feat(studio): typed run-flow form, file picker, copyable errors (v0.41.0)

The free-form key=value run-flow dialog produced two
unhelpful failures every time an operator hit Run:

  1. Submit empty → "step references missing value
     '\$inputs.document'" from the hub. Studio sent a zero-
     entry inputs map because nothing told the operator the
     flow declared a required input.
  2. Type `document=@/path/to/file` → "path not found".
     Dart's `File()` doesn't expand `~`, and on macOS
     sandboxed Studio can't read arbitrary paths anyway.

Both failure modes are gone. The dialog is now a typed form:

- On open, fetches `getFlowDefinition(name)` (new SDK
  v0.15.0 wrapper around the v0.10.89 hub RPC). While that
  resolves, a small spinner shows
  "Loading inputs…"; on failure, an inline `FaiErrorBox`
  with the exact RPC error and a copy button replaces the
  spinner.
- Renders one form-field per declared input. The flow
  YAML's verbatim type tag drives the widget choice:
  `bytes` / `file` → "Choose file…" button + picked-file
  readout, plain TextField for everything else. The type
  tag is shown next to the input name as a pill so a flow
  author who picks a less-common type still gets a hint.
- Bytes inputs route through `file_picker` with
  `withData: true`, which means the OS file dialog handles
  read access — sandboxed Studio gets the bytes inline
  rather than a path it can't open. Falls back to
  `File(path).readAsBytes()` on Linux configs that don't
  honour `withData` for large files; failures show a
  copyable SnackBar.
- The Run button enables only when every declared input has
  a value (text non-empty / file picked). Empty submission
  is impossible; the cryptic hub-side
  "missing value" error stops surfacing.
- The run-result dialog's error path uses `FaiErrorBox`
  instead of the previous plain `SelectableText`, so any
  hub-side flow error (permission denied, module crash,
  whatever) is one click to clipboard.

11 new ARB keys cover the form's labels, the file-picker
states, the loading / failed-definition messages, the
"This flow declares no inputs" empty state, and the
run-error dialog title.

`file_picker: ^8.0.0` added to pubspec.yaml.

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

lib/data/hub.dart

@@ -546,6 +546,15 @@ class HubService {
       ..sort((a, b) => a.name.compareTo(b.name));
   }
 
+  /// Return the parsed input schema of a saved flow. Used by
+  /// Studio's Flows page to render a typed run-flow form
+  /// before calling [runSavedFlow]. Each entry's `type` is
+  /// the verbatim type tag from the flow YAML (`text`,
+  /// `bytes`, `json`, …).
+  Future<List<FlowInputDef>> getFlowDefinition(String name) async {
+    return _client.getFlowDefinition(name);
+  }
+
   /// Run a saved flow with the supplied inputs. Text values
   /// land as text Payloads, byte values as bytes Payloads —
   /// flows that mix both (e.g. extract taking a `document:

lib/l10n/app_de.arb

@@ -389,8 +389,23 @@
   "flowsNoneHint": "Flow speichern mit `fai admin flows save <name> <flow.yaml>`, dann taucht er hier auf.",
   "flowsRunDialogTitle": "{name} ausführen",
   "@flowsRunDialogTitle": { "placeholders": { "name": { "type": "String" } } },
-  "flowsRunDialogBody": "Eingaben als key=value, eine pro Zeile. Klartext-Werte landen als Text. Wert mit `@` voranstellen liest die Datei als Bytes — wie `fai run --input document=@/pfad/zu/datei.pdf`.",
+  "flowsRunDialogBody": "Pro deklariertem Input ein Feld. Bytes-Inputs öffnen einen Datei-Picker; alle anderen sind Klartext. Der Starten-Button aktiviert sich, wenn alle Pflichtfelder gefüllt sind.",
-  "flowsInputsHint": "name=Welt\ndocument=@/Users/ich/Dokumente/beispiel.pdf\nstil=drei Stichpunkte",
+  "flowsLoadingDefinition": "Inputs werden geladen…",
+  "flowsDefinitionFailed": "Flow-Definition konnte nicht geladen werden",
+  "flowsNoInputs": "Dieser Flow deklariert keine Inputs. Starten klicken, um loszulegen.",
+  "flowsTypeBytesPick": "Datei wählen…",
+  "flowsTypeBytesChange": "Datei ändern",
+  "flowsTypeBytesNoFile": "Keine Datei ausgewählt",
+  "flowsTypeBytesSize": "{n} Bytes",
+  "@flowsTypeBytesSize": { "placeholders": { "n": { "type": "int" } } },
+  "flowsRunErrorTitle": "Flow-Lauf fehlgeschlagen",
+  "flowsFileReadFailed": "„{path}\" konnte nicht gelesen werden: {error}",
+  "@flowsFileReadFailed": {
+    "placeholders": {
+      "path": { "type": "String" },
+      "error": { "type": "String" }
+    }
+  },
   "flowsRunButton": "Starten",
   "flowsRunningTitle": "{name} läuft",
   "@flowsRunningTitle": { "placeholders": { "name": { "type": "String" } } },

