diff --git a/backend/src/main/java/org/raddatz/familienarchiv/controller/AnnotationController.java b/backend/src/main/java/org/raddatz/familienarchiv/controller/AnnotationController.java
index 43b715d7..01471222 100644
--- a/backend/src/main/java/org/raddatz/familienarchiv/controller/AnnotationController.java
+++ b/backend/src/main/java/org/raddatz/familienarchiv/controller/AnnotationController.java
@@ -3,6 +3,7 @@ package org.raddatz.familienarchiv.controller;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.raddatz.familienarchiv.dto.CreateAnnotationDTO;
+import org.raddatz.familienarchiv.dto.UpdateAnnotationDTO;
 import org.raddatz.familienarchiv.model.AppUser;
 import org.raddatz.familienarchiv.model.Document;
 import org.raddatz.familienarchiv.model.DocumentAnnotation;
@@ -11,6 +12,7 @@ import org.raddatz.familienarchiv.security.RequirePermission;
 import org.raddatz.familienarchiv.service.AnnotationService;
 import org.raddatz.familienarchiv.service.DocumentService;
 import org.raddatz.familienarchiv.service.UserService;
+import jakarta.validation.Valid;
 import org.springframework.http.HttpStatus;
 import org.springframework.security.core.Authentication;
 import org.springframework.web.bind.annotation.*;
@@ -45,6 +47,15 @@ public class AnnotationController {
         return annotationService.createAnnotation(documentId, dto, userId, doc.getFileHash());
     }
 
+    @PatchMapping("/{annotationId}")
+    @RequirePermission({Permission.ANNOTATE_ALL, Permission.WRITE_ALL})
+    public DocumentAnnotation updateAnnotation(
+            @PathVariable UUID documentId,
+            @PathVariable UUID annotationId,
+            @Valid @RequestBody UpdateAnnotationDTO dto) {
+        return annotationService.updateAnnotation(documentId, annotationId, dto);
+    }
+
     @DeleteMapping("/{annotationId}")
     @ResponseStatus(HttpStatus.NO_CONTENT)
     @RequirePermission({Permission.ANNOTATE_ALL, Permission.WRITE_ALL})
diff --git a/backend/src/main/java/org/raddatz/familienarchiv/dto/UpdateAnnotationDTO.java b/backend/src/main/java/org/raddatz/familienarchiv/dto/UpdateAnnotationDTO.java
new file mode 100644
index 00000000..19fa3c7d
--- /dev/null
+++ b/backend/src/main/java/org/raddatz/familienarchiv/dto/UpdateAnnotationDTO.java
@@ -0,0 +1,29 @@
+package org.raddatz.familienarchiv.dto;
+
+import jakarta.validation.constraints.DecimalMax;
+import jakarta.validation.constraints.DecimalMin;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import lombok.AllArgsConstructor;
+
+/**
+ * Partial update payload for annotation position and size.
+ * All fields are optional — only non-null values are applied.
+ */
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+public class UpdateAnnotationDTO {
+
+    @DecimalMin("0.0") @DecimalMax("1.0")
+    private Double x;
+
+    @DecimalMin("0.0") @DecimalMax("1.0")
+    private Double y;
+
+    @DecimalMin("0.01") @DecimalMax("1.0")
+    private Double width;
+
+    @DecimalMin("0.01") @DecimalMax("1.0")
+    private Double height;
+}
diff --git a/backend/src/main/java/org/raddatz/familienarchiv/exception/ErrorCode.java b/backend/src/main/java/org/raddatz/familienarchiv/exception/ErrorCode.java
index 60930824..26aab838 100644
--- a/backend/src/main/java/org/raddatz/familienarchiv/exception/ErrorCode.java
+++ b/backend/src/main/java/org/raddatz/familienarchiv/exception/ErrorCode.java
@@ -49,6 +49,8 @@ public enum ErrorCode {
     // --- Annotations ---
     /** The annotation with the given ID does not exist. 404 */
     ANNOTATION_NOT_FOUND,
+    /** The annotation position/size could not be saved (bounds constraint violated). 400 */
+    ANNOTATION_UPDATE_FAILED,
 
     // --- Transcription Blocks ---
     /** The transcription block with the given ID does not exist. 404 */
diff --git a/backend/src/main/java/org/raddatz/familienarchiv/service/AnnotationService.java b/backend/src/main/java/org/raddatz/familienarchiv/service/AnnotationService.java
index 7b3e1252..7616a9a0 100644
--- a/backend/src/main/java/org/raddatz/familienarchiv/service/AnnotationService.java
+++ b/backend/src/main/java/org/raddatz/familienarchiv/service/AnnotationService.java
@@ -1,18 +1,22 @@
 package org.raddatz.familienarchiv.service;
 
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 import org.raddatz.familienarchiv.dto.CreateAnnotationDTO;
+import org.raddatz.familienarchiv.dto.UpdateAnnotationDTO;
 import org.raddatz.familienarchiv.exception.DomainException;
 import org.raddatz.familienarchiv.exception.ErrorCode;
 import org.raddatz.familienarchiv.model.DocumentAnnotation;
 import org.raddatz.familienarchiv.repository.AnnotationRepository;
 import org.raddatz.familienarchiv.repository.TranscriptionBlockRepository;
+import org.springframework.dao.DataIntegrityViolationException;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
 import java.util.List;
 import java.util.UUID;
 
+@Slf4j
 @Service
 @RequiredArgsConstructor
 public class AnnotationService {
@@ -61,6 +65,26 @@ public class AnnotationService {
         return annotationRepository.save(annotation);
     }
 
