fix(setup): wizard errors copyable above the dialog, CLI skew explained, exec transparency

Field test of the setup wizard surfaced three trust breaks in one run:
an unexplained macOS Documents permission prompt, a perceived crash,
and an error message whose copy button could not be reached.

Root causes and fixes:
- chain init failures were shown as a SnackBar, which lands BEHIND the
  wizard's modal barrier: dimmed, clipped, copy unreachable — and the
  click aimed at it hit the barrier, dismissing the whole wizard with
  all answers (the perceived crash). Errors now open a modal dialog
  ABOVE the wizard via showChainErrorDialog with a copyable detail
  block, and the wizard is no longer barrier-dismissible.
- When the resolved chain binary is older than Studio and rejects
  --plan-json, the wizard now explains the version skew in plain
  language (binary path + update path) instead of leaking a raw clap
  usage error. A missing binary gets its own localized story.
- Step 3 announces which chain binary the preview will execute; when
  that binary physically lives (symlinks resolved) in a TCC-protected
  folder, the wizard pre-explains the macOS folder prompt.

Supporting changes: FriendlyError passes through friendlyError()
unchanged so call sites can ship precise localized stories through the
shared presentation; SystemActions gains resolvedChainBinary() plus
run/resolve test seams; ChainErrorBox hugs its content instead of
filling an unbounded dialog; the wizard's answers file is written
synchronously (the async dart:io variants never complete under the
widget-test fake-async zone).

Verified: flutter analyze clean, 53 tests green (6 new wizard error-
path tests incl. clipboard round-trip), plus a live GUI walk on macOS
in dark + light with a stale binary (skew dialog, copy verified via
clipboard) and with the real binary (TCC pre-explanation with the
resolved path, full plan preview).

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

CHANGELOG.md

@@ -5,6 +5,36 @@ version + `kStudioVersion` in `lib/main.dart` stay in lockstep.
 
 ## Unreleased
 
+### Fixed (wizard live-run findings 2026-07-14)
+
+Field test of the setup wizard surfaced three trust breaks in one
+run; all were reproduced against a stale CLI and fixed:
+
+- **Errors surfaced behind the wizard.** `chain init` failures were
+  shown as a SnackBar, which lands BEHIND the wizard's modal barrier:
+  dimmed, clipped, its copy button unreachable — and the operator's
+  click at it hit the barrier, which (dismissible by default) closed
+  the whole wizard with all answers. Now: failures open a modal error
+  dialog ABOVE the wizard (copy button works, verbatim CLI output
+  behind "Details"), and the wizard is no longer barrier-dismissible —
+  leaving it is explicit via Abbrechen/Zurück.
+- **CLI version skew explained.** When the resolved `chain` binary is
+  older than Studio and rejects `--plan-json`, the wizard now names
+  the skew in plain language — which binary was executed, that it
+  predates the assistant, and the update path — instead of leaking a
+  raw clap usage error. A missing binary gets the same treatment plus
+  a hint on step 3 before anything runs.
+- **macOS folder prompt pre-explained.** Step 3 now states which
+  `chain` binary the preview will execute; when that binary physically
+  lives (symlinks resolved) in a TCC-protected folder (Documents/
+  Desktop/Downloads), the wizard says up front that macOS may ask for
+  folder access — instead of a bare permission prompt appearing in
+  the middle of setup.
+- `FriendlyError` values now pass through `friendlyError()` unchanged
+  so call sites can route precise, localized stories through the
+  shared error presentation; `SystemActions` gained a public
+  `resolvedChainBinary()` and test seams for the run/resolve paths.
+
 ### Added (guided setup on grade-1 — steps A4/A5/B1 + doc automation)
 
 - **Clickable next steps.** After apply, the wizard renders real

lib/data/friendly_error.dart

@@ -26,12 +26,27 @@ class FriendlyError {
     required this.detail,
     this.hint,
   });
+
+  // The on-disk error log serialises thrown objects via toString —
+  // keep the whole story (headline, hint, verbatim detail) in one
+  // readable record.
+  @override
+  String toString() => [
+    headline,
+    ?hint,
+    if (detail.isNotEmpty && detail != headline) detail,
+  ].join('\n');
 }
 
