The merged-binary entrypoint is ./skywire.go at the repo root —
package main with both skywire and skycoin command trees attached.
The upstream Makefile's build-static recipe uses `go build .` from
the root, and the released tarballs come from there.

cmd/skywire/skywire.go is a leaner skywire-only main; unused for
the release flow. Switch subPackages from "cmd/skywire" to "." so
the Nix build produces the same merged binary the release ships.

The nix/ packaging only had its own README — top-level README didn't
advertise it, so a casual visitor wouldn't know it exists. Add a
short subsection ("NixOS / Nix flake") right after the Arch Linux
AUR section, with the build/run commands and a flake-input snippet.
TOC entry too.

GitHub Actions workflow that runs on PRs touching nix/, Go source,
or vendored deps:

  - cachix/install-nix-action installs Nix on ubuntu-latest with
    flakes enabled.
  - DeterminateSystems/magic-nix-cache-action populates /nix/store
    from previous runs (free shared cache).
  - `nix build .#skywire` exercises the pkgsStatic.buildGoModule
    recipe end-to-end.
  - smoke-test runs --bv on the produced binary and --help on the
    CLI/visor shims.

skywire-bin is intentionally skipped: its derivation needs per-arch
sha256 values for upstream release tarballs, which won't be filled
until a real release runs through this branch. A follow-up
workflow gated on release-tag pushes can validate it then.

The repo has no LICENSE file (the AUR PKGBUILD tags it
"license-free", meaning "no license declared"), so the meta in both
derivations is `licenses.unfree`. Stock nixpkgs refuses to evaluate
unfree packages by default — the CI run failed at eval with

    error: Refusing to evaluate package 'skywire-1.3.50' … because
           it has an unfree license

Set `config.allowUnfreePredicate` on the flake's nixpkgs import to
allow exactly skywire + skywire-bin (nothing else from nixpkgs gets
the bypass). `nix build` and `nix run` now work on a stock install
without `NIXPKGS_ALLOW_UNFREE=1` / `--impure` exports.

The "Git tree is dirty" warning the CI also printed is unrelated
and harmless — it's flake.lock being generated on first invocation;
build continues past it.

Eval fails on current nixpkgs (post-2025-11) with

  error: The "src" package has been renamed to "simple-revision-control".

callPackage auto-binds function args to attrs in pkgs; an `src`
parameter hits the alias-throw before our `?  null` default
applies. Renamed to `srcOverride` (intent stays clear; no other
callers in tree).

Also dropped `-buildid=` from ldflags — buildGoModule sets it
already and warns if redundantly passed:

  trace: evaluation warning: `-buildid=` is set by default as
         ldflag by buildGoModule