lib/l10n/app_en.arb

@@ -390,8 +390,23 @@
   "flowsNoneHint": "Save a flow with `fai admin flows save <name> <flow.yaml>` and it shows up here.",
   "flowsRunDialogTitle": "Run {name}",
   "@flowsRunDialogTitle": { "placeholders": { "name": { "type": "String" } } },
-  "flowsRunDialogBody": "Inputs as key=value, one per line. Plain values send as text. Prefix the value with `@` to read a file as bytes — same as `fai run --input document=@/path/to/file.pdf`.",
+  "flowsRunDialogBody": "One field per declared input. Pick a file for bytes-shaped inputs; type plain text for the rest. The Run button enables when every required input is set.",
-  "flowsInputsHint": "name=World\ndocument=@/Users/me/Documents/sample.pdf\nstyle=three bullet points",
+  "flowsLoadingDefinition": "Loading inputs…",
+  "flowsDefinitionFailed": "Could not load flow definition",
+  "flowsNoInputs": "This flow declares no inputs. Click Run to start.",
+  "flowsTypeBytesPick": "Choose file…",
+  "flowsTypeBytesChange": "Change file",
+  "flowsTypeBytesNoFile": "No file selected",
+  "flowsTypeBytesSize": "{n} bytes",
+  "@flowsTypeBytesSize": { "placeholders": { "n": { "type": "int" } } },
+  "flowsRunErrorTitle": "Flow run failed",
+  "flowsFileReadFailed": "Could not read \"{path}\": {error}",
+  "@flowsFileReadFailed": {
+    "placeholders": {
+      "path": { "type": "String" },
+      "error": { "type": "String" }
+    }
+  },
   "flowsRunButton": "Run",
   "flowsRunningTitle": "Running {name}",
   "@flowsRunningTitle": { "placeholders": { "name": { "type": "String" } } },

lib/l10n/app_localizations.dart

@@ -1823,14 +1823,62 @@ abstract class AppLocalizations {
   /// No description provided for @flowsRunDialogBody.
   ///
   /// In en, this message translates to:
-  /// **'Inputs as key=value, one per line. Plain values send as text. Prefix the value with `@` to read a file as bytes — same as `fai run --input document=@/path/to/file.pdf`.'**
+  /// **'One field per declared input. Pick a file for bytes-shaped inputs; type plain text for the rest. The Run button enables when every required input is set.'**
   String get flowsRunDialogBody;
 
-  /// No description provided for @flowsInputsHint.
+  /// No description provided for @flowsLoadingDefinition.
   ///
   /// In en, this message translates to:
-  /// **'name=World\ndocument=@/Users/me/Documents/sample.pdf\nstyle=three bullet points'**
+  /// **'Loading inputs…'**
-  String get flowsInputsHint;
+  String get flowsLoadingDefinition;
+
+  /// No description provided for @flowsDefinitionFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'Could not load flow definition'**
+  String get flowsDefinitionFailed;
+
+  /// No description provided for @flowsNoInputs.
+  ///
+  /// In en, this message translates to:
+  /// **'This flow declares no inputs. Click Run to start.'**
+  String get flowsNoInputs;
+
+  /// No description provided for @flowsTypeBytesPick.
+  ///
+  /// In en, this message translates to:
+  /// **'Choose file…'**
+  String get flowsTypeBytesPick;
+
+  /// No description provided for @flowsTypeBytesChange.
+  ///
+  /// In en, this message translates to:
+  /// **'Change file'**
+  String get flowsTypeBytesChange;
+
+  /// No description provided for @flowsTypeBytesNoFile.
+  ///
+  /// In en, this message translates to:
+  /// **'No file selected'**
+  String get flowsTypeBytesNoFile;
+
+  /// No description provided for @flowsTypeBytesSize.
+  ///
+  /// In en, this message translates to:
+  /// **'{n} bytes'**
+  String flowsTypeBytesSize(int n);
+
+  /// No description provided for @flowsRunErrorTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Flow run failed'**
+  String get flowsRunErrorTitle;
+
+  /// No description provided for @flowsFileReadFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'Could not read \"{path}\": {error}'**
+  String flowsFileReadFailed(String path, String error);
 
