Quickstart

Install Fuse and connect it to the coding agent for the current .NET project:

dotnet tool install -g Fuse
fuse mcp install --rules

No client environment variables are required. fuse mcp serve defaults to a shared fuse host daemon per repository, syntax-first indexing with background semantic upgrade, build capture, and auto-update between sessions.

The shared daemon starts warming the repository when the MCP server starts. Run an explicit index when you want the complete semantic index ready before reloading the client:

fuse index

This command waits for the semantic index at .fuse/fuse.db. It is optional for normal MCP use: eager warm-on-start, syntax-first serving, background semantic upgrade, and incremental file updates are enabled by default.

Reload your MCP client, then ask:

Before changing OrderService.cs, check the proposed file with fuse_check and show any
compiler diagnostics before writing it.

The agent sends the proposed content to Fuse. Fuse returns a compiler-backed result without changing the source file.

Confirm the Connection

Ask the agent to make a real status call:

Call fuse_workspace with action=status for this repository. Return the workspace path,
analysis mode, and freshness exactly as Fuse reports them.

A response with the repository path confirms the connection. A tool list or a statement that Fuse is available does not.

If you ran fuse index above, this call reads the completed index. If you skipped it, the daemon may still be warming the repository. A cold read waits only for the bounded syntax-first deadline and reports building_syntax or upgrade_pending when more work is running. Later calls reuse the local store. If a tool returns index_rebuilding: after an upgrade or corrupt recovery, retry after a few seconds or call fuse_workspace with action=index.

Check the First Proposed Edit

Give the agent a concrete file and requested change:

Add cancellation support to OrderService.PlaceOrderAsync. Before writing the edit, call
fuse_check with the proposed OrderService.cs content. Apply it only if the result has no
compiler diagnostic.

Each check names the compiler path that produced the answer. This label is the verification grade:

• Oracle grade uses a compilation captured from the real build.
• Build grade runs a scoped dotnet build for the owning project.
• Abstained means neither compiler path could answer and names what is missing.

The check call does not write the file. fuse_workspace with action=apply is the explicit write operation, and it is a dry run unless write=true.

Review the Current Branch

Ask for the Git-changed files and focused context from related code:

fuse_review(
  path="C:/Projects/MyApp/src",
  changedSince="origin/main",
  maxTokens=25000
)

Each returned file states why it was included. The maxTokens value limits the amount of focused context in the response.

Follow Application Wiring

Resolve a service interface to its registered implementation:

fuse_find(path="C:/Projects/MyApp/src", kind="service", query="IOrderService")

The same operation can follow a request to its handler, a route to its action, or a configuration section to its options type.

Use Fuse from the Terminal

The command-line interface supports indexing and branch work:

fuse index ./src
fuse review ./src --changed-since origin/main --max-tokens 25000

Fuse loads the workspace through MSBuild and Roslyn when it can, and falls back to syntax-level indexing otherwise. The index lives in a single SQLite file at .fuse/fuse.db. MCP serving starts an eager background warm by default. fuse index is the synchronous CLI path when a script or developer needs to wait for completion. Fuse keeps the index fresh automatically as files change.

You can also resolve .NET wiring directly:

fuse resolve ./src --service IOrderService
fuse resolve ./src --request CreateOrderCommand
fuse resolve ./src --route "POST /api/orders/{id}"

Set Project Defaults

To avoid repeating flags, write a configuration file once:

fuse init

This scaffolds a fuse.json you can edit. See Configuration keys for every supported key.

Next

Read Connect to your AI for project, user, manual, and rollback setup. Continue with Check an edit, Follow .NET wiring, or Review a branch.