Build a 9P service

Adding a capability to InferNode means serving files. This section walks a complete service from namespace sketch to shipped man page, using one that already exists in the tree so you can read the finished thing alongside each step.

The service is countfs: a counter with three files and three control verbs. Deliberately tiny — small enough to hold in your head, complete enough to exercise every convention a real service uses.

Artifact	Path
The service	appl/cmd/countfs.b (~200 lines)
Its bytecode	dis/countfs.dis (built by mk install)
Contract test	tests/inferno/countfs.sh
Man page	man/4/countfs

Everything it produces compiles and passes in CI.

Before you start

You need a source checkout rather than a release — you are building bytecode, so you need the toolchain. See QUICKSTART.md for the per-platform build.

You should also have read Design the interface first. This section is the practice; that page is the theory, and the tutorial assumes it.

The two pages here

• Writing a 9P service — the seven steps, from sketch to man page
• Limbo for Go programmers — the mapping, and the four gotchas that actually bite

If you write Go, you are most of the way there

Limbo has spawn where Go has go, channels with alt instead of select, garbage collection, and type-inferring :=. Concurrency will feel like home. The load-bearing differences are modules loaded at runtime and a handful of sharp edges — both covered on the Limbo page.