diff --git a/apps/web/src/editor-canvas.ts b/apps/web/src/editor-canvas.ts
index bd7f1bf..0957aa8 100644
--- a/apps/web/src/editor-canvas.ts
+++ b/apps/web/src/editor-canvas.ts
@@ -2,6 +2,27 @@ import { isCanvasState, type CanvasState } from "@dada/shared-contracts";
 
 export type BackgroundAdjustments = CanvasState["background"]["adjustments"];
 
+interface CanvasSize {
+  height: number;
+  width: number;
+}
+
+interface CanvasRect {
+  height: number;
+  width: number;
+  x: number;
+  y: number;
+}
+
+export interface BackgroundDrawPlan {
+  destination: CanvasRect;
+  source: CanvasRect;
+}
+
+function clamp(value: number, minimum: number, maximum: number) {
+  return Math.min(maximum, Math.max(minimum, value));
+}
+
 const elementKeys = new Set([
   "colors", "content", "coordinates", "created_at", "dynamic_fields", "element_id", "font_override", "font_size",
   "formatted_value", "opacity", "position", "resource_version", "rotation", "scale", "style_id", "style_parameters",
@@ -106,7 +127,99 @@ export function deserializeFabricCanvas(input: unknown): CanvasState | undefined
   return isCanvasState(candidate) ? structuredClone(candidate) : undefined;
 }
 
