feat(settings): About section — vendor, versions, license, contact

Procurement personas found no vendor, version, license, or
support information anywhere in the app (a hard checklist fail
for regulated buyers). Settings gains an About category:
product name, Studio + running-hub version, vendor Flemming.AI,
author, Apache 2.0 license, contact address, and the docs URL —
every value selectable and one-click copyable. Studio version
constant moved to data/about_info.dart so sidebar tag and About
can never drift. Bumps Studio to 0.71.0.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/data/about_info.dart

@@ -0,0 +1,14 @@
+// Product identity shown in Settings → About and the sidebar
+// version tag. One place to bump so procurement-facing facts
+// (vendor, license, contact) can never drift between surfaces.
+
+/// Studio's own build version. Bump on every UI release so the
+/// running app self-identifies.
+const String kStudioVersion = '0.71.0';
+
+const String kProductName = 'Ch∆In Studio';
+const String kVendorName = 'Flemming.AI (F∆I)';
+const String kAuthorName = 'Dr. Stefan Flemming';
+const String kLicenseName = 'Apache 2.0';
+const String kContactEmail = 'chain@flemming.ai';
+const String kDocsUrl = 'https://chain.flemming.ai';

lib/data/hub.dart

@@ -1187,6 +1187,22 @@ class HubService {
   }
 
   /// Composite "doctor" snapshot. One round-trip per piece, run
+  /// Version string of the RUNNING hub (from CheckUpdate's
+  /// local_version — a local RPC field; the manifest fetch result
+  /// is ignored). Empty when the hub is unreachable. Used by
+  /// Settings → About.
+  Future<String> hubVersion() async {
+    try {
+      final r = await _client.checkUpdate().timeout(
+            const Duration(seconds: 2),
+            onTimeout: () => CheckUpdateResponse(),
+          );
+      return r.localVersion;
+    } catch (_) {
+      return '';
+    }
+  }
+
   /// in parallel so the page populates fast.
   Future<DoctorSnapshot> doctor() async {
     final results = await Future.wait([

lib/l10n/app_de.arb

@@ -1549,6 +1549,21 @@
   "doctorPathStudioErrors": "Studio-Fehler",
   "settingsCategoryGeneral": "Allgemein",
   "settingsCategoryAppearance": "Darstellung",
+  "settingsCategoryAbout": "Über",
+  "aboutPanelTitle": "Über Ch∆In",
+  "aboutPanelBody": "Produkt-, Hersteller- und Lizenzangaben dieser Installation — alle Werte sind kopierbar.",
+  "aboutProduct": "Produkt",
+  "aboutStudioVersion": "Studio-Version",
+  "aboutHubVersion": "Hub-Version",
+  "aboutHubVersionUnknown": "nicht verbunden",
+  "aboutVendor": "Hersteller",
+  "aboutAuthor": "Autor",
+  "aboutLicense": "Lizenz",
+  "aboutContact": "Kontakt",
+  "aboutDocs": "Dokumentation",
+  "aboutOpenLink": "Im Browser öffnen",
+  "aboutCopyTooltip": "Kopieren",
+  "aboutCopiedToast": "In die Zwischenablage kopiert.",
   "sidebarSearchLabel": "Suchen & Befehle",
   "settingsSidebarPinnedTitle": "Navigation immer ausgeklappt",
   "settingsSidebarPinnedBody": "Zeigt die Beschriftungen der Seitenleiste dauerhaft an, statt sie nur beim Überfahren mit der Maus einzublenden.",

lib/l10n/app_en.arb

@@ -1573,6 +1573,21 @@
   "doctorPathStudioErrors": "Studio errors",
   "settingsCategoryGeneral": "General",
   "settingsCategoryAppearance": "Appearance",
+  "settingsCategoryAbout": "About",
+  "aboutPanelTitle": "About Ch∆In",
+  "aboutPanelBody": "Product, vendor, and license details of this installation — every value is copyable.",
+  "aboutProduct": "Product",
+  "aboutStudioVersion": "Studio version",
+  "aboutHubVersion": "Hub version",
+  "aboutHubVersionUnknown": "not connected",
+  "aboutVendor": "Vendor",
+  "aboutAuthor": "Author",
+  "aboutLicense": "License",
+  "aboutContact": "Contact",
+  "aboutDocs": "Documentation",
+  "aboutOpenLink": "Open in browser",
+  "aboutCopyTooltip": "Copy",
+  "aboutCopiedToast": "Copied to the clipboard.",
   "sidebarSearchLabel": "Search & commands",
   "settingsSidebarPinnedTitle": "Keep the navigation expanded",
   "settingsSidebarPinnedBody": "Shows the sidebar labels permanently instead of only while hovering with the mouse.",

lib/l10n/app_localizations.dart

@@ -4544,6 +4544,96 @@ abstract class AppLocalizations {
   /// **'Appearance'**
   String get settingsCategoryAppearance;
 