   /// No description provided for @flowsRunButton.
   ///

lib/l10n/app_localizations_de.dart

@@ -1025,11 +1025,40 @@ class AppLocalizationsDe extends AppLocalizations {
 
   @override
   String get flowsRunDialogBody =>
-      'Eingaben als key=value, eine pro Zeile. Klartext-Werte landen als Text. Wert mit `@` voranstellen liest die Datei als Bytes — wie `fai run --input document=@/pfad/zu/datei.pdf`.';
+      'Pro deklariertem Input ein Feld. Bytes-Inputs öffnen einen Datei-Picker; alle anderen sind Klartext. Der Starten-Button aktiviert sich, wenn alle Pflichtfelder gefüllt sind.';
 
   @override
-  String get flowsInputsHint =>
+  String get flowsLoadingDefinition => 'Inputs werden geladen…';
-      'name=Welt\ndocument=@/Users/ich/Dokumente/beispiel.pdf\nstil=drei Stichpunkte';
+
+  @override
+  String get flowsDefinitionFailed =>
+      'Flow-Definition konnte nicht geladen werden';
+
+  @override
+  String get flowsNoInputs =>
+      'Dieser Flow deklariert keine Inputs. Starten klicken, um loszulegen.';
+
+  @override
+  String get flowsTypeBytesPick => 'Datei wählen…';
+
+  @override
+  String get flowsTypeBytesChange => 'Datei ändern';
+
+  @override
+  String get flowsTypeBytesNoFile => 'Keine Datei ausgewählt';
+
+  @override
+  String flowsTypeBytesSize(int n) {
+    return '$n Bytes';
+  }
+
+  @override
+  String get flowsRunErrorTitle => 'Flow-Lauf fehlgeschlagen';
+
+  @override
+  String flowsFileReadFailed(String path, String error) {
+    return '„$path\" konnte nicht gelesen werden: $error';
+  }
 
   @override
   String get flowsRunButton => 'Starten';

lib/l10n/app_localizations_en.dart

@@ -1040,11 +1040,39 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get flowsRunDialogBody =>
-      'Inputs as key=value, one per line. Plain values send as text. Prefix the value with `@` to read a file as bytes — same as `fai run --input document=@/path/to/file.pdf`.';
+      'One field per declared input. Pick a file for bytes-shaped inputs; type plain text for the rest. The Run button enables when every required input is set.';
 
   @override
-  String get flowsInputsHint =>
+  String get flowsLoadingDefinition => 'Loading inputs…';
-      'name=World\ndocument=@/Users/me/Documents/sample.pdf\nstyle=three bullet points';
+
+  @override
+  String get flowsDefinitionFailed => 'Could not load flow definition';
+
+  @override
+  String get flowsNoInputs =>
+      'This flow declares no inputs. Click Run to start.';
+
+  @override
+  String get flowsTypeBytesPick => 'Choose file…';
+
+  @override
+  String get flowsTypeBytesChange => 'Change file';
+
+  @override
+  String get flowsTypeBytesNoFile => 'No file selected';
+
+  @override
+  String flowsTypeBytesSize(int n) {
+    return '$n bytes';
+  }
+
+  @override
+  String get flowsRunErrorTitle => 'Flow run failed';
+
+  @override
+  String flowsFileReadFailed(String path, String error) {
+    return 'Could not read \"$path\": $error';
+  }
 
   @override
   String get flowsRunButton => 'Run';

lib/main.dart

@@ -26,7 +26,7 @@ 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 = '0.40.0';
+const String kStudioVersion = '0.41.0';
 
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();

lib/pages/flows.dart

@@ -1,6 +1,8 @@
 import 'dart:io';
 import 'dart:typed_data';
 