+    @Transactional
+    public DocumentAnnotation updateAnnotation(UUID documentId, UUID annotationId, UpdateAnnotationDTO dto) {
+        DocumentAnnotation annotation = annotationRepository
+                .findByIdAndDocumentId(annotationId, documentId)
+                .orElseThrow(() -> DomainException.notFound(
+                        ErrorCode.ANNOTATION_NOT_FOUND, "Annotation not found: " + annotationId));
+
+        if (dto.getX() != null) annotation.setX(dto.getX());
+        if (dto.getY() != null) annotation.setY(dto.getY());
+        if (dto.getWidth() != null) annotation.setWidth(dto.getWidth());
+        if (dto.getHeight() != null) annotation.setHeight(dto.getHeight());
+
+        try {
+            return annotationRepository.save(annotation);
+        } catch (DataIntegrityViolationException e) {
+            log.warn("Annotation bounds constraint violated for {}: {}", annotationId, e.getMessage());
+            throw DomainException.badRequest(ErrorCode.ANNOTATION_UPDATE_FAILED, "Bounds out of range");
+        }
+    }
+
     @Transactional
     public void deleteAnnotation(UUID documentId, UUID annotationId, UUID userId) {
         DocumentAnnotation annotation = annotationRepository
diff --git a/backend/src/main/resources/db/migration/V33__add_annotation_bounds_constraint.sql b/backend/src/main/resources/db/migration/V33__add_annotation_bounds_constraint.sql
new file mode 100644
index 00000000..608ebe99
--- /dev/null
+++ b/backend/src/main/resources/db/migration/V33__add_annotation_bounds_constraint.sql
@@ -0,0 +1,12 @@
+-- Enforce valid normalized coordinate ranges for annotation bounding boxes.
+-- x and y must be within [0, 1]; width and height must be at least 1% of the
+-- document dimension and at most 100%.
+-- Consistent with the application-layer minimum draw threshold (0.01).
+ALTER TABLE document_annotations
+    ADD CONSTRAINT chk_annotation_bounds
+        CHECK (
+            x >= 0 AND x <= 1 AND
+            y >= 0 AND y <= 1 AND
+            width >= 0.01 AND width <= 1 AND
+            height >= 0.01 AND height <= 1
+        );
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/controller/AnnotationControllerTest.java b/backend/src/test/java/org/raddatz/familienarchiv/controller/AnnotationControllerTest.java
index 4b95d877..317cb4fa 100644
--- a/backend/src/test/java/org/raddatz/familienarchiv/controller/AnnotationControllerTest.java
+++ b/backend/src/test/java/org/raddatz/familienarchiv/controller/AnnotationControllerTest.java
@@ -27,6 +27,7 @@ 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;
@@ -160,6 +161,109 @@ class AnnotationControllerTest {
                 .andExpect(status().isNoContent());
     }
 
+    // ─── PATCH /api/documents/{documentId}/annotations/{annotationId} ─────────
+
+    private static final String PATCH_JSON = "{\"x\":0.2,\"y\":0.3}";
+
+    @Test
+    void patchAnnotation_returns401_whenUnauthenticated() throws Exception {
+        mockMvc.perform(patch("/api/documents/" + UUID.randomUUID() + "/annotations/" + UUID.randomUUID())
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content(PATCH_JSON))
+                .andExpect(status().isUnauthorized());
+    }
+
+    @Test
+    @WithMockUser
+    void patchAnnotation_returns403_withoutPermission() throws Exception {
+        mockMvc.perform(patch("/api/documents/" + UUID.randomUUID() + "/annotations/" + UUID.randomUUID())
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content(PATCH_JSON))
+                .andExpect(status().isForbidden());
+    }
+
+    @Test
+    @WithMockUser(authorities = "WRITE_ALL")
+    void patchAnnotation_returns200_withWriteAllPermission() throws Exception {
+        UUID docId = UUID.randomUUID();
+        UUID annotId = UUID.randomUUID();
+        DocumentAnnotation updated = DocumentAnnotation.builder()
+                .id(annotId).documentId(docId).pageNumber(1)
+                .x(0.2).y(0.3).width(0.2).height(0.2).color("#ff0000").build();
+        when(annotationService.updateAnnotation(any(), any(), any())).thenReturn(updated);
+
+        mockMvc.perform(patch("/api/documents/" + docId + "/annotations/" + annotId)
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content(PATCH_JSON))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.x").value(0.2))
+                .andExpect(jsonPath("$.y").value(0.3));
+    }
+
+    @Test
+    @WithMockUser(authorities = "ANNOTATE_ALL")
+    void patchAnnotation_returns200_withAnnotateAllPermission() throws Exception {
+        UUID docId = UUID.randomUUID();
+        UUID annotId = UUID.randomUUID();
+        DocumentAnnotation updated = DocumentAnnotation.builder()
+                .id(annotId).documentId(docId).pageNumber(1)
+                .x(0.2).y(0.3).width(0.2).height(0.2).color("#ff0000").build();
+        when(annotationService.updateAnnotation(any(), any(), any())).thenReturn(updated);
+
+        mockMvc.perform(patch("/api/documents/" + docId + "/annotations/" + annotId)
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content(PATCH_JSON))
+                .andExpect(status().isOk());
+    }
+
+    @Test
+    @WithMockUser(authorities = "WRITE_ALL")
+    void patchAnnotation_returns404_whenAnnotationBelongsToDifferentDocument() throws Exception {
+        when(annotationService.updateAnnotation(any(), any(), any()))
+                .thenThrow(DomainException.notFound(ErrorCode.ANNOTATION_NOT_FOUND, "not found"));
+
+        mockMvc.perform(patch("/api/documents/" + UUID.randomUUID() + "/annotations/" + UUID.randomUUID())
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content(PATCH_JSON))
+                .andExpect(status().isNotFound());
+    }
+
+    @Test
+    @WithMockUser(authorities = "WRITE_ALL")
+    void patchAnnotation_returns400_withOutOfBoundsCoordinates() throws Exception {
+        mockMvc.perform(patch("/api/documents/" + UUID.randomUUID() + "/annotations/" + UUID.randomUUID())
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content("{\"x\":-0.1,\"y\":0.3}"))
+                .andExpect(status().isBadRequest());
+    }
+
+    @Test
+    @WithMockUser(authorities = "WRITE_ALL")
+    void patchAnnotation_returns400_withWidthBelowMinimum() throws Exception {
+        mockMvc.perform(patch("/api/documents/" + UUID.randomUUID() + "/annotations/" + UUID.randomUUID())
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content("{\"width\":0.005}"))
+                .andExpect(status().isBadRequest());
+    }
+
+    @Test
+    @WithMockUser(authorities = "WRITE_ALL")
+    void patchAnnotation_returns400_withHeightBelowMinimum() throws Exception {
+        mockMvc.perform(patch("/api/documents/" + UUID.randomUUID() + "/annotations/" + UUID.randomUUID())
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content("{\"height\":0.005}"))
+                .andExpect(status().isBadRequest());
+    }
+
+    @Test
+    @WithMockUser(authorities = "WRITE_ALL")
+    void patchAnnotation_returns400_withXAboveMaximum() throws Exception {
+        mockMvc.perform(patch("/api/documents/" + UUID.randomUUID() + "/annotations/" + UUID.randomUUID())
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content("{\"x\":1.1}"))
+                .andExpect(status().isBadRequest());
+    }
+
     // ─── resolveUserId — unauthenticated / null user / exception branches ─────
 
