fix(editor): add dirty check and allow clearing description

Two editor bugs fixed:

1. Descriptions saved unnecessarily on every document change (no dirty
   check). Added onCreate baseline capture + string comparison in the
   debounced onUpdate handler so mutations only fire when content
   actually changes.

2. Clearing a description didn't persist — empty string was converted
   to undefined via `md || undefined`, causing the field to be omitted
   from the API request. Changed to `md` so empty strings reach the
   backend and clear the description via COALESCE.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/views/editor/content-editor.tsx

@@ -112,6 +112,7 @@ const ContentEditor = forwardRef<ContentEditorRef, ContentEditorProps>(
     const onBlurRef = useRef(onBlur);
     const onUploadFileRef = useRef(onUploadFile);
     const prevContentRef = useRef(defaultValue);
+    const lastEmittedRef = useRef<string | null>(null);
 
     // Keep refs in sync without recreating editor
     onUpdateRef.current = onUpdate;
@@ -127,6 +128,9 @@ const ContentEditor = forwardRef<ContentEditorRef, ContentEditorProps>(
       // Explicit for clarity — the real perf win is useEditorState in BubbleMenu.
       shouldRerenderOnTransaction: false,
       editable,
+      onCreate: ({ editor: ed }) => {
+        lastEmittedRef.current = stripBlobUrls(ed.getMarkdown());
+      },
       content: defaultValue ? preprocessMarkdown(defaultValue) : "",
       contentType: defaultValue ? "markdown" : undefined,
       extensions: createEditorExtensions({
@@ -141,7 +145,10 @@ const ContentEditor = forwardRef<ContentEditorRef, ContentEditorProps>(
         if (!onUpdateRef.current) return;
         if (debounceRef.current) clearTimeout(debounceRef.current);
         debounceRef.current = setTimeout(() => {
-          onUpdateRef.current?.(stripBlobUrls(ed.getMarkdown()));
+          const md = stripBlobUrls(ed.getMarkdown());
+          if (md === lastEmittedRef.current) return;
+          lastEmittedRef.current = md;
+          onUpdateRef.current?.(md);
         }, debounceMs);
       },
       onBlur: () => {

packages/views/issues/components/issue-detail.test.tsx

@@ -1,6 +1,6 @@
 import { forwardRef, useRef, useState, useImperativeHandle } from "react";
 import { describe, it, expect, vi, beforeEach } from "vitest";
-import { render, screen, waitFor } from "@testing-library/react";
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
 import type { Issue, TimelineEntry } from "@multica/core/types";
 import { WorkspaceIdProvider } from "@multica/core/hooks";
@@ -474,4 +474,22 @@ describe("IssueDetail (shared)", () => {
 
     expect(screen.getByText("I can help with this")).toBeInTheDocument();
   });
+
+  it("sends empty description when editor is cleared", async () => {
+    renderIssueDetail();
+
+    await waitFor(() => {
+      expect(screen.getByDisplayValue("Add JWT auth to the backend")).toBeInTheDocument();
+    });
+
+    const editor = screen.getByPlaceholderText("Add description...");
+    fireEvent.change(editor, { target: { value: "" } });
+
+    await waitFor(() => {
+      expect(mockApiObj.updateIssue).toHaveBeenCalledWith(
+        "issue-1",
+        expect.objectContaining({ description: "" }),
+      );
+    });
+  });
 });

packages/views/issues/components/issue-detail.tsx

@@ -1032,7 +1032,7 @@ export function IssueDetail({ issueId, onDelete, defaultSidebarOpen = true, layo
               key={id}
               defaultValue={issue.description || ""}
               placeholder="Add description..."
-              onUpdate={(md) => handleUpdateField({ description: md || undefined })}
+              onUpdate={(md) => handleUpdateField({ description: md })}
               onUploadFile={handleDescriptionUpload}
               debounceMs={1500}
             />