fix(agent): stabilize design execution

crates/op-editor-core/src/chat.rs

@@ -230,7 +230,7 @@ pub struct ChatMessage {
     pub design_block_expanded_overrides: Vec<Option<bool>>,
     /// Per-action-step (subtask card) expanded-state overrides. Missing
     /// / `None` entries fall back to the transcript default (expanded
-    /// only while the step is the active/streaming one).
+    /// while the step is active or failed, so diagnostics stay visible).
     pub action_step_expanded_overrides: Vec<Option<bool>>,
     /// True while this (assistant) message's turn streams in.
     pub streaming: bool,
@@ -869,8 +869,8 @@ impl ChatState {
     /// Begin a manual retry for the failed subtask row at
     /// `activities[source_index]` in message `msg_idx` — the click handler
     /// for the progress panel's per-row "Retry" button. Flips that
-    /// activity's status back to `Running` and clears its stale "Needs
-    /// attention" detail so the row shows a spinner immediately, then
+    /// activity's status back to `Running` and clears its stale failure
+    /// diagnostic so the row shows a spinner immediately, then
     /// raises `pending_subtask_retry` for the desktop host to drain.
     ///
     /// No-ops (leaves everything untouched) when the message/activity index
@@ -1355,7 +1355,7 @@ mod tests {
         msg.activities.push(ChatActivity {
             id: "hero".into(),
             title: "Hero".into(),
-            detail: Some("Needs attention".into()),
+            detail: Some("Reason: provider returned no nodes".into()),
             status: ChatActivityStatus::Error,
             content_offset: Some(0),
         });
@@ -1391,7 +1391,7 @@ mod tests {
         msg.activities.push(ChatActivity {
             id: "hero".into(),
             title: "Hero".into(),
-            detail: Some("Needs attention".into()),
+            detail: Some("Reason: provider returned no nodes".into()),
             status: ChatActivityStatus::Error,
             content_offset: Some(0),
         });

crates/op-editor-host-core/src/design.rs

@@ -44,6 +44,9 @@ pub enum DesignDelta {
 /// Request from worker to UI to apply one editor mutation or batch boundary.
 pub struct DesignCmdReq {
     pub op: DesignCmdOp,
+    /// Page the design turn started on. The desktop applies every command
+    /// against this page even if the user switches pages while the LLM runs.
+    pub target_page_id: Option<String>,
     pub ack: SyncSender<DesignCmdAck>,
 }
 
@@ -151,19 +154,32 @@ impl DesignSession {
 pub struct RemoteDocSink {
     cmd_tx: Sender<DesignCmdReq>,
     mirror: EditorState,
+    target_page_id: Option<String>,
 }
 
 impl RemoteDocSink {
     pub fn new(cmd_tx: Sender<DesignCmdReq>, initial_state: EditorState) -> Self {
+        let target_page_id = initial_state
+            .doc
+            .pages
+            .as_ref()
+            .and_then(|pages| pages.get(initial_state.ui.active_page_index))
+            .map(|page| page.id.clone())
+            .or_else(|| Some("0".into()));
         Self {
             cmd_tx,
             mirror: initial_state,
+            target_page_id,
         }
     }
 
     fn send_and_wait(&mut self, op: DesignCmdOp) -> bool {
         let (ack_tx, ack_rx) = mpsc::sync_channel::<DesignCmdAck>(1);
-        let req = DesignCmdReq { op, ack: ack_tx };
+        let req = DesignCmdReq {
+            op,
+            target_page_id: self.target_page_id.clone(),
+            ack: ack_tx,
+        };
         if self.cmd_tx.send(req).is_err() {
             return false;
         }

crates/op-editor-host-core/tests/design.rs

@@ -24,6 +24,7 @@ fn remote_doc_sink_updates_mirror_on_ack() {
 
     let ui_thread = thread::spawn(move || {
         let req = rx.recv().expect("request");
+        assert_eq!(req.target_page_id.as_deref(), Some("0"));
         let mut new_state = initial.clone();
         new_state.viewport.zoom = 2.0;
         req.ack
@@ -96,6 +97,7 @@ fn design_session_drains_progress_and_command_requests() {
     cmd_tx
         .send(DesignCmdReq {
             op: DesignCmdOp::Apply(EditorCommand::ClearSelection),
+            target_page_id: None,
             ack: ack_tx,
         })
         .expect("cmd");

crates/op-editor-ui/src/widgets/ai_chat_transcript.rs

@@ -317,14 +317,15 @@ pub(crate) fn build_item(
             .iter()
             .flat_map(|line| wrap_units(line, budget.saturating_sub(4)))
             .collect();
-        // Default: expanded only while this step is the active/streaming
-        // one. A user click records a per-step override (collapse/expand).
+        // Active work and failures default open: a terminal error must expose
+        // its concrete diagnostic without making the user discover a hidden
+        // accordion. A user click still records an explicit override.
         let expanded = msg
             .action_step_expanded_overrides
             .get(i)
             .copied()
             .flatten()
-            .unwrap_or(active);
+            .unwrap_or(active || failed);
         let step_h = action_step_height(expanded, details.len());
         // `i` only aligns with `msg.activities`' own index when the
         // structured (non-interleaved) path built `progress_steps` directly

crates/op-editor-ui/src/widgets/ai_chat_transcript_cache_tests.rs

@@ -116,7 +116,7 @@ fn failed_subtask_message(retryable: bool) -> ChatMessage {
     m.activities.push(op_editor_core::ChatActivity {
         id: "hero".into(),
         title: "Hero".into(),
-        detail: Some("Needs attention".into()),
+        detail: Some("Reason: provider returned no nodes".into()),
         status: op_editor_core::ChatActivityStatus::Error,
         content_offset: Some(0),
     });

crates/op-editor-ui/src/widgets/ai_chat_transcript_flow.rs

@@ -98,7 +98,7 @@ pub(crate) fn build_activity_flow(
                 .get(source_index)
                 .copied()
                 .flatten()
-                .unwrap_or(active);
+                .unwrap_or(active || failed);
             let height = action_step_height(expanded, details.len());
             // `index` is a direct `msg.activities` index here (unlike the
             // legacy thinking-text-derived steps in `build_item`), so the

crates/op-editor-ui/src/widgets/ai_chat_transcript_tests.rs

@@ -628,6 +628,41 @@ fn structured_activities_render_as_compact_rows_without_thinking_text() {
     assert!(items[0].bubble.is_none());
 }
 