     @Test
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/repository/MigrationIntegrationTest.java b/backend/src/test/java/org/raddatz/familienarchiv/repository/MigrationIntegrationTest.java
index 7fb3c406..db5b98a3 100644
--- a/backend/src/test/java/org/raddatz/familienarchiv/repository/MigrationIntegrationTest.java
+++ b/backend/src/test/java/org/raddatz/familienarchiv/repository/MigrationIntegrationTest.java
@@ -121,6 +121,53 @@ class MigrationIntegrationTest {
         assertThat(rows2).isEqualTo(1);
     }
 
+    // ─── V33: chk_annotation_bounds CHECK constraint ─────────────────────────
+
+    @Test
+    void v33_boundsCheckConstraint_rejectsXAboveOne() {
+        UUID docId = createDocument();
+
+        assertThatThrownBy(() ->
+                jdbc.update(
+                        """
+                        INSERT INTO document_annotations
+                            (id, document_id, page_number, x, y, width, height, color)
+                        VALUES (gen_random_uuid(), ?, 1, 1.5, 0.1, 0.3, 0.1, '#ff0000')
+                        """,
+                        docId)
+        ).isInstanceOf(DataIntegrityViolationException.class);
+    }
+
+    @Test
+    void v33_boundsCheckConstraint_rejectsHeightBelowMinimum() {
+        UUID docId = createDocument();
+
+        assertThatThrownBy(() ->
+                jdbc.update(
+                        """
+                        INSERT INTO document_annotations
+                            (id, document_id, page_number, x, y, width, height, color)
+                        VALUES (gen_random_uuid(), ?, 1, 0.1, 0.1, 0.3, 0.005, '#ff0000')
+                        """,
+                        docId)
+        ).isInstanceOf(DataIntegrityViolationException.class);
+    }
+
+    @Test
+    void v33_boundsCheckConstraint_acceptsValidAnnotation() {
+        UUID docId = createDocument();
+
+        int rows = jdbc.update(
+                """
+                INSERT INTO document_annotations
+                    (id, document_id, page_number, x, y, width, height, color)
+                VALUES (gen_random_uuid(), ?, 1, 0.1, 0.1, 0.3, 0.1, '#ff0000')
+                """,
+                docId);
+
+        assertThat(rows).isEqualTo(1);
+    }
+
     // ─── helpers ─────────────────────────────────────────────────────────────
 
     private UUID createDocument() {
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/service/AnnotationServiceTest.java b/backend/src/test/java/org/raddatz/familienarchiv/service/AnnotationServiceTest.java
index cd736005..bd3064a9 100644
--- a/backend/src/test/java/org/raddatz/familienarchiv/service/AnnotationServiceTest.java
+++ b/backend/src/test/java/org/raddatz/familienarchiv/service/AnnotationServiceTest.java
@@ -6,10 +6,12 @@ import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 import org.raddatz.familienarchiv.dto.CreateAnnotationDTO;
+import org.raddatz.familienarchiv.dto.UpdateAnnotationDTO;
 import org.raddatz.familienarchiv.exception.DomainException;
 import org.raddatz.familienarchiv.model.DocumentAnnotation;
 import org.raddatz.familienarchiv.repository.AnnotationRepository;
 import org.raddatz.familienarchiv.repository.TranscriptionBlockRepository;
+import org.springframework.dao.DataIntegrityViolationException;
 
 import java.util.List;
 import java.util.Optional;
@@ -21,6 +23,7 @@ import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
+import static org.springframework.http.HttpStatus.BAD_REQUEST;
 import static org.springframework.http.HttpStatus.FORBIDDEN;
 import static org.springframework.http.HttpStatus.NOT_FOUND;
 
@@ -203,6 +206,62 @@ class AnnotationServiceTest {
                 .satisfies(e -> assertThat(((DomainException) e).getStatus()).isEqualTo(FORBIDDEN));
     }
 
+    // ─── updateAnnotation ─────────────────────────────────────────────────────
+
+    @Test
+    void updateAnnotation_throwsNotFound_whenAnnotationNotInDocument() {
+        UUID docId = UUID.randomUUID();
+        UUID annotId = UUID.randomUUID();
+        when(annotationRepository.findByIdAndDocumentId(annotId, docId)).thenReturn(Optional.empty());
+
+        assertThatThrownBy(() -> annotationService.updateAnnotation(docId, annotId, new UpdateAnnotationDTO()))
+                .isInstanceOf(DomainException.class)
+                .satisfies(e -> assertThat(((DomainException) e).getStatus()).isEqualTo(NOT_FOUND));
+    }
+
+    @Test
+    void updateAnnotation_updatesOnlyPresentFields() {
+        UUID docId = UUID.randomUUID();
+        UUID annotId = UUID.randomUUID();
+        DocumentAnnotation annotation = DocumentAnnotation.builder()
+                .id(annotId).documentId(docId)
+                .x(0.1).y(0.2).width(0.3).height(0.4).build();
+        when(annotationRepository.findByIdAndDocumentId(annotId, docId))
+                .thenReturn(Optional.of(annotation));
+        when(annotationRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+
+        UpdateAnnotationDTO dto = new UpdateAnnotationDTO();
+        dto.setX(0.5);
+        dto.setY(0.6);
+
+        DocumentAnnotation result = annotationService.updateAnnotation(docId, annotId, dto);
+
+        assertThat(result.getX()).isEqualTo(0.5);
+        assertThat(result.getY()).isEqualTo(0.6);
+        assertThat(result.getWidth()).isEqualTo(0.3);  // unchanged
+        assertThat(result.getHeight()).isEqualTo(0.4); // unchanged
+        verify(annotationRepository).save(annotation);
+    }
+
+    @Test
+    void updateAnnotation_throwsAnnotationUpdateFailed_whenDbConstraintViolated() {
+        UUID docId = UUID.randomUUID();
+        UUID annotId = UUID.randomUUID();
+        DocumentAnnotation annotation = DocumentAnnotation.builder()
+                .id(annotId).documentId(docId)
+                .x(0.1).y(0.2).width(0.3).height(0.4).build();
+        when(annotationRepository.findByIdAndDocumentId(annotId, docId))
+                .thenReturn(Optional.of(annotation));
+        when(annotationRepository.save(any())).thenThrow(new DataIntegrityViolationException("constraint"));
+
+        UpdateAnnotationDTO dto = new UpdateAnnotationDTO();
+        dto.setX(1.5);
+
+        assertThatThrownBy(() -> annotationService.updateAnnotation(docId, annotId, dto))
+                .isInstanceOf(DomainException.class)
+                .satisfies(e -> assertThat(((DomainException) e).getStatus()).isEqualTo(BAD_REQUEST));
+    }
+
     // ─── listAnnotations ──────────────────────────────────────────────────────
 
