diff --git a/.github/labeler.yml b/.github/labeler.yml
new file mode 100644
index 0000000000..c91083a5ba
--- /dev/null
+++ b/.github/labeler.yml
@@ -0,0 +1,59 @@
+'2027':
+- base-branch: '2027'
+'component: apriltag':
+- changed-files:
+  - any-glob-to-any-file: apriltag/**
+'component: command-based':
+- changed-files:
+  - any-glob-to-any-file: wpilibNewCommands/**
+'component: cscore':
+- changed-files:
+  - any-glob-to-any-file: cscore/**
+'component: datalogtool':
+- changed-files:
+  - any-glob-to-any-file: datalogtool/**
+'component: epilogue':
+- changed-files:
+  - any-glob-to-any-file: epilogue-*/**
+'component: examples':
+- changed-files:
+  - any-glob-to-any-file: wpilib*Examples/**
+'component: examples':
+- changed-files:
+  - any-glob-to-any-file: wpilib*Examples/**
+'component: glass':
+- changed-files:
+  - any-glob-to-any-file: glass/**
+'component: hal':
+- changed-files:
+  - any-glob-to-any-file: hal/**
+'component: ntcore':
+- changed-files:
+  - any-glob-to-any-file: ntcore/**
+'component: outlineviewer':
+- changed-files:
+  - any-glob-to-any-file: outlineviewer/**
+'component: sysid':
+- changed-files:
+  - any-glob-to-any-file: sysid/**
+'component: teamnumbersetter':
+- changed-files:
+  - any-glob-to-any-file: roborioteamnumbersetter/**
+'component: wpilibc':
+- changed-files:
+  - any-glob-to-any-file: wpilibc/**
+'component: wpilibj':
+- changed-files:
+  - any-glob-to-any-file: wpilibj/**
+'component: wpimath':
+- changed-files:
+  - any-glob-to-any-file: wpimath/**
+'component: wpinet':
+- changed-files:
+  - any-glob-to-any-file: wpinet/**
+'component: wpiunits':
+- changed-files:
+  - any-glob-to-any-file: wpiunits/**
+'component: wpiutil':
+- changed-files:
+  - any-glob-to-any-file: wpiutil/**
diff --git a/.github/workflows/labeler.yml b/.github/workflows/labeler.yml
new file mode 100644
index 0000000000..e57cd86e2b
--- /dev/null
+++ b/.github/workflows/labeler.yml
@@ -0,0 +1,12 @@
+name: "Pull Request Labeler"
+on:
+- pull_request_target
+
+jobs:
+  labeler:
+    permissions:
+      contents: read
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/labeler@v5
diff --git a/wpimath/src/main/native/include/frc/geometry/Rotation2d.h b/wpimath/src/main/native/include/frc/geometry/Rotation2d.h
index 2c3c94540a..7cb7801e19 100644
--- a/wpimath/src/main/native/include/frc/geometry/Rotation2d.h
+++ b/wpimath/src/main/native/include/frc/geometry/Rotation2d.h
@@ -98,6 +98,43 @@ class WPILIB_DLLEXPORT Rotation2d {
     }
   }
 
+  /**
+   * Constructs a Rotation2d from a rotation matrix.
+   *
+   * @param rotationMatrix The rotation matrix.
+   * @throws std::domain_error if the rotation matrix isn't special orthogonal.
+   */
+  constexpr explicit Rotation2d(const Eigen::Matrix2d& rotationMatrix) {
+    auto impl =
+        []<typename Matrix2d>(const Matrix2d& R) -> std::pair<double, double> {
+      // Require that the rotation matrix is special orthogonal. This is true if
+      // the matrix is orthogonal (RRᵀ = I) and normalized (determinant is 1).
+      if ((R * R.transpose() - Matrix2d::Identity()).norm() > 1e-9) {
+        throw std::domain_error("Rotation matrix isn't orthogonal");
+      }
+      if (gcem::abs(R.determinant() - 1.0) > 1e-9) {
+        throw std::domain_error(
+            "Rotation matrix is orthogonal but not special orthogonal");
+      }
+
+      // R = [cosθ  −sinθ]
+      //     [sinθ   cosθ]
+      return {R(0, 0), R(1, 0)};
+    };
+
+    if (std::is_constant_evaluated()) {
+      auto cossin = impl(ct_matrix2d{rotationMatrix});
+      m_cos = std::get<0>(cossin);
+      m_sin = std::get<1>(cossin);
+    } else {
+      auto cossin = impl(rotationMatrix);
+      m_cos = std::get<0>(cossin);
+      m_sin = std::get<1>(cossin);
+    }
+
+    m_value = units::radian_t{gcem::atan2(m_sin, m_cos)};
+  }
+
   /**
    * Adds two rotations together, with the result being bounded between -π and
    * π.
diff --git a/wpiutil/build.gradle b/wpiutil/build.gradle
index 5191e17e56..9846a49cc7 100644
--- a/wpiutil/build.gradle
+++ b/wpiutil/build.gradle
@@ -184,6 +184,12 @@ nativeUtils.exportsConfigs {
     }
 }
 
+nativeUtils.platformConfigs.each {
+    if (it.name.contains('windows')) {
+        it.cppCompiler.args.add("/D_DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR")
+    }
+}
+
 cppHeadersZip {
     def thirdpartyIncDirs = [
         'src/main/native/thirdparty/argparse/include',