swift-power-assert is a Swift library that provides a `#assert` macro, delivering detailed diagnostic diagrams for assertion failures. The macro, built on SwiftSyntax, rewrites expressions to capture intermediate values and renders a tree of sub-expression results on failure, including word/line diffs for string comparisons. It supports sync and async evaluation, short-circuiting, and custom operators, aiming to replace multiple assertion APIs (XCTest, Nimble, etc.) with a single, universal assert. The package also includes a `StringWidth` module for accurate Unicode width calculations and a comprehensive test suite (2300+ lines) covering diverse expression types. Additionally, the repository contains an interactive web playground with a Deno backend and Monaco editor, allowing users to test the macro in a browser. The codebase is well-structured, with clean abstractions in the runtime library and plugin, though the macro rewriter is tightly coupled to the capture pattern and the generated Unicode width table is large.