diff --git a/frontend/apps/artcraft-webapp/src/components/prompt-box/PromptBox.tsx b/frontend/apps/artcraft-webapp/src/components/prompt-box/PromptBox.tsx
index 81f87671a1..c0cac00b4c 100644
--- a/frontend/apps/artcraft-webapp/src/components/prompt-box/PromptBox.tsx
+++ b/frontend/apps/artcraft-webapp/src/components/prompt-box/PromptBox.tsx
@@ -23,6 +23,11 @@ import { MentionTextarea } from "./MentionTextarea";
 import { getMentionColor, buildMentionColorMap } from "./mention-colors";
 import type { RefImage, MentionItem } from "./types";
 import { useEnterToGenerateStore } from "../../lib/enter-to-generate-store";
+import {
+  PromptFullscreenButton,
+  PromptFullscreenModal,
+  useFullscreenPrompt,
+} from "./PromptFullscreen";
 
 // ── Props ───────────────────────────────────────────────────────────────
 
@@ -107,6 +112,8 @@ export const PromptBox = forwardRef<HTMLDivElement, PromptBoxProps>(
     const [isFocused, setIsFocused] = useState(false);
     const [isExpanded, setIsExpanded] = useState(false);
     const [showImagePrompts, setShowImagePrompts] = useState(false);
+    const { isFullscreen, openFullscreen, closeFullscreen } =
+      useFullscreenPrompt();
 
     const EXPANDED_HEIGHT = "clamp(120px, calc(100vh - 700px), 500px)";
 
@@ -386,7 +393,7 @@ export const PromptBox = forwardRef<HTMLDivElement, PromptBoxProps>(
                     mentionItems={mentionItems}
                     placeholder={placeholder}
                     className={twMerge(
-                      "promptbox-scrollbar min-h-[2.5em] w-full text-base-fg placeholder-base-fg/60",
+                      "promptbox-scrollbar min-h-[2.5em] w-full pr-8 text-base-fg placeholder-base-fg/60",
                       isExpanded ? "max-h-[500px]" : "max-h-[5.5em]",
                     )}
                     colorMap={mentionColorMap}
@@ -411,7 +418,7 @@ export const PromptBox = forwardRef<HTMLDivElement, PromptBoxProps>(
                         ref={highlightRef}
                         aria-hidden
                         className={twMerge(
-                          "pointer-events-none absolute inset-0 overflow-y-auto whitespace-pre-wrap break-words text-sm text-base-fg",
+                          "pointer-events-none absolute inset-0 overflow-y-auto whitespace-pre-wrap break-words pr-8 text-sm text-base-fg",
                           isExpanded ? "max-h-[500px]" : "max-h-[5.5em]",
                         )}
                       >
@@ -425,7 +432,7 @@ export const PromptBox = forwardRef<HTMLDivElement, PromptBoxProps>(
                       autoFocus
                       placeholder={placeholder}
                       className={twMerge(
-                        "promptbox-scrollbar min-h-[2.5em] w-full flex-1 resize-y overflow-y-auto bg-transparent text-md text-base-fg placeholder-base-fg/60 focus:outline-none",
+                        "promptbox-scrollbar min-h-[2.5em] w-full flex-1 resize-y overflow-y-auto bg-transparent pr-8 text-md text-base-fg placeholder-base-fg/60 focus:outline-none",
                         isExpanded ? "max-h-[500px]" : "max-h-[5.5em]",
                         hasMentionItems && "text-transparent caret-white",
                       )}
@@ -504,6 +511,7 @@ export const PromptBox = forwardRef<HTMLDivElement, PromptBoxProps>(
                     )}
                   </>
                 )}
+                <PromptFullscreenButton onClick={openFullscreen} />
               </div>
             </div>
 
@@ -547,6 +555,37 @@ export const PromptBox = forwardRef<HTMLDivElement, PromptBoxProps>(
             </div>
           </div>
         </div>
+        <PromptFullscreenModal isOpen={isFullscreen} onClose={closeFullscreen}>
+          {hasMentionItems && mentionItems ? (
+            <MentionTextarea
+              value={prompt}
+              onChange={onPromptChange}
+              mentionItems={mentionItems}
+              placeholder={placeholder}
+              className="promptbox-scrollbar h-full w-full text-base-fg placeholder-base-fg/60"
+              colorMap={mentionColorMap}
+              onKeyDown={(e) => {
+                if (
+                  e.key === "Enter" &&
+                  enterToGenerate &&
+                  !e.shiftKey &&
+                  !e.metaKey
+                ) {
+                  e.preventDefault();
+                  onSubmit();
+                }
+              }}
+            />
+          ) : (
+            <textarea
+              placeholder={placeholder}
+              className="promptbox-scrollbar text-md h-full w-full resize-none bg-transparent text-base-fg placeholder-base-fg/60 focus:outline-none"
+              value={prompt}
+              onChange={handleChange}
+              onKeyDown={handleKeyDown}
+            />
+          )}
+        </PromptFullscreenModal>
       </div>
     );
   },
diff --git a/frontend/apps/artcraft-webapp/src/components/prompt-box/PromptFullscreen.tsx b/frontend/apps/artcraft-webapp/src/components/prompt-box/PromptFullscreen.tsx
new file mode 100644
index 0000000000..3bd1242f4a
--- /dev/null
+++ b/frontend/apps/artcraft-webapp/src/components/prompt-box/PromptFullscreen.tsx
@@ -0,0 +1,135 @@
+import {
+  ReactNode,
+  useCallback,
+  useEffect,
+  useRef,
+  useState,
+} from "react";
+import { Modal } from "@storyteller/ui-modal";
+import { Tooltip } from "@storyteller/ui-tooltip";
+import { FontAwesomeIcon } from "@fortawesome/react-fontawesome";
+import { faUpRightAndDownLeftFromCenter } from "@fortawesome/pro-solid-svg-icons";
+
+// Webapp "focus mode" for the prompt editor. Mirrors the desktop lib's
+// (@storyteller/ui-promptbox) fullscreen feature but lives here because the
+// webapp has its own PromptBox. Reuses the shared @storyteller/ui-modal for a
+// Trello-card-style centered panel + blurred backdrop. The overlay renders a
+// fresh editor bound to the SAME value + onChange, so text/mentions stay
+// continuous across open/close.
+
+// ── Expand button ────────────────────────────────────────────────────────
+
+interface PromptFullscreenButtonProps {
+  onClick: () => void;
+  className?: string;
+}
+
+export const PromptFullscreenButton = ({
+  onClick,
+  className,
+}: PromptFullscreenButtonProps) => {
+  // Absolute positioning lives on the outer wrapper, not the button: Tooltip
+  // wraps its child in its own relative div, so positioning the button directly
+  // would anchor it to that wrapper and land it in the wrong spot.
+  return (
+    <div className={`absolute right-0 top-0 z-10 ${className ?? ""}`}>
+      <Tooltip content="Focus mode" position="top" delay={200}>
+        <button
+          type="button"
+          aria-label="Expand prompt to focus mode"
+          onClick={onClick}
+          className="flex h-6 w-6 items-center justify-center rounded-full bg-base-fg/5 text-base-fg/50 transition-colors hover:bg-base-fg/10 hover:text-base-fg/90 focus:outline-none"
+        >
+          <FontAwesomeIcon
+            icon={faUpRightAndDownLeftFromCenter}
+            className="h-3 w-3"
+          />
+        </button>
+      </Tooltip>
+    </div>
+  );
+};
+
+// ── Fullscreen modal ─────────────────────────────────────────────────────
+
+interface PromptFullscreenModalProps {
+  isOpen: boolean;
+  onClose: () => void;
+  children: ReactNode;
+}
+
+export const PromptFullscreenModal = ({
+  isOpen,
+  onClose,
+  children,
+}: PromptFullscreenModalProps) => {
+  const contentRef = useRef<HTMLDivElement>(null);
+
+  // Focus the editor and drop the caret at the end once the overlay opens.
+  useEffect(() => {
+    if (!isOpen) return;
+    const id = window.setTimeout(() => focusEditorAtEnd(contentRef.current), 60);
+    return () => window.clearTimeout(id);
+  }, [isOpen]);
+
+  return (
+    <Modal
+      isOpen={isOpen}
+      onClose={onClose}
+      accessibleTitle="Prompt focus mode"
+      closeOnOutsideClick
+      closeOnEsc
+      className="h-[70vh] w-full max-w-4xl"
+      backdropClassName="backdrop-blur-md"
+    >
+      {/* Title lives inside the flex column (not the Modal title slot) so the
+          editor fits the fixed panel height cleanly. No overflow-hidden here —
+          the mention autocomplete dropdown renders outside the editor bounds
+          and must not be clipped. */}
+      <div ref={contentRef} className="flex h-full flex-col gap-2">
+        <h2 className="text-lg font-bold text-base-fg">Prompt</h2>
+        {/* flex column so a flex-1 editor (the MentionTextarea root wrapper)
+            or an h-full textarea fills the remaining space. */}
+        <div className="flex min-h-0 flex-1 flex-col">{children}</div>
+      </div>
+    </Modal>
+  );
+};
+
+// Focuses the first prompt editor inside `container` and places the caret at
+// the end of its content. Handles both a plain <textarea> and a contentEditable
+// div (the MentionTextarea), since the overlay can hold either.
+function focusEditorAtEnd(container: HTMLElement | null): void {
+  if (!container) return;
+
+  const textarea = container.querySelector("textarea");
+  if (textarea) {
+    textarea.focus();
+    const end = textarea.value.length;
+    textarea.setSelectionRange(end, end);
+    return;
+  }
+
+  const editable = container.querySelector<HTMLElement>(
+    '[contenteditable="true"]',
+  );
+  if (editable) {
+    editable.focus();
+    const selection = window.getSelection();
+    if (!selection) return;
+    const range = document.createRange();
+    range.selectNodeContents(editable);
+    range.collapse(false); // collapse to the end
+    selection.removeAllRanges();
+    selection.addRange(range);
+  }
+}
+
+// ── State hook ───────────────────────────────────────────────────────────
+
+export function useFullscreenPrompt() {
+  const [isFullscreen, setIsFullscreen] = useState(false);
+  const openFullscreen = useCallback(() => setIsFullscreen(true), []);
+  const closeFullscreen = useCallback(() => setIsFullscreen(false), []);
+  return { isFullscreen, openFullscreen, closeFullscreen };
+}
diff --git a/frontend/apps/artcraft-webapp/src/main.tsx b/frontend/apps/artcraft-webapp/src/main.tsx
index e22bd5eeee..97cf0d70cf 100644
--- a/frontend/apps/artcraft-webapp/src/main.tsx
+++ b/frontend/apps/artcraft-webapp/src/main.tsx
@@ -22,7 +22,7 @@ if (import.meta.env.DEV) {
     // (disabled — it overrides the origin above and points at localhost:12345,
     // which breaks dev unless a local backend is running. Re-enable only when
     // testing against a local storyteller-web.)
-    StorytellerApiHostStore.getInstance().setDevelopment();
+    //StorytellerApiHostStore.getInstance().setDevelopment();
   } catch (e) {
     console.warn("Failed to set dev API host override", e);
   }
diff --git a/frontend/apps/artcraft-webapp/src/pages/pagescene/pagescene.tsx b/frontend/apps/artcraft-webapp/src/pages/pagescene/pagescene.tsx
index 68a4f66f6a..c9d862df2d 100644
--- a/frontend/apps/artcraft-webapp/src/pages/pagescene/pagescene.tsx
+++ b/frontend/apps/artcraft-webapp/src/pages/pagescene/pagescene.tsx
@@ -13,6 +13,7 @@ import { Stage3D, usePageSceneStore } from "@storyteller/ui-pagescene";
 import {
   GalleryModal,
   GalleryDragComponent,
+  galleryDragHidesImmediately,
 } from "@storyteller/ui-gallery-modal";
 import { useSession } from "../../lib/session";
 import { useStage3DCostEstimate } from "../../lib/cost-estimate-api";
@@ -122,6 +123,17 @@ function PageSceneEditor() {
     didAutoCollapseRef.current = true;
   }, [setOpen]);
 
