feat: paste composer text without formatting (#4801)

## Summary

- handle Cmd+Shift+V on macOS and Ctrl+Shift+V on Windows/Linux in the
message composer
- read plain text through the native Tauri/arboard clipboard path in
packaged builds, with a browser-only Clipboard API fallback
- re-enter ProseMirror's paste pipeline with populated `text/plain`
clipboard data so selection, undo, multiline behavior, and paste
observers remain intact
- cover both platform mappings with rendered composer E2E tests that
assert the native command path

## Testing

- `pnpm test` — 4,286 passed
- `pnpm check`
- `pnpm typecheck`
- `pnpm exec playwright test composer-selection-formatting.spec.ts
--project=smoke` — 26 passed
- `cargo check --manifest-path desktop/src-tauri/Cargo.toml --workspace
--all-targets --target aarch64-apple-darwin`
- `just desktop-tauri-test` — 2,206 core tests plus integration and
doc-test groups passed
- full pre-push hooks passed

## Manual verification

Physical packaged-app clipboard verification remains recommended on
macOS, Windows, and Linux. The automated E2E uses mocked Tauri IPC but
asserts the native `read_clipboard_text` command is invoked.

Signed-off-by: npub1dccv64krpcpse5cmkzfeh998cftungyatw3djt8jwdw6g43f7fyqzzmrf7 <6e30cd56c30e030cd31bb0939b94a7c257c9a09d5ba2d92cf2735da45629f248@buzz.block.builderlab.xyz>
Co-authored-by: npub1dccv64krpcpse5cmkzfeh998cftungyatw3djt8jwdw6g43f7fyqzzmrf7 <6e30cd56c30e030cd31bb0939b94a7c257c9a09d5ba2d92cf2735da45629f248@buzz.block.builderlab.xyz>

desktop/src-tauri/src/commands/clipboard.rs

@@ -34,3 +34,22 @@ pub fn with_clipboard<T>(
     operation(stored.as_mut().expect("clipboard initialized"))
         .map_err(|e| format!("clipboard error: {e}"))
 }
+
+/// Read plain text from the system clipboard through the native shell.
+///
+/// Browser clipboard reads are permission-gated or unavailable in embedded
+/// webviews. Arboard provides one consistent path across WKWebView, WebView2,
+/// and WebKitGTK. The operation runs on the main thread for macOS/AppKit safety.
+#[tauri::command]
+pub async fn read_clipboard_text(app: tauri::AppHandle) -> Result<String, String> {
+    let (tx, rx) = std::sync::mpsc::sync_channel::<Result<String, String>>(1);
+    let clipboard_app = app.clone();
+    app.run_on_main_thread(move || {
+        let result = with_clipboard(&clipboard_app, arboard::Clipboard::get_text);
+        let _ = tx.send(result);
+    })
+    .map_err(|e| format!("main thread dispatch failed: {e}"))?;
+
+    rx.recv()
+        .map_err(|_| "clipboard result channel closed unexpectedly".to_string())?
+}

desktop/src-tauri/src/lib.rs

@@ -732,6 +732,7 @@ pub fn run() {
             fetch_media_bytes,
             copy_image_to_clipboard,
             copy_text_to_clipboard,
+            read_clipboard_text,
             fetch_snapshot_bytes,
             relay_requires_membership,
             list_relay_members,

desktop/src/features/messages/lib/useRichTextEditor.ts

@@ -9,6 +9,7 @@ import { Extension, type KeyboardShortcutCommand } from "@tiptap/core";
 import { Plugin, Selection, TextSelection } from "@tiptap/pm/state";
 import type { ResolvedPos } from "@tiptap/pm/model";
 
+import { readTextFromSystemClipboard } from "@/shared/api/tauriMedia";
 import {
   hasPrimaryShortcutModifier,
   isMacPlatform,
@@ -532,6 +533,39 @@ export function useRichTextEditor({
             return true;
           }
 
+          // Cmd+Shift+V / Ctrl+Shift+V → paste the clipboard's plain-text
+          // representation. Embedded webviews permission-gate the browser
+          // clipboard API differently across operating systems, so packaged
+          // builds read through the native arboard command. Browser builds use
+          // navigator.clipboard as a fallback. Feed the result through
+          // ProseMirror's paste pipeline with clipboardData populated so its
+          // plain-text observers keep normal paste behavior.
+          if (
+            event.key.toLowerCase() === "v" &&
+            hasPrimaryShortcutModifier(event) &&
+            event.shiftKey &&
+            !event.altKey &&
+            !event.repeat &&
+            !event.isComposing
+          ) {
+            event.preventDefault();
+            void readTextFromSystemClipboard()
+              .then((text) => {
+                const clipboardData = new DataTransfer();
+                clipboardData.setData("text/plain", text);
+                view.pasteText(
+                  text,
+                  new ClipboardEvent("paste", { clipboardData }),
+                );
+              })
+              .catch(() => {
+                // The key is already consumed. Letting a delayed native paste
+                // race the asynchronous read could duplicate or unexpectedly
+                // format content.
+              });
+            return true;
+          }
+
           // ⌘K / Ctrl+K → link editor. The formatting toolbar has always
           // advertised this shortcut on its link button; bind it here so it
           // actually works. Kept alongside the ArrowUp handling below rather

