Move attribution toggle from YAML metadata to Settings sidebar

Attribution was previously opt-in via `attribution: true` in the qmd
YAML frontmatter. This is a viewing concern, not a document property,
so move it to a persistent UI toggle in the Settings sidebar instead.

The toggle appears only when the preview format is q2-debug and is
labeled "Authorship" for clarity. The preference persists across
sessions via localStorage.

Author: shikokuchuo

hub-client/src/components/Editor.tsx

@@ -1,4 +1,4 @@
-import { useState, useCallback, useRef, useEffect, useMemo } from 'react';
+import { useState, useCallback, useRef, useEffect } from 'react';
 import MonacoEditor from '@monaco-editor/react';
 import type * as Monaco from 'monaco-editor';
 import type { ProjectEntry, FileEntry } from '../types/project';
@@ -360,19 +360,9 @@ export default function Editor({ project, files, fileContents, onDisconnect, onC
   // effect's setContent(automergeContent) always produces a state change.
   const displayContent = replayState.isActive ? replayState.currentContent : content;
 
-  // Per-node attribution for q2-debug AST view (opt-in via `attribution: true` in YAML metadata)
-  const attributionEnabled = useMemo(() => {
-    if (currentFormat !== 'q2-debug' || !astJson) return false;
-    try {
-      const ast = JSON.parse(astJson);
-      const val = ast?.meta?.attribution;
-      // MetaBool: { t: "MetaBool", c: true }
-      if (val?.t === 'MetaBool') return val.c === true;
-      // MetaString: { t: "MetaString", c: "true" }
-      if (val?.t === 'MetaString') return val.c === 'true';
-      return false;
-    } catch { return false; }
-  }, [currentFormat, astJson]);
+  // Per-node attribution for q2-debug AST view (opt-in via Settings sidebar toggle)
+  const [attributionPref, setAttributionPref] = usePreference('attributionEnabled');
+  const attributionEnabled = currentFormat === 'q2-debug' && attributionPref;
   const attribution = useAttribution(attributionEnabled ? (currentFile?.path ?? null) : null, displayContent);
   const attributionContextValue = attribution ? {
     attributionMap: attribution.attributionMap,
@@ -986,6 +976,9 @@ export default function Editor({ project, files, fileContents, onDisconnect, onC
                     <SettingsTab
                       scrollSyncEnabled={scrollSyncEnabled}
                       onScrollSyncChange={setScrollSyncEnabled}
+                      attributionEnabled={attributionPref}
+                      onAttributionChange={setAttributionPref}
+                      currentFormat={currentFormat ?? ''}
                     />
                   );
                 case 'about':

hub-client/src/components/tabs/SettingsTab.tsx

@@ -15,11 +15,17 @@ import { usePreference } from '../../hooks/usePreference';
 interface SettingsTabProps {
   scrollSyncEnabled: boolean;
   onScrollSyncChange: (enabled: boolean) => void;
+  attributionEnabled: boolean;
+  onAttributionChange: (enabled: boolean) => void;
+  currentFormat: string;
 }
 
 export default function SettingsTab({
   scrollSyncEnabled,
   onScrollSyncChange,
+  attributionEnabled,
+  onAttributionChange,
+  currentFormat,
 }: SettingsTabProps) {
   const [errorOverlayCollapsed, setErrorOverlayCollapsed] = usePreference('errorOverlayCollapsed');
   const [isCapturing, setIsCapturing] = useState(false);
@@ -93,6 +99,19 @@ export default function SettingsTab({
             Show errors as a small indicator instead of expanded panel
           </span>
         </label>
+        {currentFormat === 'q2-debug' && (
+          <label className="setting-toggle">
+            <input
+              type="checkbox"
+              checked={attributionEnabled}
+              onChange={(e) => onAttributionChange(e.target.checked)}
+            />
+            <span className="setting-name">Authorship</span>
+            <span className="setting-description">
+              Highlight who wrote each part of the document
+            </span>
+          </label>
+        )}
         <div style={{ marginTop: '16px' }}>
           <button
             className="screenshot-button"

hub-client/src/services/preferences/schema.ts

@@ -9,6 +9,7 @@ export const UserPreferencesSchema = z.object({
   version: z.literal(1),
   scrollSyncEnabled: z.boolean(),
   errorOverlayCollapsed: z.boolean(),
+  attributionEnabled: z.boolean(),
   colorScheme: ColorSchemeSchema,
 });
 
@@ -23,6 +24,7 @@ export const DEFAULT_PREFERENCES: UserPreferences = {
   version: 1,
   scrollSyncEnabled: true,
   errorOverlayCollapsed: true, // collapsed by default
+  attributionEnabled: false,
   colorScheme: 'auto',
 };