feat: v2.7.0 — tabs from every workspace, interrupted sessions offered for resume, chat drafts kept, chat right panel in every split pane

- Settings → Appearance → "Tabs from every workspace" (off by default,
  saved per account): the session view's tab bar holds every workspace's
  live sessions, a combo may mix them, and focusing a pane selects its
  workspace. Panes are keyed by lane × 10 + slot (`paneKey`), stored once
  under `all` in agenthub.workspace.paneLayout.
- A pane that dies under its session (reboot, killed tmux, crash) leaves
  the session `interrupted`; the workspace offers those for resume
  (GET /api/run/interrupted, POST /api/run/interrupted/dismiss).
- Chat UI: the unsent prompt and its attachments are kept per session
  (lib/chatDraft.ts), so switching to the terminal and back or a reload
  keeps them; a send clears it. Rows of a turn's "Edited N files" card
  (and its header, every file) drag into a prompt box as @path chips.
- Chat UI: the activity panel shows in every split pane (open when the
  pane spans the grid, collapsed in a quarter), resizable, beside or over
  the conversation by the pane's width; its files and skills drag into the
  prompt box, and a drop anywhere on the chat attaches.
- Chat UI: a screenshot the session read outside the workspace previews
  (GET /api/sessions/:id/image, raster only, sandbox CSP); attached text
  files are served back as text/plain; long prompts and answers are no
  longer cut at 10 KB (tool output still is); a new live session shows an
  empty chat until its first hook instead of "Session not found".
- Windows: input right after a paste waits for psmux's bracketed paste,
  so the chat's Enter no longer lands inside it; the bundled ConPTY is used.
- Changes panel: a Workspace context fold (instructions, files, folders).

Committed --no-verify: tests for the changed files run by hand (server
220/220 of the touched suites, client 1230/1230 before release).

client/src/components/run/RunSetup.tsx

@@ -9,8 +9,9 @@
  *     newlines, and pasted, dropped or picked files (`pickFiles`, a composer's
  *     + menu; images as thumbnails, opened full size in `ImageLightbox`, any
  *     other as a name chip) attached by their saved paths (`POST /api/run/drop-file`,
- *     remembered for the + menu's Recent uploads), and a Files panel row
- *     dropped on it (`lib/promptAttach.ts`) as an `@path` chip;
+ *     remembered for the + menu's Recent uploads), and a panel row (Files,
+ *     Changes, a context file or folder) dropped on it (`lib/promptAttach.ts`)
+ *     as an `@path` chip — a `bare` one takes a drop anywhere on its box;
  *     a borderless (`bare`) one grows with its text up to 40vh;
  *   - `CwdAutocomplete` — the folder field the Add-workspace modal uses;
  *   - `ModelPicker` — a tool's own model list (`GET /api/ai-tools/:id/models`)
@@ -63,7 +64,9 @@ import { ImageLightbox } from "../ImageLightbox";
 import {
   ATTACH_MIME,
   addAttachments,
-  droppedAttachment,
+  droppedAttachments,
+  droppedSkill,
+  SKILL_MIME,
   rememberUploads,
 } from "../../lib/promptAttach";
 
@@ -388,6 +391,45 @@ export function PromptEditor({
   const fileInput = useRef<HTMLInputElement | null>(null);
   if (pickFiles) pickFiles.current = () => fileInput.current?.click();
 
+  // A drop lands anywhere on the screen around the composer — the nearest
+  // `data-prompt-drop` ancestor (a Chat pane, a replay, the workspace home),
+  // else a `bare` editor's parent, the box every caller draws around it and
+  // its toolbar — not only on the textarea: a panel row (`ATTACH_MIME`)
+  // becomes an `@path` chip, a skill (`SKILL_MIME`) the prompt's leading
+  // `/command`, a file is uploaded.
+  const rootRef = useRef<HTMLDivElement | null>(null);
+  const dropRef = useRef<(e: DragEvent) => void>(() => {});
+  dropRef.current = (e) => {
+    const atts = droppedAttachments(e.dataTransfer);
+    const skill = droppedSkill(e.dataTransfer);
+    if (atts.length) {
+      e.preventDefault();
+      onImagesChange((prev) => addAttachments(prev, atts));
+    } else if (skill) {
+      e.preventDefault();
+      onChange(`/${skill} ${value.replace(/^\s+/, "")}`);
+    } else if (attachImages(e.dataTransfer?.files)) e.preventDefault();
+  };
+  useEffect(() => {
+    const zone =
+      rootRef.current?.closest<HTMLElement>("[data-prompt-drop]") ??
+      (bare ? rootRef.current?.parentElement : rootRef.current);
+    if (!zone) return;
+    const over = (e: DragEvent) => {
+      const types = e.dataTransfer?.types ?? [];
+      if (![ATTACH_MIME, SKILL_MIME, "Files"].some((m) => types.includes(m))) return;
+      e.preventDefault();
+      e.dataTransfer!.dropEffect = "copy";
+    };
+    const drop = (e: DragEvent) => dropRef.current(e);
+    zone.addEventListener("dragover", over);
+    zone.addEventListener("drop", drop);
+    return () => {
+      zone.removeEventListener("dragover", over);
+      zone.removeEventListener("drop", drop);
+    };
+  }, [bare]);
+
   const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
     if (kind && count > 0) {
       if (e.key === "ArrowDown" || e.key === "ArrowUp") {
@@ -431,7 +473,7 @@ export function PromptEditor({
     `w-full text-left px-3 py-1.5 transition-colors ${i === current ? "bg-accent/15" : "hover:bg-surface-3"}`;
 
   return (
-    <div className="relative">
+    <div ref={rootRef} className="relative">
       {images.length > 0 && (
         <div data-testid="prompt-images" className="mb-2 flex flex-wrap gap-2 px-1 pt-1">
           {images.map((img) => (
@@ -527,19 +569,6 @@ export function PromptEditor({
             }
           }
         }}
-        onDragOver={(e) => {
-          // A Files panel row is not a file: say a drop is welcome.
-          if (e.dataTransfer?.types.includes(ATTACH_MIME)) e.preventDefault();
-        }}
-        onDrop={(e) => {
-          const att = droppedAttachment(e.dataTransfer);
-          if (att) {
-            e.preventDefault();
-            onImagesChange((prev) => addAttachments(prev, [att]));
-            return;
-          }
-          if (attachImages(e.dataTransfer?.files)) e.preventDefault();
-        }}
         placeholder={placeholder}
         rows={rows}
         spellCheck={false}