     @Test
diff --git a/frontend/messages/de.json b/frontend/messages/de.json
index 48135368..aea547f0 100644
--- a/frontend/messages/de.json
+++ b/frontend/messages/de.json
@@ -1,6 +1,10 @@
 {
 	"$schema": "https://inlang.com/schema/inlang-message-format",
 	"error_annotation_not_found": "Die Annotation wurde nicht gefunden.",
+	"error_annotation_update_failed": "Annotation konnte nicht gespeichert werden.",
+	"annotation_edit_mode_active": "Annotation ausgewählt — Ziehpunkte sichtbar.",
+	"annotation_resize_area": "Annotationsgröße und -position ändern",
+	"annotation_resize_handle": "Ziehpunkt {direction}",
 	"annotation_outdated_notice": "Einige Annotationen beziehen sich auf eine frühere Dateiversion und werden nicht angezeigt.",
 	"error_document_not_found": "Das Dokument wurde nicht gefunden.",
 	"error_document_no_file": "Diesem Dokument ist noch keine Datei zugeordnet.",
diff --git a/frontend/messages/en.json b/frontend/messages/en.json
index 8f55b111..f4b958d0 100644
--- a/frontend/messages/en.json
+++ b/frontend/messages/en.json
@@ -1,6 +1,10 @@
 {
 	"$schema": "https://inlang.com/schema/inlang-message-format",
 	"error_annotation_not_found": "Annotation not found.",
+	"error_annotation_update_failed": "Could not save annotation position.",
+	"annotation_edit_mode_active": "Annotation selected — resize handles visible.",
+	"annotation_resize_area": "Resize and reposition annotation",
+	"annotation_resize_handle": "Resize handle: {direction}",
 	"annotation_outdated_notice": "Some annotations refer to an earlier file version and are not shown.",
 	"error_document_not_found": "Document not found.",
 	"error_document_no_file": "No file is associated with this document.",
diff --git a/frontend/messages/es.json b/frontend/messages/es.json
index b4b0ba65..2a784daa 100644
--- a/frontend/messages/es.json
+++ b/frontend/messages/es.json
@@ -1,6 +1,10 @@
 {
 	"$schema": "https://inlang.com/schema/inlang-message-format",
 	"error_annotation_not_found": "Anotación no encontrada.",
+	"error_annotation_update_failed": "No se pudo guardar la posición de la anotación.",
+	"annotation_edit_mode_active": "Anotación seleccionada — tiradores visibles.",
+	"annotation_resize_area": "Cambiar tamaño y posición de la anotación",
+	"annotation_resize_handle": "Control de redimensión: {direction}",
 	"annotation_outdated_notice": "Algunas anotaciones hacen referencia a una versión anterior del archivo y no se muestran.",
 	"error_document_not_found": "Documento no encontrado.",
 	"error_document_no_file": "No hay ningún archivo asociado a este documento.",
diff --git a/frontend/src/lib/components/AnnotationEditOverlay.svelte b/frontend/src/lib/components/AnnotationEditOverlay.svelte
new file mode 100644
index 00000000..d4da250e
--- /dev/null
+++ b/frontend/src/lib/components/AnnotationEditOverlay.svelte
@@ -0,0 +1,349 @@
+<script lang="ts">
+import { getContext } from 'svelte';
+import type { Annotation } from '$lib/types';
+import { m } from '$lib/paraglide/messages.js';
+
+type UpdateAnnotationFn = (
+	id: string,
+	coords: { x: number; y: number; width: number; height: number }
+) => Promise<void>;
+
+const updateAnnotation: UpdateAnnotationFn =
+	getContext('annotationUpdate') ?? (() => Promise.resolve());
+
+let { annotation }: { annotation: Annotation } = $props();
+
+let liveX = $state<number>(0);
+let liveY = $state<number>(0);
+let liveWidth = $state<number>(0);
+let liveHeight = $state<number>(0);
+
+$effect(() => {
+	liveX = annotation.x;
+	liveY = annotation.y;
+	liveWidth = annotation.width;
+	liveHeight = annotation.height;
+});
+
+let svgEl = $state<SVGSVGElement | null>(null);
+
+// Actual rendered pixel dimensions of the SVG — updated by ResizeObserver.
+// Used as the viewBox so handles are always physically 16×16px regardless of annotation aspect ratio.
+let svgWidth = $state(1);
+let svgHeight = $state(1);
+
+$effect(() => {
+	if (!svgEl) return;
+	const ro = new ResizeObserver(([entry]) => {
+		svgWidth = entry.contentRect.width || 1;
+		svgHeight = entry.contentRect.height || 1;
+	});
+	ro.observe(svgEl);
+	return () => ro.disconnect();
+});
+
+// Auto-focus the SVG when the overlay mounts so arrow keys work immediately.
+$effect(() => {
+	svgEl?.focus({ preventScroll: true });
+});
+
+type HandleId = 'nw' | 'ne' | 'sw' | 'se' | 'n' | 's' | 'e' | 'w';
+
+// L-bracket arm length in pixels. Each corner shows two short lines meeting at 90°.
+const ARM = 10;
+
+type DragState = {
+	type: 'handle' | 'move';
+	handleId?: HandleId;
+	startPointerX: number;
+	startPointerY: number;
+	preDragX: number;
+	preDragY: number;
+	preDragWidth: number;
+	preDragHeight: number;
+};
+
+let dragState = $state<DragState | null>(null);
+
+// 8 handles: 4 L-bracket corners + 4 tick-mark edge midpoints.
+// Each `path` is relative to the handle centre (0,0).
+const handles = $derived<
+	Array<{ id: HandleId; cx: number; cy: number; cursor: string; path: string }>
+>([
+	{ id: 'nw', cx: 0, cy: 0, cursor: 'nwse-resize', path: `M ${ARM},0 L 0,0 L 0,${ARM}` },
+	{ id: 'ne', cx: svgWidth, cy: 0, cursor: 'nesw-resize', path: `M ${-ARM},0 L 0,0 L 0,${ARM}` },
+	{ id: 'sw', cx: 0, cy: svgHeight, cursor: 'nesw-resize', path: `M ${ARM},0 L 0,0 L 0,${-ARM}` },
+	{
+		id: 'se',
+		cx: svgWidth,
+		cy: svgHeight,
+		cursor: 'nwse-resize',
+		path: `M ${-ARM},0 L 0,0 L 0,${-ARM}`
+	},
+	{ id: 'n', cx: svgWidth / 2, cy: 0, cursor: 'ns-resize', path: `M ${-ARM},0 L ${ARM},0` },
+	{
+		id: 's',
+		cx: svgWidth / 2,
+		cy: svgHeight,
+		cursor: 'ns-resize',
+		path: `M ${-ARM},0 L ${ARM},0`