+export function backgroundDrawPlan(
+  image: CanvasSize,
+  canvas: CanvasSize,
+  adjustments: BackgroundAdjustments,
+): BackgroundDrawPlan {
+  if (image.width <= 0 || image.height <= 0 || canvas.width <= 0 || canvas.height <= 0) {
+    throw new Error("background_dimensions_invalid");
+  }
+  const crop = adjustments.crop;
+  const normalizedX = crop ? clamp(crop.x, 0, 1) : 0;
+  const normalizedY = crop ? clamp(crop.y, 0, 1) : 0;
+  const normalizedWidth = crop ? Math.min(crop.width, 1 - normalizedX) : 1;
+  const normalizedHeight = crop ? Math.min(crop.height, 1 - normalizedY) : 1;
+  const source = normalizedWidth > 0 && normalizedHeight > 0
+    ? {
+        height: image.height * normalizedHeight,
+        width: image.width * normalizedWidth,
+        x: image.width * normalizedX,
+        y: image.height * normalizedY,
+      }
+    : { height: image.height, width: image.width, x: 0, y: 0 };
+
+  if (adjustments.fit === "fill") {
+    return { destination: { height: canvas.height, width: canvas.width, x: 0, y: 0 }, source };
+  }
+  if (adjustments.fit === "fit") {
+    const scale = Math.min(canvas.width / source.width, canvas.height / source.height);
+    const width = source.width * scale;
+    const height = source.height * scale;
+    return {
+      destination: { height, width, x: (canvas.width - width) / 2, y: (canvas.height - height) / 2 },
+      source,
+    };
+  }
+
+  const sourceAspect = source.width / source.height;
+  const canvasAspect = canvas.width / canvas.height;
+  if (sourceAspect > canvasAspect) {
+    const width = source.height * canvasAspect;
+    source.x += (source.width - width) / 2;
+    source.width = width;
+  } else if (sourceAspect < canvasAspect) {
+    const height = source.width / canvasAspect;
+    source.y += (source.height - height) / 2;
+    source.height = height;
+  }
+  return {
+    destination: { height: canvas.height, width: canvas.width, x: 0, y: 0 },
+    source,
+  };
+}
+
+export function adjustBackgroundPixels(
+  pixels: Uint8ClampedArray,
+  width: number,
+  height: number,
+  adjustments: Pick<BackgroundAdjustments, "sharpness" | "temperature">,
+) {
+  if (!Number.isInteger(width) || !Number.isInteger(height) || width <= 0 || height <= 0 || pixels.length !== width * height * 4) {
+    throw new Error("background_pixel_buffer_invalid");
+  }
+  const source = new Uint8ClampedArray(pixels);
+  const output = new Uint8ClampedArray(source);
+  const sharpness = clamp(adjustments.sharpness, 0, 100) / 100;
+  const temperature = clamp(adjustments.temperature, -100, 100) / 100;
+  const channelOffsets = [35 * temperature, 8 * temperature, -35 * temperature];
+
+  for (let y = 0; y < height; y += 1) {
+    for (let x = 0; x < width; x += 1) {
+      const index = (y * width + x) * 4;
+      for (let channel = 0; channel < 3; channel += 1) {
+        let value = source[index + channel]!;
+        if (sharpness > 0 && x > 0 && x < width - 1 && y > 0 && y < height - 1) {
+          const left = source[index + channel - 4]!;
+          const right = source[index + channel + 4]!;
+          const above = source[index + channel - width * 4]!;
+          const below = source[index + channel + width * 4]!;
+          value = value * (1 + 4 * sharpness) - (left + right + above + below) * sharpness;
+        }
+        output[index + channel] = value + channelOffsets[channel]!;
+      }
+      output[index + 3] = source[index + 3]!;
+    }
+  }
+  return output;
+}
+
 export function cssFilterForBackground(adjustments: BackgroundAdjustments) {
-  const filter = adjustments.filter === "grayscale" ? "grayscale(1)" : adjustments.filter === "sepia" ? "sepia(0.75)" : "none";
-  return `${filter} brightness(${100 + adjustments.brightness}%) contrast(${100 + adjustments.contrast}%) saturate(${100 + adjustments.saturation}%)`;
+  const filters: string[] = [];
+  if (adjustments.filter === "grayscale") filters.push("grayscale(1)");
+  else if (adjustments.filter === "sepia") filters.push("sepia(0.75)");
+  if (adjustments.brightness !== 0) filters.push(`brightness(${100 + adjustments.brightness}%)`);
+  if (adjustments.contrast !== 0) filters.push(`contrast(${100 + adjustments.contrast}%)`);
+  if (adjustments.saturation !== 0) filters.push(`saturate(${100 + adjustments.saturation}%)`);
+  return filters.length > 0 ? filters.join(" ") : "none";
 }
diff --git a/apps/web/src/editor-elements.ts b/apps/web/src/editor-elements.ts
index cb2fa1b..4dd73f6 100644
--- a/apps/web/src/editor-elements.ts
+++ b/apps/web/src/editor-elements.ts
@@ -187,7 +187,7 @@ export class CanvasElementController {
       .map((element) => structuredClone(element));
   }
 
-  selectAt(point: CanvasPoint, options: { append?: boolean } = {}) {
+  selectAt(point: CanvasPoint, options: { append?: boolean; preserveSelection?: boolean } = {}) {
     const candidates = this.candidatesAt(point);
     if (candidates.length === 0) {
       if (!options.append) this.selection = [];
@@ -196,7 +196,9 @@ export class CanvasElementController {
     }
     if (options.append) {
       this.pointerMoved();
-      return this.selectById(candidates[0]!.element_id, true);
+      const elementId = candidates[0]!.element_id;
+      if (options.preserveSelection && this.selection.includes(elementId)) return this.selectedIds;
+      return this.selectById(elementId, true);
     }
     const signature = candidates.map((candidate) => candidate.element_id).join("|");
     if (samePoint(this.cyclePoint, point) && signature === this.cycleSignature) this.cycleIndex = (this.cycleIndex + 1) % candidates.length;
@@ -255,7 +257,8 @@ export class CanvasElementController {
 