+import 'package:fai_dart_sdk/fai_dart_sdk.dart' show FlowInputDef;
+import 'package:file_picker/file_picker.dart';
 import 'package:flutter/material.dart';
 
 import '../data/hub.dart';
@@ -32,43 +34,14 @@ class _FlowsPageState extends State<FlowsPage> {
   Future<void> _runFlow(SavedFlow flow) async {
     final inputs = await _FlowInputDialog.show(context, flow);
     if (inputs == null) return;
-    // Split the dialog's text-shaped key=value pairs into text
-    // vs file payloads. Values starting with `@` mean "treat
-    // the rest as a path; read the file as bytes" — same
-    // syntax `fai run --input` uses on the CLI. File-read
-    // failures bubble up as the run dialog's error state so
-    // the operator sees a useful message.
-    final textInputs = <String, String>{};
-    final fileInputs = <String, Uint8List>{};
-    String? readError;
-    for (final entry in inputs.entries) {
-      final value = entry.value;
-      if (value.startsWith('@')) {
-        final path = value.substring(1).trim();
-        try {
-          fileInputs[entry.key] = await File(path).readAsBytes();
-        } catch (e) {
-          readError = '${entry.key}: $e';
-          break;
-        }
-      } else {
-        textInputs[entry.key] = value;
-      }
-    }
     if (!mounted) return;
-    if (readError != null) {
-      ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text(readError)),
-      );
-      return;
-    }
     showDialog<void>(
       context: context,
       barrierDismissible: false,
       builder: (_) => _FlowRunDialog(
         flow: flow,
-        textInputs: textInputs,
+        textInputs: inputs.textInputs,
-        fileInputs: fileInputs,
+        fileInputs: inputs.fileInputs,
       ),
     );
   }
@@ -184,16 +157,56 @@ class _FlowCard extends StatelessWidget {
   }
 }
 
+/// Inputs collected by `_FlowInputDialog` and forwarded to
+/// the run dialog. Text and file values arrive in separate
+/// maps so the SDK can wrap each as the appropriate Payload
+/// variant.
+class _FlowRunInputs {
+  final Map<String, String> textInputs;
+  final Map<String, Uint8List> fileInputs;
+  const _FlowRunInputs({
+    required this.textInputs,
+    required this.fileInputs,
+  });
+}
+
+class _PickedFile {
+  final String name;
+  final Uint8List bytes;
+  const _PickedFile({required this.name, required this.bytes});
+}
+
+/// Run-flow input dialog. Fetches the flow's declared input
+/// schema first via `getFlowDefinition`, then renders one
+/// type-aware field per declared input:
+///
+///   * `bytes` / `file` → "Choose file" button + picked-file
+///                         readout. Routes through the OS
+///                         file dialog so sandboxed Studio
+///                         still gets read access to the
+///                         chosen file. `withData: true` so
+///                         the bytes flow through the
+///                         FilePicker result instead of a
+///                         path that may be unreadable.
+///   * everything else  → TextField. Opaque type tag is
+///                         shown as a pill next to the input
+///                         name so a flow author who picks
+///                         a less-common type still gets a
+///                         hint.
+///
+/// The Run button enables only when every input has a value
+/// — required-field validation happens client-side before
+/// the hub sees an empty inputs map.
 class _FlowInputDialog extends StatefulWidget {
   final SavedFlow flow;
 
   const _FlowInputDialog({required this.flow});
 
-  static Future<Map<String, String>?> show(
+  static Future<_FlowRunInputs?> show(
     BuildContext context,
     SavedFlow flow,
   ) {
-    return showDialog<Map<String, String>>(
+    return showDialog<_FlowRunInputs>(
       context: context,
       builder: (_) => _FlowInputDialog(flow: flow),
     );
@@ -204,28 +217,92 @@ class _FlowInputDialog extends StatefulWidget {
 }
 
 class _FlowInputDialogState extends State<_FlowInputDialog> {
-  // The hub does not yet expose the flow's input schema over
+  late final Future<List<FlowInputDef>> _defFuture;
-  // gRPC, so this dialog accepts free-form key=value pairs.
+  final Map<String, TextEditingController> _textControllers = {};
-  // Operator pastes pairs separated by newlines; we split on
+  final Map<String, _PickedFile> _pickedFiles = {};
-  // the first `=` per line.
+
-  final _ctrl = TextEditingController();
+  @override
+  void initState() {
+    super.initState();
+    _defFuture = HubService.instance.getFlowDefinition(widget.flow.name);
+  }
 
   @override
   void dispose() {
-    _ctrl.dispose();
+    for (final c in _textControllers.values) {
+      c.dispose();
+    }
     super.dispose();
   }
 
