data-mesher: init module

Co-authored-by: Brian McGee <brian@bmcgee.ie>

devShell.nix

@@ -1,10 +1,12 @@
-{ ... }:
+{ inputs, ... }:
 {
   perSystem =
     {
+      lib,
       pkgs,
       self',
       config,
+      system,
       ...
     }:
     let
@@ -24,18 +26,26 @@
     in
     {
       devShells.default = pkgs.mkShell {
-        packages = [
-          select-shell
-          pkgs.nix-unit
-          pkgs.tea
-          # Better error messages than nix 2.18
-          pkgs.nixVersions.latest
-          self'.packages.tea-create-pr
-          self'.packages.merge-after-ci
-          self'.packages.pending-reviews
-          # treefmt with config defined in ./flake-parts/formatting.nix
-          config.treefmt.build.wrapper
-        ];
+        packages =
+          [
+            select-shell
+            pkgs.nix-unit
+            pkgs.tea
+            # Better error messages than nix 2.18
+            pkgs.nixVersions.latest
+            self'.packages.tea-create-pr
+            self'.packages.merge-after-ci
+            self'.packages.pending-reviews
+            # treefmt with config defined in ./flake-parts/formatting.nix
+            config.treefmt.build.wrapper
+          ]
+          # bring in data-mesher for the cli which can help with things like key generation
+          ++ (
+            let
+              data-mesher = inputs.data-mesher.packages.${system}.data-mesher or null;
+            in
+            lib.optional (data-mesher != null) data-mesher
+          );
         shellHook = ''
           echo -e "${ansiEscapes.green}switch to another dev-shell using: select-shell${ansiEscapes.reset}"
           export PRJ_ROOT=$(git rev-parse --show-toplevel)