   moveSelected(delta: CanvasPoint, options: { snap?: boolean } = {}) {
     const selected = new Set(this.selection);
-    const primary = this.current.elements.find((element) => selected.has(element.element_id));
+    const selectedElements = this.current.elements.filter((element) => selected.has(element.element_id));
+    const primary = selectedElements[0];
     if (!primary) return { guides: [] as string[], state: this.value };
     let nextX = primary.position.x + delta.x;
     let nextY = primary.position.y + delta.y;
@@ -278,10 +281,20 @@ export class CanvasElementController {
       nextX = snapAxis(nextX, "x");
       nextY = snapAxis(nextY, "y");
     }
-    const adjusted = { x: nextX - primary.position.x, y: nextY - primary.position.y };
+    const minimumX = Math.min(...selectedElements.map((element) => element.position.x));
+    const maximumX = Math.max(...selectedElements.map((element) => element.position.x));
+    const minimumY = Math.min(...selectedElements.map((element) => element.position.y));
+    const maximumY = Math.max(...selectedElements.map((element) => element.position.y));
+    const adjusted = {
+      x: clamp(nextX - primary.position.x, -minimumX, 1 - maximumX),
+      y: clamp(nextY - primary.position.y, -minimumY, 1 - maximumY),
+    };
     const state = this.updateSelected((element) => ({
       ...element,
-      position: { x: clamp(element.position.x + adjusted.x, 0, 1), y: clamp(element.position.y + adjusted.y, 0, 1) },
+      position: {
+        x: clamp(Number((element.position.x + adjusted.x).toFixed(12)), 0, 1),
+        y: clamp(Number((element.position.y + adjusted.y).toFixed(12)), 0, 1),
+      },
     }));
     return { guides, state };
   }
diff --git a/apps/web/src/editor-page.tsx b/apps/web/src/editor-page.tsx
index e5f4841..12bde2f 100644
--- a/apps/web/src/editor-page.tsx
+++ b/apps/web/src/editor-page.tsx
@@ -706,7 +706,10 @@ export function EditorPage({ projectId }: { projectId: string }) {
     const controller = controllerForCurrent();
     if (!controller || !canvasState) return false;
     const candidates = controller.candidatesAt(point);
-    const selection = controller.selectAt(point, { append: append || multiMode });
+    const selection = controller.selectAt(point, {
+      append: append || multiMode,
+      preserveSelection: multiMode && !append,
+    });
     setSelectedIds(selection);
     setCandidateMenu(undefined);
     dragRef.current = { base: canvasState, last: canvasState, selectedIds: selection };
@@ -789,10 +792,14 @@ export function EditorPage({ projectId }: { projectId: string }) {
   }
 
   if (!project || !canvasState) return <main className="editor-loading" aria-live="polite">正在加载编辑器</main>;
-  const renderedCanvasState = textEdit ? {
+  const backgroundPreviewState: CanvasState = {
     ...canvasState,
-    elements: canvasState.elements.map((element) => element.element_id === textEdit.elementId ? textEdit.draft : element),
-  } : canvasState;
+    background: { ...canvasState.background, adjustments: draftAdjustments },
+  };
+  const renderedCanvasState = textEdit ? {
+    ...backgroundPreviewState,
+    elements: backgroundPreviewState.elements.map((element) => element.element_id === textEdit.elementId ? textEdit.draft : element),
+  } : backgroundPreviewState;
   const imageUrl = `/api/v1/private-assets/projects/${projectId}/images/${canvasState.background.asset_id ?? project.current_image_id ?? ""}`;
   const canEdit = saveStatus !== "conflicted";
   const selectedElements = renderedCanvasState.elements.filter((element) => selectedIds.includes(element.element_id));
diff --git a/apps/web/src/editor-stage.tsx b/apps/web/src/editor-stage.tsx
index 6f6d0c0..dc58bc2 100644
--- a/apps/web/src/editor-stage.tsx
+++ b/apps/web/src/editor-stage.tsx
@@ -1,7 +1,7 @@
 import { useEffect, useRef, useState, type KeyboardEvent, type PointerEvent } from "react";
 import type { CanvasState } from "@dada/shared-contracts";
 