 /// Map an arbitrary thrown object to a [FriendlyError]. Always
 /// returns a value — never throws — so callers can drop the
 /// result straight into UI without try/catch ceremony.
 FriendlyError friendlyError(Object error, AppLocalizations l) {
+  // A pre-built FriendlyError passes through unchanged — call
+  // sites that already know the precise story (e.g. the setup
+  // wizard's CLI-version-skew case) construct one directly and
+  // still route through the shared presentation helpers.
+  if (error is FriendlyError) return error;
   // We deliberately don't import package:grpc here so Studio
   // doesn't have to add it to its own pubspec — the dependency
   // lives one layer down in chain_client_sdk. `GrpcError` has a

lib/data/system_actions.dart

@@ -18,6 +18,7 @@
 
 import 'dart:io';
 
+import 'package:meta/meta.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
 /// Sentinel returned in `_runFai(...).stderr` when no `fai`
@@ -73,6 +74,28 @@ class SystemActions {
   /// binary / read the install guide" recovery path.
   static bool chainBinaryExists() => _faiExecutable() != null;
 
+  /// Test seam: when set, [_runFai] returns this function's result
+  /// instead of spawning a real process, and [resolvedChainBinary] /
+  /// [chainBinaryExists] answer from [debugResolveOverride]. Lets
+  /// widget tests drive the CLI error paths deterministically.
+  @visibleForTesting
+  static Future<({bool ok, String stdout, String stderr})> Function(
+    List<String> args,
+  )?
+  debugRunFaiOverride;
+
+  /// Test seam companion to [debugRunFaiOverride]: overrides binary
+  /// resolution (may return null to simulate "no binary found").
+  @visibleForTesting
+  static String? Function()? debugResolveOverride;
+
+  /// Absolute path of the `chain` binary Studio would execute right
+  /// now, or null when none can be located. Public so surfaces that
+  /// are about to spawn the binary (the guided-setup wizard) can say
+  /// WHAT they will run — before macOS asks the operator for folder
+  /// permission because of where that binary happens to live.
+  static String? resolvedChainBinary() => _faiExecutable();
+
   /// Ask the OS to open [path] in the default handler. On macOS
   /// this opens text files in TextEdit, configs in the registered
   /// editor, etc. Returns true on a clean spawn (process exited
@@ -219,6 +242,8 @@ class SystemActions {
   static Future<({bool ok, String stdout, String stderr})> _runFai(
     List<String> args,
   ) async {
+    final runOverride = debugRunFaiOverride;
+    if (runOverride != null) return runOverride(args);
     final exe = _faiExecutable();
     if (exe == null) {
       // Sentinel, not a user-facing string. Callers detect this
@@ -249,6 +274,8 @@ class SystemActions {
   /// the file picker), $CHAIN_BIN, PATH, fallback to the canonical
   /// install location under the user's home dir.
   static String? _faiExecutable() {
+    final resolveOverride = debugResolveOverride;
+    if (resolveOverride != null) return resolveOverride();
     final override = _faiBinaryOverride;
     if (override != null &&
         override.isNotEmpty &&

