Bug: csharpier-documented-command-incompatible-with-pinned-version #509

• Work Mode: minor-audit

Summary

The C# format command documented in CLAUDE.md and .claude/rules/csharp.md is dotnet tool run csharpier ., which is CSharpier v0 syntax. The repository pins CSharpier 1.2.6 in dotnet-tools.json, and 1.2.6 requires a subcommand (format <directoryOrFile> or check <directoryOrFile>). The documented command therefore cannot format the repository as written.

Environment

• OS/version: Windows 11 Pro 10.0.26200
• Runtime: repo-local .NET SDK 8.0.205 installed to .dotnet-sdk by scripts/vscode/Install-RepoDotNetSdk.ps1
• Command/flags used: ./.dotnet-sdk/dotnet.exe tool run csharpier . (documented) versus ./.dotnet-sdk/dotnet.exe tool run csharpier format . (working)
• Data source or fixture: dotnet-tools.json at repository root, which pins csharpier to 1.2.6

Steps to Reproduce

1. From the repository root, run ./.dotnet-sdk/dotnet.exe tool restore so the pinned CSharpier 1.2.6 is available.
2. Run the command documented in CLAUDE.md § "C# Toolchain (run in this exact order)" step 1: dotnet tool run csharpier .
3. Compare with ./.dotnet-sdk/dotnet.exe tool run csharpier -- --help, which lists the available commands.

Expected Behavior

The format command documented in the policy files is the command that actually formats the repository with the pinned formatter version, so an agent or developer following the documented toolchain order can complete step 1 without substitution.

Actual Behavior

CSharpier 1.2.6 exposes only the subcommands format, check, pipe-files, and server. Invoking it with a bare path argument does not run the documented format step. Verified on 2026-08-08:

Commands:
  format <directoryOrFile>  Format files.
  check <directoryOrFile>   Check that files are formatted. Will not write any changes.
  pipe-files                Keep csharpier running so that multiples files can be piped to it via stdin.
  server                    Run CSharpier as a server so that multiple files may be formatted.

Logs / Screenshots

• Attached minimal logs or screenshot
• Snippet: ./.dotnet-sdk/dotnet.exe tool run csharpier --version returns 1.2.6; the subcommand list above is the output of ... tool run csharpier -- --help.

Impact / Severity

• Blocker
• High
• Medium
• Low

The documented toolchain is the authority every agent session and contributor follows, and formatting is step 1 of a mandatory four-stage loop that must restart from step 1 on any change. A stale invocation string forces each session to independently discover the correct syntax and deviate from a policy document, which is precisely the kind of silent divergence the policy exists to prevent. There is also a correctness trap: a globally installed CSharpier (1.3.0 was present on the affected machine) can satisfy the bare-path form, so a session may format with an unpinned version and produce diffs that disagree with CI.

Source

From: docs/features/potential/2026-08-08-csharpier-documented-command-incompatible-with-pinned-version.md