feat(errors): classify the install 'no store entry' failure

Even with the honest install badge the hub error stays reachable
(stale store snapshot, race with a store refresh, older hub). The
friendly-error mapper now gives it its own headline plus a hint
naming the three acquisition paths — local module install, adding
the providing store, configuring the MCP/n8n integration — in EN
and DE, with the verbatim hub message kept copyable. Matcher unit
tests EN+DE guard the classification.

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

lib/data/friendly_error.dart

@@ -204,6 +204,20 @@ FriendlyError? _matchHubPattern(String detail, AppLocalizations l) {
       hint: l.errMcpUnreachableHint,
     );
   }
+  // Install target unresolvable — the hub's install resolver found
+  // no store entry with that exact name ("no store entry for 'X' —
+  // hint"). Distinct from capability-not-installed below: the store
+  // cannot deliver it at all, so the recovery is one of the three
+  // acquisition paths, not the Fix button. Reachable despite the
+  // honest badge (stale store snapshot, race with a store refresh,
+  // older hub).
+  if (detail.contains('no store entry for')) {
+    return FriendlyError(
+      headline: l.errNoStoreEntry,
+      detail: detail,
+      hint: l.errNoStoreEntryHint,
+    );
+  }
   // Capability not in registry — hub returns NotFound with this
   // shape from the flow engine.
   if (detail.toLowerCase().contains('no capability provider') ||

lib/l10n/app_de.arb

@@ -69,6 +69,8 @@
   "errMcpUnreachableHint": "Der MCP-Server hat nicht geantwortet. Endpunkt in Einstellungen → Integrationen prüfen und sicherstellen, dass er läuft.",
   "errCapabilityNotInstalled": "Benötigte Capability nicht installiert.",
   "errCapabilityNotInstalledHint": "Im Text-Tab des Flows klicken Sie auf den Fix-Button — der installiert die Capability, sofern sie im Store ist.",
+  "errNoStoreEntry": "Kein Store-Eintrag bietet diese Capability an.",
+  "errNoStoreEntryHint": "Drei Wege: lokales Modul installieren (chain install --link <pfad>), den passenden Store hinzufügen (Einstellungen → Stores) oder die Anbindung (MCP/n8n) einrichten, die sie bereitstellt. Falls gerade erst veröffentlicht: zuerst die Store-Seite aktualisieren.",
   "welcomeDocClose": "Schließen",
   "welcomeDocFailedToLoad": "Doku konnte nicht geladen werden: {error}",
   "@welcomeDocFailedToLoad": {

lib/l10n/app_en.arb

@@ -77,6 +77,8 @@
   "errMcpUnreachableHint": "The MCP server didn't respond. Check the endpoint in Settings → Integrations and confirm it's running.",
   "errCapabilityNotInstalled": "Required capability is not installed.",
   "errCapabilityNotInstalledHint": "Open the flow's Text tab — the analyzer's Fix button installs the capability if it's in the store.",
+  "errNoStoreEntry": "No store entry provides this capability.",
+  "errNoStoreEntryHint": "Three ways to get it: install a local module (chain install --link <path>), add the store that provides it (Settings → Stores), or configure the integration (MCP/n8n) that supplies it. If it was just published, refresh the Store page first.",
   "welcomeDocClose": "Close",
   "welcomeDocFailedToLoad": "Could not load documentation: {error}",
   "@welcomeDocFailedToLoad": {

lib/l10n/app_localizations.dart

@@ -512,6 +512,18 @@ abstract class AppLocalizations {
   /// **'Open the flow\'s Text tab — the analyzer\'s Fix button installs the capability if it\'s in the store.'**
   String get errCapabilityNotInstalledHint;
 
+  /// No description provided for @errNoStoreEntry.
+  ///
+  /// In en, this message translates to:
+  /// **'No store entry provides this capability.'**
+  String get errNoStoreEntry;
+
+  /// No description provided for @errNoStoreEntryHint.
+  ///
+  /// In en, this message translates to:
+  /// **'Three ways to get it: install a local module (chain install --link <path>), add the store that provides it (Settings → Stores), or configure the integration (MCP/n8n) that supplies it. If it was just published, refresh the Store page first.'**
+  String get errNoStoreEntryHint;
+
   /// No description provided for @welcomeDocClose.
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_de.dart

