From ec7d9c7907b75cd25442017998f0922371c3925e Mon Sep 17 00:00:00 2001
From: nandi <nandi@nixos.local>
Date: Fri, 31 Jul 2026 13:30:01 -0700
Subject: [PATCH] Add nix run .#build for local cargo build via devshell tools

Runs cargo build --release with rustc/cargo and egui LD_LIBRARY_PATH
from the flake, without pure sandbox or remote builders.
---
 README.md  | 18 ++++++++++++++----
 flake.nix  | 48 +++++++++++++++++++++++++++++++++++++++++++++++-
 src/app.rs |  4 ++--
 3 files changed, 63 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index f62591b..500e7c7 100644
--- a/README.md
+++ b/README.md
@@ -7,15 +7,24 @@ Dark charcoal shell, accent-blue arcs, auto-scaling ceilings, and a per-device b
 ## Run
 
 ```bash
-nix run                 # apps.default → usage
+nix run                 # apps.default → usage (Nix-packaged binary)
 nix run .#usage
 ```
 
-Optional (from a checkout next to `../vidya`):
+### Build with the devshell toolchain (no remote builders)
+
+From this checkout (with sibling `../vidya`):
+
+```bash
+nix run .#build         # cargo build --release (rustc/cargo from flake)
+./target/release/usage
+```
+
+Optional interactive shell:
 
 ```bash
 nix develop
-cargo run
+cargo run --release
 ```
 
 ## What you see
@@ -40,7 +49,8 @@ Below the gauges: cards listing individual disks and network interfaces with min
 
 | Output | Role |
 |--------|------|
-| `apps.default` / `apps.usage` | Launch the window |
+| `apps.default` / `apps.usage` | Launch the window (packaged derivation) |
+| `apps.build` | `cargo build --release` via devshell tools (local, no sandbox) |
 | `packages.default` / `packages.usage` | Wrapped binary (`LD_LIBRARY_PATH` for GL/Wayland) |
 | `devShells.default` | rustc + cargo + egui runtime libs |
 
diff --git a/flake.nix b/flake.nix
index 8fed791..5e6ae97 100644
--- a/flake.nix
+++ b/flake.nix
@@ -85,7 +85,48 @@
       apps = forAllSystems (
         system:
         let
+          pkgs = nixpkgs.legacyPackages.${system};
+          inherit (pkgs) lib;
+          libs = eguiLibs pkgs;
+          libPath = lib.makeLibraryPath libs;
           pkg = self.packages.${system}.usage;
+
+          # Local cargo build with the same toolchain/libs as devShells.default.
+          # Avoids remote builders / pure sandbox — run from the checkout:
+          #   nix run .#build
+          build = pkgs.writeShellApplication {
+            name = "usage-build";
+            runtimeInputs = with pkgs; [
+              rustc
+              cargo
+              pkg-config
+            ];
+            text = ''
+              set -euo pipefail
+              export LD_LIBRARY_PATH="${libPath}''${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}"
+
+              # Prefer the flake checkout when invoked as `nix run .#build` from elsewhere.
+              if [ ! -f Cargo.toml ] && [ -f "''${FLAKE_ROOT:-}/Cargo.toml" ]; then
+                cd "$FLAKE_ROOT"
+              fi
+              if [ ! -f Cargo.toml ]; then
+                echo "usage-build: no Cargo.toml here (cwd=$PWD)" >&2
+                echo "  cd into the usage checkout, then: nix run .#build" >&2
+                exit 1
+              fi
+              if [ ! -d ../vidya ]; then
+                echo "usage-build: expected sibling ../vidya (Cargo path dep)" >&2
+                echo "  clone vidya next to usage, or use: nix build .#usage" >&2
+                exit 1
+              fi
+
+              echo "→ cargo build --release $*"
+              cargo build --release "$@"
+              echo "✓ target/release/usage"
+              echo "  run:  LD_LIBRARY_PATH=${libPath}:\''${LD_LIBRARY_PATH:-} ./target/release/usage"
+              echo "  or:   nix develop -c cargo run --release"
+            '';
+          };
         in
         {
           default = {
@@ -96,6 +137,10 @@
             type = "app";
             program = "${pkg}/bin/usage";
           };
+          build = {
+            type = "app";
+            program = "${build}/bin/usage-build";
+          };
         }
       );
 
@@ -112,11 +157,12 @@
               cargo
               rustfmt
               clippy
+              pkg-config
             ];
             buildInputs = libs;
             LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath libs;
             shellHook = ''
-              echo "usage — cargo run  |  nix run"
+              echo "usage — cargo run | nix run .#build | nix run"
             '';
           };
         }
diff --git a/src/app.rs b/src/app.rs
index 7cef321..33558cd 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -105,9 +105,9 @@ impl eframe::App for UsageApp {
                     .show(ui, |ui| {
                         self.gauges_row(ui, &th);
                         ui.add_space(th.spacing.lg);
-                        self.breakdown(ui, &th);
-                        ui.add_space(th.spacing.lg);
                         self.proc_table(ui, &th);
+                        ui.add_space(th.spacing.lg);
+                        self.breakdown(ui, &th);
                     });
             });
     }
-- 
2.51.2