-import { cssFilterForBackground } from "./editor-canvas.js";
+import { adjustBackgroundPixels, backgroundDrawPlan, cssFilterForBackground } from "./editor-canvas.js";
 import { DYN012_RENDER_LAYOUT, dyn012DisplayParts } from "./dynamic-provider.js";
 import type { DynamicTemplateId } from "./dynamic-provider.js";
 import { DYNAMIC_RENDER_MODELS, dynamicFontOptionsFor, dynamicImageUrl, dynamicTextValue } from "./dynamic-render-models.js";
@@ -274,9 +274,41 @@ function renderEditorScene(
   context.clearRect(0, 0, canvasState.pixel_width, canvasState.pixel_height);
   context.fillStyle = "#ffffff";
   context.fillRect(0, 0, canvasState.pixel_width, canvasState.pixel_height);
-  context.filter = cssFilterForBackground(canvasState.background.adjustments);
-  if (background) context.drawImage(background, 0, 0, canvasState.pixel_width, canvasState.pixel_height);
-  context.filter = "none";
+  if (background) {
+    const plan = backgroundDrawPlan(
+      { height: background.naturalHeight || background.height, width: background.naturalWidth || background.width },
+      { height: canvasState.pixel_height, width: canvasState.pixel_width },
+      canvasState.background.adjustments,
+    );
+    context.save();
+    context.filter = cssFilterForBackground(canvasState.background.adjustments);
+    context.drawImage(
+      background,
+      plan.source.x,
+      plan.source.y,
+      plan.source.width,
+      plan.source.height,
+      plan.destination.x,
+      plan.destination.y,
+      plan.destination.width,
+      plan.destination.height,
+    );
+    context.restore();
+
+    if (canvasState.background.adjustments.temperature !== 0 || canvasState.background.adjustments.sharpness !== 0) {
+      const x = Math.max(0, Math.floor(plan.destination.x));
+      const y = Math.max(0, Math.floor(plan.destination.y));
+      const right = Math.min(canvasState.pixel_width, Math.ceil(plan.destination.x + plan.destination.width));
+      const bottom = Math.min(canvasState.pixel_height, Math.ceil(plan.destination.y + plan.destination.height));
+      const width = right - x;
+      const height = bottom - y;
+      if (width > 0 && height > 0) {
+        const imageData = context.getImageData(x, y, width, height);
+        imageData.data.set(adjustBackgroundPixels(imageData.data, width, height, canvasState.background.adjustments));
+        context.putImageData(imageData, x, y);
+      }
+    }
+  }
   for (const element of [...canvasState.elements].sort((left, right) => left.z_index - right.z_index)) {
     drawElement(context, element, canvasState.pixel_width, canvasState.pixel_height, fontStatuses, resourceImages);
   }
diff --git a/tests/e2e/wp4-01-editor-background.spec.ts b/tests/e2e/wp4-01-editor-background.spec.ts
index f50fbea..223b52d 100644
--- a/tests/e2e/wp4-01-editor-background.spec.ts
+++ b/tests/e2e/wp4-01-editor-background.spec.ts
@@ -67,6 +67,20 @@ async function routeEditor(page: Page) {
   });
 }
 