desktop/src/shared/api/tauriMedia.ts

@@ -1,4 +1,4 @@
-import { invoke as invokeTauriRaw } from "@tauri-apps/api/core";
+import { invoke as invokeTauriRaw, isTauri } from "@tauri-apps/api/core";
 import { type BlobDescriptor, invokeTauri } from "./tauri";
 
 function encodeRawIpcHeader(value: string): string {
@@ -66,6 +66,23 @@ export async function fetchMediaBytes(
   return new Uint8Array(bytes);
 }
 
+/** Read plain text without depending on embedded-webview clipboard grants. */
+export async function readTextFromSystemClipboard(): Promise<string> {
+  // E2E installs Tauri's mocked IPC surface in a browser page, where the SDK's
+  // `isTauri()` marker remains false. Exercise the packaged-app command path in
+  // that build so tests detect accidental regressions to permission-gated DOM
+  // clipboard reads.
+  if (isTauri() || import.meta.env.MODE === "e2e") {
+    return invokeTauri<string>("read_clipboard_text");
+  }
+
+  const clipboard = navigator.clipboard;
+  if (!clipboard?.readText) {
+    throw new Error("Clipboard text reading is unavailable");
+  }
+  return clipboard.readText();
+}
+
 /** Write text through the native clipboard after an asynchronous workflow. */
 export async function copyTextToSystemClipboard(
   text: string,

desktop/src/testing/e2eBridge.ts

@@ -12516,6 +12516,8 @@ export function maybeInstallE2eTauriMocks() {
       case "copy_text_to_clipboard":
         await navigator.clipboard.writeText((payload as { text: string }).text);
         return;
+      case "read_clipboard_text":
+        return navigator.clipboard.readText();
       case "get_event":
         return handleGetEvent(
           payload as Parameters<typeof handleGetEvent>[0],

desktop/tests/e2e/composer-selection-formatting.spec.ts

@@ -177,6 +177,68 @@ async function applyCaretFormat(
   await page.getByRole("button", { name: label, exact: true }).click();
 }
 
+for (const platform of [
+  { name: "macOS", navigatorPlatform: "MacIntel", shortcut: "Meta+Shift+V" },
+  {
+    name: "Windows/Linux",
+    navigatorPlatform: "Win32",
+    shortcut: "Control+Shift+V",
+  },
+]) {
+  test(`pastes rich clipboard content without formatting on ${platform.name}`, async ({
+    page,
+  }) => {
+    await page.addInitScript((navigatorPlatform) => {
+      Object.defineProperty(navigator, "platform", {
+        configurable: true,
+        value: navigatorPlatform,
+      });
+    }, platform.navigatorPlatform);
+    await page
+      .context()
+      .grantPermissions(["clipboard-read", "clipboard-write"], {
+        origin: "http://127.0.0.1:4173",
+      });
+    await openGeneral(page);
+
+    await page.evaluate(async () => {
+      await navigator.clipboard.write([
+        new ClipboardItem({
+          "text/html": new Blob(
+            [
+              '<p><strong>Bold</strong> and <a href="https://example.com">linked</a></p><ul><li>list item</li></ul>',
+            ],
+            { type: "text/html" },
+          ),
+          "text/plain": new Blob(["Bold and linked\nlist item"], {
+            type: "text/plain",
+          }),
+        }),
+      ]);
+    });
+
+    const input = page.getByTestId("message-input");
+    await input.click();
+    await page.keyboard.press(platform.shortcut);
+
+    await expect
+      .poll(() =>
+        page.evaluate(
+          () =>
+            (window as Window & { __BUZZ_E2E_COMMANDS__?: string[] })
+              .__BUZZ_E2E_COMMANDS__ ?? [],
+        ),
+      )
+      .toContain("read_clipboard_text");
+    await expect(input).toHaveText("Bold and linkedlist item");
+    await expect(input.locator("strong, a, ul, li")).toHaveCount(0);
+    await expect(input.locator(":scope > p")).toHaveText([
+      "Bold and linked",
+      "list item",
+    ]);
+  });
+}
+
 for (const format of [
   { label: "Code block", selector: "pre" },
   { label: "Bullet list", selector: "ul" },