docs(solidity): Supported FheType lists duplicated across FHEVMExecutor operations

Category

• docs(user) — user-facing content: guides, tutorials, concept explanations, etc.
• docs(api) — interfaces: contracts, SDKs, plugin APIs, etc.
• docs(code) — code examples, templates, scripts, tests, etc.
• docs(misc) — structure, navigation, styling, feedback, housekeeping, etc.

Context / Background

While reviewing the FHEVMExecutor contract, I noticed several areas where documentation could be improved to help developers better understand usage assumptions, constraints, and edge cases.

Many functions rely on implicit rules (such as scalarByte expectations, supported type bitmasks, and specific revert conditions) that are not clearly documented. This may lead to confusion for developers integrating with the executor or troubleshooting failed transactions.

Target Files/Pages

• contracts/FHEVMExecutor.sol
• Developer documentation referencing FHE operators (addition, subtraction, division, comparisons, and bitwise operations)

Tasks

• Document the expected meaning and valid values of scalarByte across all binary operators.
• Clarify revert conditions such as IsNotScalar, DivisionByZero, and IncompatibleTypes.
• Add a short explanation of how supported type bitmasks (supportedTypes) are constructed and validated.
• Explain why comparison operators always return FheType.Bool regardless of input types.