fix(studio): audit batch — debug.echo install, copyable errors, fast Diagnose

From a live-test audit:
- Install via the flow-editor 'Fix' sent 'debug.echo@^0' (version
  constraint included) as the install source; the hub resolves by bare
  name so it missed ('no store entry for debug.echo@^0'). Strip the
  @<constraint> like the Store page does — debug.echo now installs.
- Errors the operator could not copy: route the daemon-start failure
  (its stderr!), the flow-editor install failure and the federation
  issue failure through showFaiErrorSnack / a new showFaiProcessError
  helper, so every error is selectable, one-tap copyable and logged.
- Diagnose page opened slowly because doctor() Future.wait-ed on a live
  manifest fetch (8s server timeout); cap that one check at 2s so the
  page no longer waits on the network.

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

lib/data/error_presentation.dart

@@ -85,6 +85,30 @@ void showFaiErrorSnack(
   );
 }
 
+/// Surface a failed external-process result (daemon start, binary
+/// probe, file-open) as a copyable error snack. The `ok/stdout/stderr`
+/// record these actions return is not a thrown error, so call sites used
+/// to drop it into a raw `SnackBar(Text(...))` — uncopyable, the exact
+/// thing the operator needs to paste back. This joins stderr + stdout
+/// into one selectable, one-tap-copyable, logged message.
+void showFaiProcessError(
+  BuildContext context,
+  String source,
+  String stdout,
+  String stderr, {
+  String? title,
+}) {
+  final detail = [stderr.trim(), stdout.trim()]
+      .where((s) => s.isNotEmpty)
+      .join('\n\n');
+  showFaiErrorSnack(
+    context,
+    source,
+    detail.isEmpty ? 'process exited non-zero (no output)' : detail,
+    title: title,
+  );
+}
+
 /// Show [error] as a centered modal dialog. Use this when the
 /// failure blocks meaningful interaction (auth missing, hub
 /// unreachable) — a SnackBar would be too easy to dismiss.

lib/data/hub.dart

@@ -902,7 +902,18 @@ class HubService {
           .catchError((_) => <PendingApprovalEntry>[]),
       _client.verifyEventChain().catchError((_) => VerifyEventChainResponse()),
       _client.listServices().catchError((_) => <DeclaredService>[]),
-      _client.checkUpdate().catchError((_) => CheckUpdateResponse()),
+      // checkUpdate does a live manifest fetch (server-side 8s timeout).
+      // The other five are local-socket RPCs that return in ms, so cap
+      // this one tightly — otherwise it alone gates the whole Diagnose
+      // page open. A timeout reads as "release host unreachable", which
+      // the UI already renders as an offline banner, not an error.
+      _client
+          .checkUpdate()
+          .timeout(
+            const Duration(seconds: 2),
+            onTimeout: () => CheckUpdateResponse(),
+          )
+          .catchError((_) => CheckUpdateResponse()),
       _client.daemonPaths().catchError((_) => DaemonPathsResponse()),
     ]);
 

