diff --git a/docs/current-architecture.md b/docs/current-architecture.md
index 1ad0eab..0fd4c14 100644
--- a/docs/current-architecture.md
+++ b/docs/current-architecture.md
@@ -386,6 +386,10 @@ Gerätezeilen atomar. Delete/Undo erfasst denselben Datensatz vollständig.
 Im Editor sind die bisherigen Schutzspalten deshalb nur noch eine
 schreibgeschützte Projektion der 1:1-Daten; Änderungen erfolgen über ein
 geräteabhängiges Schutzgeräte-Modal und `circuit-protection.update`.
+Gruppen lassen sich im Editor schrittweise nur gegenüber einer benachbarten
+Gruppe derselben Kategorie verschieben. Der Client sendet dabei immer die
+vollständige erwartete und gewünschte Sortierreihenfolge über
+`circuit-group.reorder`; Gruppennummer, Präfix und Kind-BMK bleiben unverändert.
 `distribution-board.update` versioniert Etage, Netzart und den
 verteilerweiten Gleichzeitigkeitsfaktor gemeinsam und stellt alle Werte über
 dauerhaftes Undo/Redo wieder her. Der Faktor liegt zwischen `0` und `1` und
diff --git a/docs/spec/08-current-product-backlog.md b/docs/spec/08-current-product-backlog.md
index b44aa9a..b8db24d 100644
--- a/docs/spec/08-current-product-backlog.md
+++ b/docs/spec/08-current-product-backlog.md
@@ -38,7 +38,8 @@ requirements and intended sequencing, not proof of implementation.
 - [x] Phase E3b1: create, rename and safely delete empty circuit groups.
 - [x] Phase E3b2a: persistent circuit-protection update command.
 - [x] Phase E3b2b: circuit-protection defaults on insert and editor modal.
-- [ ] Phase E4: group reorder, renumber, circuit moves and populated-delete warning.
+- [x] Phase E4a: persistent same-category group reorder controls.
+- [ ] Phase E4b: explicit group renumber, circuit moves and populated-delete warning.
 - [ ] Phase E: editor projection and editing.
 - [ ] Phase F: documentation and full GUI verification.
 - [ ] Keep full electrical sizing and cable-dimensioning rules separate until
diff --git a/docs/spec/09-distribution-board-components-and-protection-groups.md b/docs/spec/09-distribution-board-components-and-protection-groups.md
index 236fcd2..ff96ed6 100644
--- a/docs/spec/09-distribution-board-components-and-protection-groups.md
+++ b/docs/spec/09-distribution-board-components-and-protection-groups.md
@@ -789,6 +789,8 @@ Implemented in E1/E2a/E2b/E3a:
   together with the circuit and all device rows
 - the editor modal exposes only fields valid for the selected protection type;
   the old flat protection columns now project the new 1:1 data read-only
+- group controls move a group only to the adjacent peer of the same category;
+  the complete list order is one persistent command and no number or BMK changes
 
 Acceptance:
 
diff --git a/src/frontend/components/circuit-tree-editor.tsx b/src/frontend/components/circuit-tree-editor.tsx
index d3ce898..2869c86 100644
--- a/src/frontend/components/circuit-tree-editor.tsx
+++ b/src/frontend/components/circuit-tree-editor.tsx
@@ -52,6 +52,7 @@ import {
   buildCircuitSectionRenumberAssignments,
 } from "../utils/circuit-section-renumber-command";
 import {
+  buildCircuitGroupReorderAssignments,
   buildNewCircuitGroupSnapshot,
   canDeleteCircuitGroup,
   renameCircuitGroupSnapshot,
@@ -95,6 +96,7 @@ import {
   moveCircuitDeviceRowsToNewCircuitCommand,
   reorderCircuitSectionCommand,
   reorderCircuitSectionsCommand,
+  reorderCircuitGroupsCommand,
   renumberCircuitSectionCommand,
   redoProjectCommand,
   updateCircuitById,
@@ -1235,6 +1237,36 @@ export function CircuitTreeEditor(props: { projectId: string; circuitListId: str
     });
   }
 
+  async function handleMoveCircuitGroup(
+    groupId: string,
+    direction: -1 | 1
+  ) {
+    if (!data) {
+      return;
+    }
+    const assignments = buildCircuitGroupReorderAssignments(
+      data.sections,
+      groupId,
+      direction
+    );
+    if (!assignments) {
+      return;
+    }
+    await runCommand({
+      label: "Stromkreisgruppen sortieren",
+      redo: async () => {
+        const result = await reorderCircuitGroupsCommand(
+          projectId,
+          getExpectedProjectRevision(),
+          circuitListId,
+          assignments
+        );
+        applyProjectCommandResult(result);
+        return null;
+      },
+    });
+  }
+
   async function handleSaveCircuitProtection(
     protection: CircuitTreeProtectionDeviceDto
   ) {
@@ -3477,6 +3509,40 @@ export function CircuitTreeEditor(props: { projectId: string; circuitListId: str
                           >
                             Gruppe bearbeiten
                           </button>
+                          <button
+                            type="button"
+                            tabIndex={-1}
+                            disabled={
+                              !buildCircuitGroupReorderAssignments(
+                                data.sections,
+                                section.id,
+                                -1
+                              )
+                            }
+                            onClick={() =>
+                              void handleMoveCircuitGroup(section.id, -1)
+                            }
+                            title="Innerhalb derselben Kategorie nach oben verschieben"
+                          >
+                            Gruppe nach oben
+                          </button>
+                          <button
+                            type="button"
+                            tabIndex={-1}
+                            disabled={
+                              !buildCircuitGroupReorderAssignments(
+                                data.sections,
+                                section.id,
+                                1
+                              )
+                            }
+                            onClick={() =>
+                              void handleMoveCircuitGroup(section.id, 1)
+                            }
+                            title="Innerhalb derselben Kategorie nach unten verschieben"
+                          >
+                            Gruppe nach unten
+                          </button>
                           <button
                             type="button"
                             tabIndex={-1}
diff --git a/src/frontend/utils/api.ts b/src/frontend/utils/api.ts
index c372880..ec72d21 100644
--- a/src/frontend/utils/api.ts
+++ b/src/frontend/utils/api.ts
@@ -57,6 +57,7 @@ import type {
 } from "../../domain/models/distribution-board-component-structure-project-command.model";
 import type {
   CircuitGroupSnapshot,
+  CircuitGroupReorderAssignment,
 } from "../../domain/models/circuit-group-structure-project-command.model";
 import type {
   CircuitProtectionSnapshot,
@@ -433,6 +434,24 @@ export function deleteCircuitGroupCommand(
   );
 }
 