lib/l10n/app_de.arb

@@ -1778,6 +1778,20 @@
   "setupFreeTextPrivacyRemote": "Ihre Beschreibung wird an die eingerichtete System-KI gesendet: {model} ({provider}).",
   "@setupFreeTextPrivacyRemote": {"placeholders": {"model": {"type": "String"}, "provider": {"type": "String"}}},
   "setupFreeTextUnavailable": "Für den Freitext-Weg braucht Ch∆In eine eingerichtete System-KI (Einstellungen → System-KI). Die Auswahl oben funktioniert immer — ganz ohne KI.",
+  "setupExecHint": "Für Vorschau und Einrichtung führt Studio das Programm „chain“ aus: {path}",
+  "@setupExecHint": {"placeholders": {"path": {"type": "String"}}},
+  "setupExecHintTcc": "Das Programm liegt unter {path} — macOS fragt dafür eventuell einmalig nach Zugriff auf diesen Ordner (z. B. „Dokumente“). Das ist zu erwarten und in Ordnung.",
+  "@setupExecHintTcc": {"placeholders": {"path": {"type": "String"}}},
+  "setupNoBinaryStepHint": "Das Programm „chain“ wurde auf diesem Rechner nicht gefunden — die Vorschau im nächsten Schritt wird fehlschlagen. Unter „Diagnose“ können Sie es auswählen oder Ch∆In installieren.",
+  "setupNoBinary": "Das Programm „chain“ wurde auf diesem Rechner nicht gefunden.",
+  "setupNoBinaryHint": "Ohne das Programm kann der Assistent die Einrichtung nicht anwenden. Wählen Sie es unter „Diagnose“ aus oder installieren Sie Ch∆In neu.",
+  "setupCliTooOld": "Das installierte „chain“-Programm ist älter als Studio und kennt diesen Assistenten noch nicht.",
+  "setupCliTooOldHint": "Gefunden wurde: {path}. Bitte Ch∆In aktualisieren (Seite „Diagnose“ → Update, oder im Terminal: chain update apply) und den Assistenten danach erneut öffnen.",
+  "@setupCliTooOldHint": {"placeholders": {"path": {"type": "String"}}},
+  "setupPreviewFailed": "Die Plan-Vorschau konnte nicht erstellt werden — das Programm „chain“ meldet einen Fehler.",
+  "setupApplyFailed": "Die Einrichtung konnte nicht angewendet werden — das Programm „chain“ meldet einen Fehler.",
+  "setupCliUsedBinary": "Ausgeführt wurde: {path}",
+  "@setupCliUsedBinary": {"placeholders": {"path": {"type": "String"}}},
   "setupFreeTextParseError": "Die System-KI hat keinen verwertbaren Vorschlag geliefert. Wählen Sie oben aus dem Menü — oder versuchen Sie es noch einmal.",
   "setupReflectionTitle": "So verstehe ich Ihre Aufgabe",
   "setupReflectionScenario": "Worum es geht: {label}",

lib/l10n/app_en.arb

@@ -1817,6 +1817,20 @@
   "setupFreeTextPrivacyRemote": "Your description is sent to the configured system AI: {model} ({provider}).",
   "@setupFreeTextPrivacyRemote": {"placeholders": {"model": {"type": "String"}, "provider": {"type": "String"}}},
   "setupFreeTextUnavailable": "The free-text path needs a configured system AI (Settings → System AI). The choices above always work — no AI required.",
+  "setupExecHint": "For the preview and setup, Studio runs the “chain” program: {path}",
+  "@setupExecHint": {"placeholders": {"path": {"type": "String"}}},
+  "setupExecHintTcc": "The program lives at {path} — macOS may ask once for access to that folder (e.g. “Documents”). That is expected and fine.",
+  "@setupExecHintTcc": {"placeholders": {"path": {"type": "String"}}},
+  "setupNoBinaryStepHint": "The “chain” program could not be found on this machine — the preview in the next step will fail. You can pick it under “Doctor”, or install Ch∆In.",
+  "setupNoBinary": "The “chain” program could not be found on this machine.",
+  "setupNoBinaryHint": "Without it the assistant cannot apply the setup. Pick it under “Doctor”, or reinstall Ch∆In.",
+  "setupCliTooOld": "The installed “chain” program is older than Studio and does not know this assistant yet.",
+  "setupCliTooOldHint": "Found: {path}. Please update Ch∆In (“Doctor” page → update, or in a terminal: chain update apply) and reopen the assistant afterwards.",
+  "@setupCliTooOldHint": {"placeholders": {"path": {"type": "String"}}},
+  "setupPreviewFailed": "The plan preview could not be created — the “chain” program reported an error.",
+  "setupApplyFailed": "The setup could not be applied — the “chain” program reported an error.",
+  "setupCliUsedBinary": "Executed: {path}",
+  "@setupCliUsedBinary": {"placeholders": {"path": {"type": "String"}}},
   "setupFreeTextParseError": "The system AI did not return a usable suggestion. Pick from the menu above — or try again.",
   "setupReflectionTitle": "This is how I read your task",
   "setupReflectionScenario": "What it is about: {label}",

lib/l10n/app_localizations.dart

@@ -5479,6 +5479,66 @@ abstract class AppLocalizations {
   /// **'The free-text path needs a configured system AI (Settings → System AI). The choices above always work — no AI required.'**
   String get setupFreeTextUnavailable;
 