-  Map<String, String> _parsePairs() {
+  bool _isBytesType(String type) => type == 'bytes' || type == 'file';
-    final out = <String, String>{};
+
-    for (final raw in _ctrl.text.split('\n')) {
+  bool _isComplete(List<FlowInputDef> defs) {
-      final line = raw.trim();
+    for (final d in defs) {
-      if (line.isEmpty) continue;
+      if (_isBytesType(d.type)) {
-      final eq = line.indexOf('=');
+        if (_pickedFiles[d.name] == null) return false;
-      if (eq < 0) continue;
+      } else {
-      out[line.substring(0, eq).trim()] = line.substring(eq + 1).trim();
+        final v = _textControllers[d.name]?.text.trim() ?? '';
+        if (v.isEmpty) return false;
+      }
+    }
+    return true;
+  }
+
+  _FlowRunInputs _collect(List<FlowInputDef> defs) {
+    final textInputs = <String, String>{};
+    final fileInputs = <String, Uint8List>{};
+    for (final d in defs) {
+      if (_isBytesType(d.type)) {
+        final picked = _pickedFiles[d.name];
+        if (picked != null) fileInputs[d.name] = picked.bytes;
+      } else {
+        final c = _textControllers[d.name];
+        if (c != null) textInputs[d.name] = c.text;
+      }
+    }
+    return _FlowRunInputs(textInputs: textInputs, fileInputs: fileInputs);
+  }
+
+  Future<void> _pickFile(String inputName) async {
+    final result = await FilePicker.platform.pickFiles(withData: true);
+    if (result == null || result.files.isEmpty) return;
+    final f = result.files.first;
+    var bytes = f.bytes;
+    if (bytes == null && f.path != null) {
+      // Some Linux configurations don't honour `withData: true`
+      // for large files; fall back to reading via path.
+      try {
+        bytes = await File(f.path!).readAsBytes();
+      } catch (e) {
+        if (!mounted) return;
+        final l = AppLocalizations.of(context)!;
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text(l.flowsFileReadFailed(f.path!, '$e'))),
+        );
+        return;
+      }
+    }
+    if (bytes == null || !mounted) return;
+    setState(() {
+      _pickedFiles[inputName] = _PickedFile(name: f.name, bytes: bytes!);
+    });
+  }
+
+  /// Lazily ensure each text-shaped input has a controller +
+  /// a setState-triggering listener so the Run button reflects
+  /// validity as the operator types.
+  void _ensureTextControllers(List<FlowInputDef> defs) {
+    for (final d in defs) {
+      if (_isBytesType(d.type)) continue;
+      _textControllers.putIfAbsent(d.name, () {
+        final c = TextEditingController();
+        c.addListener(() {
+          if (mounted) setState(() {});
+        });
+        return c;
+      });
     }
-    return out;
   }
 