+export function reorderCircuitGroupsCommand(
+  projectId: string,
+  expectedRevision: number,
+  circuitListId: string,
+  assignments: CircuitGroupReorderAssignment[]
+) {
+  return executeProjectCommand(
+    projectId,
+    expectedRevision,
+    {
+      schemaVersion: 1,
+      type: "circuit-group.reorder",
+      payload: { circuitListId, assignments },
+    },
+    "Stromkreisgruppen sortieren"
+  );
+}
+
 export function updateCircuitProtectionCommand(
   projectId: string,
   expectedRevision: number,
diff --git a/src/frontend/utils/circuit-group-editing.ts b/src/frontend/utils/circuit-group-editing.ts
index d1a6560..ad5a76f 100644
--- a/src/frontend/utils/circuit-group-editing.ts
+++ b/src/frontend/utils/circuit-group-editing.ts
@@ -7,6 +7,9 @@ import {
   type CircuitGroupCategory,
 } from "../../shared/constants/circuit-group";
 import type { CircuitTreeSectionDto } from "../types";
+import type {
+  CircuitGroupReorderAssignment,
+} from "../../domain/models/circuit-group-structure-project-command.model";
 
 export function toCircuitGroupSnapshot(
   section: CircuitTreeSectionDto,
@@ -77,6 +80,41 @@ export function canDeleteCircuitGroup(
   return section.circuits.length === 0 && section.components.length === 0;
 }
 
+export function buildCircuitGroupReorderAssignments(
+  sections: readonly CircuitTreeSectionDto[],
+  groupId: string,
+  direction: -1 | 1
+): CircuitGroupReorderAssignment[] | null {
+  const current = sections.find((section) => section.id === groupId);
+  if (!current?.category) {
+    return null;
+  }
+  const categoryGroups = sections
+    .filter((section) => section.category === current.category)
+    .sort(
+      (left, right) =>
+        left.sortOrder - right.sortOrder ||
+        left.id.localeCompare(right.id)
+    );
+  const currentIndex = categoryGroups.findIndex(
+    (section) => section.id === groupId
+  );
+  const target = categoryGroups[currentIndex + direction];
+  if (!target) {
+    return null;
+  }
+  return sections.map((section) => ({
+    groupId: section.id,
+    expectedSortOrder: section.sortOrder,
+    targetSortOrder:
+      section.id === current.id
+        ? target.sortOrder
+        : section.id === target.id
+          ? current.sortOrder
+          : section.sortOrder,
+  }));
+}
+
 function getNewGroupSortOrder(
   category: CircuitGroupCategory,
   sections: readonly (CircuitTreeSectionDto & {
diff --git a/tests/circuit-group-numbering.test.ts b/tests/circuit-group-numbering.test.ts
index d6c04da..5066f3a 100644
--- a/tests/circuit-group-numbering.test.ts
+++ b/tests/circuit-group-numbering.test.ts
@@ -16,6 +16,7 @@ import "./circuit-group-move-project-command.repository.test.js";
 import "./circuit-group-subtree-snapshot.test.js";
 import "./circuit-group-subtree-project-command.repository.test.js";
 import {
+  buildCircuitGroupReorderAssignments,
   buildNewCircuitGroupSnapshot,
   canDeleteCircuitGroup,
   renameCircuitGroupSnapshot,
@@ -69,6 +70,54 @@ describe("circuit group numbering", () => {
     );
   });
 
+  it("reorders complete group lists only between category peers", () => {
+    const sections = [
+      groupSection("lighting-1", "lighting", 1, 10),
+      groupSection("lighting-2", "lighting", 2, 15),
+      groupSection("single-1", "single_phase", 1, 20),
+    ];
+    assert.deepEqual(
+      buildCircuitGroupReorderAssignments(
+        sections,
+        "lighting-1",
+        1
+      ),
+      [
+        {
+          groupId: "lighting-1",
+          expectedSortOrder: 10,
+          targetSortOrder: 15,
+        },
+        {
+          groupId: "lighting-2",
+          expectedSortOrder: 15,
+          targetSortOrder: 10,
+        },
+        {
+          groupId: "single-1",
+          expectedSortOrder: 20,
+          targetSortOrder: 20,
+        },
+      ]
+    );
+    assert.equal(
+      buildCircuitGroupReorderAssignments(
+        sections,
+        "lighting-1",
+        -1
+      ),
+      null
+    );
+    assert.equal(
+      buildCircuitGroupReorderAssignments(
+        sections,
+        "single-1",
+        1
+      ),
+      null
+    );
+  });
+
   it("formats the agreed identifiers including the leading hyphen", () => {
     assert.equal(
       formatGroupUpstreamProtectionIdentifier("lighting", 1),