+  /// No description provided for @setupExecHint.
+  ///
+  /// In en, this message translates to:
+  /// **'For the preview and setup, Studio runs the “chain” program: {path}'**
+  String setupExecHint(String path);
+
+  /// No description provided for @setupExecHintTcc.
+  ///
+  /// In en, this message translates to:
+  /// **'The program lives at {path} — macOS may ask once for access to that folder (e.g. “Documents”). That is expected and fine.'**
+  String setupExecHintTcc(String path);
+
+  /// No description provided for @setupNoBinaryStepHint.
+  ///
+  /// In en, this message translates to:
+  /// **'The “chain” program could not be found on this machine — the preview in the next step will fail. You can pick it under “Doctor”, or install Ch∆In.'**
+  String get setupNoBinaryStepHint;
+
+  /// No description provided for @setupNoBinary.
+  ///
+  /// In en, this message translates to:
+  /// **'The “chain” program could not be found on this machine.'**
+  String get setupNoBinary;
+
+  /// No description provided for @setupNoBinaryHint.
+  ///
+  /// In en, this message translates to:
+  /// **'Without it the assistant cannot apply the setup. Pick it under “Doctor”, or reinstall Ch∆In.'**
+  String get setupNoBinaryHint;
+
+  /// No description provided for @setupCliTooOld.
+  ///
+  /// In en, this message translates to:
+  /// **'The installed “chain” program is older than Studio and does not know this assistant yet.'**
+  String get setupCliTooOld;
+
+  /// No description provided for @setupCliTooOldHint.
+  ///
+  /// In en, this message translates to:
+  /// **'Found: {path}. Please update Ch∆In (“Doctor” page → update, or in a terminal: chain update apply) and reopen the assistant afterwards.'**
+  String setupCliTooOldHint(String path);
+
+  /// No description provided for @setupPreviewFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'The plan preview could not be created — the “chain” program reported an error.'**
+  String get setupPreviewFailed;
+
+  /// No description provided for @setupApplyFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'The setup could not be applied — the “chain” program reported an error.'**
+  String get setupApplyFailed;
+
+  /// No description provided for @setupCliUsedBinary.
+  ///
+  /// In en, this message translates to:
+  /// **'Executed: {path}'**
+  String setupCliUsedBinary(String path);
+
   /// No description provided for @setupFreeTextParseError.
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_de.dart

@@ -3238,6 +3238,50 @@ class AppLocalizationsDe extends AppLocalizations {
   String get setupFreeTextUnavailable =>
       'Für den Freitext-Weg braucht Ch∆In eine eingerichtete System-KI (Einstellungen → System-KI). Die Auswahl oben funktioniert immer — ganz ohne KI.';
 
+  @override
+  String setupExecHint(String path) {
+    return 'Für Vorschau und Einrichtung führt Studio das Programm „chain“ aus: $path';
+  }
+
+  @override
+  String setupExecHintTcc(String path) {
+    return 'Das Programm liegt unter $path — macOS fragt dafür eventuell einmalig nach Zugriff auf diesen Ordner (z. B. „Dokumente“). Das ist zu erwarten und in Ordnung.';
+  }
+
+  @override
+  String get setupNoBinaryStepHint =>
+      'Das Programm „chain“ wurde auf diesem Rechner nicht gefunden — die Vorschau im nächsten Schritt wird fehlschlagen. Unter „Diagnose“ können Sie es auswählen oder Ch∆In installieren.';
+
+  @override
+  String get setupNoBinary =>
+      'Das Programm „chain“ wurde auf diesem Rechner nicht gefunden.';
+
+  @override
+  String get setupNoBinaryHint =>
+      'Ohne das Programm kann der Assistent die Einrichtung nicht anwenden. Wählen Sie es unter „Diagnose“ aus oder installieren Sie Ch∆In neu.';
+
+  @override
+  String get setupCliTooOld =>
+      'Das installierte „chain“-Programm ist älter als Studio und kennt diesen Assistenten noch nicht.';
+
+  @override
+  String setupCliTooOldHint(String path) {
+    return 'Gefunden wurde: $path. Bitte Ch∆In aktualisieren (Seite „Diagnose“ → Update, oder im Terminal: chain update apply) und den Assistenten danach erneut öffnen.';
+  }
+
+  @override
+  String get setupPreviewFailed =>
+      'Die Plan-Vorschau konnte nicht erstellt werden — das Programm „chain“ meldet einen Fehler.';
+
+  @override
+  String get setupApplyFailed =>
+      'Die Einrichtung konnte nicht angewendet werden — das Programm „chain“ meldet einen Fehler.';
+
+  @override
+  String setupCliUsedBinary(String path) {
+    return 'Ausgeführt wurde: $path';
+  }
+
   @override
   String get setupFreeTextParseError =>
       'Die System-KI hat keinen verwertbaren Vorschlag geliefert. Wählen Sie oben aus dem Menü — oder versuchen Sie es noch einmal.';

lib/l10n/app_localizations_en.dart

@@ -3234,6 +3234,50 @@ class AppLocalizationsEn extends AppLocalizations {
   String get setupFreeTextUnavailable =>
       'The free-text path needs a configured system AI (Settings → System AI). The choices above always work — no AI required.';
 
