feat: add workspace files to chat from Files and Changes

* feat(app): open changed files from context menu

* fix(app): preserve changed-file row behavior

* feat(app): add changed files to open chats

* feat(app): share file actions across explorer and changes

* feat(app): attach workspace files to focused chat

* feat(app): drag workspace files into chat

* refactor(app): use file actions menu for changed files

* fix(app): open changed-file actions on right click

* test(app): cover direct file attachment flow

* fix(app): enable add to chat on native

* fix(app): align workspace file pane rows

* refactor(app): simplify workspace file attachments

* fix(app): preserve uploaded file draft attachments

---------

Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>

packages/app/src/components/file-drop/types.ts

@@ -1,4 +1,5 @@
 import type { ImageAttachment } from "@/composer/types";
+import type { WorkspaceFileDragPayload } from "@/attachments/workspace-file-drag";
 
 export interface DroppedFileItem {
   kind: "web-file";
@@ -18,4 +19,5 @@ export type DroppedItem = DroppedFileItem | DroppedPathItem;
 export interface FileDropSink {
   onFiles: (images: ImageAttachment[]) => void;
   onGenericFiles?: (items: DroppedItem[]) => void;
+  onWorkspaceFile?: (payload: WorkspaceFileDragPayload) => void;
 }

packages/app/src/components/file-drop/use-drop-listeners.ts

@@ -11,6 +11,10 @@ import {
 } from "@/attachments/file-types";
 import { isWeb } from "@/constants/platform";
 import type { DroppedItem, DroppedPathItem, FileDropSink } from "./types";
+import {
+  parseWorkspaceFileDragPayload,
+  WORKSPACE_FILE_DRAG_MIME,
+} from "@/attachments/workspace-file-drag";
 
 type DesktopDragDropPayload =
   | { type: "enter"; paths: string[] }
@@ -185,7 +189,11 @@ export function useDropListeners({
         if (disabledRef.current) return;
 
         dragCounter.current++;
-        if (e.dataTransfer?.types.includes("Files")) {
+        if (suppressed.value || !hasSink.value) return;
+        const types = new Set(e.dataTransfer?.types ?? []);
+        const acceptsWorkspaceFile =
+          types.has(WORKSPACE_FILE_DRAG_MIME) && Boolean(getSink()?.onWorkspaceFile);
+        if (types.has("Files") || acceptsWorkspaceFile) {
           isDragging.value = true;
         }
       }
@@ -197,7 +205,11 @@ export function useDropListeners({
         if (!e.dataTransfer) return;
         // Only advertise "copy" when the drop would actually be accepted, so the cursor doesn't
         // promise a drop that the handler then discards (suppressed/archived/no consumer mounted).
-        const canAccept = !disabledRef.current && !suppressed.value && hasSink.value;
+        const types = new Set(e.dataTransfer.types);
+        const acceptsWorkspaceFile =
+          types.has(WORKSPACE_FILE_DRAG_MIME) && Boolean(getSink()?.onWorkspaceFile);
+        const acceptsDrop = types.has("Files") || acceptsWorkspaceFile;
+        const canAccept = acceptsDrop && !disabledRef.current && !suppressed.value && hasSink.value;
         e.dataTransfer.dropEffect = canAccept ? "copy" : "none";
       }
 
@@ -225,6 +237,14 @@ export function useDropListeners({
         const sink = getSink();
         if (!sink) return;
 
+        const serializedWorkspaceFile = e.dataTransfer?.getData(WORKSPACE_FILE_DRAG_MIME);
+        if (serializedWorkspaceFile && sink.onWorkspaceFile) {
+          const payload = parseWorkspaceFileDragPayload(serializedWorkspaceFile);
+          if (payload) {
+            sink.onWorkspaceFile(payload);
+          }
+        }
+
         const files = Array.from(e.dataTransfer?.files ?? []);
         const genericItems: DroppedItem[] = files.map((file) => ({
           kind: "web-file",