@@ -248,6 +248,14 @@ class AppLocalizationsDe extends AppLocalizations {
   String get errCapabilityNotInstalledHint =>
       'Im Text-Tab des Flows klicken Sie auf den Fix-Button — der installiert die Capability, sofern sie im Store ist.';
 
+  @override
+  String get errNoStoreEntry =>
+      'Kein Store-Eintrag bietet diese Capability an.';
+
+  @override
+  String get errNoStoreEntryHint =>
+      'Drei Wege: lokales Modul installieren (chain install --link <pfad>), den passenden Store hinzufügen (Einstellungen → Stores) oder die Anbindung (MCP/n8n) einrichten, die sie bereitstellt. Falls gerade erst veröffentlicht: zuerst die Store-Seite aktualisieren.';
+
   @override
   String get welcomeDocClose => 'Schließen';
 

lib/l10n/app_localizations_en.dart

@@ -248,6 +248,13 @@ class AppLocalizationsEn extends AppLocalizations {
   String get errCapabilityNotInstalledHint =>
       'Open the flow\'s Text tab — the analyzer\'s Fix button installs the capability if it\'s in the store.';
 
+  @override
+  String get errNoStoreEntry => 'No store entry provides this capability.';
+
+  @override
+  String get errNoStoreEntryHint =>
+      'Three ways to get it: install a local module (chain install --link <path>), add the store that provides it (Settings → Stores), or configure the integration (MCP/n8n) that supplies it. If it was just published, refresh the Store page first.';
+
   @override
   String get welcomeDocClose => 'Close';
 

test/friendly_error_test.dart

@@ -40,12 +40,12 @@ void main() {
     final l = await _loadL10n(const Locale('en'));
     final r = friendlyError(
       _FakeGrpcError(9, 'FAILED_PRECONDITION',
-          'install error: no store entry for system.approval'),
+          'install error: module manifest is invalid'),
       l,
     );
     expect(r.headline, l.errFailedPrecondition);
     expect(r.hint, l.errFailedPreconditionHint);
-    expect(r.detail, contains('system.approval'));
+    expect(r.detail, contains('manifest'));
   });
 
   test('NOT_FOUND has a recovery hint', () async {
@@ -151,5 +151,45 @@ void main() {
     );
     expect(r.headline, l.errMissingValue);
   });
+
+  test('no-store-entry maps to the three-path recovery hint', () async {
+    // The flow quick-fix dead end: even with the honest badge this
+    // error stays reachable (stale store snapshot, refresh race,
+    // older hub) — it must never render as the generic
+    // FAILED_PRECONDITION copy again.
+    final l = await _loadL10n(const Locale('en'));
+    final r = friendlyError(
+      _FakeGrpcError(
+        9,
+        'FAILED_PRECONDITION',
+        "install error: no store entry for 'example-provider/tool.summarize'"
+            ' — run `chain store search <term>` to see what\'s available',
+      ),
+      l,
+    );
+    expect(r.headline, l.errNoStoreEntry);
+    expect(r.hint, l.errNoStoreEntryHint);
+    // The hint names all three acquisition paths.
+    expect(r.hint, contains('chain install --link'));
+    expect(r.hint, contains('Stores'));
+    expect(r.hint, contains('integration'));
+    // The verbatim hub message stays copyable.
+    expect(r.detail, contains("example-provider/tool.summarize"));
+  });
+
+  test('no-store-entry is classified in German too', () async {
+    final l = await _loadL10n(const Locale('de'));
+    final r = friendlyError(
+      _FakeGrpcError(
+        9,
+        'FAILED_PRECONDITION',
+        "no store entry for 'x.y' — run `chain store search <term>`",
+      ),
+      l,
+    );
+    expect(r.headline, l.errNoStoreEntry);
+    expect(r.hint, contains('chain install --link'));
+    expect(r.hint, contains('Anbindung'));
+  });
 }