diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index d6ece60..6b51e86 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -1,5 +1,5 @@
 {
-	"name": "DCal",
+	"name": "Forja",
 	"build": {
 		"dockerfile": "Dockerfile"
 	},
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 3958729..eaa5853 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -17,3 +17,7 @@ jobs:
         with:
           jvm: ${{ matrix.jvm }}
       - run: scala-cli test .
+      - name: "Run all formatters on a clean tree"
+        run: scala-cli run . --main-class scripts.rewrite_src_sc
+      - name: "Check: the tree did not change due to the formatters"
+        run: scala-cli run . --main-class scripts.check_no_diff_sc
diff --git a/langs/calc/CalcParser.scala b/langs/calc/CalcParser.scala
index a8ed8fb..7a62926 100644
--- a/langs/calc/CalcParser.scala
+++ b/langs/calc/CalcParser.scala
@@ -96,6 +96,7 @@ object CalcParser extends PassSeq:
   object AddSubPass extends Pass:
     val wellformed = prevWellformed.makeDerived:
       Node.Top.removeCases(AddOp, SubOp)
+      Group.removeCases(AddOp, SubOp)
       Expression.addCases(Add, Sub)
       Add ::= fields(
         Expression,
diff --git a/scripts/check_no_diff.scala b/scripts/check_no_diff.scala
new file mode 100644
index 0000000..39913a9
--- /dev/null
+++ b/scripts/check_no_diff.scala
@@ -0,0 +1,31 @@
+// Copyright 2024-2025 Forja Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package scripts
+
+@main
+def check_no_diff_sc(): Unit =
+  val result = os
+    .proc("git", "status", "--porcelain")
+    .call(cwd = os.pwd, mergeErrIntoOut = true)
+  val strippedOut = result.out.text().strip()
+
+  if strippedOut.isEmpty
+  then
+    println("ok: no diff detected")
+    sys.exit(0)
+  else
+    println("diff detected!")
+    strippedOut.linesIterator.foreach(println)
+    sys.exit(1)