+  // On the 3D editor the primary drop target is the scene behind the gallery
+  // modal, so dragging an asset should hide the gallery immediately (rather than
+  // only once the cursor leaves the modal). This page mounts/unmounts with the
+  // /edit-3d route, so flip the flag back off on leave.
+  useEffect(() => {
+    galleryDragHidesImmediately.value = true;
+    return () => {
+      galleryDragHidesImmediately.value = false;
+    };
+  }, []);
+
   useEffect(() => {
     usePageSceneStore.getState().setCurrentUserToken(user?.user_token);
   }, [user?.user_token]);
diff --git a/frontend/apps/artcraft/app/src/pages/PageImageTo3DObject/ImageTo3DStore.ts b/frontend/apps/artcraft/app/src/pages/PageImageTo3DObject/ImageTo3DStore.ts
index ea3a6e4079..b38348ea84 100644
--- a/frontend/apps/artcraft/app/src/pages/PageImageTo3DObject/ImageTo3DStore.ts
+++ b/frontend/apps/artcraft/app/src/pages/PageImageTo3DObject/ImageTo3DStore.ts
@@ -50,6 +50,9 @@ async function captureModelThumbnail(modelUrl: string): Promise<string | null> {
       scene.add(frontLight);
 
       const loader = new GLTFLoader();
+      // Without anonymous CORS the GLTF + textures taint the WebGL canvas, so
+      // toDataURL() below throws a SecurityError and the thumbnail is lost.
+      loader.setCrossOrigin("anonymous");
       loader.load(
         modelUrl,
         (gltf) => {
@@ -99,7 +102,17 @@ async function captureModelThumbnail(modelUrl: string): Promise<string | null> {
 
           // Render and capture
           renderer.render(scene, camera);
-          const dataUrl = renderer.domElement.toDataURL("image/png");
+          let dataUrl: string | null = null;
+          try {
+            dataUrl = renderer.domElement.toDataURL("image/png");
+          } catch (err) {
+            // A tainted canvas (CORS) throws SecurityError here. Log so the
+            // failure is diagnosable instead of silently producing no thumbnail.
+            console.warn(
+              "[captureModelThumbnail] toDataURL failed (likely CORS taint):",
+              err,
+            );
+          }
 
           // Cleanup
           renderer.dispose();
diff --git a/frontend/apps/artcraft/app/src/pages/PageScene/PageScene.tsx b/frontend/apps/artcraft/app/src/pages/PageScene/PageScene.tsx
index 6d69e79263..dedddc9ebc 100644
--- a/frontend/apps/artcraft/app/src/pages/PageScene/PageScene.tsx
+++ b/frontend/apps/artcraft/app/src/pages/PageScene/PageScene.tsx
@@ -5,9 +5,11 @@
 // The website host mounts the same Stage3D with a web-built adapter
 // and its own router-flavored equivalents of these effects.
 
+import { useEffect } from "react";
 import { useLocation, useNavigate, useParams } from "react-router-dom";
 import { useSignalEffect } from "@preact/signals-react/runtime";
 import { Stage3D, usePageSceneStore } from "@storyteller/ui-pagescene";
+import { galleryDragHidesImmediately } from "@storyteller/ui-gallery-modal";
 import { useTabStore } from "~/pages/Stores/TabState";
 import { authentication, scene } from "~/signals";
 import { getCurrentLocationWithoutParams } from "~/utilities";
@@ -36,6 +38,17 @@ export const PageScene = ({ sceneToken }: { sceneToken?: string }) => {
       .setCurrentUserToken(authentication.userInfo.value?.user_token);
   });
 