+  @override
+  String setupExecHint(String path) {
+    return 'For the preview and setup, Studio runs the “chain” program: $path';
+  }
+
+  @override
+  String setupExecHintTcc(String path) {
+    return 'The program lives at $path — macOS may ask once for access to that folder (e.g. “Documents”). That is expected and fine.';
+  }
+
+  @override
+  String get setupNoBinaryStepHint =>
+      'The “chain” program could not be found on this machine — the preview in the next step will fail. You can pick it under “Doctor”, or install Ch∆In.';
+
+  @override
+  String get setupNoBinary =>
+      'The “chain” program could not be found on this machine.';
+
+  @override
+  String get setupNoBinaryHint =>
+      'Without it the assistant cannot apply the setup. Pick it under “Doctor”, or reinstall Ch∆In.';
+
+  @override
+  String get setupCliTooOld =>
+      'The installed “chain” program is older than Studio and does not know this assistant yet.';
+
+  @override
+  String setupCliTooOldHint(String path) {
+    return 'Found: $path. Please update Ch∆In (“Doctor” page → update, or in a terminal: chain update apply) and reopen the assistant afterwards.';
+  }
+
+  @override
+  String get setupPreviewFailed =>
+      'The plan preview could not be created — the “chain” program reported an error.';
+
+  @override
+  String get setupApplyFailed =>
+      'The setup could not be applied — the “chain” program reported an error.';
+
+  @override
+  String setupCliUsedBinary(String path) {
+    return 'Executed: $path';
+  }
+
   @override
   String get setupFreeTextParseError =>
       'The system AI did not return a usable suggestion. Pick from the menu above — or try again.';

lib/widgets/chain_error_box.dart

@@ -97,6 +97,10 @@ class _ChainErrorBoxState extends State<ChainErrorBox> {
         border: Border.all(color: accent.withValues(alpha: 0.4)),
       ),
       child: Column(
+        // min, not max: inside an unbounded-height dialog the box
+        // must hug its content — otherwise a one-line error renders
+        // as a screen-tall empty red frame.
+        mainAxisSize: MainAxisSize.min,
         crossAxisAlignment: CrossAxisAlignment.stretch,
         children: [
           Align(

lib/widgets/guided_setup_dialog.dart

@@ -16,6 +16,7 @@ import 'dart:io';
 import 'package:flutter/material.dart';
 
 import '../data/error_presentation.dart';
+import '../data/friendly_error.dart';
 import '../data/hub.dart';
 import '../data/system_actions.dart';
 import '../l10n/app_localizations.dart';
@@ -118,8 +119,14 @@ class GuidedSetupDialog extends StatefulWidget {
 
   static Future<void> show(BuildContext context) {
     final shell = StudioShellState.of(context);
+    // Not barrier-dismissible: a stray click outside the dialog must
+    // not throw away a half-answered wizard (and error SnackBars used
+    // to lure exactly that click — the operator aimed for the message
+    // below the barrier and lost everything). Leaving is explicit:
+    // Abbrechen on step 1, Zurück everywhere else.
     return showDialog<void>(
       context: context,
+      barrierDismissible: false,
       builder: (_) => GuidedSetupDialog(shell: shell),
     );
   }
@@ -276,12 +283,15 @@ class _GuidedSetupDialogState extends State<GuidedSetupDialog> {
   /// racy on multi-user machines. Cleaned up in [dispose].
   Directory? _answersDir;
 
-  Future<String> _writeAnswers() async {
-    _answersDir ??= await Directory.systemTemp.createTemp('chain-setup-');
+  String _writeAnswers() {
+    // Sync on purpose: the file is a handful of lines, and the async
+    // dart:io variants never complete inside the fake-async zone
+    // widget tests run in — the wizard would hang there forever.
+    _answersDir ??= Directory.systemTemp.createTempSync('chain-setup-');
     final f = File(
       '${_answersDir!.path}${Platform.pathSeparator}answers.yaml',
     );
-    await f.writeAsString(_answersYaml());
+    f.writeAsStringSync(_answersYaml());
     return f.path;
   }
 