+async function canvasFingerprint(page: Page) {
+  return page.getByLabel("编辑画布").evaluate((canvas: HTMLCanvasElement) => {
+    const context = canvas.getContext("2d");
+    if (!context) throw new Error("Canvas context unavailable.");
+    return [
+      ...context.getImageData(108, 720, 1, 1).data,
+      ...context.getImageData(324, 720, 1, 1).data,
+      ...context.getImageData(540, 720, 1, 1).data,
+      ...context.getImageData(756, 720, 1, 1).data,
+      ...context.getImageData(972, 720, 1, 1).data,
+    ];
+  });
+}
+
 test("TDD-WP4-BG-001 preserves overlays while switching the background", async ({ page }) => {
   await routeEditor(page);
   const saves: Array<Record<string, unknown>> = [];
@@ -144,3 +158,35 @@ test("TDD-WP4-BG-002 commits, reopens, undoes, and resets background processing"
   writeEvidence("TDD-WP4-BG-002-processing-controls", "pixel-diff.json", { preview_commit_undo_reset: true, export_source_canvas_state_stable: true });
   await page.screenshot({ fullPage: true, path: process.env.DADA_EVIDENCE_DIR_EDITOR ? resolve(process.env.DADA_EVIDENCE_DIR_EDITOR, "TDD-WP4-BG-002-processing-controls", "processing-controls.png") : undefined });
 });
+
+test("TDD-WP4-BG-002 previews background pixels before committing", async ({ page }) => {
+  await routeEditor(page);
+  const saves: Array<Record<string, unknown>> = [];
+  let version = 7;
+  await page.route(`**/api/v1/projects/${projectId}/state`, async (route) => {
+    saves.push(route.request().postDataJSON() as Record<string, unknown>);
+    version += 1;
+    await route.fulfill({ body: JSON.stringify({ save_status: "saved", state_version: version }), contentType: "application/json", status: 200 });
+  });
+  await page.goto(`${webUrl}/app/projects/${projectId}/editor`);
+  await page.getByRole("button", { name: "恢复原图" }).click();
+  await page.getByRole("button", { name: "应用调整" }).click();
+  await expect.poll(() => saves.length, { timeout: 4_000 }).toBeGreaterThan(0);
+  await expect.poll(async () => (await canvasFingerprint(page)).some((channel) => channel < 240)).toBe(true);
+  const baseline = (await canvasFingerprint(page)).join(",");
+
+  const ranges = page.locator(".editor-inspector input[type=range]");
+  await ranges.nth(0).fill("40");
+  await ranges.nth(1).fill("25");
+  await ranges.nth(2).fill("-35");
+  await ranges.nth(3).fill("70");
+  await ranges.nth(4).fill("100");
+  await expect.poll(async () => (await canvasFingerprint(page)).join(",")).not.toBe(baseline);
+
+  await page.getByRole("button", { name: "应用调整" }).click();
+  await expect.poll(() => saves.length, { timeout: 4_000 }).toBeGreaterThan(1);
+  const committed = saves.at(-1) as { canvas_state: typeof initialCanvasState };
+  expect(committed.canvas_state.background.adjustments).toMatchObject({
+    brightness: 40, contrast: 25, saturation: -35, sharpness: 100, temperature: 70,
+  });
+});
diff --git a/tests/e2e/wp4-02-editor-elements.spec.ts b/tests/e2e/wp4-02-editor-elements.spec.ts
index 58c260a..469fd99 100644
--- a/tests/e2e/wp4-02-editor-elements.spec.ts
+++ b/tests/e2e/wp4-02-editor-elements.spec.ts
@@ -26,7 +26,8 @@ const session = {
   user: { creator_name: "Canvas User", role: "user", social_id: "@canvas_user", status: "active", user_id: "00000000-0000-4000-8000-000000000501" },
 };
 
-const stickerRoot = process.env.DADA_STATIC_STICKER_ROOT ?? join(homedir(), "Desktop", "贴纸素材");
+const stickerRoot = process.env.DADA_STATIC_STICKER_ROOT
+  ?? join(homedir(), "Desktop", "sticker_web_replication_assets", "sticker_normal");
 const originalStickerFixtures: Readonly<Record<string, string>> = {
   STK001: join(stickerRoot, "sticker_part1", "01af6384c2a962d17f55736f9895b505.png"),
   STK002: join(stickerRoot, "sticker_part2", "011db0fb6ac4184e4a708374003bce66.png"),
@@ -131,6 +132,41 @@ test("TDD-WP4-CAN-001 keeps fifty elements editable and blocks the fifty-first",
   if (process.env.DADA_EVIDENCE_DIR_EDITOR_ELEMENTS) await page.screenshot({ fullPage: true, path: resolve(process.env.DADA_EVIDENCE_DIR_EDITOR_ELEMENTS, "TDD-WP4-CAN-001-fifty-elements", "fifty-elements.png") });
 });
 