+  // On the 3D editor the primary drop target is the scene behind the gallery
+  // modal, so dragging an asset should hide the gallery immediately (rather than
+  // only once the cursor leaves the modal). PageScene mounts/unmounts with the
+  // 3D tab, so flip the flag back off on leave.
+  useEffect(() => {
+    galleryDragHidesImmediately.value = true;
+    return () => {
+      galleryDragHidesImmediately.value = false;
+    };
+  }, []);
+
   // URL ↔ loaded scene sync. Lives in the host wrapper so the lib
   // stays router-agnostic.
   const params = useParams();
@@ -70,6 +83,7 @@ export const PageScene = ({ sceneToken }: { sceneToken?: string }) => {
         sceneToken={sceneToken}
         cacheJsonString={cacheJsonString}
         onSceneSerialized={onSceneSerialized}
+        modelSelectorPlacement="prompt-box"
       />
     </div>
   );
diff --git a/frontend/libs/api/src/lib/models/Folder.ts b/frontend/libs/api/src/lib/models/Folder.ts
index 23332d57e7..fbccd9aed3 100644
--- a/frontend/libs/api/src/lib/models/Folder.ts
+++ b/frontend/libs/api/src/lib/models/Folder.ts
@@ -20,6 +20,12 @@ export interface MediaLinks {
  * placeholders.
  */
 export interface MediaFileCoverImageDetails {
+  /** Modern CDN links for the cover image; prefer `maybe_links.cdn_url`. */
+  maybe_links?: {
+    cdn_url: string;
+    thumbnail_template?: string | null;
+  } | null;
+  /** @deprecated Points at the bucket; use `maybe_links` instead. */
   maybe_cover_image_public_bucket_url?: string | null;
   maybe_cover_image_public_bucket_path?: string | null;
   default_cover?: {
diff --git a/frontend/libs/components/gallery-modal/src/lib/gallery-modal.tsx b/frontend/libs/components/gallery-modal/src/lib/gallery-modal.tsx
index 478ef205d1..beae2467c8 100644
--- a/frontend/libs/components/gallery-modal/src/lib/gallery-modal.tsx
+++ b/frontend/libs/components/gallery-modal/src/lib/gallery-modal.tsx
@@ -748,6 +748,12 @@ export const GalleryModal = React.memo(
       const modalIsOpen =
         isOpen || (mode === "view" && galleryModalVisibleViewMode.value);
       if (!modalIsOpen) return;
+      // Clear any stale drag-under state from a previous session. A canvas-drop
+      // close (reopen-off) intentionally leaves this true so the panel stays
+      // faded through the close animation; if we didn't reset it on reopen, the
+      // freshly-opened modal would render hidden (contentHidden) and the user
+      // couldn't see it — making the library button appear broken.
+      galleryModalDraggingUnder.value = false;
       let cancelled = false;
       (async () => {
         setUsernameError(false);
@@ -793,7 +799,10 @@ export const GalleryModal = React.memo(
           item.media_class === "video"
             ? item.media_links.maybe_video_previews?.animated
             : item.media_class === "dimensional"
-              ? item.cover_image?.maybe_cover_image_public_bucket_url
+              ? // Prefer the modern CDN link; fall back to the deprecated
+                // bucket URL for older responses.
+                (item.cover_image?.maybe_links?.cdn_url ??
+                item.cover_image?.maybe_cover_image_public_bucket_url)
               : getThumbnailUrl(item.media_links.maybe_thumbnail_template, {
                   width: THUMBNAIL_SIZES.MEDIUM,
                 }),
@@ -825,7 +834,9 @@ export const GalleryModal = React.memo(
         label: getLabel(item),
         thumbnail:
           item.media_class === "dimensional"
-            ? (item.cover_image?.maybe_cover_image_public_bucket_url ?? null)
+            ? (item.cover_image?.maybe_links?.cdn_url ??
+              item.cover_image?.maybe_cover_image_public_bucket_url ??
+              null)
             : getMediaThumbnail(item.media_links, item.media_class, {
                 size: THUMBNAIL_SIZES.MEDIUM,
               }),
diff --git a/frontend/libs/components/gallery-modal/src/lib/galleryDnd.ts b/frontend/libs/components/gallery-modal/src/lib/galleryDnd.ts
index 801daebb31..e47fe242df 100644
--- a/frontend/libs/components/gallery-modal/src/lib/galleryDnd.ts
+++ b/frontend/libs/components/gallery-modal/src/lib/galleryDnd.ts
@@ -1,5 +1,6 @@
 import { GalleryItem } from "./gallery-modal";
 import {
+  galleryDragHidesImmediately,
   galleryModalDraggingUnder,
   galleryModalVisibleViewMode,
   galleryReopenAfterDragSignal,
@@ -13,6 +14,11 @@ interface DragState {
   startY: number;
   currX: number;
   currY: number;
+  // True once the cursor has left the modal bounds during a drag. We only then
+  // make the modal pointer-transparent so the drop can pass through to the
+  // canvas. While the cursor is still over the modal (e.g. aiming at a sidebar
+  // folder), the modal stays fully visible and interactive.
+  modalHidden: boolean;
 }
 
 const dragState: DragState = {
@@ -23,6 +29,7 @@ const dragState: DragState = {
   startY: 0,
   currX: 0,
   currY: 0,
+  modalHidden: false,
 };
 
 const dragThreshold = 5;
@@ -121,11 +128,30 @@ function onPointerDown(
   dragState.currX = event.pageX;
   dragState.currY = event.pageY;
   dragState.isDragging = false;
+  dragState.modalHidden = false;
   document.body.style.cursor = "grabbing";
   window.addEventListener("pointermove", onPointerMove);
   window.addEventListener("pointerup", onPointerUp);
 }
 
+/**
+ * Whether a screen point is outside the gallery modal's content bounds. Used to
+ * decide when to make the modal pointer-transparent so a drag can pass under it
+ * onto the canvas. Returns false (treat as inside) when the modal element can't
+ * be found, so we never hide it spuriously.
+ */
+function isOutsideModal(clientX: number, clientY: number): boolean {
+  const modalEl = document.querySelector("[data-gallery-modal]");
+  if (!modalEl) return false;
+  const rect = modalEl.getBoundingClientRect();
+  return (
+    clientX < rect.left ||
+    clientX > rect.right ||
+    clientY < rect.top ||
+    clientY > rect.bottom
+  );
+}
+
 /**
  * The folder chip under a screen point, found geometrically. We can't use
  * `elementFromPoint` here: once a drag begins the modal goes pointer-transparent
@@ -160,11 +186,13 @@ function onPointerMove(event: PointerEvent) {
   ) {
     dragState.isDragging = true;
     createDragPreview(dragState.items.length);
-    // Let pointer events pass through the gallery the moment the drag begins, so
-    // the item can be dropped anywhere — including under the modal. The panel
-    // eases to translucent (reopen on) or all the way out (reopen off) via the
-    // Modal's contentDimmed/contentHidden, so the transition is never abrupt.
-    galleryModalDraggingUnder.value = true;
+    // Hosts with a full-screen canvas behind the modal (e.g. the 3D editor)
+    // hide the gallery the instant the drag starts so the asset can drop
+    // straight into the scene — folders are still hit-tested geometrically.
+    if (galleryDragHidesImmediately.value) {
+      dragState.modalHidden = true;
+      galleryModalDraggingUnder.value = true;
+    }
   }
   dragState.currX = event.pageX;
   dragState.currY = event.pageY;
@@ -172,6 +200,17 @@ function onPointerMove(event: PointerEvent) {
   if (dragState.isDragging) {
     updateDragPreviewPosition(event.clientX, event.clientY);
 
+    // Otherwise only make the modal pointer-transparent once the cursor leaves
+    // its bounds — that's when the user intends a drop onto the canvas behind
+    // it. While the cursor is still over the modal (e.g. aiming at a sidebar
+    // folder) the modal stays fully visible and interactive so folders can be
+    // targeted. Once hidden it stays hidden for the rest of the drag, so
+    // re-entering the (now transparent) panel area doesn't flicker it back.
+    if (!dragState.modalHidden && isOutsideModal(event.clientX, event.clientY)) {
+      dragState.modalHidden = true;
+      galleryModalDraggingUnder.value = true;
+    }
+
     // Highlight the folder under the cursor (if any) — folders still accept
     // drops even while the gallery is dimmed.
     const overFolder = folderIdAt(event.clientX, event.clientY);
@@ -243,10 +282,13 @@ function onPointerUp(event: PointerEvent) {
       emitFolderDrop(dragState.items, folderId);
       spawnDropRipple(event.clientX, event.clientY);
     } else if (
-      dragState.item.mediaClass === "image" ||
-      dragState.item.mediaClass === "dimensional"
+      dragState.modalHidden &&
+      (dragState.item.mediaClass === "image" ||
+        dragState.item.mediaClass === "dimensional")
     ) {
-      // Dropped onto the canvas (anywhere not on a folder) — add to the scene.
+      // The cursor left the modal and dropped onto the canvas (not a folder) —
+      // add to the scene. Gated on `modalHidden` so a missed folder drop *inside*
+      // the modal is a harmless no-op rather than a scene-add that closes it.
       emitImageDrop(dragState.item, { x: event.pageX, y: event.pageY });
       spawnDropRipple(event.clientX, event.clientY);
       // Close the gallery after adding unless the user asked it to stay open.
@@ -267,6 +309,7 @@ function onPointerUp(event: PointerEvent) {
   dragState.item = null;
   dragState.items = [];
   dragState.isDragging = false;
+  dragState.modalHidden = false;
 