+  /// No description provided for @settingsCategoryAbout.
+  ///
+  /// In en, this message translates to:
+  /// **'About'**
+  String get settingsCategoryAbout;
+
+  /// No description provided for @aboutPanelTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'About Ch∆In'**
+  String get aboutPanelTitle;
+
+  /// No description provided for @aboutPanelBody.
+  ///
+  /// In en, this message translates to:
+  /// **'Product, vendor, and license details of this installation — every value is copyable.'**
+  String get aboutPanelBody;
+
+  /// No description provided for @aboutProduct.
+  ///
+  /// In en, this message translates to:
+  /// **'Product'**
+  String get aboutProduct;
+
+  /// No description provided for @aboutStudioVersion.
+  ///
+  /// In en, this message translates to:
+  /// **'Studio version'**
+  String get aboutStudioVersion;
+
+  /// No description provided for @aboutHubVersion.
+  ///
+  /// In en, this message translates to:
+  /// **'Hub version'**
+  String get aboutHubVersion;
+
+  /// No description provided for @aboutHubVersionUnknown.
+  ///
+  /// In en, this message translates to:
+  /// **'not connected'**
+  String get aboutHubVersionUnknown;
+
+  /// No description provided for @aboutVendor.
+  ///
+  /// In en, this message translates to:
+  /// **'Vendor'**
+  String get aboutVendor;
+
+  /// No description provided for @aboutAuthor.
+  ///
+  /// In en, this message translates to:
+  /// **'Author'**
+  String get aboutAuthor;
+
+  /// No description provided for @aboutLicense.
+  ///
+  /// In en, this message translates to:
+  /// **'License'**
+  String get aboutLicense;
+
+  /// No description provided for @aboutContact.
+  ///
+  /// In en, this message translates to:
+  /// **'Contact'**
+  String get aboutContact;
+
+  /// No description provided for @aboutDocs.
+  ///
+  /// In en, this message translates to:
+  /// **'Documentation'**
+  String get aboutDocs;
+
+  /// No description provided for @aboutOpenLink.
+  ///
+  /// In en, this message translates to:
+  /// **'Open in browser'**
+  String get aboutOpenLink;
+
+  /// No description provided for @aboutCopyTooltip.
+  ///
+  /// In en, this message translates to:
+  /// **'Copy'**
+  String get aboutCopyTooltip;
+
+  /// No description provided for @aboutCopiedToast.
+  ///
+  /// In en, this message translates to:
+  /// **'Copied to the clipboard.'**
+  String get aboutCopiedToast;
+
   /// No description provided for @sidebarSearchLabel.
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_de.dart

@@ -2666,6 +2666,52 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get settingsCategoryAppearance => 'Darstellung';
 
+  @override
+  String get settingsCategoryAbout => 'Über';
+
+  @override
+  String get aboutPanelTitle => 'Über Ch∆In';
+
+  @override
+  String get aboutPanelBody =>
+      'Produkt-, Hersteller- und Lizenzangaben dieser Installation — alle Werte sind kopierbar.';
+
+  @override
+  String get aboutProduct => 'Produkt';
+
+  @override
+  String get aboutStudioVersion => 'Studio-Version';
+
+  @override
+  String get aboutHubVersion => 'Hub-Version';
+
+  @override
+  String get aboutHubVersionUnknown => 'nicht verbunden';
+
+  @override
+  String get aboutVendor => 'Hersteller';
+
+  @override
+  String get aboutAuthor => 'Autor';
+
+  @override
+  String get aboutLicense => 'Lizenz';
+
+  @override
+  String get aboutContact => 'Kontakt';
+
+  @override
+  String get aboutDocs => 'Dokumentation';
+
+  @override
+  String get aboutOpenLink => 'Im Browser öffnen';
+
+  @override
+  String get aboutCopyTooltip => 'Kopieren';
+
+  @override
+  String get aboutCopiedToast => 'In die Zwischenablage kopiert.';
+
   @override
   String get sidebarSearchLabel => 'Suchen & Befehle';
 

lib/l10n/app_localizations_en.dart

@@ -2668,6 +2668,52 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get settingsCategoryAppearance => 'Appearance';
 
