feat: project chip + file-wins guard (multi-project stage 2)

When the open flow declares its own top-level project:, show it as a
chip in the tab action strip. On mismatch with the host's active
workspace, an amber file-wins pill offers a one-click Switch to
<project> — the file always wins for the run; switching only aligns
the workspace view.

New optional FlowEditorPage.activeProject + onSwitchToFileProject.
Parse + normalize (mirrors the hub's normalize_project_slug) lives in
flow_project.dart, unit-tested. flutter analyze clean, 57 tests green.

Signed-off-by: flemming-it <sf@flemming.it>

lib/src/flow_editor_page.dart

@@ -31,6 +31,7 @@ import 'package:flutter_code_editor/flutter_code_editor.dart';
 
 import 'editor_controller.dart';
 import 'editor_style.dart';
+import 'flow_project.dart';
 import 'flow_yaml_controller.dart';
 import 'l10n.dart';
 import 'model/flow_graph.dart';
@@ -100,6 +101,19 @@ class FlowEditorPage extends StatefulWidget {
   /// silent — no install button offered.
   final List<String> storeCapabilities;
 
+  /// The host's active workspace/project slug (empty = "all
+  /// projects", no active workspace). Used only to flag a
+  /// mismatch when the open flow file declares a *different*
+  /// top-level `project:` — the file always wins for the run;
+  /// the mismatch banner just offers to align the workspace view.
+  final String activeProject;
+
+  /// Invoked when the operator accepts the "switch to the file's
+  /// project" action on a mismatch. The host switches its active
+  /// workspace to the given slug. `null` hides the switch action
+  /// (the mismatch note still shows — the file still wins).
+  final void Function(String fileProject)? onSwitchToFileProject;
+
   const FlowEditorPage({
     super.key,
     this.initialFlowName,
@@ -110,6 +124,8 @@ class FlowEditorPage extends StatefulWidget {
     this.onInstallCapability,
     this.onAddModuleSource,
     this.storeCapabilities = const [],
+    this.activeProject = '',
+    this.onSwitchToFileProject,
   });
 
   @override
@@ -170,6 +186,14 @@ class _FlowEditorPageState extends State<FlowEditorPage>
     if (mounted) setState(() {});
   }
 
+  /// The open flow's own top-level `project:` slug, or empty when
+  /// the YAML declares none. Parsed live from the buffer so the
+  /// chip tracks edits.
+  String _fileProject() {
+    if (_controller.activeName == null) return '';
+    return parseFlowProject(_controller.codeController.fullText);
+  }
+
   void _onHoverChanged() {
     final req = _controller.codeController.hoverRequest.value;
     if (req == null) {
@@ -617,6 +641,9 @@ outputs:
                   _controller.analyzerErrorCount == 0
               ? () => _tabs.animateTo(2)
               : null,
+          fileProject: _fileProject(),
+          activeProject: widget.activeProject,
+          onSwitchToFileProject: widget.onSwitchToFileProject,
         ),
         Expanded(
           child: TabBarView(
@@ -1014,6 +1041,13 @@ class _TabActionStrip extends StatelessWidget {
   final VoidCallback? onAddStep;
   final VoidCallback? onSave;
   final VoidCallback? onRun;
+
+  /// The open file's own `project:` (empty when it declares none).
+  final String fileProject;
+
+  /// The host's active workspace slug (empty = all projects).
+  final String activeProject;
+  final void Function(String fileProject)? onSwitchToFileProject;
   const _TabActionStrip({
     required this.strings,
     required this.tabs,
@@ -1023,6 +1057,9 @@ class _TabActionStrip extends StatelessWidget {
     required this.onAddStep,
     required this.onSave,
     required this.onRun,
+    required this.fileProject,
+    required this.activeProject,
+    required this.onSwitchToFileProject,
   });
 
