diff --git a/backend/src/test/java/org/raddatz/familienarchiv/controller/CommentControllerTest.java b/backend/src/test/java/org/raddatz/familienarchiv/controller/CommentControllerTest.java
new file mode 100644
index 00000000..9b3bfbe8
--- /dev/null
+++ b/backend/src/test/java/org/raddatz/familienarchiv/controller/CommentControllerTest.java
@@ -0,0 +1,203 @@
+package org.raddatz.familienarchiv.controller;
+
+import org.junit.jupiter.api.Test;
+import org.raddatz.familienarchiv.config.SecurityConfig;
+import org.raddatz.familienarchiv.model.DocumentComment;
+import org.raddatz.familienarchiv.security.PermissionAspect;
+import org.raddatz.familienarchiv.service.CommentService;
+import org.raddatz.familienarchiv.service.CustomUserDetailsService;
+import org.raddatz.familienarchiv.service.UserService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.aop.AopAutoConfiguration;
+import org.springframework.boot.webmvc.test.autoconfigure.WebMvcTest;
+import org.springframework.context.annotation.Import;
+import org.springframework.http.MediaType;
+import org.springframework.security.test.context.support.WithMockUser;
+import org.springframework.test.context.bean.override.mockito.MockitoBean;
+import org.springframework.test.web.servlet.MockMvc;
+
+import java.util.List;
+import java.util.UUID;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.when;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.delete;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.patch;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+@WebMvcTest(CommentController.class)
+@Import({SecurityConfig.class, PermissionAspect.class, AopAutoConfiguration.class})
+class CommentControllerTest {
+
+    @Autowired MockMvc mockMvc;
+
+    @MockitoBean CommentService commentService;
+    @MockitoBean UserService userService;
+    @MockitoBean CustomUserDetailsService customUserDetailsService;
+
+    private static final String COMMENT_JSON = "{\"content\":\"Test comment\"}";
+    private static final UUID DOC_ID = UUID.randomUUID();
+    private static final UUID ANN_ID = UUID.randomUUID();
+    private static final UUID COMMENT_ID = UUID.randomUUID();
+
+    // ─── GET /api/documents/{documentId}/comments ─────────────────────────────
+
+    @Test
+    void getDocumentComments_returns401_whenUnauthenticated() throws Exception {
+        mockMvc.perform(get("/api/documents/" + DOC_ID + "/comments"))
+                .andExpect(status().isUnauthorized());
+    }
+
+    @Test
+    @WithMockUser
+    void getDocumentComments_returns200_whenAuthenticated() throws Exception {
+        when(commentService.getCommentsForDocument(any())).thenReturn(List.of());
+        mockMvc.perform(get("/api/documents/" + DOC_ID + "/comments"))
+                .andExpect(status().isOk());
+    }
+
+    // ─── POST /api/documents/{documentId}/comments ────────────────────────────
+
+    @Test
+    void postDocumentComment_returns401_whenUnauthenticated() throws Exception {
+        mockMvc.perform(post("/api/documents/" + DOC_ID + "/comments")
+                        .contentType(MediaType.APPLICATION_JSON).content(COMMENT_JSON))
+                .andExpect(status().isUnauthorized());
+    }
+
+    @Test
+    @WithMockUser
+    void postDocumentComment_returns403_whenMissingPermission() throws Exception {
+        mockMvc.perform(post("/api/documents/" + DOC_ID + "/comments")
+                        .contentType(MediaType.APPLICATION_JSON).content(COMMENT_JSON))
+                .andExpect(status().isForbidden());
+    }
+
+    @Test
+    @WithMockUser(authorities = "ANNOTATE_ALL")
+    void postDocumentComment_returns201_whenHasPermission() throws Exception {
+        DocumentComment saved = DocumentComment.builder()
+                .id(COMMENT_ID).documentId(DOC_ID).authorName("Hans").content("Test comment").build();
+        when(commentService.postComment(any(), any(), any(), any())).thenReturn(saved);
+
+        mockMvc.perform(post("/api/documents/" + DOC_ID + "/comments")
+                        .contentType(MediaType.APPLICATION_JSON).content(COMMENT_JSON))
+                .andExpect(status().isCreated())
+                .andExpect(jsonPath("$.content").value("Test comment"));
+    }
+
+    // ─── POST /api/documents/{documentId}/comments/{commentId}/replies ────────
+
+    @Test
+    void replyToComment_returns401_whenUnauthenticated() throws Exception {
+        mockMvc.perform(post("/api/documents/" + DOC_ID + "/comments/" + COMMENT_ID + "/replies")
+                        .contentType(MediaType.APPLICATION_JSON).content(COMMENT_JSON))
+                .andExpect(status().isUnauthorized());
+    }
+
+    @Test
+    @WithMockUser(authorities = "ANNOTATE_ALL")
+    void replyToComment_returns201_whenHasPermission() throws Exception {
