Developer guide

Roslyn Bridge MCP is a native executable that serves C# tools over the Model Context Protocol (MCP). It starts the official Roslyn language server, keeps it in sync with the workspace files and turns tool calls into Language Server Protocol (LSP) requests.

Design rules

Keep the bridge standalone and usable from any MCP client.
Use the official MCP SDK for the tools and StreamJsonRpc for Roslyn.
Reserve standard output for MCP messages. Send logs to standard error.
Run in invariant globalization mode, so behavior does not depend on the machine’s culture.
Before applying Roslyn changes, check that each file still matches the version used to compute them.
.gitignore is an allowlist. Allow each new project path explicitly.

Sections

Setup covers the tools to install and local settings.
Validation lists the checks to run and how to run a subset of tests.
Branches and commits covers branch names, commit types and pull requests.
Releases covers native builds and publishing.
C# conventions and testing conventions state the rules for code and tests.
Documentation defines what these pages cover and how to write them.

Layout

Path	Contents
`src/RoslynBridge/Tools`	MCP tools and the dispatcher they share
`src/RoslynBridge/Requests`	What a tool call asks for
`src/RoslynBridge/Results`	What a tool call returns, as records
`src/RoslynBridge/Output`	Text rendering of results
`src/RoslynBridge/Queries`	Read-only Roslyn queries
`src/RoslynBridge/Changes`	Rename and code action proposals and their application
`src/RoslynBridge/Symbols`	Symbol name resolution
`src/RoslynBridge/Editing`	Workspace file edits, snapshots and preview diffs
`src/RoslynBridge/Lsp`	Roslyn process, protocol and document synchronization
`src/RoslynBridge/Settings`	Command-line options, the project settings file and the options they produce
`src/RoslynBridge`	Entry point, commands, and the errors and workspace paths that every layer shares
`tests/RoslynBridge.Tests`	Unit tests, integration tests and fixtures
`eng`	Analyzer rules and CI tasks
`docs`	Starlight pages and configuration

Common changes

Change	Start with
Change an analyzer or style rule	Analyzers
Report a new kind of failure	Errors
Add or change a test	Testing conventions
Name a branch or write a commit	Branches and commits
Publish a release	Releases
Add or change a documentation page	Documentation