   // Refocus the gallery (un-dim, restore pointer events) — unless it's closing,
   // in which case it stays faded until reopened (reset on open).
diff --git a/frontend/libs/components/gallery-modal/src/lib/galleryModalSignals.ts b/frontend/libs/components/gallery-modal/src/lib/galleryModalSignals.ts
index f3a23720c0..d8a960e836 100644
--- a/frontend/libs/components/gallery-modal/src/lib/galleryModalSignals.ts
+++ b/frontend/libs/components/gallery-modal/src/lib/galleryModalSignals.ts
@@ -10,6 +10,13 @@ export const galleryModalVisibleViewMode = signal(false);
 // on drop.
 export const galleryModalDraggingUnder = signal(false);
 
+// When true, the gallery hides the moment a drag starts (instead of only once
+// the cursor leaves the modal bounds). Set by hosts where the primary drop
+// target is a full-screen canvas directly behind the modal — e.g. the 3D editor
+// page — so the user can immediately drop an asset into the scene. Elsewhere
+// (Library, Draw, Moodboard) it stays false so sidebar folders remain targetable.
+export const galleryDragHidesImmediately = signal(false);
+
 // Lightbox Modal Signals
 export const galleryModalLightboxMediaId = signal<string | null>(null);
 export const galleryModalLightboxVisible = signal(false);
diff --git a/frontend/libs/components/menu-icon-selector/src/lib/menu-icon-selector.tsx b/frontend/libs/components/menu-icon-selector/src/lib/menu-icon-selector.tsx
index abe8930722..7520823ff8 100644
--- a/frontend/libs/components/menu-icon-selector/src/lib/menu-icon-selector.tsx
+++ b/frontend/libs/components/menu-icon-selector/src/lib/menu-icon-selector.tsx
@@ -125,7 +125,11 @@ export const MenuIconSelector: React.FC<MenuIconSelectorProps> = ({
             : item.description;
           return (
             <Tooltip
-              key={item.id}
+              // Include activeMenu in the key so the tooltip subtree remounts on
+              // tab change and starts closed. Without this, switching tabs while
+              // hovering leaves the trigger's pointerleave unfired and the tooltip
+              // gets stuck open until the user manually hovers + leaves.
+              key={`${item.id}-${activeMenu}`}
               content={content}
               position={position}
               delay={100}
diff --git a/frontend/libs/components/modal/src/lib/modal.tsx b/frontend/libs/components/modal/src/lib/modal.tsx
index 4dd34f7ef0..1a830c0406 100644
--- a/frontend/libs/components/modal/src/lib/modal.tsx
+++ b/frontend/libs/components/modal/src/lib/modal.tsx
@@ -1042,7 +1042,8 @@ export const Modal = ({
                         ),
                         transform: to(
                           [styles.transform, dimSpring.factor],
-                          (tr, f) => `${tr} scale(${0.93 + 0.07 * (f as number)})`,
+                          (tr, f) =>
+                            `${tr} scale(${0.93 + 0.07 * (f as number)})`,
                         ),
                         transformOrigin: "center center",
                         willChange: "transform, opacity", // Optimize for animations
diff --git a/frontend/libs/components/pagescene/src/lib/engine/keybinds_controls.ts b/frontend/libs/components/pagescene/src/lib/engine/keybinds_controls.ts
index 813b9ae585..72367da64a 100644
--- a/frontend/libs/components/pagescene/src/lib/engine/keybinds_controls.ts
+++ b/frontend/libs/components/pagescene/src/lib/engine/keybinds_controls.ts
@@ -239,6 +239,10 @@ export class MouseControls {
 
     if (currentObject.userData.isCharacter) {
       this.deps.bus.emit(new PoseControlsVisibilityChangedEvent(true));
+    } else {
+      // Selecting a non-character object must hide the pose controls; otherwise
+      // the floating pose button stays stuck from a prior character selection.
+      this.deps.bus.emit(new PoseControlsVisibilityChangedEvent(false));
     }
 
     // Normal selection behavior
@@ -306,6 +310,10 @@ export class MouseControls {
       if (this.deps.getPoseMode() === "pose") {
         this.deps.bus.emit(new PoseModeChangedEvent("select"));
       }
+      // NB: Do NOT hide the pose controls here. Leaving pose mode ("Done") while
+      // the character is still selected should keep the button visible and just
+      // flip it back to "Enter Pose Mode". It only dismisses on actual
+      // deselection (empty-space / Escape / Delete / selecting a non-character).
       console.log("FK mode off");
       return;
     }
diff --git a/frontend/libs/components/promptbox/src/index.ts b/frontend/libs/components/promptbox/src/index.ts
index d133333913..13bf60244b 100644
--- a/frontend/libs/components/promptbox/src/index.ts
+++ b/frontend/libs/components/promptbox/src/index.ts
@@ -3,5 +3,8 @@ export * from "./lib/PromptBox3D";
 export * from "./lib/PromptBoxEdit";
 export * from "./lib/PromptBoxVideo";
 export * from "./lib/PromptBoxImage";
+export * from "./lib/useAutoGrowEditorHeight";
+export * from "./lib/PromptFullscreenModal";
+export * from "./lib/PromptFullscreenButton";
 export * from "./lib/promptStore";
 export * from "./lib/PromptBoxErrorBoundary";
diff --git a/frontend/libs/components/promptbox/src/lib/PromptBox2D.tsx b/frontend/libs/components/promptbox/src/lib/PromptBox2D.tsx
index 1c66983548..ce1993fab5 100644
--- a/frontend/libs/components/promptbox/src/lib/PromptBox2D.tsx
+++ b/frontend/libs/components/promptbox/src/lib/PromptBox2D.tsx
@@ -28,6 +28,11 @@ import { ImagePromptRow, UploadImageFn } from "./ImagePromptRow";
 import { twMerge } from "tailwind-merge";
 import { GenerationProvider } from "@storyteller/api-enums";
 import { GenerationCountPicker } from "./common/GenerationCountPicker";
+import {
+  PromptFullscreenModal,
+  useFullscreenPrompt,
+} from "./PromptFullscreenModal";
+import { PromptFullscreenButton } from "./PromptFullscreenButton";
 import { StoreApi, UseBoundStore } from "zustand";
 import { toast } from "@storyteller/ui-toaster";
 
@@ -78,6 +83,8 @@ export const PromptBox2D = ({
 
   const [isModalOpen, setIsModalOpen] = useState(false);
   const [isExpanded, setIsExpanded] = useState(false);
+  const { isFullscreen, openFullscreen, closeFullscreen } =
+    useFullscreenPrompt();
 