+  @override
+  String get settingsCategoryAbout => 'About';
+
+  @override
+  String get aboutPanelTitle => 'About Ch∆In';
+
+  @override
+  String get aboutPanelBody =>
+      'Product, vendor, and license details of this installation — every value is copyable.';
+
+  @override
+  String get aboutProduct => 'Product';
+
+  @override
+  String get aboutStudioVersion => 'Studio version';
+
+  @override
+  String get aboutHubVersion => 'Hub version';
+
+  @override
+  String get aboutHubVersionUnknown => 'not connected';
+
+  @override
+  String get aboutVendor => 'Vendor';
+
+  @override
+  String get aboutAuthor => 'Author';
+
+  @override
+  String get aboutLicense => 'License';
+
+  @override
+  String get aboutContact => 'Contact';
+
+  @override
+  String get aboutDocs => 'Documentation';
+
+  @override
+  String get aboutOpenLink => 'Open in browser';
+
+  @override
+  String get aboutCopyTooltip => 'Copy';
+
+  @override
+  String get aboutCopiedToast => 'Copied to the clipboard.';
+
   @override
   String get sidebarSearchLabel => 'Search & commands';
 

lib/main.dart

@@ -10,6 +10,7 @@ import 'package:flutter/foundation.dart' show defaultTargetPlatform;
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
+import 'data/about_info.dart';
 import 'data/chain_log.dart';
 import 'data/error_presentation.dart';
 import 'data/hub.dart';
@@ -33,10 +34,9 @@ import 'theme/tokens.dart';
 import 'widgets/chain_search_palette.dart';
 import 'widgets/widgets.dart';
 
-/// Studio's own build version. Bump on every UI commit so the
-/// running app self-identifies — visible in the sidebar header
-/// and quick-glance proof that you're seeing the current build.
-const String kStudioVersion = '0.70.0';
+/// Studio's own build version — canonical value lives in
+/// data/about_info.dart (shared with Settings → About).
+export 'data/about_info.dart' show kStudioVersion;
 
 /// Run one pre-frame restore step, absorbing any failure. Everything
 /// before `runApp` is a black window waiting to happen: an exception

lib/widgets/chain_settings_dialog.dart

@@ -4,7 +4,9 @@
 
 import 'package:chain_client_sdk/chain_client_sdk.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart' show Clipboard, ClipboardData;
 
+import '../data/about_info.dart';
 import '../data/error_presentation.dart';
 import '../data/hub.dart';
 import '../data/hub_auth_token.dart';
@@ -41,7 +43,15 @@ class ChainSettingsDialog extends StatefulWidget {
 /// Sidebar categories — every Settings panel belongs to exactly
 /// one. Order here drives the sidebar order and the
 /// first-opened category.
-enum _Category { general, appearance, ai, integrations, security, maintenance }
+enum _Category {
+  general,
+  appearance,
+  ai,
+  integrations,
+  security,
+  maintenance,
+  about,
+}
 
 class _FaiSettingsDialogState extends State<ChainSettingsDialog> {
   late final TextEditingController _host;
@@ -70,6 +80,10 @@ class _FaiSettingsDialogState extends State<ChainSettingsDialog> {
   /// auth-policy panel below re-queries with the new credentials.
   int _authPolicyReloadTick = 0;
 
+  /// Running hub's version for the About panel. Null while
+  /// loading, empty string when the hub is unreachable.
+  String? _hubVersion;
+
   @override
   void initState() {
     super.initState();
@@ -83,6 +97,13 @@ class _FaiSettingsDialogState extends State<ChainSettingsDialog> {
     _loadN8nEndpoints();
     _loadRegistryToken();
     _loadHubAuthToken();
+    _loadHubVersion();
+  }
+
+  Future<void> _loadHubVersion() async {
+    final v = await HubService.instance.hubVersion();
+    if (!mounted) return;
+    setState(() => _hubVersion = v);
   }
 
