diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
new file mode 100644
index 000000000..e25e9b3a6
--- /dev/null
+++ b/.github/workflows/lint.yml
@@ -0,0 +1,30 @@
+name: Code format check
+on:
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+      - ready_for_review
+      - labeled
+
+# Cancel the current workflow when new commit pushed
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+  check-format:
+    if: '! github.event.pull_request.draft'
+    name: "Check code format"
+    runs-on: [self-hosted, linux, nixos]
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: "Check Scala code format"
+        run: nix run ".#t1.elaborator.format" check
+      - name: "Check difftest code format"
+        run: |
+          nix shell '.#cargo' '.#rustfmt' -c bash -c 'cd difftest && cargo fmt --check'
+
diff --git a/difftest/default.nix b/difftest/default.nix
index dc7f760d0..bd2d56743 100644
--- a/difftest/default.nix
+++ b/difftest/default.nix
@@ -1,6 +1,5 @@
 { lib
 , rustPlatform
-, rustfmt
 , libspike
 , libspike_interfaces
 , rtlDesignMetadata
@@ -36,17 +35,6 @@ rustPlatform.buildRustPackage {
     ];
   };
 
-  nativeBuildInputs = [
-    rustfmt
-  ];
-
-  postConfigure = ''
-    if ! cargo fmt --check; then
-      echo "Please run 'cd difftest && cargo fmt' before building emulator!" >&2
-      exit 1
-    fi
-  '';
-
   buildFeatures = [ ] ++ lib.optionals (lib.hasPrefix "dpi" moduleType) [ "dpi_common/${emuType}" ] ++ lib.optionals enableTrace [ "dpi_common/trace" ];
   buildAndTestSubdir = "./${moduleType}";
 
diff --git a/nix/t1/mill-modules.nix b/nix/t1/mill-modules.nix
index 5eaa5d1fa..af84df9fc 100644
--- a/nix/t1/mill-modules.nix
+++ b/nix/t1/mill-modules.nix
@@ -11,6 +11,7 @@
 , circt-full
 , jextract-21
 , add-determinism
+, writeShellApplication
 
 , dependencies
 }:
@@ -80,47 +81,10 @@ let
       CIRCT_INSTALL_PATH = circt-full;
       JEXTRACT_INSTALL_PATH = jextract-21;
       JAVA_TOOL_OPTIONS = "--enable-preview";
-      formatHook = ''
-        targets=( $(mill -i resolve _.reformat) )
-        localTargets=()
-        for t in ''${targets[@]}; do
-          if ! mill -i show "''${t//reformat/sources}" | grep -q dependencies; then
-            localTargets+=($t)
-          fi
-        done
-        for t in ''${localTargets[@]}; do
-          mill -i "$t"
-        done
-      '';
     };
 
-    outputs = [ "out" "omreader" "elaborator" "t1package" ];
 
-    # Check code format before starting build, so that we can enforce all developer run reformat before build.
-    configurePhase = ''
-      runHook preConfigure
-
-      _targetsToCheck=(
-        "elaborator"
-        "omreader"
-        "omreaderlib"
-        "rocketemu"
-        "rocketv"
-        "t1"
-        "t1emu"
-        "t1rocket"
-        "t1rocketemu"
-      )
-      for _t in ''${_targetsToCheck[@]}; do
-        if ! mill -i "$_t".checkFormat; then
-          echo "[ERROR] Please run 'mill -i $_t.reformat' before elaborate!" >&2
-          exit 1
-        fi
-      done
-      unset _targetsToCheck
-
-      runHook postConfigure
-    '';
+    outputs = [ "out" "omreader" "elaborator" "t1package" ];
 
     buildPhase = ''
       runHook preBuild
@@ -165,6 +129,52 @@ let
         --add-flags "-Djava.library.path=${circt-full}/lib" \
         --add-flags "-cp $out/share/java/omreader.jar"
     '';
+
+    passthru.format = writeShellApplication {
+      name = "mill-format-for-t1";
+      runtimeInputs = [ mill ];
+      text = ''
+        # shellcheck disable=SC1091
+        source ${dependencies.setupHook}/nix-support/setup-hook
+        setupSubmodules
+
+        subcmd="''${1:-}"
+        [[ -z "$subcmd" ]] && \
+          echo "no subcmd specify, available: (check, run)" >&2 && exit 1
+
+        _targetsToCheck=(
+          "elaborator"
+          "omreader"
+          "omreaderlib"
+          "rocketemu"
+          "rocketv"
+          "t1"
+          "t1emu"
+          "t1rocket"
+          "t1rocketemu"
+        )
+
+        case "$subcmd" in
+          check)
+            for _t in "''${_targetsToCheck[@]}"; do
+              if ! mill -i "$_t".checkFormat; then
+                echo "[ERROR] Please run 'mill -i $_t.reformat' before elaborate!" >&2
+                exit 1
+              fi
+            done
+            ;;
+          run)
+            for _t in "''${_targetsToCheck[@]}"; do
+              mill -i "$_t".reformat || true
+            done
+            ;;
+          *)
+            echo "Invalid subcmd $subcmd, available: (check, run)" >&2
+            exit 1
+            ;;
+        esac
+      '';
+    };
   };
 in
 self