+test("TDD-WP4-CAN-001 drags distant multi-selected objects as one group", async ({ page }) => {
+  const projectId = uuid(519);
+  const backend = {
+    canvas: canvas([sticker(1, { x: 0.2, y: 0.2 }, 0), sticker(2, { x: 0.8, y: 0.8 }, 1)]),
+    saves: 0,
+    version: 5,
+  };
+  await routeEditor(page, projectId, backend);
+  await page.goto(`${webUrl}/app/projects/${projectId}/editor`);
+  const stage = page.getByLabel("编辑画布");
+  const bounds = await stage.boundingBox();
+  if (!bounds) throw new Error("Canvas bounds unavailable.");
+  const point = (x: number, y: number) => ({ x: bounds.x + bounds.width * x, y: bounds.y + bounds.height * y });
+
+  await page.getByRole("button", { name: "多选模式" }).click();
+  await page.mouse.click(point(0.2, 0.2).x, point(0.2, 0.2).y);
+  await page.mouse.click(point(0.8, 0.8).x, point(0.8, 0.8).y);
+  await expect(page.getByRole("heading", { name: "已选 2 个对象" })).toBeVisible();
+
+  await page.mouse.move(point(0.2, 0.2).x, point(0.2, 0.2).y);
+  await page.mouse.down();
+  await page.mouse.move(point(0.3, 0.3).x, point(0.3, 0.3).y, { steps: 4 });
+  await page.mouse.up();
+
+  await expect.poll(() => backend.saves, { timeout: 4_000 }).toBeGreaterThan(0);
+  const [first, second] = backend.canvas.elements.map(({ position }) => position);
+  expect(first?.x).toBeCloseTo(0.3, 6);
+  expect(first?.y).toBeCloseTo(0.3, 6);
+  expect(second?.x).toBeCloseTo(0.9, 6);
+  expect(second?.y).toBeCloseTo(0.9, 6);
+  expect((first?.x ?? 0) - 0.2).toBeCloseTo((second?.x ?? 0) - 0.8, 10);
+  expect((first?.y ?? 0) - 0.2).toBeCloseTo((second?.y ?? 0) - 0.8, 10);
+  await expect(page.getByRole("heading", { name: "已选 2 个对象" })).toBeVisible();
+});
+
 test("TDD-WP4-STK-001 transforms, cycles, selects and reopens ordinary stickers", async ({ page }) => {
   const projectId = uuid(520);
   const backend = { canvas: canvas([sticker(1, { x: 0.5, y: 0.5 }, 0), sticker(2, { x: 0.5, y: 0.5 }, 1)]), saves: 0, version: 5 };
diff --git a/tests/unit/wp4-01-editor-canvas.test.ts b/tests/unit/wp4-01-editor-canvas.test.ts
index f924f67..8a9f643 100644
--- a/tests/unit/wp4-01-editor-canvas.test.ts
+++ b/tests/unit/wp4-01-editor-canvas.test.ts
@@ -1,8 +1,11 @@
 import { describe, expect, it } from "vitest";
 
 import {
+  adjustBackgroundPixels,
+  backgroundDrawPlan,
   CanvasEditHistory,
   createEditorCanvasState,
+  cssFilterForBackground,
   defaultBackgroundAdjustments,
   deserializeFabricCanvas,
   switchBackground,
@@ -24,6 +27,35 @@ const element = {
 };
 