   @override
@@ -238,33 +315,77 @@ class _FlowInputDialogState extends State<_FlowInputDialog> {
         borderRadius: BorderRadius.circular(FaiRadius.md),
       ),
       content: ConstrainedBox(
-        constraints: const BoxConstraints(maxWidth: 480, maxHeight: 360),
+        constraints: const BoxConstraints(maxWidth: 540, maxHeight: 540),
-        child: Column(
+        child: FutureBuilder<List<FlowInputDef>>(
-          mainAxisSize: MainAxisSize.min,
+          future: _defFuture,
-          crossAxisAlignment: CrossAxisAlignment.start,
+          builder: (context, snap) {
-          children: [
+            if (snap.connectionState == ConnectionState.waiting) {
-            Text(
+              return Row(
-              l.flowsRunDialogBody,
+                mainAxisSize: MainAxisSize.min,
-              style: theme.textTheme.bodySmall?.copyWith(
+                children: [
-                color: theme.colorScheme.onSurfaceVariant,
+                  const SizedBox(
+                    width: 14,
+                    height: 14,
+                    child: CircularProgressIndicator(strokeWidth: 2),
+                  ),
+                  const SizedBox(width: FaiSpace.sm),
+                  Text(l.flowsLoadingDefinition),
+                ],
+              );
+            }
+            if (snap.hasError) {
+              return Column(
+                mainAxisSize: MainAxisSize.min,
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Text(
+                    l.flowsDefinitionFailed,
+                    style: theme.textTheme.bodyMedium?.copyWith(
+                      color: theme.colorScheme.error,
+                    ),
+                  ),
+                  const SizedBox(height: FaiSpace.sm),
+                  FaiErrorBox(
+                    text: snap.error.toString(),
+                    isError: true,
+                    maxHeight: 200,
+                  ),
+                ],
+              );
+            }
+            final defs = snap.data ?? const <FlowInputDef>[];
+            _ensureTextControllers(defs);
+            return SingleChildScrollView(
+              child: Column(
+                mainAxisSize: MainAxisSize.min,
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Text(
+                    l.flowsRunDialogBody,
+                    style: theme.textTheme.bodySmall?.copyWith(
+                      color: theme.colorScheme.onSurfaceVariant,
+                    ),
+                  ),
+                  const SizedBox(height: FaiSpace.md),
+                  if (defs.isEmpty)
+                    Text(
+                      l.flowsNoInputs,
+                      style: theme.textTheme.bodyMedium,
+                    ),
+                  for (final d in defs) ...[
+                    _InputField(
+                      def: d,
+                      isBytes: _isBytesType(d.type),
+                      textController: _textControllers[d.name],
+                      pickedFile: _pickedFiles[d.name],
+                      onPick: () => _pickFile(d.name),
+                    ),
+                    const SizedBox(height: FaiSpace.md),
+                  ],
+                ],
               ),
-            ),
+            );
-            const SizedBox(height: FaiSpace.md),
+          },
-            Expanded(
-              child: TextField(
-                controller: _ctrl,
-                maxLines: null,
-                expands: true,
-                textAlignVertical: TextAlignVertical.top,
-                style: FaiTheme.mono(size: 12),
-                decoration: InputDecoration(
-                  hintText: l.flowsInputsHint,
-                  border: const OutlineInputBorder(),
-                  isDense: true,
-                ),
-              ),
-            ),
-          ],
         ),
       ),
       actions: [
@@ -272,16 +393,106 @@ class _FlowInputDialogState extends State<_FlowInputDialog> {
           onPressed: () => Navigator.pop(context, null),
           child: Text(l.buttonCancel),
         ),
-        FilledButton.icon(
+        FutureBuilder<List<FlowInputDef>>(
-          icon: const Icon(Icons.play_arrow, size: 16),
+          future: _defFuture,
-          label: Text(l.flowsRunButton),
+          builder: (context, snap) {
-          onPressed: () => Navigator.pop(context, _parsePairs()),
+            final defs = snap.data ?? const <FlowInputDef>[];
+            final canRun = snap.hasData && _isComplete(defs);
+            return FilledButton.icon(
+              icon: const Icon(Icons.play_arrow, size: 16),
+              label: Text(l.flowsRunButton),
+              onPressed: canRun
+                  ? () => Navigator.pop(context, _collect(defs))
+                  : null,
+            );
+          },
         ),
       ],
     );
   }
 }
 