+	},
+	{ id: 'e', cx: svgWidth, cy: svgHeight / 2, cursor: 'ew-resize', path: `M 0,${-ARM} L 0,${ARM}` },
+	{ id: 'w', cx: 0, cy: svgHeight / 2, cursor: 'ew-resize', path: `M 0,${-ARM} L 0,${ARM}` }
+]);
+
+function pixelToNorm(dx: number, dy: number): { nx: number; ny: number } {
+	if (!svgEl) return { nx: 0, ny: 0 };
+	const rect = svgEl.getBoundingClientRect();
+	return {
+		nx: (dx / rect.width) * annotation.width,
+		ny: (dy / rect.height) * annotation.height
+	};
+}
+
+function applyHandleDrag(handleId: HandleId, nx: number, ny: number, ds: DragState): void {
+	const MIN = 0.01;
+	let x = ds.preDragX,
+		y = ds.preDragY,
+		w = ds.preDragWidth,
+		h = ds.preDragHeight;
+
+	const movesLeftEdge = handleId === 'nw' || handleId === 'sw' || handleId === 'w';
+	const movesRightEdge = handleId === 'ne' || handleId === 'se' || handleId === 'e';
+	const movesTopEdge = handleId === 'nw' || handleId === 'ne' || handleId === 'n';
+	const movesBottomEdge = handleId === 'sw' || handleId === 'se' || handleId === 's';
+
+	if (movesLeftEdge) {
+		const newX = Math.max(0, Math.min(x + w - MIN, x + nx));
+		w = w - (newX - x);
+		x = newX;
+	} else if (movesRightEdge) {
+		w = Math.max(MIN, Math.min(1 - x, w + nx));
+	}
+
+	if (movesTopEdge) {
+		const newY = Math.max(0, Math.min(y + h - MIN, y + ny));
+		h = h - (newY - y);
+		y = newY;
+	} else if (movesBottomEdge) {
+		h = Math.max(MIN, Math.min(1 - y, h + ny));
+	}
+
+	liveX = x;
+	liveY = y;
+	liveWidth = w;
+	liveHeight = h;
+}
+
+function handlePointerDown(
+	event: PointerEvent,
+	type: 'handle' | 'move',
+	handleId?: HandleId
+): void {
+	if (!event.isPrimary) return;
+	event.stopPropagation();
+	(event.currentTarget as Element).setPointerCapture(event.pointerId);
+	dragState = {
+		type,
+		handleId,
+		startPointerX: event.clientX,
+		startPointerY: event.clientY,
+		preDragX: liveX,
+		preDragY: liveY,
+		preDragWidth: liveWidth,
+		preDragHeight: liveHeight
+	};
+}
+
+function handlePointerMove(event: PointerEvent): void {
+	if (!dragState || !event.isPrimary) return;
+	const dx = event.clientX - dragState.startPointerX;
+	const dy = event.clientY - dragState.startPointerY;
+	const { nx, ny } = pixelToNorm(dx, dy);
+
+	if (dragState.type === 'move') {
+		liveX = Math.max(0, Math.min(1 - dragState.preDragWidth, dragState.preDragX + nx));
+		liveY = Math.max(0, Math.min(1 - dragState.preDragHeight, dragState.preDragY + ny));
+	} else if (dragState.handleId) {
+		applyHandleDrag(dragState.handleId, nx, ny, dragState);
+	}
+}
+
+async function handlePointerUp(event: PointerEvent): Promise<void> {
+	if (!dragState || !event.isPrimary) return;
+	const ds = dragState;
+	dragState = null;
+
+	if (
+		liveX === ds.preDragX &&
+		liveY === ds.preDragY &&
+		liveWidth === ds.preDragWidth &&
+		liveHeight === ds.preDragHeight
+	) {
+		return;
+	}
+
+	try {
+		await updateAnnotation(annotation.id, {
+			x: liveX,
+			y: liveY,
+			width: liveWidth,
+			height: liveHeight
+		});
+	} catch (err) {
+		console.error('annotation drag update failed', err);
+		liveX = ds.preDragX;
+		liveY = ds.preDragY;
+		liveWidth = ds.preDragWidth;
+		liveHeight = ds.preDragHeight;
+	}
+}
+
+let keyDebounceTimer: ReturnType<typeof setTimeout> | null = null;
+
+function handleKeyDown(event: KeyboardEvent): void {
+	if (!['ArrowUp', 'ArrowDown', 'ArrowLeft', 'ArrowRight'].includes(event.key)) return;
+	event.preventDefault();
+	const STEP = event.shiftKey ? 0.05 : 0.005;
+
+	if (event.key === 'ArrowLeft') liveX = Math.max(0, liveX - STEP);
+	if (event.key === 'ArrowRight') liveX = Math.min(1 - liveWidth, liveX + STEP);
+	if (event.key === 'ArrowUp') liveY = Math.max(0, liveY - STEP);
+	if (event.key === 'ArrowDown') liveY = Math.min(1 - liveHeight, liveY + STEP);
+
+	if (keyDebounceTimer) clearTimeout(keyDebounceTimer);
+	keyDebounceTimer = setTimeout(async () => {
+		try {
+			await updateAnnotation(annotation.id, {
+				x: liveX,
+				y: liveY,
+				width: liveWidth,
+				height: liveHeight
+			});
+		} catch (err) {
+			console.error('annotation keyboard update failed', err);
+			liveX = annotation.x;
+			liveY = annotation.y;
+			liveWidth = annotation.width;
+			liveHeight = annotation.height;
+		}
+	}, 300);
+}
+
+const directionLabels: Record<HandleId, string> = {
+	nw: 'NW',
+	ne: 'NE',
+	sw: 'SW',
+	se: 'SE',
+	n: 'N',
+	s: 'S',
+	e: 'E',
+	w: 'W'
+};
+
+// Preview rect in pixel space (maps live normalized coords back to SVG pixel coordinates).
+// Shown during pointer drag and during keyboard nudging (whenever live coords differ from stored).
+let previewX = $derived(((liveX - annotation.x) / annotation.width) * svgWidth);
+let previewY = $derived(((liveY - annotation.y) / annotation.height) * svgHeight);
+let previewW = $derived((liveWidth / annotation.width) * svgWidth);
+let previewH = $derived((liveHeight / annotation.height) * svgHeight);
+let hasLiveChanges = $derived(
+	liveX !== annotation.x ||
+		liveY !== annotation.y ||
+		liveWidth !== annotation.width ||
+		liveHeight !== annotation.height
+);
+</script>
+
+<div aria-live="polite" class="sr-only">
+	{m.annotation_edit_mode_active()}
+</div>
+
+<svg
+	bind:this={svgEl}
+	viewBox="0 0 {svgWidth} {svgHeight}"
+	role="application"
+	tabindex="0"
+	aria-label={m.annotation_resize_area()}
+	style="position: absolute; top: 0; left: 0; width: 100%; height: 100%; pointer-events: none; touch-action: none; overflow: visible;"
+	onpointermove={handlePointerMove}
+	onpointerup={handlePointerUp}
+	onkeydown={handleKeyDown}
+>
+	<rect
+		data-move-area
+		role="none"
+		x="0"
