chain-studio/lib/widgets/chain_workspace_switcher.dart

// ChainWorkspaceSwitcher — the AppBar workspace (project) control.
//
// One control, two mechanics (docs/architecture/projects.md,
// § Studio): for open/protected projects the choice sets the page
// filter AND the label new runs are stamped with. "All projects"
// stays reachable — a filter, not a jail. Sealed areas are a real
// CONNECTION SWITCH: selecting one reconnects Studio to the area's
// own hub (starting it first if stopped, with a notice) and colours
// the identity bar. Studio's blue stays the app accent — the project
// colour is marking, not theming.

import 'package:flutter/material.dart';

import '../data/sealed_areas.dart';
import '../data/workspace.dart';
import '../l10n/app_localizations.dart';
import '../theme/tokens.dart';

/// Menu-value scheme: '' = all projects, `p:<slug>` = shared project,
/// `s:<slug>` = sealed area.
const _kAll = '';
const _pProject = 'p:';
const _pSealed = 's:';

class ChainWorkspaceSwitcher extends StatelessWidget {
  const ChainWorkspaceSwitcher({super.key});

  @override
  Widget build(BuildContext context) {
    return ListenableBuilder(
      listenable: Workspace.instance,
      builder: (context, _) {
        final l = AppLocalizations.of(context)!;
        final theme = Theme.of(context);
        final ws = Workspace.instance;

        final label = ws.inSealedArea
            ? ws.activeSealed!.name
            : (ws.isAll ? l.workspaceAll : (ws.active?.name ?? ws.activeSlug));

        return Tooltip(
          message: l.workspaceSwitcherTooltip,
          child: PopupMenuButton<String>(
            onOpened: ws.refresh,
            onSelected: (v) => _onSelected(context, v),
            itemBuilder: (context) => _items(context, ws, l, theme),
            child: _pill(context, ws, l, theme, label),
          ),
        );
      },
    );
  }

  List<PopupMenuEntry<String>> _items(
    BuildContext context,
    Workspace ws,
    AppLocalizations l,
    ThemeData theme,
  ) {
    final items = <PopupMenuEntry<String>>[
      PopupMenuItem(
        value: _kAll,
        child: Row(
          children: [
            Icon(
              Icons.grid_view_outlined,
              size: 16,
              color: theme.colorScheme.onSurfaceVariant,
            ),
            const SizedBox(width: ChainSpace.sm),
            Text(l.workspaceAll),
          ],
        ),
      ),
    ];
    if (ws.projects.isNotEmpty) items.add(const PopupMenuDivider());
    for (final p in ws.projects) {
      items.add(
        PopupMenuItem(
          value: '$_pProject${p.slug}',
          child: Row(
            children: [
              _ProjectDot(color: p.color),
              const SizedBox(width: ChainSpace.sm),
              Flexible(child: Text(p.name, overflow: TextOverflow.ellipsis)),
              if (p.isProtected) ...[
                const SizedBox(width: ChainSpace.sm),
                Tooltip(
                  message: l.workspaceProtectedHint,
                  child: Icon(
                    Icons.shield_outlined,
                    size: 14,
                    color: theme.colorScheme.onSurfaceVariant,
                  ),
                ),
              ],
            ],
          ),
        ),
      );
    }
    if (ws.sealedAreas.isNotEmpty) {
      items.add(const PopupMenuDivider());
      items.add(
        PopupMenuItem(
          enabled: false,
          height: 28,
          child: Text(
            l.workspaceSealedHeader,
            style: theme.textTheme.labelSmall?.copyWith(
              color: theme.colorScheme.onSurfaceVariant,
              letterSpacing: 0.6,
            ),
          ),
        ),
      );
      for (final a in ws.sealedAreas) {
        items.add(
          PopupMenuItem(
            value: '$_pSealed${a.slug}',
            child: Row(
              children: [
                _ProjectDot(color: a.color),
                const SizedBox(width: ChainSpace.sm),
                Icon(
                  Icons.lock_outline,
                  size: 13,
                  color: theme.colorScheme.onSurfaceVariant,
                ),
                const SizedBox(width: 4),
                Flexible(child: Text(a.name, overflow: TextOverflow.ellipsis)),
                const SizedBox(width: ChainSpace.sm),
                Text(
                  a.running ? l.workspaceSealedRunning : l.workspaceSealedStopped,
                  style: theme.textTheme.labelSmall?.copyWith(
                    color: a.running
                        ? ChainColors.success
                        : theme.colorScheme.onSurfaceVariant,
                  ),
                ),
              ],
            ),
          ),
        );
      }
    }
    return items;
  }