   // CSS viewport units handle resize reactivity automatically
   const EXPANDED_HEIGHT = "clamp(120px, calc(100vh - 700px), 500px)";
@@ -429,7 +436,7 @@ export const PromptBox2D = ({
                 ref={textareaRef}
                 rows={1}
                 placeholder="Describe your image..."
-                className={`promptbox-scrollbar text-md mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-2 pt-1 text-base-fg placeholder-base-fg/60 focus:outline-none ${isExpanded ? "max-h-[500px]" : "max-h-[5.5em]"}`}
+                className={`promptbox-scrollbar text-md mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-8 pt-1 text-base-fg placeholder-base-fg/60 focus:outline-none ${isExpanded ? "max-h-[500px]" : "max-h-[5.5em]"}`}
                 value={prompt}
                 onChange={handleChange}
                 onPaste={handlePaste}
@@ -437,6 +444,7 @@ export const PromptBox2D = ({
                 onFocus={() => {}}
                 onBlur={() => {}}
               />
+              <PromptFullscreenButton onClick={openFullscreen} />
               <span
                 className={`absolute -bottom-1 right-0 text-[10px] tabular-nums ${isFinite(maxLen) && prompt.length > maxLen ? "text-red-500" : "text-base-fg/40"}`}
               >
@@ -545,6 +553,21 @@ export const PromptBox2D = ({
           </div>
         </div>
       </div>
+      <PromptFullscreenModal
+        isOpen={isFullscreen}
+        onClose={closeFullscreen}
+        promptLength={prompt.length}
+        maxLength={maxLen}
+      >
+        <textarea
+          placeholder="Describe your image..."
+          className="promptbox-scrollbar text-md h-full w-full resize-none rounded bg-transparent text-base-fg placeholder-base-fg/60 focus:outline-none"
+          value={prompt}
+          onChange={handleChange}
+          onPaste={handlePaste}
+          onKeyDown={handleKeyDown}
+        />
+      </PromptFullscreenModal>
     </>
   );
 };
diff --git a/frontend/libs/components/promptbox/src/lib/PromptBox3D.tsx b/frontend/libs/components/promptbox/src/lib/PromptBox3D.tsx
index a0fe8a540f..86e766988f 100644
--- a/frontend/libs/components/promptbox/src/lib/PromptBox3D.tsx
+++ b/frontend/libs/components/promptbox/src/lib/PromptBox3D.tsx
@@ -49,6 +49,11 @@ import {
 import { GenerationProvider } from "@storyteller/api-enums";
 import { ImagePromptRow } from "./ImagePromptRow";
 import { AspectRatioPicker } from "./common/AspectRatioPicker";
+import {
+  PromptFullscreenModal,
+  useFullscreenPrompt,
+} from "./PromptFullscreenModal";
+import { PromptFullscreenButton } from "./PromptFullscreenButton";
 
 interface PromptBox3DProps {
   cameras: Camera[];
@@ -136,6 +141,8 @@ export const PromptBox3D = ({
   const setResolution = usePrompt3DStore((s) => s.setResolution);
   const [isEnqueueing, setIsEnqueueing] = useState(false);
   const [isExpanded, setIsExpanded] = useState(false);
+  const { isFullscreen, openFullscreen, closeFullscreen } =
+    useFullscreenPrompt();
 
   const toggleExpand = () => {
     setIsExpanded((prev) => {
@@ -684,7 +691,7 @@ export const PromptBox3D = ({
                 ref={textareaRef}
                 rows={1}
                 placeholder="Describe your image..."
-                className={`promptbox-scrollbar text-md mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-2 pt-1 text-base-fg placeholder-base-fg/60 focus:outline-none ${isExpanded ? "max-h-[300px]" : "max-h-[5.5em]"}`}
+                className={`promptbox-scrollbar text-md mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-8 pt-1 text-base-fg placeholder-base-fg/60 focus:outline-none ${isExpanded ? "max-h-[300px]" : "max-h-[5.5em]"}`}
                 value={prompt}
                 onChange={handleChange}
                 onPaste={handlePaste}
@@ -698,6 +705,7 @@ export const PromptBox3D = ({
                   setIsPromptBoxFocused(false);
                 }}
               />
+              <PromptFullscreenButton onClick={openFullscreen} />
               <span
                 className={`absolute -bottom-1 right-0 text-[10px] tabular-nums ${isFinite(maxLen) && prompt.length > maxLen ? "text-red-500" : "text-base-fg/40"}`}
               >
@@ -885,6 +893,29 @@ export const PromptBox3D = ({
           setFocalLengthDragging={setFocalLengthDragging}
         />
       </div>
+      <PromptFullscreenModal
+        isOpen={isFullscreen}
+        onClose={closeFullscreen}
+        promptLength={prompt.length}
+        maxLength={maxLen}
+      >
+        <textarea
+          placeholder="Describe your image..."
+          className="promptbox-scrollbar text-md h-full w-full resize-none rounded bg-transparent text-base-fg placeholder-base-fg/60 focus:outline-none"
+          value={prompt}
+          onChange={handleChange}
+          onPaste={handlePaste}
+          onKeyDown={handleKeyDown}
+          onFocus={() => {
+            disableHotkeyInput(DomLevels.INPUT);
+            setIsPromptBoxFocused(true);
+          }}
+          onBlur={() => {
+            enableHotkeyInput(DomLevels.INPUT);
+            setIsPromptBoxFocused(false);
+          }}
+        />
+      </PromptFullscreenModal>
     </>
   );
 };
diff --git a/frontend/libs/components/promptbox/src/lib/PromptBoxEdit.tsx b/frontend/libs/components/promptbox/src/lib/PromptBoxEdit.tsx
index 3304402d69..94ed3d9c8e 100644
--- a/frontend/libs/components/promptbox/src/lib/PromptBoxEdit.tsx
+++ b/frontend/libs/components/promptbox/src/lib/PromptBoxEdit.tsx
@@ -30,6 +30,11 @@ import { toast } from "@storyteller/ui-toaster";
 import { GenerationProvider } from "@storyteller/api-enums";
 import { AspectRatioPicker } from "./common/AspectRatioPicker";
 import { GenerationCountPicker } from "./common/GenerationCountPicker";
+import {
+  PromptFullscreenModal,
+  useFullscreenPrompt,
+} from "./PromptFullscreenModal";
+import { PromptFullscreenButton } from "./PromptFullscreenButton";
 
 export interface PromptBoxEditProps {
   onModeChange?: (mode: string) => void;
@@ -83,6 +88,8 @@ export const PromptBoxEdit = ({
   const [prompt, setPrompt] = useState("");
   const [isFocused, setIsFocused] = useState(false);
   const [isExpanded, setIsExpanded] = useState(false);
+  const { isFullscreen, openFullscreen, closeFullscreen } =
+    useFullscreenPrompt();
 
   // CSS viewport units handle resize reactivity automatically
   const EXPANDED_HEIGHT = "clamp(120px, calc(100vh - 700px), 500px)";
@@ -430,7 +437,7 @@ export const PromptBoxEdit = ({
                   ref={textareaRef}
                   rows={1}
                   placeholder="Write what you want to change in your image and click generate..."
-                  className={`promptbox-scrollbar text-md mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-2 pt-1 text-white placeholder-white placeholder:text-white/60 focus:outline-none ${isExpanded ? "max-h-[500px]" : "max-h-[5.5em]"}`}
+                  className={`promptbox-scrollbar text-md mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-8 pt-1 text-white placeholder-white placeholder:text-white/60 focus:outline-none ${isExpanded ? "max-h-[500px]" : "max-h-[5.5em]"}`}
                   value={prompt}
                   onChange={handleChange}
                   onPaste={handlePaste}
@@ -438,6 +445,7 @@ export const PromptBoxEdit = ({
                   onFocus={() => setIsFocused(true)}
                   onBlur={() => setIsFocused(false)}
                 />
+                <PromptFullscreenButton onClick={openFullscreen} />
                 <span
                   className={`absolute -bottom-1 right-0 text-[10px] tabular-nums ${isFinite(maxLen) && prompt.length > maxLen ? "text-red-500" : "text-white/40"}`}
                 >
@@ -555,6 +563,21 @@ export const PromptBoxEdit = ({
           </div>
         </div>
       </div>
+      <PromptFullscreenModal
+        isOpen={isFullscreen}
+        onClose={closeFullscreen}
+        promptLength={prompt.length}
+        maxLength={maxLen}
+      >
+        <textarea
+          placeholder="Write what you want to change in your image and click generate..."
+          className="promptbox-scrollbar text-md h-full w-full resize-none rounded bg-transparent text-base-fg placeholder-base-fg/60 focus:outline-none"
+          value={prompt}
+          onChange={handleChange}
+          onPaste={handlePaste}
+          onKeyDown={handleKeyDown}
+        />
+      </PromptFullscreenModal>
     </>
   );
 };
diff --git a/frontend/libs/components/promptbox/src/lib/PromptBoxImage.tsx b/frontend/libs/components/promptbox/src/lib/PromptBoxImage.tsx
index c1ed36822f..abb57be6f5 100644
--- a/frontend/libs/components/promptbox/src/lib/PromptBoxImage.tsx
+++ b/frontend/libs/components/promptbox/src/lib/PromptBoxImage.tsx
@@ -19,6 +19,9 @@ import {
   RefImage,
   useEnterToGenerateStore,
 } from "./promptStore";
+import { useAutoGrowEditorHeight } from "./useAutoGrowEditorHeight";
+import { PromptFullscreenModal, useFullscreenPrompt } from "./PromptFullscreenModal";
+import { PromptFullscreenButton } from "./PromptFullscreenButton";
 import { gtagEvent } from "@storyteller/google-analytics";
 import { twMerge } from "tailwind-merge";
 import { ImagePromptRow } from "./ImagePromptRow";
@@ -101,20 +104,16 @@ export const PromptBoxImage = ({
   const setGenerationCount = usePromptImageStore((s) => s.setGenerationCount);
   const [isEnqueueing, setIsEnqueueing] = useState(false);
   const [isFocused, setIsFocused] = useState(false);
-  const [isExpanded, setIsExpanded] = useState(false);
 