   Future<void> _loadHubAuthToken() async {
@@ -392,6 +413,7 @@ class _FaiSettingsDialogState extends State<ChainSettingsDialog> {
       _Category.integrations => _integrationsPanel(l, theme),
       _Category.security => _securityPanel(l, theme),
       _Category.maintenance => _maintenancePanel(l, theme),
+      _Category.about => _aboutPanel(l, theme),
     };
     return SingleChildScrollView(
       padding: const EdgeInsets.fromLTRB(
@@ -621,6 +643,39 @@ class _FaiSettingsDialogState extends State<ChainSettingsDialog> {
     ];
   }
 
+  List<Widget> _aboutPanel(AppLocalizations l, ThemeData theme) {
+    // Procurement-facing identity: who makes this, which
+    // versions run, under which license, whom to contact.
+    // Every value is selectable AND has a copy affordance.
+    return [
+      _panelTitle(l.aboutPanelTitle, l.aboutPanelBody, theme),
+      _AboutRow(label: l.aboutProduct, value: kProductName),
+      _AboutRow(label: l.aboutStudioVersion, value: kStudioVersion),
+      _AboutRow(
+        label: l.aboutHubVersion,
+        value: _hubVersion == null
+            ? '…'
+            : _hubVersion!.isEmpty
+                ? l.aboutHubVersionUnknown
+                : _hubVersion!,
+      ),
+      _AboutRow(label: l.aboutVendor, value: kVendorName),
+      _AboutRow(label: l.aboutAuthor, value: kAuthorName),
+      _AboutRow(label: l.aboutLicense, value: kLicenseName),
+      _AboutRow(label: l.aboutContact, value: kContactEmail),
+      _AboutRow(
+        label: l.aboutDocs,
+        value: kDocsUrl,
+        trailing: IconButton(
+          icon: const Icon(Icons.open_in_new, size: 16),
+          tooltip: l.aboutOpenLink,
+          visualDensity: VisualDensity.compact,
+          onPressed: () => SystemActions.openInOs(kDocsUrl),
+        ),
+      ),
+    ];
+  }
+
   List<Widget> _aiPanel(AppLocalizations l, ThemeData theme) {
     return [
       _panelTitle(
@@ -779,6 +834,55 @@ class _FaiSettingsDialogState extends State<ChainSettingsDialog> {
   }
 }
 
+/// Label/value row of the About panel. The value is selectable
+/// and carries an explicit copy button (procurement reviewers
+/// paste these into checklists).
+class _AboutRow extends StatelessWidget {
+  final String label;
+  final String value;
+  final Widget? trailing;
+
+  const _AboutRow({required this.label, required this.value, this.trailing});
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final l = AppLocalizations.of(context)!;
+    return Padding(
+      padding: const EdgeInsets.symmetric(vertical: ChainSpace.xs),
+      child: Row(
+        children: [
+          SizedBox(
+            width: 150,
+            child: Text(
+              label,
+              style: theme.textTheme.bodySmall?.copyWith(
+                color: theme.colorScheme.onSurfaceVariant,
+              ),
+            ),
+          ),
+          Expanded(
+            child: SelectableText(value, style: theme.textTheme.bodyMedium),
+          ),
+          IconButton(
+            icon: const Icon(Icons.copy_outlined, size: 14),
+            tooltip: l.aboutCopyTooltip,
+            visualDensity: VisualDensity.compact,
+            onPressed: () async {
+              await Clipboard.setData(ClipboardData(text: value));
+              if (!context.mounted) return;
+              ScaffoldMessenger.of(context).showSnackBar(
+                SnackBar(content: Text(l.aboutCopiedToast)),
+              );
+            },
+          ),
+          ?trailing,
+        ],
+      ),
+    );
+  }
+}
+
 class _ChannelRow extends StatelessWidget {
   final ChannelInfo channel;
   final bool active;
@@ -2635,6 +2739,7 @@ class _Sidebar extends StatelessWidget {
         Icons.build_outlined,
         l.settingsCategoryMaintenance,
       ),
+      (_Category.about, Icons.info_outline, l.settingsCategoryAbout),
     ];
     return SizedBox(
       width: 220,