  Future<void> _onSelected(BuildContext context, String value) async {
    final ws = Workspace.instance;
    final l = AppLocalizations.of(context)!;
    final messenger = ScaffoldMessenger.of(context);

    if (value == _kAll) {
      await ws.setActive('');
      return;
    }
    if (value.startsWith(_pProject)) {
      await ws.setActive(value.substring(_pProject.length));
      return;
    }
    if (value.startsWith(_pSealed)) {
      final slug = value.substring(_pSealed.length);
      SealedArea? area;
      for (final a in ws.sealedAreas) {
        if (a.slug == slug) area = a;
      }
      if (area == null) return;
      // Announce the intent — starting a stopped area takes a beat.
      if (!area.running) {
        messenger.showSnackBar(
          SnackBar(content: Text(l.workspaceSealedStarting(area.name))),
        );
      }
      final r = await ws.switchToSealed(area);
      messenger.hideCurrentSnackBar();
      if (!r.ok) {
        messenger.showSnackBar(
          SnackBar(
            content: SelectableText(l.workspaceSealedSwitchFailed(r.error)),
            duration: const Duration(seconds: 8),
          ),
        );
      } else if (r.started) {
        messenger.showSnackBar(
          SnackBar(content: Text(l.workspaceSealedStarted(area.name))),
        );
      }
    }
  }

  Widget _pill(
    BuildContext context,
    Workspace ws,
    AppLocalizations l,
    ThemeData theme,
    String label,
  ) {
    final Widget leading;
    if (ws.inSealedArea) {
      leading = Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          _ProjectDot(color: ws.activeSealed!.color),
          const SizedBox(width: 4),
          Icon(
            Icons.lock_outline,
            size: 13,
            color: theme.colorScheme.onSurfaceVariant,
          ),
          const SizedBox(width: 4),
        ],
      );
    } else if (ws.active != null) {
      leading = Padding(
        padding: const EdgeInsets.only(right: 6),
        child: _ProjectDot(color: ws.active!.color),
      );
    } else {
      leading = Padding(
        padding: const EdgeInsets.only(right: 6),
        child: Icon(
          Icons.grid_view_outlined,
          size: 14,
          color: theme.colorScheme.onSurfaceVariant,
        ),
      );
    }

    return Container(
      padding: const EdgeInsets.symmetric(horizontal: ChainSpace.md, vertical: 5),
      decoration: BoxDecoration(
        color: theme.colorScheme.surfaceContainerHighest,
        borderRadius: BorderRadius.circular(ChainRadius.sm),
      ),
      child: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          leading,
          ConstrainedBox(
            constraints: const BoxConstraints(maxWidth: 160),
            child: Text(
              label,
              overflow: TextOverflow.ellipsis,
              style: theme.textTheme.labelMedium,
            ),
          ),
          if (!ws.inSealedArea && (ws.active?.isProtected ?? false)) ...[
            const SizedBox(width: 4),
            Icon(
              Icons.shield_outlined,
              size: 13,
              color: theme.colorScheme.onSurfaceVariant,
            ),
          ],
          const SizedBox(width: 2),
          Icon(
            Icons.arrow_drop_down,
            size: 18,
            color: theme.colorScheme.onSurfaceVariant,
          ),
        ],
      ),
    );
  }
}

/// The project's registry colour as a small marking dot. Falls back
/// to the theme's outline colour when unset.
class _ProjectDot extends StatelessWidget {
  final String color;

  const _ProjectDot({required this.color});

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Container(
      width: 10,
      height: 10,
      decoration: BoxDecoration(
        color: parseAreaColor(color) ?? theme.colorScheme.outline,
        shape: BoxShape.circle,
      ),
    );
  }
}

/// Parse a `#rrggbb` hex colour, or null when unparseable.
Color? parseAreaColor(String hex) {
  final h = hex.replaceFirst('#', '');
  if (h.length != 6) return null;
  final v = int.tryParse(h, radix: 16);
  if (v == null) return null;
  return Color(0xFF000000 | v);
}