-  // CSS viewport units handle resize reactivity automatically
-  const EXPANDED_HEIGHT = "clamp(120px, calc(100vh - 700px), 500px)";
-
-  const toggleExpand = () => {
-    setIsExpanded((prev) => {
-      const next = !prev;
-      if (textareaRef.current) {
-        textareaRef.current.style.height = next ? EXPANDED_HEIGHT : "auto";
-      }
-      return next;
-    });
-  };
+  const textareaRef = useRef<HTMLTextAreaElement>(null);
+  // Collapsed auto-grow + manual expand, position-aware and recomputed only on
+  // toggle / content change / viewport resize (not every render).
+  const { isExpanded, toggleExpand } = useAutoGrowEditorHeight(
+    textareaRef,
+    prompt,
+  );
+  const { isFullscreen, openFullscreen, closeFullscreen } =
+    useFullscreenPrompt();
 
   const referenceImages = usePromptImageStore((s) => s.referenceImages);
   const setReferenceImages = usePromptImageStore((s) => s.setReferenceImages);
@@ -176,22 +175,6 @@ export const PromptBoxImage = ({
     },
   ]);
 
-  const textareaRef = useRef<HTMLTextAreaElement>(null);
-
-  useEffect(() => {
-    if (textareaRef.current) {
-      // Hard pixel limit so the resize handle can never exceed viewport
-      const maxH = isExpanded ? 500 : Math.min(window.innerHeight - 700, 500);
-      textareaRef.current.style.maxHeight = `${Math.max(maxH, 88)}px`;
-      textareaRef.current.style.minHeight = "0";
-      if (!isExpanded) {
-        // Cap auto-grow at ~5.5em so it doesn't fight with manual resize
-        const capped = Math.min(textareaRef.current.scrollHeight, 88);
-        textareaRef.current.style.minHeight = `${capped}px`;
-      }
-    }
-  });
-
   useEffect(() => {
     if (imageMediaId && url) {
       const referenceImage: RefImage = {
@@ -467,7 +450,7 @@ export const PromptBoxImage = ({
                 ref={textareaRef}
                 rows={1}
                 placeholder="Describe what you want in the image..."
-                className="promptbox-scrollbar text-md mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-2 pt-1 text-base-fg placeholder-base-fg/60 focus:outline-none"
+                className="promptbox-scrollbar text-md mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-8 pt-1 text-base-fg placeholder-base-fg/60 transition-[height] duration-200 ease-out focus:outline-none"
                 value={prompt}
                 onChange={handleChange}
                 onPaste={handlePaste}
@@ -475,6 +458,7 @@ export const PromptBoxImage = ({
                 onFocus={() => setIsFocused(true)}
                 onBlur={() => setIsFocused(false)}
               />
+              <PromptFullscreenButton onClick={openFullscreen} />
               <span
                 className={`absolute -bottom-1 right-0 text-[10px] tabular-nums ${isFinite(maxLen) && prompt.length > maxLen ? "text-red-500" : "text-base-fg/40"}`}
               >
@@ -585,6 +569,21 @@ export const PromptBoxImage = ({
           </div>
         </div>
       </div>
+      <PromptFullscreenModal
+        isOpen={isFullscreen}
+        onClose={closeFullscreen}
+        promptLength={prompt.length}
+        maxLength={maxLen}
+      >
+        <textarea
+          placeholder="Describe what you want in the image..."
+          className="promptbox-scrollbar text-md h-full w-full resize-none rounded bg-transparent text-base-fg placeholder-base-fg/60 focus:outline-none"
+          value={prompt}
+          onChange={handleChange}
+          onPaste={handlePaste}
+          onKeyDown={handleKeyDown}
+        />
+      </PromptFullscreenModal>
     </>
   );
 };
diff --git a/frontend/libs/components/promptbox/src/lib/PromptBoxVideo.tsx b/frontend/libs/components/promptbox/src/lib/PromptBoxVideo.tsx
index da9c14f8af..a8f5e7b02b 100644
--- a/frontend/libs/components/promptbox/src/lib/PromptBoxVideo.tsx
+++ b/frontend/libs/components/promptbox/src/lib/PromptBoxVideo.tsx
@@ -43,6 +43,11 @@ import { CharactersModal } from "./CharactersModal";
 import { CharactersApi } from "@storyteller/api";
 import { MentionTextarea } from "./MentionTextarea";
 import type { MentionItem } from "./MentionTextarea";
+import {
+  PromptFullscreenModal,
+  useFullscreenPrompt,
+} from "./PromptFullscreenModal";
+import { PromptFullscreenButton } from "./PromptFullscreenButton";
 
 declare global {
   interface Window {
@@ -165,6 +170,8 @@ export const PromptBoxVideo = ({
   const [isEnqueueing, setIsEnqueueing] = useState(false);
   const [isFocused, setIsFocused] = useState(false);
   const [isExpanded, setIsExpanded] = useState(false);
+  const { isFullscreen, openFullscreen, closeFullscreen } =
+    useFullscreenPrompt();
   const [isCharactersModalOpen, setIsCharactersModalOpen] = useState(false);
 