+        DocumentComment saved = DocumentComment.builder()
+                .id(UUID.randomUUID()).documentId(DOC_ID).parentId(COMMENT_ID)
+                .authorName("Anna").content("Test comment").build();
+        when(commentService.replyToComment(any(), any(), any(), any())).thenReturn(saved);
+
+        mockMvc.perform(post("/api/documents/" + DOC_ID + "/comments/" + COMMENT_ID + "/replies")
+                        .contentType(MediaType.APPLICATION_JSON).content(COMMENT_JSON))
+                .andExpect(status().isCreated());
+    }
+
+    // ─── PATCH /api/documents/{documentId}/comments/{commentId} ──────────────
+
+    @Test
+    void editComment_returns401_whenUnauthenticated() throws Exception {
+        mockMvc.perform(patch("/api/documents/" + DOC_ID + "/comments/" + COMMENT_ID)
+                        .contentType(MediaType.APPLICATION_JSON).content(COMMENT_JSON))
+                .andExpect(status().isUnauthorized());
+    }
+
+    @Test
+    @WithMockUser(authorities = "ANNOTATE_ALL")
+    void editComment_returns200_whenHasPermission() throws Exception {
+        DocumentComment updated = DocumentComment.builder()
+                .id(COMMENT_ID).documentId(DOC_ID).authorName("Hans").content("Test comment").build();
+        when(commentService.editComment(any(), any(), any(), any())).thenReturn(updated);
+
+        mockMvc.perform(patch("/api/documents/" + DOC_ID + "/comments/" + COMMENT_ID)
+                        .contentType(MediaType.APPLICATION_JSON).content(COMMENT_JSON))
+                .andExpect(status().isOk());
+    }
+
+    // ─── DELETE /api/documents/{documentId}/comments/{commentId} ─────────────
+
+    @Test
+    void deleteComment_returns401_whenUnauthenticated() throws Exception {
+        mockMvc.perform(delete("/api/documents/" + DOC_ID + "/comments/" + COMMENT_ID))
+                .andExpect(status().isUnauthorized());
+    }
+
+    @Test
+    @WithMockUser
+    void deleteComment_returns204_whenAuthenticated() throws Exception {
+        mockMvc.perform(delete("/api/documents/" + DOC_ID + "/comments/" + COMMENT_ID))
+                .andExpect(status().isNoContent());
+    }
+
+    // ─── GET /api/documents/{documentId}/annotations/{annId}/comments ─────────
+
+    @Test
+    void getAnnotationComments_returns401_whenUnauthenticated() throws Exception {
+        mockMvc.perform(get("/api/documents/" + DOC_ID + "/annotations/" + ANN_ID + "/comments"))
+                .andExpect(status().isUnauthorized());
+    }
+
+    @Test
+    @WithMockUser
+    void getAnnotationComments_returns200_whenAuthenticated() throws Exception {
+        when(commentService.getCommentsForAnnotation(any())).thenReturn(List.of());
+        mockMvc.perform(get("/api/documents/" + DOC_ID + "/annotations/" + ANN_ID + "/comments"))
+                .andExpect(status().isOk());
+    }
+
+    // ─── POST /api/documents/{documentId}/annotations/{annId}/comments ────────
+
+    @Test
+    @WithMockUser
+    void postAnnotationComment_returns403_whenMissingPermission() throws Exception {
+        mockMvc.perform(post("/api/documents/" + DOC_ID + "/annotations/" + ANN_ID + "/comments")
+                        .contentType(MediaType.APPLICATION_JSON).content(COMMENT_JSON))
+                .andExpect(status().isForbidden());
+    }
+
+    @Test
+    @WithMockUser(authorities = "ANNOTATE_ALL")
+    void postAnnotationComment_returns201_whenHasPermission() throws Exception {
+        DocumentComment saved = DocumentComment.builder()
+                .id(UUID.randomUUID()).documentId(DOC_ID).annotationId(ANN_ID)
+                .authorName("Hans").content("Test comment").build();
+        when(commentService.postComment(any(), any(), any(), any())).thenReturn(saved);
+
+        mockMvc.perform(post("/api/documents/" + DOC_ID + "/annotations/" + ANN_ID + "/comments")
+                        .contentType(MediaType.APPLICATION_JSON).content(COMMENT_JSON))
+                .andExpect(status().isCreated());
+    }
+
+    // ─── POST /api/documents/{documentId}/annotations/{annId}/comments/{commentId}/replies ─
+
+    @Test
+    @WithMockUser(authorities = "ANNOTATE_ALL")
+    void replyToAnnotationComment_returns201_whenHasPermission() throws Exception {
+        DocumentComment saved = DocumentComment.builder()
+                .id(UUID.randomUUID()).documentId(DOC_ID).annotationId(ANN_ID)
+                .parentId(COMMENT_ID).authorName("Anna").content("Test comment").build();
+        when(commentService.replyToComment(any(), any(), any(), any())).thenReturn(saved);
+
+        mockMvc.perform(post("/api/documents/" + DOC_ID + "/annotations/" + ANN_ID + "/comments/" + COMMENT_ID + "/replies")
+                        .contentType(MediaType.APPLICATION_JSON).content(COMMENT_JSON))
+                .andExpect(status().isCreated());
+    }
+}