 describe("TDD-WP4-BG-001/002 canvas boundary", () => {
+  it("builds valid filters and distinct contain/crop draw plans", () => {
+    const adjustments = { ...defaultBackgroundAdjustments(), brightness: 25, contrast: 15, saturation: -20 };
+    expect(cssFilterForBackground(adjustments)).toBe("brightness(125%) contrast(115%) saturate(80%)");
+    expect(cssFilterForBackground(defaultBackgroundAdjustments())).toBe("none");
+
+    expect(backgroundDrawPlan({ height: 200, width: 400 }, { height: 100, width: 100 }, { ...adjustments, fit: "fit" })).toEqual({
+      destination: { height: 50, width: 100, x: 0, y: 25 },
+      source: { height: 200, width: 400, x: 0, y: 0 },
+    });
+    expect(backgroundDrawPlan({ height: 200, width: 400 }, { height: 100, width: 100 }, { ...adjustments, fit: "crop" })).toEqual({
+      destination: { height: 100, width: 100, x: 0, y: 0 },
+      source: { height: 200, width: 200, x: 100, y: 0 },
+    });
+  });
+
+  it("changes pixels for temperature and sharpness without changing alpha", () => {
+    const flat = new Uint8ClampedArray([100, 100, 100, 255]);
+    expect([...adjustBackgroundPixels(flat, 1, 1, { sharpness: 0, temperature: 100 })]).toEqual([135, 108, 65, 255]);
+
+    const edged = new Uint8ClampedArray([
+      100, 100, 100, 255, 100, 100, 100, 255, 100, 100, 100, 255,
+      100, 100, 100, 255, 180, 180, 180, 255, 100, 100, 100, 255,
+      100, 100, 100, 255, 100, 100, 100, 255, 100, 100, 100, 255,
+    ]);
+    const sharpened = adjustBackgroundPixels(edged, 3, 3, { sharpness: 100, temperature: 0 });
+    expect(sharpened[16]).toBe(255);
+    expect(sharpened[19]).toBe(255);
+  });
+
   it("switches background without moving overlays, resets processing, and re-extracts palette", () => {
     const initial = createEditorCanvasState({ assetId: "00000000-0000-4000-8000-000000000010", ratio: "3:4" });
     const withOverlay = { ...initial, background: { ...initial.background, adjustments: { ...initial.background.adjustments, brightness: 42, filter: "mono" } }, elements: [element] };
diff --git a/tests/unit/wp4-02-editor-elements.test.ts b/tests/unit/wp4-02-editor-elements.test.ts
index 4991fa7..acf7df3 100644
--- a/tests/unit/wp4-02-editor-elements.test.ts
+++ b/tests/unit/wp4-02-editor-elements.test.ts
@@ -73,6 +73,10 @@ describe("TDD-WP4-CAN-001 canvas selection and limit", () => {
       identity(1).elementId,
       identity(2).elementId,
     ]);
+    expect(controller.selectAt({ x: 0.2, y: 0.2 }, { append: true, preserveSelection: true })).toEqual([
+      identity(1).elementId,
+      identity(2).elementId,
+    ]);
   });
 });
 
@@ -97,6 +101,19 @@ describe("TDD-WP4-STK-001 sticker transformations", () => {
     });
   });
 
+  it("uses one bounded delta for distant selected elements", () => {
+    const controller = new CanvasElementController(state([
+      sticker(1, { position: { x: 0.1, y: 0.2 } }),
+      sticker(2, { position: { x: 0.9, y: 0.8 } }),
+    ]));
+    controller.selectIds([identity(1).elementId, identity(2).elementId]);
+    controller.moveSelected({ x: 0.2, y: 0.3 }, { snap: false });
+    expect(controller.value.elements.map(({ position }) => position)).toEqual([
+      { x: 0.2, y: 0.4 },
+      { x: 1, y: 1 },
+    ]);
+  });
+
   it("duplicates, reorders and deletes selected stickers while preserving stable resource identity", () => {
     const controller = new CanvasElementController(state([sticker(1), sticker(2, { position: { x: 0.7, y: 0.7 } })]));
     controller.selectById(identity(1).elementId);