   // Characters store for @-mentions
@@ -1048,7 +1055,7 @@ export const PromptBoxVideo = ({
                       ? "Use @Image1, @Video1, @Audio1... to reference uploads in prompt..."
                       : "Describe what you want to happen in the video..."
                   }
-                  className="promptbox-scrollbar text-md relative mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-2 pt-1 text-base-fg"
+                  className="promptbox-scrollbar text-md relative mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-8 pt-1 text-base-fg"
                   onKeyDown={(e) => {
                     if (e.key !== "Enter") return;
                     const isSubmitCombo = enterToGenerate && !e.shiftKey;
@@ -1071,7 +1078,7 @@ export const PromptBoxVideo = ({
                   ref={textareaRef}
                   rows={1}
                   placeholder="Describe what you want to happen in the video..."
-                  className="promptbox-scrollbar text-md relative mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-2 pt-1 text-base-fg placeholder-base-fg/60 focus:outline-none"
+                  className="promptbox-scrollbar text-md relative mb-2 min-h-[2.5em] w-full resize-y overflow-y-auto rounded bg-transparent pb-2 pr-8 pt-1 text-base-fg placeholder-base-fg/60 focus:outline-none"
                   value={prompt}
                   onChange={handleChange}
                   onPaste={handlePaste}
@@ -1080,6 +1087,7 @@ export const PromptBoxVideo = ({
                   onBlur={() => setIsFocused(false)}
                 />
               )}
+              <PromptFullscreenButton onClick={openFullscreen} />
               <span
                 className={`absolute -bottom-1 right-0 text-[10px] tabular-nums ${isFinite(maxLen) && prompt.length > maxLen ? "text-red-500" : "text-base-fg/40"}`}
               >
@@ -1323,6 +1331,36 @@ export const PromptBoxVideo = ({
         onDownloadClicked={downloadFileFromUrl}
         forceFilter="image"
       />
+      <PromptFullscreenModal
+        isOpen={isFullscreen}
+        onClose={closeFullscreen}
+        promptLength={prompt.length}
+        maxLength={maxLen}
+      >
+        {hasAnyMentionables ? (
+          <MentionTextarea
+            value={prompt}
+            onChange={setPrompt}
+            mentionItems={allMentionItems}
+            colorMap={mentionColorMap}
+            placeholder={
+              isReferenceMode
+                ? "Use @Image1, @Video1, @Audio1... to reference uploads in prompt..."
+                : "Describe what you want to happen in the video..."
+            }
+            className="promptbox-scrollbar text-md h-full w-full resize-none overflow-y-auto rounded bg-transparent text-base-fg"
+          />
+        ) : (
+          <textarea
+            placeholder="Describe what you want to happen in the video..."
+            className="promptbox-scrollbar text-md h-full w-full resize-none rounded bg-transparent text-base-fg placeholder-base-fg/60 focus:outline-none"
+            value={prompt}
+            onChange={handleChange}
+            onPaste={handlePaste}
+            onKeyDown={handleKeyDown}
+          />
+        )}
+      </PromptFullscreenModal>
     </>
   );
 };
diff --git a/frontend/libs/components/promptbox/src/lib/PromptFullscreenButton.tsx b/frontend/libs/components/promptbox/src/lib/PromptFullscreenButton.tsx
new file mode 100644
index 0000000000..064a81eea6
--- /dev/null
+++ b/frontend/libs/components/promptbox/src/lib/PromptFullscreenButton.tsx
@@ -0,0 +1,39 @@
+import { Tooltip } from "@storyteller/ui-tooltip";
+import { FontAwesomeIcon } from "@fortawesome/react-fontawesome";
+import { faUpRightAndDownLeftFromCenter } from "@fortawesome/pro-solid-svg-icons";
+
+// Circular "expand to focus mode" icon, anchored top-right of a prompt editor.
+// Shared so all promptbox variants render an identical control.
+//
+// The absolute positioning lives on an OUTER wrapper (not the button) because
+// Tooltip wraps its child in its own `position: relative` div — putting the
+// absolute styles on the button would anchor it to that inline wrapper instead
+// of the editor, landing it in the wrong spot.
+
+interface PromptFullscreenButtonProps {
+  onClick: () => void;
+  className?: string;
+}
+
+export const PromptFullscreenButton = ({
+  onClick,
+  className,
+}: PromptFullscreenButtonProps) => {
+  return (
+    <div className={`absolute right-0 top-0 z-10 ${className ?? ""}`}>
+      <Tooltip content="Focus mode" position="left">
+        <button
+          type="button"
+          aria-label="Expand prompt to focus mode"
+          onClick={onClick}
+          className="flex h-6 w-6 items-center justify-center rounded-full bg-base-fg/5 text-base-fg/50 transition-colors hover:bg-base-fg/10 hover:text-base-fg/90 focus:outline-none"
+        >
+          <FontAwesomeIcon
+            icon={faUpRightAndDownLeftFromCenter}
+            className="h-3 w-3"
+          />
+        </button>
+      </Tooltip>
+    </div>
+  );
+};
diff --git a/frontend/libs/components/promptbox/src/lib/PromptFullscreenModal.tsx b/frontend/libs/components/promptbox/src/lib/PromptFullscreenModal.tsx
new file mode 100644
index 0000000000..20981964a0
--- /dev/null
+++ b/frontend/libs/components/promptbox/src/lib/PromptFullscreenModal.tsx
@@ -0,0 +1,83 @@
+import { ReactNode, useCallback, useEffect, useRef, useState } from "react";
+import { Modal } from "@storyteller/ui-modal";
+import { focusEditorAtEnd } from "./focusEditorAtEnd";
+
+// Shared "focus mode" overlay for prompt editors. Reuses @storyteller/ui-modal
+// (Trello-card style: centered panel + blurred backdrop) and renders whatever
+// editor the caller passes — a fresh textarea / MentionTextarea instance bound
+// to the SAME store value + onChange, so text and mentions stay continuous
+// across open/close (only the caret resets, as expected for a new instance).
+
+interface PromptFullscreenModalProps {
+  isOpen: boolean;
+  onClose: () => void;
+  /** Current prompt length, for the character counter. */
+  promptLength: number;
+  /** Max prompt length (Infinity for unlimited). */
+  maxLength: number;
+  /**
+   * The editor to render inside the overlay. Pass a fresh textarea /
+   * MentionTextarea bound to the same value + onChange as the inline one.
+   */
+  children: ReactNode;
+}
+
+export const PromptFullscreenModal = ({
+  isOpen,
+  onClose,
+  promptLength,
+  maxLength,
+  children,
+}: PromptFullscreenModalProps) => {
+  const overLimit = isFinite(maxLength) && promptLength > maxLength;
+  const contentRef = useRef<HTMLDivElement>(null);
+
+  // Focus the editor and drop the caret at the end once the overlay opens.
+  useEffect(() => {
+    if (!isOpen) return;
+    const id = window.setTimeout(() => focusEditorAtEnd(contentRef.current), 60);
+    return () => window.clearTimeout(id);
+  }, [isOpen]);
+
+  return (
+    <Modal
+      isOpen={isOpen}
+      onClose={onClose}
+      accessibleTitle="Prompt focus mode"
+      closeOnOutsideClick
+      closeOnEsc
+      className="h-[70vh] w-full max-w-4xl"
+      backdropClassName="backdrop-blur-md"
+    >
+      {/* Title lives inside the flex column (not the Modal title slot) so the
+          editor + counter fit the fixed panel height cleanly. No overflow-hidden
+          here — the mention autocomplete dropdown renders outside the editor
+          bounds and must not be clipped. */}
+      <div className="flex h-full flex-col gap-2">
+        <h2 className="text-lg font-bold text-base-fg">Prompt</h2>
+        {/* flex column so a flex-1 editor (the MentionTextarea root wrapper)
+            or an h-full textarea fills the remaining space. */}
+        <div ref={contentRef} className="flex min-h-0 flex-1 flex-col">
+          {children}
+        </div>
+        <div className="flex items-center justify-end">
+          <span
+            className={`text-[11px] tabular-nums ${
+              overLimit ? "text-red-500" : "text-base-fg/40"
+            }`}
+          >
+            {promptLength} / {isFinite(maxLength) ? maxLength : "∞"}
+          </span>
+        </div>
+      </div>
+    </Modal>
+  );
+};
+
+/** Holds open/close state for a prompt's fullscreen focus mode. */
+export function useFullscreenPrompt() {
+  const [isFullscreen, setIsFullscreen] = useState(false);
+  const openFullscreen = useCallback(() => setIsFullscreen(true), []);
+  const closeFullscreen = useCallback(() => setIsFullscreen(false), []);
+  return { isFullscreen, openFullscreen, closeFullscreen };
+}
diff --git a/frontend/libs/components/promptbox/src/lib/focusEditorAtEnd.ts b/frontend/libs/components/promptbox/src/lib/focusEditorAtEnd.ts
new file mode 100644
index 0000000000..d3c7fd6b76
--- /dev/null
+++ b/frontend/libs/components/promptbox/src/lib/focusEditorAtEnd.ts
@@ -0,0 +1,29 @@
+// Focuses the first prompt editor inside `container` and places the caret at
+// the end of its content. Handles both a plain <textarea> and a contentEditable
+// div (the MentionTextarea), since the fullscreen overlay can hold either.
+
+export function focusEditorAtEnd(container: HTMLElement | null): void {
+  if (!container) return;
+
+  const textarea = container.querySelector("textarea");
+  if (textarea) {
+    textarea.focus();
+    const end = textarea.value.length;
+    textarea.setSelectionRange(end, end);
+    return;
+  }
+
+  const editable = container.querySelector<HTMLElement>(
+    '[contenteditable="true"]',
+  );
+  if (editable) {
+    editable.focus();
+    const selection = window.getSelection();
+    if (!selection) return;
+    const range = document.createRange();
+    range.selectNodeContents(editable);
+    range.collapse(false); // collapse to the end
+    selection.removeAllRanges();
+    selection.addRange(range);
+  }
+}
diff --git a/frontend/libs/components/promptbox/src/lib/useAutoGrowEditorHeight.ts b/frontend/libs/components/promptbox/src/lib/useAutoGrowEditorHeight.ts
new file mode 100644
index 0000000000..623048938f
--- /dev/null
+++ b/frontend/libs/components/promptbox/src/lib/useAutoGrowEditorHeight.ts
@@ -0,0 +1,106 @@
+import { RefObject, useCallback, useEffect, useRef, useState } from "react";
+
+// Reserves room for the inline action-buttons row plus the fixed
+// Model / Costs / Help row at the bottom of the page.
+const BOTTOM_SAFE_AREA_PX = 160;
+
+// Collapsed auto-grow cap (~5.5em) so a long prompt doesn't fight manual resize.
+const COLLAPSED_MAX_PX = 88;
+
+// Absolute ceiling shared by both collapsed and expanded states.
+const HARD_MAX_PX = 500;
+
+// Viewport-relative expansion ceiling. Mirrors the historical
+// `clamp(120px, calc(100vh - 700px), 500px)` so the editor stretches the same
+// amount regardless of where the (bottom-fixed) prompt box sits on screen.
+export const EXPANDED_HEIGHT_CSS = "clamp(120px, calc(100vh - 700px), 500px)";
+
+interface AutoGrowEditorHeight {
+  isExpanded: boolean;
+  toggleExpand: () => void;
+}
+
+/**
+ * Manages a prompt editor's collapsed auto-grow + manual expand behavior.
+ *
+ * - Collapsed: caps height to the editor's actual position so a long prompt
+ *   never pushes the box under the fixed bottom action row.
+ * - Expanded: stretches to a viewport-relative ceiling.
+ *
+ * Heights are recomputed on expand toggle, on content change (`contentKey`),
+ * and on viewport changes (window resize / fullscreen / monitor move) — not on
+ * every render, so it stays out of React's way and avoids layout thrash.
+ *
+ * @param editorRef ref to the textarea (or contenteditable) element being sized
+ * @param contentKey a value that changes when the editor content changes
+ *   (e.g. the prompt string) so auto-grow re-runs on input
+ */
+export function useAutoGrowEditorHeight(
+  editorRef: RefObject<HTMLElement | null>,
+  contentKey: unknown,
+): AutoGrowEditorHeight {
+  const [isExpanded, setIsExpanded] = useState(false);
+
+  const computeExpandedMaxPx = (): number =>
+    Math.max(120, Math.min(window.innerHeight - 700, HARD_MAX_PX));
+
+  const computeCollapsedMaxPx = (el: HTMLElement): number => {
+    const topFromViewport = el.getBoundingClientRect().top;
+    return Math.max(
+      COLLAPSED_MAX_PX,
+      Math.min(
+        HARD_MAX_PX,
+        Math.floor(window.innerHeight - topFromViewport - BOTTOM_SAFE_AREA_PX),
+      ),
+    );
+  };
+
+  const applyHeights = useCallback(() => {
+    const el = editorRef.current;
+    if (!el) return;
+    const maxH = isExpanded ? computeExpandedMaxPx() : computeCollapsedMaxPx(el);
+    el.style.maxHeight = `${maxH}px`;
+    el.style.minHeight = "0";
+    if (!isExpanded) {
+      const capped = Math.min(el.scrollHeight, COLLAPSED_MAX_PX);
+      el.style.minHeight = `${capped}px`;
+    }
+  }, [editorRef, isExpanded]);
+
+  const toggleExpand = useCallback(() => {
+    setIsExpanded((prev) => {
+      const next = !prev;
+      const el = editorRef.current;
+      if (el) {
+        el.style.height = next ? EXPANDED_HEIGHT_CSS : "auto";
+      }
+      return next;
+    });
+  }, [editorRef]);
+
+  // Recompute on expand toggle and whenever the content changes (input/paste).
+  useEffect(() => {
+    applyHeights();
+  }, [applyHeights, contentKey]);
+
+  // Re-apply on viewport changes. Held in a ref so the once-installed listener
+  // always invokes the latest closure. Fires immediately + after a short settle
+  // so getBoundingClientRect reads the final position, not a mid-tween one.
+  const applyHeightsRef = useRef(applyHeights);
+  applyHeightsRef.current = applyHeights;
+  useEffect(() => {
+    let settledId: number | undefined;
+    const onResize = () => {
+      applyHeightsRef.current();
+      if (settledId !== undefined) window.clearTimeout(settledId);
+      settledId = window.setTimeout(() => applyHeightsRef.current(), 100);
+    };
+    window.addEventListener("resize", onResize);
+    return () => {
+      window.removeEventListener("resize", onResize);
+      if (settledId !== undefined) window.clearTimeout(settledId);
+    };
+  }, []);
+
+  return { isExpanded, toggleExpand };
+}
diff --git a/frontend/libs/components/tooltip/src/lib/tooltip.tsx b/frontend/libs/components/tooltip/src/lib/tooltip.tsx
index 3217eb9ebd..4eae74fdff 100644
--- a/frontend/libs/components/tooltip/src/lib/tooltip.tsx
+++ b/frontend/libs/components/tooltip/src/lib/tooltip.tsx
@@ -263,23 +263,52 @@ export const Tooltip = ({
     onOpenChange?.(isShowing);
   }, [isShowing, onOpenChange]);
 