+class _InputField extends StatelessWidget {
+  final FlowInputDef def;
+  final bool isBytes;
+  final TextEditingController? textController;
+  final _PickedFile? pickedFile;
+  final VoidCallback onPick;
+
+  const _InputField({
+    required this.def,
+    required this.isBytes,
+    required this.textController,
+    required this.pickedFile,
+    required this.onPick,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final l = AppLocalizations.of(context)!;
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        Row(
+          children: [
+            Text(
+              def.name,
+              style: FaiTheme.mono(
+                size: 12,
+                weight: FontWeight.w600,
+                color: theme.colorScheme.onSurface,
+              ),
+            ),
+            const SizedBox(width: FaiSpace.sm),
+            FaiPill(
+              label: def.type,
+              tone: isBytes ? FaiPillTone.warning : FaiPillTone.neutral,
+              monospace: true,
+            ),
+          ],
+        ),
+        const SizedBox(height: 6),
+        if (isBytes)
+          Row(
+            children: [
+              OutlinedButton.icon(
+                onPressed: onPick,
+                icon: const Icon(Icons.attach_file, size: 14),
+                label: Text(
+                  pickedFile == null
+                      ? l.flowsTypeBytesPick
+                      : l.flowsTypeBytesChange,
+                ),
+              ),
+              const SizedBox(width: FaiSpace.md),
+              Expanded(
+                child: Text(
+                  pickedFile == null
+                      ? l.flowsTypeBytesNoFile
+                      : '${pickedFile!.name} · '
+                          '${l.flowsTypeBytesSize(pickedFile!.bytes.length)}',
+                  style: theme.textTheme.bodySmall?.copyWith(
+                    color: theme.colorScheme.onSurfaceVariant,
+                  ),
+                  overflow: TextOverflow.ellipsis,
+                ),
+              ),
+            ],
+          )
+        else
+          TextField(
+            controller: textController,
+            decoration: const InputDecoration(
+              border: OutlineInputBorder(),
+              isDense: true,
+            ),
+          ),
+      ],
+    );
+  }
+}
+
 class _FlowRunDialog extends StatefulWidget {
   final SavedFlow flow;
   final Map<String, String> textInputs;
@@ -346,18 +557,28 @@ class _FlowRunDialogState extends State<_FlowRunDialog> {
                   crossAxisAlignment: CrossAxisAlignment.start,
                   mainAxisSize: MainAxisSize.min,
                   children: [
-                    Icon(
+                    Row(
-                      Icons.error_outline,
+                      children: [
-                      color: theme.colorScheme.error,
+                        Icon(
-                      size: 32,
+                          Icons.error_outline,
+                          color: theme.colorScheme.error,
+                          size: 20,
+                        ),
+                        const SizedBox(width: FaiSpace.sm),
+                        Text(
+                          l.flowsRunErrorTitle,
+                          style: theme.textTheme.titleSmall?.copyWith(
+                            color: theme.colorScheme.error,
+                            fontWeight: FontWeight.w600,
+                          ),
+                        ),
+                      ],
                     ),
                     const SizedBox(height: FaiSpace.md),
-                    SelectableText(
+                    FaiErrorBox(
-                      snapshot.error.toString(),
+                      text: snapshot.error.toString(),
-                      style: FaiTheme.mono(
+                      isError: true,
-                        size: 11,
+                      maxHeight: 280,
-                        color: theme.colorScheme.error,
-                      ),
                     ),
                   ],
                 ),

pubspec.lock

@@ -57,6 +57,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.19.1"
+  cross_file:
+    dependency: transitive
+    description:
+      name: cross_file
+      sha256: "28bb3ae56f117b5aec029d702a90f57d285cd975c3c5c281eaca38dbc47c5937"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.3.5+2"
   crypto:
     dependency: transitive
     description:
@@ -79,7 +87,7 @@ packages:
       path: "../fai_dart_sdk"
       relative: true
     source: path
-    version: "0.13.0"
+    version: "0.15.0"
   fake_async:
     dependency: transitive
     description:
@@ -104,6 +112,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "7.0.1"
+  file_picker:
+    dependency: "direct main"
+    description:
+      name: file_picker
+      sha256: ab13ae8ef5580a411c458d6207b6774a6c237d77ac37011b13994879f68a8810
+      url: "https://pub.dev"
+    source: hosted
+    version: "8.3.7"
   fixnum:
     dependency: transitive
     description:
@@ -138,6 +154,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.7.7+1"
+  flutter_plugin_android_lifecycle:
+    dependency: transitive
+    description:
+      name: flutter_plugin_android_lifecycle
+      sha256: "38d1c268de9097ff59cf0e844ac38759fc78f76836d37edad06fa21e182055a0"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.34"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -601,6 +625,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.1"
+  win32:
+    dependency: transitive
+    description:
+      name: win32
+      sha256: d7cb55e04cd34096cd3a79b3330245f54cb96a370a1c27adb3c84b917de8b08e
+      url: "https://pub.dev"
+    source: hosted
+    version: "5.15.0"
   xdg_directories:
     dependency: transitive
     description:

pubspec.yaml

@@ -1,7 +1,7 @@
 name: fai_studio
 description: "F∆I Studio — desktop GUI for the F∆I hub"
 publish_to: 'none'
-version: 0.40.0
+version: 0.41.0
 
 environment:
   sdk: ^3.11.0-200.1.beta
@@ -25,6 +25,12 @@ dependencies:
   # ~/.fai/today/active.yaml — see docs/today-pipeline.md.
   yaml: ^3.1.2
   path: ^1.9.0
+  # System-native file picker — used by the Flows run-flow
+  # form for `bytes`-shaped inputs (extract takes a PDF, the
+  # operator clicks "Choose file" and macOS / Linux / Windows
+  # routes through the OS dialog so sandboxed Studio still
+  # gets read access to the chosen file).
+  file_picker: ^8.0.0
 
 dev_dependencies:
   flutter_test: