responsibilities, or data sources. 9. Read [references/official-sources.md](references/official-sources.md) only when the answer depends on live data that the reference files do not contain -- feed addresses for a specific chain, current deprecation schedules, specific network parameters. 10. Read [references/source-code.md](references/source-code.md) only when debugging interface mismatches or the user needs to inspect contract source code on GitHub. 11. Do not load reference files speculatively. ## Routing 1. Use reading-price-feeds.md as the default for any EVM price feed request — this covers the vast majority of Data Feeds use cases. 2. Use templates/starter-kit for project-level example requests, especially Foundry starter requests. Return a concise file tree, the relevant template files, install/test commands, and the Sepolia ETH/USD feed configuration unless the user asks for another chain. 3. Route to the chain-specific section of multi-chain.md for non-EVM chains (Solana, Aptos, StarkNet, Tron). 4. Route to mvr-feeds.md for bundle or multi-variable feed requests. 5. Route to svr-feeds.md for OEV or MEV recapture requests. 6. Route to feed-operations.md for operational concerns (L2 sequencer checks, deprecation, monitoring). 7. Ask one focused question if the chain, feed type, or integration method is unclear. 8. Proceed without asking for read-only work: explanations, code generation, debugging. ## Safety Defaults These are non-negotiable in generated code. Every consumer contract or integration must include them. 1. Always validate freshness: check `updatedAt` against a staleness threshold based on the feed's heartbeat. Never skip this. 2. Always call `decimals()` on the feed: never hardcode decimal counts. Different feeds use different decimals. 3. On L2 chains (Arbitrum, Optimism, Base, Scroll, etc.): always include an L2 Sequencer Uptime Feed check with a grace period after recovery. 4. Never use `answeredInRound` for freshness validation — this field is deprecated. 5. Remind users that example code is unaudited and not for production use without a security review. 6. If the user is targeting mainnet, emphasize developer responsibilities and recommend a security audit. ## Documentation Access This skill references official Data Feeds documentation URLs throughout its reference files. Whether the model can fetch those URLs depends on the host agent's capabilities. 1. If WebFetch, a browser tool, or an MCP server that can retrieve documentation is available, use it to fetch the referenced URL before answering. 2. If no documentation-fetching tool is available, do not silently improvise Data Feeds patterns from training data alone. Instead: - Use the embedded reference content in this skill's reference files as the floor for guidance. - Tell the user that live documentation could not be verified. - Provide the specific URL so the user can check it directly. 3. For contract-first workflows where correctness matters most, prefer the concrete examples in [references/reading-price-feeds.md](references/reading-price-feeds.md) over generating patterns from memory. ## Working Rules 1. Generate working code from knowledge and reference files first. Fetch only when a specific detail is missing. 2. Treat 0-1 fetches as normal, 2-3 as the ceiling. Most questions need no fetches because the reference files contain the implementation guidance. 3. When a fetch is needed, apply the cascade: WebFetch first; if it returns <1000 chars of useful content, fall back to `curl -s -L -A "Mozilla/5.0 ..." "<url>"`; if both fail, report the URL to the user. 4. Keep answers proportional — a simple "read a price feed" question gets a code block and brief explanation, not a full tutorial. 5. Generate code only when code is actually needed. 6. Keep unsupported or out-of-scope features out of the answer rather than speculating. 7. When using the starter-kit template, preserve its Foundry layout unless the user asks for a different framework. The template is based on the Chainlink Foundry Starter Kit `PriceFeedConsumer.sol` example, with the required Data Feeds validation added for safer generated code. Follow the template README's "Adapt This Template" section: hold its invariant list exactly, and replace the illustrative contract name, raw-price accessors, and placeholder parameter values when the user's use case differs from the template's.