@@ -299,7 +309,7 @@ class _GuidedSetupDialogState extends State<GuidedSetupDialog> {
       _busy = true;
       _plan = null;
     });
-    final path = await _writeAnswers();
+    final path = _writeAnswers();
     final r = await SystemActions.chainInit(['--answers', path, '--plan-json']);
     if (!mounted) return;
     setState(() => _busy = false);
@@ -311,13 +321,85 @@ class _GuidedSetupDialogState extends State<GuidedSetupDialog> {
           _step = _totalSteps; // review
         });
       } catch (_) {
-        showFaiProcessError(context, 'chain init --plan-json', r.stdout, r.stderr);
+        await _showCliError('chain init --plan-json', r.stdout, r.stderr);
       }
     } else {
-      showFaiProcessError(context, 'chain init --plan-json', r.stdout, r.stderr);
+      await _showCliError('chain init --plan-json', r.stdout, r.stderr);
     }
   }
 
+  /// Surface a failed `chain init` call as a modal dialog stacked
+  /// ABOVE this wizard. A SnackBar would land BEHIND the wizard's
+  /// modal barrier: visible but dimmed, its copy button unreachable —
+  /// and the operator's attempt to click it hits the barrier instead.
+  /// Known failure shapes get a localized plain-language headline;
+  /// the verbatim CLI output stays copyable behind "Details".
+  Future<void> _showCliError(String source, String stdout, String stderr) {
+    final l = AppLocalizations.of(context)!;
+    final raw = [
+      stderr.trim(),
+      stdout.trim(),
+    ].where((s) => s.isNotEmpty).join('\n\n');
+    final bin = SystemActions.resolvedChainBinary();
+    final FriendlyError friendly;
+    if (stderr.trim() == kFaiBinaryNotFound) {
+      // Sentinel, never shown verbatim (see SystemActions docs).
+      friendly = FriendlyError(
+        headline: l.setupNoBinary,
+        detail: '',
+        hint: l.setupNoBinaryHint,
+      );
+    } else if (raw.contains('unexpected argument')) {
+      // Version skew: this Studio speaks a newer `chain init` dialect
+      // than the binary it found (e.g. a stale build behind a channel
+      // symlink). Name the binary and the way out instead of leaking
+      // a raw clap usage error.
+      friendly = FriendlyError(
+        headline: l.setupCliTooOld,
+        detail: raw,
+        hint: l.setupCliTooOldHint(bin ?? 'chain'),
+      );
+    } else {
+      friendly = FriendlyError(
+        headline: source == 'chain init --apply'
+            ? l.setupApplyFailed
+            : l.setupPreviewFailed,
+        detail: raw.isEmpty ? 'process exited non-zero (no output)' : raw,
+        hint: bin == null ? null : l.setupCliUsedBinary(bin),
+      );
+    }
+    return showChainErrorDialog(context, source, friendly);
+  }
+
+  /// Physical location of the resolved `chain` binary (symlinks
+  /// followed) — the path that decides whether macOS shows a folder-
+  /// permission prompt when Studio executes it, regardless of how
+  /// harmless the symlink's own path looks.
+  String? _physicalChainBinary() {
+    final bin = SystemActions.resolvedChainBinary();
+    if (bin == null) return null;
+    try {
+      return File(bin).resolveSymbolicLinksSync();
+    } on FileSystemException {
+      return bin;
+    }
+  }
+
+  /// True when executing the resolved binary can trigger a macOS
+  /// folder-permission (TCC) prompt because it physically lives in a
+  /// protected folder. The wizard says so BEFORE the first exec —
+  /// an unexplained "Studio wants access to Documents" prompt in the
+  /// middle of setup reads as a trust break.
+  bool _binaryNeedsFolderPermission() {
+    if (!Platform.isMacOS) return false;
+    final physical = _physicalChainBinary();
+    final home = Platform.environment['HOME'];
+    if (physical == null || home == null || home.isEmpty) return false;
+    return physical.startsWith('$home/Documents/') ||
+        physical.startsWith('$home/Desktop/') ||
+        physical.startsWith('$home/Downloads/');
+  }
+
   /// Warning lines the apply emitted on success (e.g. the empty
   /// trusted_publishers caveat). Swallowing them made the wizard
   /// claim more than the config delivers — show them instead.
@@ -325,7 +407,7 @@ class _GuidedSetupDialogState extends State<GuidedSetupDialog> {
 