   @override
@@ -1093,12 +1130,94 @@ class _TabActionStrip extends StatelessWidget {
                 ),
               ],
               const Spacer(),
+              ..._projectChip(context, theme),
             ],
           ),
         );
       },
     );
   }
+
+  /// The right-aligned project affordance. Nothing when the file
+  /// declares no `project:`. A neutral chip when the file's project
+  /// matches (or there is no active workspace). A mismatch pill with
+  /// a one-click switch when the file's project differs from the
+  /// active workspace — the file always wins for the run; switching
+  /// only aligns the workspace view.
+  List<Widget> _projectChip(BuildContext context, ThemeData theme) {
+    if (fileProject.isEmpty) return const [];
+    final mismatch = activeProject.isNotEmpty && activeProject != fileProject;
+    if (!mismatch) {
+      return [
+        Tooltip(
+          message: strings.projectChipTooltip,
+          child: Container(
+            padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
+            decoration: BoxDecoration(
+              color: theme.colorScheme.surfaceContainerHighest,
+              borderRadius: BorderRadius.circular(FaiRadius.sm),
+            ),
+            child: Row(
+              mainAxisSize: MainAxisSize.min,
+              children: [
+                Icon(
+                  Icons.folder_outlined,
+                  size: 13,
+                  color: theme.colorScheme.onSurfaceVariant,
+                ),
+                const SizedBox(width: 6),
+                Text(
+                  strings.projectChip(fileProject),
+                  style: theme.textTheme.labelSmall,
+                ),
+              ],
+            ),
+          ),
+        ),
+      ];
+    }
+    // Mismatch: file wins. Amber pill + optional switch action.
+    final amber = theme.colorScheme.brightness == Brightness.dark
+        ? const Color(0xFFE0A458)
+        : const Color(0xFFB4791F);
+    return [
+      Tooltip(
+        message: strings.projectMismatch(fileProject),
+        child: Container(
+          padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
+          decoration: BoxDecoration(
+            color: amber.withValues(alpha: 0.12),
+            borderRadius: BorderRadius.circular(FaiRadius.sm),
+            border: Border.all(color: amber.withValues(alpha: 0.4)),
+          ),
+          child: Row(
+            mainAxisSize: MainAxisSize.min,
+            children: [
+              Icon(Icons.info_outline, size: 13, color: amber),
+              const SizedBox(width: 6),
+              Text(
+                strings.projectChip(fileProject),
+                style: theme.textTheme.labelSmall?.copyWith(color: amber),
+              ),
+              if (onSwitchToFileProject != null) ...[
+                const SizedBox(width: 8),
+                InkWell(
+                  onTap: () => onSwitchToFileProject!(fileProject),
+                  child: Text(
+                    strings.projectMismatchSwitch(fileProject),
+                    style: theme.textTheme.labelSmall?.copyWith(
+                      color: theme.colorScheme.primary,
+                      fontWeight: FontWeight.w600,
+                    ),
+                  ),
+                ),
+              ],
+            ],
+          ),
+        ),
+      ),
+    ];
+  }
 }
 
 // --- file list ---

lib/src/flow_project.dart

@@ -0,0 +1,50 @@
+/// Parsing + normalization for a flow file's own top-level
+/// `project:` key. Kept separate from the page so the "file wins"
+/// semantics are unit-testable without pumping the whole editor.
+///
+/// Mirrors the hub's `resolve_project` (file's `project:` is the
+/// run's project unless the caller overrides it) and
+/// `normalize_project_slug`, so the chip the editor shows compares
+/// equal to what the hub actually stamps.
+library;
+
+/// The flow's own top-level `project:` slug (normalized), or empty
+/// when the YAML declares none. Only a *non-indented* `project:`
+/// line counts — a nested `project:` inside a step's `with:` block
+/// is ignored.
+String parseFlowProject(String yaml) {
+  for (final raw in yaml.split('\n')) {
+    if (raw.startsWith(' ') || raw.startsWith('\t')) continue;
+    final m = RegExp(r'^project:\s*(.+?)\s*$').firstMatch(raw);
+    if (m != null) {
+      final value = m.group(1)!.replaceAll(RegExp('''^["']|["']\$'''), '');
+      return normalizeProjectSlug(value);
+    }
+  }
+  return '';
+}
+
+/// Mirror of the hub's `normalize_project_slug`: lowercase,
+/// collapse spaces/underscores/dashes to a single `-`, drop
+/// everything else, trim trailing dashes. Empty in → empty out
+/// (the editor treats "no project" and "blank project" alike).
+String normalizeProjectSlug(String raw) {
+  final buf = StringBuffer();
+  var prevDash = false;
+  for (final ch in raw.trim().toLowerCase().split('')) {
+    if (RegExp(r'[a-z0-9]').hasMatch(ch)) {
+      buf.write(ch);
+      prevDash = false;
+    } else if ((ch == ' ' || ch == '_' || ch == '-') &&
+        !prevDash &&
+        buf.isNotEmpty) {
+      buf.write('-');
+      prevDash = true;
+    }
+  }
+  var out = buf.toString();
+  while (out.endsWith('-')) {
+    out = out.substring(0, out.length - 1);
+  }
+  return out;
+}

lib/src/l10n.dart

@@ -44,6 +44,28 @@ class FlowEditorStrings {
   );
   String get discardKeep => _t('Keep editing', 'Weiterbearbeiten');
   String get discardThrow => _t('Throw away', 'Verwerfen');
+
+  /// Chip shown when the open flow file declares its own
+  /// top-level `project:`. The file always wins over the active
+  /// workspace — this label states which project the run lands in.
+  String projectChip(String project) =>
+      _t('Project: $project', 'Projekt: $project');
+  String get projectChipTooltip => _t(
+    'This flow file declares its own project — the run lands there, '
+        'regardless of the active workspace (the file wins).',
+    'Diese Flow-Datei deklariert ihr eigenes Projekt — der Lauf landet '
+        'dort, unabhängig vom aktiven Arbeitsbereich (die Datei gewinnt).',
+  );
+
+  /// Mismatch banner: the file's project differs from the active
+  /// workspace. Offers a one-click switch (the file still wins for
+  /// the run; switching just aligns the workspace view).
+  String projectMismatch(String fileProject) => _t(
+    'This flow belongs to "$fileProject", not the active workspace.',
+    'Dieser Flow gehört zu „$fileProject", nicht zum aktiven Arbeitsbereich.',
+  );
+  String projectMismatchSwitch(String fileProject) =>
+      _t('Switch to $fileProject', 'Zu $fileProject wechseln');
   String get newDialogTitle => _t('New flow', 'Neuer Flow');
   String get newDialogLabel => _t('Flow name', 'Flow-Name');
   String get newDialogHelper => _t(