feat: add bsc support to CoW swapper by 0xApotheosis · Pull Request #11360 · shapeshift/web

0xApotheosis · 2025-12-11T01:41:59Z

Description

Add Binance Smart Chain support to CoW swapper.

Issue (if applicable)

None, I just realised we didn't support this, but we should.

Risk

Low

What protocols, transaction types, wallets or contract interactions might be affected by this PR?

CoW swaps on BSC

Testing

Ensure CoW trades on BSC work.

Engineering

👆

Operations

🏁 My feature is behind a flag and doesn't require operations testing (yet)

👆

Screenshots (if applicable)

Note

Adds BNB Smart Chain support by enabling BSC chain ID, network mapping, and CowNetwork enum value.

CoW Swapper utils:
- Update SUPPORTED_CHAIN_IDS in packages/swapper/src/cowswap-utils/constants.ts to include KnownChainIds.BnbSmartChainMainnet.
- Map KnownChainIds.BnbSmartChainMainnet to CowNetwork.Bnb in getCowNetwork (packages/swapper/src/cowswap-utils/index.ts).
Types:
- Add CowNetwork.Bnb to packages/types/src/cowSwap.ts.

^{Written by Cursor Bugbot for commit b15e421. This will update automatically on new commits. Configure here.}

Summary by CodeRabbit

New Features
- Added support for BNB Smart Chain Mainnet to the swapper service, expanding available blockchain networks for trading operations.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

coderabbitai · 2025-12-11T01:42:13Z

📝 Walkthrough

Walkthrough

BNB Smart Chain Mainnet support is added to the cowswap utilities across three files: the CowNetwork enum is extended with a new Bnb member, the supported chain IDs constant is updated to include the BNB chain ID, and the chain-to-network mapping logic is extended with a corresponding case for routing.

Changes

Cohort / File(s)	Summary
BNB Network Support `packages/types/src/cowSwap.ts`, `packages/swapper/src/cowswap-utils/constants.ts`, `packages/swapper/src/cowswap-utils/index.ts`	Adds BNB Smart Chain Mainnet support by introducing `CowNetwork.Bnb` enum member, including `KnownChainIds.BnbSmartChainMainnet` in `SUPPORTED_CHAIN_IDS`, and mapping the chain ID to `CowNetwork.Bnb` in the `getCowNetwork` switch statement.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~5–10 minutes

Verify enum value matches expected string identifier ('bnb')
Confirm chain ID constant is correctly placed in the array
Validate switch case mapping logic connects all three changes consistently

Suggested reviewers

NeOMakinG
kaladinlight

Poem

🐰 Hop, hop, the chains multiply!
BNB joins the cowswap supply,
Enum, constant, mapping aligned,
Three little changes, perfectly designed! ✨

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title 'feat: add bsc support to CoW swapper' directly and accurately summarizes the main change: adding Binance Smart Chain (BSC) support to the CoW swapper, which aligns perfectly with the modifications across three files.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing touches

📝 Generate docstrings

🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch add-bnb-to-cow

📜 Recent review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

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📥 Commits

Reviewing files that changed from the base of the PR and between a834359 and b15e421.

📒 Files selected for processing (3)

packages/swapper/src/cowswap-utils/constants.ts (1 hunks)
packages/swapper/src/cowswap-utils/index.ts (1 hunks)
packages/types/src/cowSwap.ts (1 hunks)

🧰 Additional context used

📓 Path-based instructions (5)

**/*.{ts,tsx,js,jsx}

📄 CodeRabbit inference engine (CLAUDE.md)

**/*.{ts,tsx,js,jsx}: Never assume a library is available - always check imports/package.json first
Prefer composition over inheritance
Write self-documenting code with clear variable and function names
Keep functions small and focused on a single responsibility
Avoid deep nesting - use early returns instead
Prefer procedural and easy to understand code
Never expose, log, or commit secrets, API keys, or credentials
Validate all inputs, especially user inputs
Handle errors gracefully with meaningful messages
Don't silently catch and ignore exceptions
Log errors appropriately for debugging
Provide fallback behavior when possible
Use appropriate data structures for the task
Never add code comments unless explicitly requested
When modifying code, do not add comments that reference previous implementations or explain what changed. Comments should only describe the current logic and functionality.
Use meaningful names for branches, variables, and functions
Always run yarn lint --fix and yarn type-check after making changes
Avoid let variable assignments - prefer const with inline IIFE switch statements or extract to functions for conditional logic