+  // Force-dismiss when the trigger may have moved out from under the cursor
+  // without firing a pointerleave: window/focus loss (e.g. a tab/route change
+  // that re-renders the element under the pointer) and component unmount. Without
+  // this the tooltip stays stuck open until the user manually hovers + leaves.
+  useEffect(() => {
+    const forceClose = () => {
+      setIsHoveringTrigger(false);
+      setIsHoveringTooltip(false);
+      setIsShowing(false);
+    };
+    window.addEventListener("blur", forceClose);
+    document.addEventListener("visibilitychange", forceClose);
+    return () => {
+      window.removeEventListener("blur", forceClose);
+      document.removeEventListener("visibilitychange", forceClose);
+      forceClose();
+    };
+  }, []);
+
   const isFixed = strategy === "fixed";
 
   return (
     <div
       ref={triggerRef}
-      onMouseEnter={() => {
+      onPointerEnter={() => {
         setIsHoveringTrigger(true);
         if (!checkForOpenPopovers() && !disabled) {
           setIsShowing(true);
         }
       }}
-      onMouseLeave={() => {
+      onPointerLeave={() => {
         setIsHoveringTrigger(false);
         if (!interactive) {
           setIsShowing(false);
         }
       }}
+      onPointerCancel={() => {
+        setIsHoveringTrigger(false);
+        setIsHoveringTooltip(false);
+        setIsShowing(false);
+      }}
+      onBlur={() => {
+        setIsHoveringTrigger(false);
+        setIsHoveringTooltip(false);
+        setIsShowing(false);
+      }}
       onClick={handleClick}
       className="relative"
     >
@@ -298,8 +327,8 @@ export const Tooltip = ({
       >
         <div
           ref={setTooltipRef}
-          onMouseEnter={() => interactive && setIsHoveringTooltip(true)}
-          onMouseLeave={() => interactive && setIsHoveringTooltip(false)}
+          onPointerEnter={() => interactive && setIsHoveringTooltip(true)}
+          onPointerLeave={() => interactive && setIsHoveringTooltip(false)}
           onClick={() => {
             if (closeOnClick) {
               setIsShowing(false);
diff --git a/frontend/libs/components/viewer-3d/src/lib/viewer-3d.tsx b/frontend/libs/components/viewer-3d/src/lib/viewer-3d.tsx
index ab9eae7052..9142481859 100644
--- a/frontend/libs/components/viewer-3d/src/lib/viewer-3d.tsx
+++ b/frontend/libs/components/viewer-3d/src/lib/viewer-3d.tsx
@@ -305,6 +305,9 @@ export function Viewer3D({
       });
     } else {
       const loader = new GLTFLoader();
+      // Anonymous CORS keeps the WebGL canvas untainted so thumbnail capture
+      // (offscreen toDataURL elsewhere) works on models loaded from the CDN.
+      loader.setCrossOrigin("anonymous");
       loader.load(
         modelUrl,
         (gltf) => {