   Future<void> _apply() async {
     setState(() => _busy = true);
-    final path = await _writeAnswers();
+    final path = _writeAnswers();
     final r = await SystemActions.chainInit(
       ['--answers', path, '--apply', '--force'],
     );
@@ -343,7 +425,7 @@ class _GuidedSetupDialogState extends State<GuidedSetupDialog> {
       });
       unawaited(_probeHub());
     } else {
-      showFaiProcessError(context, 'chain init --apply', r.stdout, r.stderr);
+      await _showCliError('chain init --apply', r.stdout, r.stderr);
     }
   }
 
@@ -527,6 +609,18 @@ class _GuidedSetupDialogState extends State<GuidedSetupDialog> {
             value: _dataLocal,
             onChanged: (v) => setState(() => _dataLocal = v),
           ),
+          // Exec transparency: the next click runs the `chain` binary.
+          // Say which one — and warn when its physical location will
+          // make macOS ask for folder access, so the prompt (if any)
+          // arrives explained instead of as a trust break.
+          const SizedBox(height: ChainSpace.sm),
+          if (!SystemActions.chainBinaryExists())
+            _hintRow(l.setupNoBinaryStepHint)
+          else ...[
+            _hintRow(l.setupExecHint(SystemActions.resolvedChainBinary()!)),
+            if (_binaryNeedsFolderPermission())
+              _hintRow(l.setupExecHintTcc(_physicalChainBinary()!)),
+          ],
         ],
         // The free-text alternative lives on the first step: describe
         // the goal, the system AI pre-selects the menu answers. Menu

test/guided_setup_test.dart

@@ -1,12 +1,18 @@
 // Guided-setup wizard — the three explained answer steps. Verifies
 // that options render as localized cards with their one-line
 // explanation (no English enum humanization) and that Weiter/Zurück
-// walk the steps. The review step calls the CLI (a subprocess) and is
-// out of scope for a widget test.
+// walk the steps. CLI calls run through the SystemActions test seam
+// so the error paths (stale binary, generic failure) are covered
+// without a subprocess.
+
+import 'dart:io' show Directory, Platform;
 
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 
+import 'package:chain_studio/data/chain_log.dart';
+import 'package:chain_studio/data/system_actions.dart';
 import 'package:chain_studio/l10n/app_localizations.dart';
 import 'package:chain_studio/widgets/guided_setup_dialog.dart';
 
@@ -247,6 +253,168 @@ void main() {
     },
   );
 