+		y="0"
+		width={svgWidth}
+		height={svgHeight}
+		fill="transparent"
+		style="cursor: move; pointer-events: all;"
+		onpointerdown={(e) => handlePointerDown(e, 'move')}
+	/>
+
+	{#if dragState || hasLiveChanges}
+		<rect
+			x={previewX}
+			y={previewY}
+			width={previewW}
+			height={previewH}
+			fill="none"
+			stroke="#002850"
+			stroke-width="1.5"
+			stroke-dasharray="4 3"
+			pointer-events="none"
+		/>
+	{/if}
+
+	<!-- Dashed selection border — signals the annotation is in edit mode -->
+	<rect
+		x="0"
+		y="0"
+		width={svgWidth}
+		height={svgHeight}
+		fill="none"
+		stroke="#002850"
+		stroke-width="1"
+		stroke-dasharray="4 3"
+		opacity="0.6"
+		pointer-events="none"
+	/>
+
+	{#each handles as handle (handle.id)}
+		<g
+			data-handle={handle.id}
+			role="button"
+			tabindex="0"
+			aria-label={m.annotation_resize_handle({ direction: directionLabels[handle.id] })}
+			transform="translate({handle.cx}, {handle.cy})"
+			style="cursor: {handle.cursor}; pointer-events: all;"
+			onpointerdown={(e) => handlePointerDown(e, 'handle', handle.id)}
+			onkeydown={(e) => {
+				if (e.key === 'Enter' || e.key === ' ') e.preventDefault();
+			}}
+		>
+			<rect data-handle-hit x="-22" y="-22" width="44" height="44" fill="transparent" />
+			<path d={handle.path} fill="none" stroke="#002850" stroke-width="2" stroke-linecap="square" />
+		</g>
+	{/each}
+</svg>
+
+<style>
+svg[role='application']:focus-visible {
+	outline: 2px solid #002850;
+	outline-offset: 2px;
+}
+
+.sr-only {
+	position: absolute;
+	width: 1px;
+	height: 1px;
+	padding: 0;
+	margin: -1px;
+	overflow: hidden;
+	clip: rect(0, 0, 0, 0);
+	white-space: nowrap;
+	border-width: 0;
+}
+</style>
diff --git a/frontend/src/lib/components/AnnotationEditOverlay.svelte.test.ts b/frontend/src/lib/components/AnnotationEditOverlay.svelte.test.ts
new file mode 100644
index 00000000..61ab18d6
--- /dev/null
+++ b/frontend/src/lib/components/AnnotationEditOverlay.svelte.test.ts
@@ -0,0 +1,71 @@
+import { describe, it, expect } from 'vitest';
+import { render } from 'vitest-browser-svelte';
+import AnnotationEditOverlay from './AnnotationEditOverlay.svelte';
+import type { Annotation } from '$lib/types';
+
+const annotation: Annotation = {
+	id: 'ann-1',
+	documentId: 'doc-1',
+	pageNumber: 1,
+	x: 0.1,
+	y: 0.2,
+	width: 0.3,
+	height: 0.4,
+	color: '#00c7b1',
+	createdAt: '2026-01-01T00:00:00Z'
+};
+
+describe('AnnotationEditOverlay', () => {
+	it('renders 8 handle elements', async () => {
+		render(AnnotationEditOverlay, { annotation });
+
+		const handles = document.querySelectorAll('[data-handle]');
+		expect(handles).toHaveLength(8);
+	});
+
+	it('renders handles for all four corners and four edge midpoints', async () => {
+		render(AnnotationEditOverlay, { annotation });
+
+		expect(document.querySelector('[data-handle="nw"]')).not.toBeNull();
+		expect(document.querySelector('[data-handle="ne"]')).not.toBeNull();
+		expect(document.querySelector('[data-handle="sw"]')).not.toBeNull();
+		expect(document.querySelector('[data-handle="se"]')).not.toBeNull();
+		expect(document.querySelector('[data-handle="n"]')).not.toBeNull();
+		expect(document.querySelector('[data-handle="s"]')).not.toBeNull();
+		expect(document.querySelector('[data-handle="e"]')).not.toBeNull();
+		expect(document.querySelector('[data-handle="w"]')).not.toBeNull();
+	});
+
+	it('each handle has a 44x44 hit area', async () => {
+		render(AnnotationEditOverlay, { annotation });
+
+		const hitAreas = document.querySelectorAll('[data-handle-hit]');
+		expect(hitAreas).toHaveLength(8);
+		hitAreas.forEach((el) => {
+			expect(el.getAttribute('width')).toBe('44');
+			expect(el.getAttribute('height')).toBe('44');
+		});
+	});
+
+	it('renders a move area covering the full box', async () => {
+		render(AnnotationEditOverlay, { annotation });
+
+		const moveArea = document.querySelector('[data-move-area]');
+		expect(moveArea).not.toBeNull();
+	});
+
+	it('renders an aria-live region for screen reader announcement', async () => {
+		render(AnnotationEditOverlay, { annotation });
+
+		const liveRegion = document.querySelector('[aria-live="polite"]');
+		expect(liveRegion).not.toBeNull();
+	});
+
+	it('SVG root has tabindex="0" so it can receive keyboard focus', async () => {
+		render(AnnotationEditOverlay, { annotation });
+
+		const svg = document.querySelector('svg[role="application"]');
+		expect(svg).not.toBeNull();
+		expect(svg!.getAttribute('tabindex')).toBe('0');
+	});
+});
diff --git a/frontend/src/lib/components/AnnotationLayer.svelte b/frontend/src/lib/components/AnnotationLayer.svelte
index 65e87b42..ac7dbc7c 100644
--- a/frontend/src/lib/components/AnnotationLayer.svelte
+++ b/frontend/src/lib/components/AnnotationLayer.svelte
@@ -107,6 +107,7 @@ const containerStyle = $derived(
 			annotation={annotation}
 			isHovered={hoveredId === annotation.id}
 			isActive={annotation.id === activeAnnotationId}
+			isResizable={canDraw && annotation.id === activeAnnotationId && !annotation.polygon}
 			faded={!dimmed && !!activeAnnotationId && annotation.id !== activeAnnotationId}
 			dimmed={dimmed}
 			blockNumber={blockNumbers[annotation.id]}
diff --git a/frontend/src/lib/components/AnnotationLayer.svelte.test.ts b/frontend/src/lib/components/AnnotationLayer.svelte.test.ts
index 1f549cd3..5c78f3a2 100644
--- a/frontend/src/lib/components/AnnotationLayer.svelte.test.ts
+++ b/frontend/src/lib/components/AnnotationLayer.svelte.test.ts
@@ -16,6 +16,17 @@ const annotation: Annotation = {
 	createdAt: '2026-01-01T00:00:00Z'
 };
 
+const polygonAnnotation: Annotation = {
+	...annotation,
+	id: 'ann-poly',
+	polygon: [
+		[0.1, 0.2],
+		[0.4, 0.21],
+		[0.39, 0.29],
+		[0.11, 0.28]
+	]
+};
+
 describe('AnnotationLayer', () => {
 	describe('dimmed prop', () => {
 		it('should hide block number badges when dimmed is true', async () => {
@@ -65,6 +76,60 @@ describe('AnnotationLayer', () => {
 		});
 	});
 
+	describe('isResizable computation', () => {
+		it('passes isResizable=true when canDraw, annotation is active, and has no polygon', async () => {
+			render(AnnotationLayer, {
+				annotations: [annotation],
+				canDraw: true,
+				color: '#00c7b1',
+				activeAnnotationId: 'ann-1',
+				onDraw: () => {}
+			});
+
+			const handles = document.querySelectorAll('[data-handle]');
+			expect(handles).toHaveLength(8);
+		});
+
+		it('passes isResizable=false when annotation has a polygon', async () => {
+			render(AnnotationLayer, {
+				annotations: [polygonAnnotation],
+				canDraw: true,
+				color: '#00c7b1',
+				activeAnnotationId: 'ann-poly',
+				onDraw: () => {}
+			});
+
+			const handles = document.querySelectorAll('[data-handle]');
+			expect(handles).toHaveLength(0);
+		});
+
+		it('passes isResizable=false when canDraw is false', async () => {
+			render(AnnotationLayer, {
+				annotations: [annotation],
+				canDraw: false,
+				color: '#00c7b1',
+				activeAnnotationId: 'ann-1',
+				onDraw: () => {}
+			});
+
+			const handles = document.querySelectorAll('[data-handle]');
+			expect(handles).toHaveLength(0);
+		});
+
+		it('passes isResizable=false when annotation is not active', async () => {
+			render(AnnotationLayer, {
+				annotations: [annotation],
+				canDraw: true,
+				color: '#00c7b1',
+				activeAnnotationId: 'other-id',
+				onDraw: () => {}
+			});
+
+			const handles = document.querySelectorAll('[data-handle]');
+			expect(handles).toHaveLength(0);
+		});
+	});
+
 	describe('flashAnnotationId prop', () => {
 		it('should apply annotation-flash class when flashAnnotationId matches', async () => {
 			render(AnnotationLayer, {
diff --git a/frontend/src/lib/components/AnnotationShape.svelte b/frontend/src/lib/components/AnnotationShape.svelte
index 69c41223..a7c667f2 100644
--- a/frontend/src/lib/components/AnnotationShape.svelte
+++ b/frontend/src/lib/components/AnnotationShape.svelte
@@ -1,5 +1,6 @@
 <script lang="ts">
 import type { Annotation } from '$lib/types';
+import AnnotationEditOverlay from './AnnotationEditOverlay.svelte';
 
