+++
title = "Nix flake for nbd"
priority = 4
status = "done"
ticket_type = "task"
dependencies = []
+++
Add `nbd/flake.nix` so that `nbd` can be consumed as a Nix package and used as a CLI tool in other projects in the mono-repo.

## Motivation

Other `vibed` services and external projects should be able to include `nbd` as a dev dependency via Nix, getting a pinned, reproducible binary without needing Cargo installed.

## Approach

### nbd/flake.nix

Follow the pattern from the repo root `flake.nix`. The service flake should:
1. Inherit the base flake's inputs (nixpkgs, rust-overlay, etc.) or declare its own.
2. Define a `packages.default` attribute that builds the `nbd` crate with `rustPlatform.buildRustPackage`.
3. Define a `devShells.default` that includes the `nbd` binary and standard Rust tooling (rustfmt, clippy, cargo).
4. Optionally expose an `apps.default` for `nix run .#nbd`.

### Cargo.lock
Ensure `Cargo.lock` is committed (it already is) — required for reproducible Nix builds.

### cargoHash / cargoSha256
The `buildRustPackage` derivation requires a `cargoHash` (or `cargoSha256`). Use the correct fetcher approach (vendored deps or `fetchCargoTarball`).

## Steps
1. Read the root `flake.nix` to understand the base structure.
2. Write `nbd/flake.nix` following the same conventions.
3. Run `nix build .#nbd` from the `nbd/` directory to verify it builds.
4. Run `nix run .#nbd -- --help` to verify the binary works.

## Files touched
- `nbd/flake.nix` — new file
- `README.md` — add `nix run` usage section