Why not just dotnet format?

dotnet format is the right answer for teams that want IDE0055 formatting enforced as part of the build. Curb agrees with it — by design and by measurement — and adds on top.

dotnet format whitespace implements all 39 csharp_* and dotnet_* formatting options from IDE0055. It normalises indentation, spacing, braces, and a dozen other whitespace decisions. It is the reference implementation.

What it does not do: wrap long lines. IDE0055 has no opinion about line width, so dotnet format has none either.

dotnet format style adds semantic code style — var decisions, naming conventions, unused member detection. It loads a compilation to do this, which costs roughly 40 seconds per project in a large solution.

• Reflow. Add max_line_length = 120 to your .editorconfig and Curb wraps long lines. dotnet format never will.
• Syntax-level code style without a compilation. Several IDE analysers — IDE0011 (braces), IDE0022–0027 (expression bodies), IDE0036 (modifier order), IDE0065 (using placement), IDE0161 (file-scoped namespaces) — need a compilation in dotnet format style but are decidable from syntax alone. Curb applies them in the same pass as layout.
• ReSharper formatting keys. The csharp_wrap_*, csharp_place_*, csharp_blank_lines_* and csharp_trailing_comma_* families are read by Rider but not by dotnet format. Curb honours them.
• Speed. About 15× faster at the same task, on the same files. That gap is what makes running inside every build viable rather than as a separate step. See performance.

Curb's output is a fixed point of dotnet format whitespace. That is a CI-gated measurement, not a claim: run dotnet format over Curb's output and nothing changes. The two tools will never fight each other in a repository that uses both. Format Document in the IDE won't undo what Curb wrote.

With reflow off, the match is 100%. With reflow on and deterministic layout, also 100%. With reflow on and csharp_keep_existing_linebreaks = true, 99.9% — one file, a property pattern, measured and held.

The build integration (workflow/msbuild.md) puts Curb at BeforeTargets="CoreCompile". When EnforceCodeStyleInBuild is set, the IDE analysers run inside CoreCompile and report whatever Curb could not fix — the semantic remainder. The two tools complement each other rather than duplicating work.