Bundle runtime helper binaries into module packages (postInstall files are dropped by the portable bundler)

[xAlisher]

Problem

A module often needs runtime helper executables alongside its plugin — e.g. radio-basecamp spawns mediamtx (HLS origin), tor/torsocks (onion mode), and ffplay. There's currently no supported way to ship them inside the .lgx: files a module writes via its flake postInstall to $out are dropped by the portable bundler. nix-bundle-dir closures only the plugin .so + its DT_NEEDED lib deps, so anything extra (a sidecar binary in $out/bin) never reaches modules/<name>/.

Repro

# module flake.nix
mkLogosModule {
  src = ./.; configFile = ./metadata.json; flakeInputs = inputs;
  postInstall = ''
    mkdir -p "$out/bin"
    install -m555 ${pkgs.mediamtx}/bin/mediamtx "$out/bin/mediamtx"
  '';
}

nix build .#install-portable → find result -name mediamtx → empty. The binary is stripped from the bundle.

Impact

Modules that spawn helper binaries can't be self-contained. Today the user must install the binaries system-wide (or set env overrides), otherwise the module fails at runtime with e.g. "MediaMTX isn't available on this system." — a poor install UX, especially for catalog/lgpm installs where no setup script runs. metadata.json's nix.packages.runtime declares such deps but doesn't bundle them.

Ask

A supported "extra runtime files" mechanism — e.g. a runtimeBins / extraFiles argument to mkLogosModule that the portable bundler relocates into modules/<name>/bin/:

• Static binaries (Go, e.g. MediaMTX) → just copy.
• Dynamic binaries (tor, ffmpeg) → relocate their lib closure + patchelf --set-rpath '$ORIGIN/../lib', the same treatment the plugin .so already gets — so the .lgx stays portable on machines without Nix.

That would let modules ship a complete, self-contained package.

Context / workaround

Hit while building radio-basecamp (decentralized audio broadcast). Current workaround: the module resolves binaries from its own dir (env → <module-dir>/bin/<tool> → PATH) and the dev install script drops a static MediaMTX post-install — but catalog installs don't run that script, so it isn't a real fix. Hence this request.

[xAlisher]

Second consumer + a cross-platform angle for the runtimeBins/extraFiles ask.

receiver-basecamp (a listen-only sibling of radio-basecamp: discover + play decentralized radio over delivery_module, no hosting) hits the exact same wall. It needs tor + ffmpeg/ffplay (onion playback via a listener tor + torsocks ffplay), and the portable bundler drops anything dropped into $out via postInstall — so the .lgx can't be self-contained. Current workaround is the same: resolveBin() (env → <module-dir>/bin → PATH) + per-OS install of the binaries, which catalog/lgpm installs don't provide.

Cross-platform dimension worth baking into the design: receiver is meant to run on the latest platform on Linux and macOS/arm64 (the platform ships a darwin-arm64 build, and delivery_module builds for macOS). For the Mac story, PATH-resolution means a Homebrew tor+ffmpeg — workable, but a true zero-install package needs the darwin lgx variant to carry macOS-native binaries, not just Linux ELF. So the proposed runtimeBins mechanism should be per-variant (each platform variant relocates its own arch/OS-native binaries + lib closure with the same rpath/$ORIGIN treatment the plugin .so already gets), so a single module can ship self-contained on linux-amd64 / linux-arm64 / darwin-arm64.

Until then we're going with PATH + documented per-OS deps. Happy to test a runtimeBins prototype against receiver + radio.