Files:

packages/swapper/src/cowswap-utils/index.ts
packages/swapper/src/cowswap-utils/constants.ts
packages/types/src/cowSwap.ts

**/*.{ts,tsx}

📄 CodeRabbit inference engine (CLAUDE.md)

**/*.{ts,tsx}: Avoid useEffect where practical - use it only when necessary and following best practices
Avoid 'any' types - use specific type annotations instead
For default values with user overrides, use computed values (useMemo) instead of useEffect - pattern: userSelected ?? smartDefault ?? fallback
When function parameters are unused due to interface requirements, refactor the interface or implementation to remove them rather than prefixing with underscore
Sanitize data before displaying to prevent XSS
Memoize aggressively - wrap component variables in useMemo and callbacks in useCallback where possible
For static JSX icon elements (e.g., <TbCopy />) that don't depend on state/props, define them as constants outside the component to avoid re-renders instead of using useMemo
Account for light/dark mode using useColorModeValue hook
Account for responsive mobile designs in all UI components
When applying styles, use the existing standards and conventions of the codebase
Use Chakra UI components and conventions
All copy/text must use translation keys - never hardcode strings
Use the translation hook: useTranslate() from react-polyglot
Use useFeatureFlag('FlagName') hook to access feature flag values in components
Prefer type over interface for type definitions
Use strict typing - avoid any
Use Nominal types for domain identifiers (e.g., WalletId, AccountId)
Import types from @shapeshiftoss/caip for chain/account/asset IDs
Use useAppSelector for Redux state
Use useAppDispatch for Redux actions
Memoize expensive computations with useMemo
Memoize callbacks with useCallback

**/*.{ts,tsx}: Use Result<T, E> pattern for error handling in swappers and APIs; ALWAYS use Ok() and Err() from @sniptt/monads; AVOID throwing within swapper API implementations
ALWAYS use custom error classes from @shapeshiftoss/errors with meaningful error codes for internationalization and relevant details in error objects
ALWAYS wrap async op...

Files:

packages/swapper/src/cowswap-utils/index.ts
packages/swapper/src/cowswap-utils/constants.ts
packages/types/src/cowSwap.ts

**/swapper{s,}/**/*.{ts,tsx}

📄 CodeRabbit inference engine (.cursor/rules/error-handling.mdc)

ALWAYS use makeSwapErrorRight for swapper errors with TradeQuoteError enum for error codes and provide detailed error information

Files:

packages/swapper/src/cowswap-utils/index.ts
packages/swapper/src/cowswap-utils/constants.ts

**/*.{js,jsx,ts,tsx}

📄 CodeRabbit inference engine (.cursor/rules/naming-conventions.mdc)

**/*.{js,jsx,ts,tsx}: Use camelCase for variables, functions, and methods with descriptive names that explain the purpose
Use verb prefixes for functions that perform actions (e.g., fetch, validate, execute, update, calculate)
Use UPPER_SNAKE_CASE for constants and configuration values with descriptive names
Use handle prefix for event handlers with descriptive names in camelCase
Use descriptive boolean variable names with is, has, can, should prefixes
Use named exports for components, functions, and utilities instead of default exports
Use descriptive import names and avoid renaming imports unless necessary
Avoid non-descriptive variable names like data, item, obj, and single-letter variable names except in loops
Avoid abbreviations in names unless they are widely understood
Avoid generic function names like fn, func, or callback

Files:

packages/swapper/src/cowswap-utils/index.ts
packages/swapper/src/cowswap-utils/constants.ts
packages/types/src/cowSwap.ts

packages/swapper/**/*.ts

📄 CodeRabbit inference engine (.cursor/rules/swapper.mdc)

packages/swapper/**/*.ts: Use TypeScript with explicit types (e.g., SupportedChainIds) for all code in the Swapper system
Use camelCase for variable and function names in the Swapper system
Use PascalCase for types, interfaces, and enums in the Swapper system
Use kebab-case for filenames in the Swapper system

Files:

packages/swapper/src/cowswap-utils/index.ts
packages/swapper/src/cowswap-utils/constants.ts

🧠 Learnings (11)