nixos: add daily Rust target sweep

dotfiles/agents/skills/disk-space-cleanup/SKILL.md

@@ -112,6 +112,8 @@ Recommended sequence:
 Machine-specific note:
 
 - Project-local `.worktrees/*/target` directories are common cleanup wins on this machine and are easy to miss with the old hard-coded workflow.
+- `cargo-sweep` is installed through the NixOS `code.nix` package set, but stale manually-installed binaries under `~/.cargo/bin` can shadow `/run/current-system/sw/bin/cargo-sweep`. If `cargo sweep` fails with a missing loader or `No such file or directory`, run `type -a cargo-sweep` and remove the stale `~/.cargo/bin/cargo-sweep` entry.
+- `nixos/imalison.nix` defines a daily user timer, `cargo-sweep-rust-targets.timer`, that runs `cargo-sweep sweep -r --hidden --maxsize 15GB` across `/home/imalison/Projects`, `/home/imalison/org`, and `/home/imalison/dotfiles`.
 
 ## Step 4: Investigation with `ncdu` and `du`
 

nixos/imalison.nix

@@ -1,5 +1,16 @@
 {pkgs, ...}: let
   session = import ./session-variables.nix;
+  cargoSweepRustTargets = pkgs.writeShellApplication {
+    name = "cargo-sweep-rust-targets";
+    runtimeInputs = [pkgs.cargo-sweep];
+    text = ''
+      for root in /home/imalison/Projects /home/imalison/org /home/imalison/dotfiles; do
+        if [[ -d "$root" ]]; then
+          cargo-sweep sweep -r --hidden --maxsize 15GB "$root"
+        fi
+      done
+    '';
+  };
 in {
   home-manager.users.imalison = {
     imports = [
@@ -52,6 +63,33 @@ in {
       };
     };
 
+    systemd.user.services.cargo-sweep-rust-targets = {
+      Unit = {
+        Description = "Sweep Rust target directories";
+      };
+
+      Service = {
+        Type = "oneshot";
+        ExecStart = "${cargoSweepRustTargets}/bin/cargo-sweep-rust-targets";
+      };
+    };
+
+    systemd.user.timers.cargo-sweep-rust-targets = {
+      Unit = {
+        Description = "Sweep Rust target directories daily";
+      };
+
+      Timer = {
+        OnCalendar = "daily";
+        Persistent = true;
+        RandomizedDelaySec = "2h";
+      };
+
+      Install = {
+        WantedBy = ["timers.target"];
+      };
+    };
+
     systemd.user.services.hyprpaper = let
       hyprpaperConf = pkgs.writeText "hyprpaper.conf" ''
         ipc = true