+  group('CLI paths (SystemActions test seam)', () {
+    late Directory tmp;
+
+    setUp(() {
+      tmp = Directory.systemTemp.createTempSync('wizard-test-');
+      ChainLog.testPathOverride = '${tmp.path}/studio-errors.log';
+    });
+
+    tearDown(() {
+      ChainLog.testPathOverride = null;
+      SystemActions.debugRunFaiOverride = null;
+      SystemActions.debugResolveOverride = null;
+      tmp.deleteSync(recursive: true);
+    });
+
+    Future<void> walkToStep3(WidgetTester tester) async {
+      await tester.pumpWidget(_host());
+      await tester.tap(find.text('open'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Weiter'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Weiter'));
+      await tester.pumpAndSettle();
+      expect(find.text('Schritt 3 von 3'), findsOneWidget);
+    }
+
+    testWidgets('a stray click outside the wizard does not dismiss it', (
+      tester,
+    ) async {
+      await tester.pumpWidget(_host());
+      await tester.tap(find.text('open'));
+      await tester.pumpAndSettle();
+      expect(find.text('Schritt 1 von 3'), findsOneWidget);
+
+      // The exact click that used to end the wizard: aiming at an
+      // error SnackBar dimmed below the modal barrier.
+      await tester.tapAt(const Offset(4, 4));
+      await tester.pumpAndSettle();
+      expect(find.text('Schritt 1 von 3'), findsOneWidget);
+    });
+
+    testWidgets(
+      'stale chain binary → explained, copyable error dialog above the intact wizard',
+      (tester) async {
+        const clapError =
+            "error: unexpected argument '--plan-json' found\n\n"
+            "  tip: a similar argument exists: '--plan-out'\n\n"
+            'Usage: chain init --answers <ANSWERS> --plan-out <PLAN_OUT>';
+        SystemActions.debugResolveOverride = () => '/Users/op/.chain/bin/chain';
+        SystemActions.debugRunFaiOverride = (args) async =>
+            (ok: false, stdout: '', stderr: clapError);
+
+        final copied = <String>[];
+        tester.binding.defaultBinaryMessenger.setMockMethodCallHandler(
+          SystemChannels.platform,
+          (call) async {
+            if (call.method == 'Clipboard.setData') {
+              copied.add((call.arguments as Map)['text'] as String);
+            }
+            return null;
+          },
+        );
+
+        await walkToStep3(tester);
+        await tester.tap(find.text('Weiter')); // triggers `chain init`
+        await tester.pumpAndSettle();
+
+        // Plain-language headline naming the skew — not a raw clap
+        // usage wall — plus the binary that was executed.
+        expect(find.textContaining('älter als Studio'), findsOneWidget);
+        expect(
+          find.textContaining('/Users/op/.chain/bin/chain'),
+          findsWidgets,
+        );
+
+        // The verbatim CLI output is one copy-click away (the old
+        // SnackBar rendition sat behind the modal barrier where the
+        // copy button could not be reached at all).
+        await tester.tap(find.byIcon(Icons.content_copy));
+        await tester.pump();
+        expect(copied, hasLength(1));
+        expect(copied.single, contains('unexpected argument'));
+        // Let the button's transient "copied" checkmark reset so no
+        // timer outlives the test.
+        await tester.pump(const Duration(seconds: 2));
+
+        // Dismissing the error returns to the intact wizard — the
+        // failure must not cost the operator their answers.
+        await tester.tap(find.text('OK'));
+        await tester.pumpAndSettle();
+        expect(find.text('Schritt 3 von 3'), findsOneWidget);
+      },
+    );
+
+    testWidgets('generic init failure names the executed binary', (
+      tester,
+    ) async {
+      SystemActions.debugResolveOverride = () => '/Users/op/.chain/bin/chain';
+      SystemActions.debugRunFaiOverride = (args) async =>
+          (ok: false, stdout: '', stderr: 'boom: config unreadable');
+
+      await walkToStep3(tester);
+      await tester.tap(find.text('Weiter'));
+      await tester.pumpAndSettle();
+
+      expect(
+        find.textContaining('Die Plan-Vorschau konnte nicht erstellt werden'),
+        findsOneWidget,
+      );
+      expect(find.textContaining('Ausgeführt wurde:'), findsOneWidget);
+    });
+
+    testWidgets('step 3 announces which binary the wizard will run', (
+      tester,
+    ) async {
+      SystemActions.debugResolveOverride = () => '/Users/op/.chain/bin/chain';
+      SystemActions.debugRunFaiOverride = (args) async =>
+          (ok: false, stdout: '', stderr: 'unused');
+
+      await walkToStep3(tester);
+      expect(
+        find.textContaining('führt Studio das Programm „chain“ aus'),
+        findsOneWidget,
+      );
+      expect(
+        find.textContaining('/Users/op/.chain/bin/chain'),
+        findsOneWidget,
+      );
+    });
+
+    testWidgets(
+      'step 3 pre-explains the macOS folder prompt for a Documents-resident binary',
+      (tester) async {
+        final home = Platform.environment['HOME'];
+        if (!Platform.isMacOS || home == null || home.isEmpty) {
+          return; // TCC folder prompts are a macOS-only concern.
+        }
+        SystemActions.debugResolveOverride = () => '$home/Documents/dev/chain';
+        SystemActions.debugRunFaiOverride = (args) async =>
+            (ok: false, stdout: '', stderr: 'unused');
+
+        await walkToStep3(tester);
+        expect(
+          find.textContaining('nach Zugriff auf diesen Ordner'),
+          findsOneWidget,
+        );
+      },
+    );
+
+    testWidgets('step 3 says so when no chain binary can be found', (
+      tester,
+    ) async {
+      SystemActions.debugResolveOverride = () => null;
+
+      await walkToStep3(tester);
+      expect(
+        find.textContaining('wurde auf diesem Rechner nicht gefunden'),
+        findsOneWidget,
+      );
+    });
+  });
+
   group('parseSetupSuggestion', () {
     test('accepts a valid JSON object embedded in prose', () {
       final r = parseSetupSuggestion(