cslq 0.2.0

cslq

Semantic C# queries for coding agents, over Microsoft's official roslyn-language-server — the same engine behind the VS Code C# extension. cslq is a thin LSP client that turns LSP's URIs and zero-based ranges into path:line plus source context, so an agent can find every caller of a method instead of grepping for its name.

Install

cslq is built for coding agents, so there are two pieces: the tool on PATH, and the skill that makes an agent reach for it instead of grep. The tool on its own is inert — nothing will invoke it.

Prerequisites: the .NET 10 SDK and git. Nothing else — cslq fetches the language server itself on first run.

dotnet tool install -g cslq       # the tool
npx skills add idotta/cslq -g     # the skill, into every agent on the machine

The second command is npx skills, which installs skills/csharp-semantic-queries/SKILL.md from the repository into each agent's skills directory — ~/.claude/skills/csharp-semantic-queries/ for Claude Code. Drop -g to install into the current repository instead. Without npx, copy that one file there yourself: it is plain markdown with YAML frontmatter and needs nothing else on disk.

Or hand both steps to the agent:

Install cslq and its skill so you can answer C# questions semantically instead of grepping: run dotnet tool install -g cslq, then npx skills add idotta/cslq -g, then cslq restore. Then run cslq ready --root . here and tell me what it printed.

The first command that needs the language server restores it for you and says so:

cslq: the pinned language server is not restored; restoring it in <dir>. This is a one-time ~300 MB download.

<dir> is the tool's own manifest directory — the .config/dotnet-tools.json packed alongside the binary, never your repository. The restore is idempotent and later runs skip it. When an update brings a new pin, the restore that fetches it deletes every other version of the server from NuGet's global packages folder (~/.nuget/packages unless NUGET_PACKAGES or a NuGet.Config moves it) and says which, so updating weekly does not stack 300 MB payloads. cslq restore does it on demand, with no workspace, for a Dockerfile or a CI step that would rather not pay the download inside the first query.

Then, in the repository you want to query:

dotnet restore                 # not required, but a restore that fails is invisible without it
cslq ready --root <dir>

The server restores as part of its design-time build — measured on a never-restored solution, ready in 7 s. What it cannot do is tell you when that restore failed: every project then loads empty, and dotnet restore is what names the package.

--root must be the directory holding the .sln or .slnx — cslq loads the projects that solution lists. A root with no solution at its top is an error, reported in about a second rather than after the timeout, and a solution one directory down does not count.

Use

cslq ready                                    # block until the workspace has loaded
cslq refs <symbol | file:line:col> [--max N]  # every reference, with context
cslq def <symbol | file:line:col>             # where it is declared
cslq impl <symbol | file:line:col>            # what implements or overrides it
cslq hover <symbol | file:line:col>           # what it is: type, signature, docs
cslq sym <query> [--max N]                    # search the workspace by name
cslq outline <file | symbol> [--max N]        # the declarations in one document
cslq diag [path] [--errors-only]              # compiler and analyzer diagnostics
cslq project <file>                           # which .csproj compiles it, for which TFM
cslq restore                                  # fetch the pinned language server, then exit

$ cslq refs Fixture.Core.Greeter.Greet --root fixture
App/Program.cs:9:35
   8 |     {
>  9 |         Console.WriteLine(Greeter.Greet("world"));
  10 |     }

Core/Greeter.cs:5:26
  4 | {
> 5 |     public static string Greet(string name) => $"Hello, {name}!";
  6 | }

Paths are relative to --root; lines and columns are one-based. Add --json for a { count, truncated, results } envelope.

The README on GitHub has the rest: the agent skill, measured latency and the shared daemon, every failure mode cslq handles, and the evidence behind the dependency choices.