 let {
 	annotation,
@@ -9,6 +10,7 @@ let {
 	dimmed = false,
 	blockNumber = undefined,
 	isFlashing = false,
+	isResizable = false,
 	onclick,
 	onpointerenter,
 	onpointerleave
@@ -20,6 +22,7 @@ let {
 	dimmed?: boolean;
 	blockNumber?: number | undefined;
 	isFlashing?: boolean;
+	isResizable?: boolean;
 	onclick: () => void;
 	onpointerenter: () => void;
 	onpointerleave: () => void;
@@ -109,6 +112,9 @@ let shapeStyle = $derived(
 			{blockNumber}
 		</div>
 	{/if}
+	{#if isResizable}
+		<AnnotationEditOverlay annotation={annotation} />
+	{/if}
 </div>
 
 <style>
diff --git a/frontend/src/lib/components/AnnotationShape.svelte.test.ts b/frontend/src/lib/components/AnnotationShape.svelte.test.ts
new file mode 100644
index 00000000..f5ad754e
--- /dev/null
+++ b/frontend/src/lib/components/AnnotationShape.svelte.test.ts
@@ -0,0 +1,50 @@
+import { describe, it, expect } from 'vitest';
+import { render } from 'vitest-browser-svelte';
+import AnnotationShape from './AnnotationShape.svelte';
+import type { Annotation } from '$lib/types';
+
+const annotation: Annotation = {
+	id: 'ann-1',
+	documentId: 'doc-1',
+	pageNumber: 1,
+	x: 0.1,
+	y: 0.2,
+	width: 0.3,
+	height: 0.4,
+	color: '#00c7b1',
+	createdAt: '2026-01-01T00:00:00Z'
+};
+
+describe('AnnotationShape', () => {
+	describe('isResizable prop', () => {
+		it('does not render AnnotationEditOverlay when isResizable is false', async () => {
+			render(AnnotationShape, {
+				annotation,
+				isHovered: false,
+				isActive: false,
+				isResizable: false,
+				onclick: () => {},
+				onpointerenter: () => {},
+				onpointerleave: () => {}
+			});
+
+			const handles = document.querySelectorAll('[data-handle]');
+			expect(handles).toHaveLength(0);
+		});
+
+		it('renders AnnotationEditOverlay when isResizable is true', async () => {
+			render(AnnotationShape, {
+				annotation,
+				isHovered: false,
+				isActive: true,
+				isResizable: true,
+				onclick: () => {},
+				onpointerenter: () => {},
+				onpointerleave: () => {}
+			});
+
+			const handles = document.querySelectorAll('[data-handle]');
+			expect(handles).toHaveLength(8);
+		});
+	});
+});
diff --git a/frontend/src/lib/components/PdfViewer.svelte b/frontend/src/lib/components/PdfViewer.svelte
index 2574e8d0..359c9700 100644
--- a/frontend/src/lib/components/PdfViewer.svelte
+++ b/frontend/src/lib/components/PdfViewer.svelte
@@ -1,9 +1,10 @@
 <script lang="ts">
-import { onMount } from 'svelte';
+import { onMount, setContext } from 'svelte';
 import type { PDFDocumentProxy, PDFPageProxy, RenderTask } from 'pdfjs-dist';
 import AnnotationLayer from './AnnotationLayer.svelte';
 import type { Annotation } from '$lib/types';
 import { m } from '$lib/paraglide/messages.js';
+import { parseBackendError, getErrorMessage } from '$lib/errors';
 
 type DrawRect = { x: number; y: number; width: number; height: number; pageNumber: number };
 
@@ -55,6 +56,7 @@ let pdfjsReady = $state(false);
 
 let annotations = $state<Annotation[]>([]);
 let showAnnotations = $state(true);
+let annotationUpdateError = $state<string | null>(null);
 
 const TRANSCRIPTION_COLOR = '#00C7B1';
 
@@ -186,6 +188,29 @@ async function loadAnnotations(docId: string) {
 	}
 }
 
+async function updateAnnotation(
+	annotationId: string,
+	coords: { x: number; y: number; width: number; height: number }
+) {
+	if (!documentId) return;
+	const res = await fetch(`/api/documents/${documentId}/annotations/${annotationId}`, {
+		method: 'PATCH',
+		headers: { 'Content-Type': 'application/json' },
+		body: JSON.stringify(coords)
+	});
+	if (!res.ok) {
+		const err = await parseBackendError(res);
+		const msg = getErrorMessage(err?.code ?? 'ANNOTATION_UPDATE_FAILED');
+		annotationUpdateError = msg;
+		setTimeout(() => (annotationUpdateError = null), 4000);
+		throw new Error(msg);
+	}
+	const updated = await res.json();
+	annotations = annotations.map((a) => (a.id === annotationId ? updated : a));
+}
+
+setContext('annotationUpdate', updateAnnotation);
+
 async function handleDraw(rect: { x: number; y: number; width: number; height: number }) {
 	if (!documentId || !transcribeMode) return;
 	await onTranscriptionDraw?.({ ...rect, pageNumber: currentPage });
@@ -306,6 +331,26 @@ function zoomOut() {
 				<span class="font-sans text-xs text-amber-300">{m.annotation_outdated_notice()}</span>
 			</div>
 		{/if}
+		{#if annotationUpdateError}
+			<div
+				class="flex shrink-0 items-center gap-2 border-b border-red-500/30 bg-red-500/10 px-4 py-2"
+				aria-live="assertive"
+				role="alert"
+			>
+				<svg
+					class="h-4 w-4 shrink-0 text-red-400"
+					viewBox="0 0 24 24"
+					fill="none"
+					stroke="currentColor"
+					stroke-width="2"
+				>
+					<circle cx="12" cy="12" r="10" />
+					<line x1="15" y1="9" x2="9" y2="15" />
+					<line x1="9" y1="9" x2="15" y2="15" />
+				</svg>
+				<span class="font-sans text-xs text-red-300">{annotationUpdateError}</span>
+			</div>
+		{/if}
 		<!-- Controls -->
 		<div
 			class="flex shrink-0 items-center justify-between gap-2 border-b border-pdf-ctrl px-4 py-2"
diff --git a/frontend/src/lib/errors.ts b/frontend/src/lib/errors.ts
index da769462..23a76344 100644
--- a/frontend/src/lib/errors.ts
+++ b/frontend/src/lib/errors.ts
@@ -18,6 +18,7 @@ export type ErrorCode =
 	| 'IMPORT_ALREADY_RUNNING'
 	| 'INVALID_RESET_TOKEN'
 	| 'ANNOTATION_NOT_FOUND'
+	| 'ANNOTATION_UPDATE_FAILED'
 	| 'TRANSCRIPTION_BLOCK_NOT_FOUND'
 	| 'TRANSCRIPTION_BLOCK_CONFLICT'
 	| 'COMMENT_NOT_FOUND'
@@ -81,6 +82,8 @@ export function getErrorMessage(code: ErrorCode | string | undefined): string {
 			return m.error_invalid_reset_token();
 		case 'ANNOTATION_NOT_FOUND':
 			return m.error_annotation_not_found();
+		case 'ANNOTATION_UPDATE_FAILED':
+			return m.error_annotation_update_failed();
 		case 'TRANSCRIPTION_BLOCK_NOT_FOUND':
 			return m.error_transcription_block_not_found();
 		case 'TRANSCRIPTION_BLOCK_CONFLICT':