lib/main.dart

@@ -9,6 +9,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 import 'data/chain_log.dart';
+import 'data/error_presentation.dart';
 import 'data/hub.dart';
 import 'data/system_actions.dart';
 import 'data/theme_plugin.dart';
@@ -270,14 +271,21 @@ class StudioShellState extends State<StudioShell> {
     final l = AppLocalizations.of(context)!;
     final r = await SystemActions.chainDaemon(['start']);
     if (!mounted) return;
-    final detail = r.stderr.trim().isEmpty ? r.stdout.trim() : r.stderr.trim();
+    if (r.ok) {
       ScaffoldMessenger.of(context).showSnackBar(
-      SnackBar(
-        content: Text(
-          r.ok ? l.daemonStartRequested : l.daemonStartFailed(detail),
-        ),
-      ),
+        SnackBar(content: Text(l.daemonStartRequested)),
       );
+    } else {
+      // Surface the daemon's stderr/stdout as a copyable error — this
+      // is the message the operator most often needs to paste back.
+      showFaiProcessError(
+        context,
+        'daemon.start',
+        r.stdout,
+        r.stderr,
+        title: l.daemonStartFailed(''),
+      );
+    }
     // Probe again shortly so the UI flips to "connected" without
     // waiting for the next 5 s tick.
     Future.delayed(const Duration(seconds: 1), _checkHealth);
@@ -690,14 +698,21 @@ class _SidebarState extends State<_Sidebar>
     final l = AppLocalizations.of(context)!;
     final r = await SystemActions.chainDaemon(['start']);
     if (!context.mounted) return;
-    final detail = r.stderr.trim().isEmpty ? r.stdout.trim() : r.stderr.trim();
+    if (r.ok) {
       ScaffoldMessenger.of(context).showSnackBar(
-      SnackBar(
-        content: Text(
-          r.ok ? l.daemonStartRequested : l.daemonStartFailed(detail),
-        ),
-      ),
+        SnackBar(content: Text(l.daemonStartRequested)),
       );
+    } else {
+      // Surface the daemon's stderr/stdout as a copyable error — this
+      // is the message the operator most often needs to paste back.
+      showFaiProcessError(
+        context,
+        'daemon.start',
+        r.stdout,
+        r.stderr,
+        title: l.daemonStartFailed(''),
+      );
+    }
   }
 
   @override

lib/pages/federation.dart

@@ -5,6 +5,7 @@ import '../data/hub.dart';
 import '../l10n/app_localizations.dart';
 import '../theme/theme.dart';
 import '../theme/tokens.dart';
+import '../data/error_presentation.dart';
 import '../widgets/widgets.dart';
 import 'welcome.dart' show showFaiDoc;
 
@@ -48,9 +49,8 @@ class _FederationPageState extends State<FederationPage> {
       _refresh();
     } catch (e) {
       if (!mounted) return;
-      ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text(l.federationIssueFailed(e.toString()))),
-      );
+      showFaiErrorSnack(context, 'federation.issue', e,
+          title: l.federationIssueFailed(''));
     }
   }
 

lib/pages/flows.dart

@@ -13,6 +13,7 @@
 import 'package:chain_studio_flow_editor/chain_studio_flow_editor.dart';
 import 'package:flutter/material.dart';
 
+import '../data/error_presentation.dart';
 import '../data/flow_run_driver.dart';
 import '../data/hub.dart';
 import '../l10n/app_localizations.dart';
@@ -94,7 +95,13 @@ class _FlowsPageState extends State<FlowsPage> {
   /// list so the editor can re-analyze without waiting for the
   /// parent widget rebuild.
   Future<List<String>?> _onInstallCapability(String capability) async {
-    return _runInstall(source: capability);
+    // The analyzer hands us the full `use:` value (e.g. `debug.echo@^0`).
+    // The hub resolves install sources by bare capability name; the
+    // `@<constraint>` suffix would make the store lookup miss ("no store
+    // entry for 'debug.echo@^0'"). Strip it — same as the Store page.
+    final at = capability.indexOf('@');
+    final bare = at < 0 ? capability : capability.substring(0, at);
+    return _runInstall(source: bare);
   }
 
   /// `Add source for <cap>…` handler. Prompts the operator
@@ -123,15 +130,13 @@ class _FlowsPageState extends State<FlowsPage> {
     } catch (e) {
       if (mounted) {
         final l = AppLocalizations.of(context);
-        final msg = l != null
-            ? l.installFailed(e.toString())
-            : 'Install failed: $e';
-        ScaffoldMessenger.of(context).removeCurrentSnackBar();
-        ScaffoldMessenger.of(context).showSnackBar(
-          SnackBar(
-            content: Text(msg),
-            behavior: SnackBarBehavior.floating,
-          ),
+        // Copyable error (was a plain SnackBar) — install failures
+        // carry the real cause (network, signature, store lookup).
+        showFaiErrorSnack(
+          context,
+          'flows.install',
+          e,
+          title: l != null ? l.installFailed('') : 'Install failed',
         );
       }
       return null;