> For the complete documentation index, see [llms.txt](https://docs.fira.money/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fira.money/developers/protocol-contracts/core.md). # Core The core module houses the contracts users interact with (through the router) to trade, provide liquidity, and split yield into fixed and floating components. ## How Market and YieldContracts interact The two subsystems are tightly coupled. A `FiraMarket` is parameterized by a BT address, and every swap queries the associated CT contract for the current BC index (via `CT.newIndex()`). The BC index determines how BT (denominated in asset units) should price against FW. When the BC index rises (because the underlying vault earns yield), BT becomes cheaper in FW terms. The AMM incorporates this automatically: `getMarketPreCompute` converts FW reserves to asset terms before computing the exchange rate, so the pricing curve always reflects the current yield environment. At expiry, the market freezes: swaps and new deposits revert. Burns still work, letting LPs exit. Post-expiry exits go through `CT.redeemBC()` rather than AMM swaps. ## State management pattern Both the market and yield contracts use a **read-modify-write pattern** with in-memory structs. The market loads `MarketState` into memory via `readState`, mutates it through `MarketMathCore` library calls, and persists it through `_writeState`. This avoids repeated SLOAD/SSTORE operations and keeps the math library pure. ## Contracts * [FiraMarket](/developers/protocol-contracts/core/fira-market.md) — BT/FW AMM with LP tokens * [FiraMarketFactory](/developers/protocol-contracts/core/fira-market-factory.md) — Split-code CREATE2 market deployment * [MarketMathCore](/developers/protocol-contracts/core/market-math-core.md) — Pricing curve and trade execution math --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.fira.money/developers/protocol-contracts/core.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.