+#[test]
+fn failed_structured_activity_defaults_open_to_show_its_diagnostic() {
+    let mut message = ChatMessage::assistant("Finished with issues");
+    message.activities.push(op_editor_core::ChatActivity {
+        id: "customer-table".into(),
+        title: "Customer Table".into(),
+        detail: Some("Reason: parent_id=dashboard was not found".into()),
+        status: op_editor_core::ChatActivityStatus::Error,
+        content_offset: Some(0),
+    });
+
+    let items = build_transcript(
+        std::slice::from_ref(&message),
+        body(),
+        op_editor_core::Locale::EnUs,
+    );
+    assert!(items[0].steps[0].failed);
+    assert!(items[0].steps[0].expanded);
+    assert_eq!(
+        items[0].steps[0].details,
+        vec!["Reason: parent_id=dashboard was not found"]
+    );
+
+    message.action_step_expanded_overrides = vec![Some(false)];
+    let collapsed = build_transcript(
+        std::slice::from_ref(&message),
+        body(),
+        op_editor_core::Locale::EnUs,
+    );
+    assert!(
+        !collapsed[0].steps[0].expanded,
+        "an explicit user collapse must still win over the failure default"
+    );
+}
+
 #[test]
 fn structured_activities_interleave_with_cli_narration_by_offset() {
     let first = "I mapped the screen.";

crates/op-host-desktop/src/chat_session_launch.rs

@@ -88,7 +88,9 @@ pub fn launch_if_pending(
         if launch_direct_modify_turn(host, &user_text, current_chat, current_design) {
             return true;
         }
-    } else if matches!(classify_intent(&user_text), Intent::Design) {
+    } else if !op_host_services::chat_intent::is_non_request_text(&user_text)
+        && matches!(classify_intent(&user_text), Intent::Design)
+    {
         // Phase 2.3: When the design-agent-loop flag is ON and a built-in
         // provider is configured, run the agentic tool-loop with the 14-tool
         // design toolset instead of the orchestrator pipeline. Flag OFF falls

crates/op-host-desktop/src/design_session.rs

@@ -46,10 +46,37 @@ pub fn pump_commands(
     let state = host.editor_state_mut();
     let mut any_applied = false;
     for req in reqs {
+        let target_page_index =
+            req.target_page_id
+                .as_deref()
+                .and_then(|page_id| match state.doc.pages.as_ref() {
+                    Some(pages) if !pages.is_empty() => pages
+                        .iter()
+                        .position(|page| page.id == page_id)
+                        .or_else(|| {
+                            page_id
+                                .parse::<usize>()
+                                .ok()
+                                .filter(|idx| *idx < pages.len())
+                        }),
+                    _ if page_id == "0" => Some(0),
+                    _ => None,
+                });
+        let original_page_index = state.ui.active_page_index;
+        let original_selection = state.selection.clone();
+        if let Some(target) = target_page_index {
+            state.ui.active_page_index = target;
+            if target != original_page_index {
+                state.clear_selection();
+            }
+        }
+        let target_available = req.target_page_id.is_none() || target_page_index.is_some();
+        let target_is_visible =
+            req.target_page_id.is_none() || target_page_index == Some(original_page_index);
         let applied = match req.op {
             DesignCmdOp::Apply(cmd) => {
-                let applied = state.apply(cmd);
-                if applied {
+                let applied = target_available && state.apply(cmd);
+                if applied && target_is_visible {
                     fit_design_viewport_to_content(state, viewport_width, viewport_height);
                 }
                 applied
@@ -60,7 +87,13 @@ pub fn pump_commands(
             // functionally correct, just finer-grained than ideal.
             DesignCmdOp::BeginUndoBatch | DesignCmdOp::EndUndoBatch => true,
         };
+        // The worker mirror stays on the design target, while the visible
+        // editor returns to the page and selection the user is viewing.
         let snapshot = state.clone();
+        if target_page_index.is_some_and(|target| target != original_page_index) {
+            state.ui.active_page_index = original_page_index;
+            state.selection = original_selection;
+        }
         let ack = DesignCmdAck {
             applied,
             new_state: snapshot,
@@ -293,11 +326,11 @@ fn apply_progress(msg: &mut ChatMessage, progress: &[Progress], locale: Locale)
                 ChatActivityStatus::Done,
                 Some(element_count(locale, *node_count)),
             ),
-            Progress::SubtaskFailed { id, .. } => update_activity(
+            Progress::SubtaskFailed { id, error } => update_activity(
                 msg,
                 id,
                 ChatActivityStatus::Error,
-                Some(op_i18n::translate(locale, "ai.designProgress.detail.needsAttention").into()),
+                Some(subtask_failure_detail(locale, error)),
             ),
             Progress::SubtaskRetry { id, attempt, .. } => update_activity(
                 msg,
@@ -500,6 +533,19 @@ fn element_count(locale: Locale, count: usize) -> String {
     op_i18n::translate(locale, key).replace("{{count}}", &count.to_string())
 }
 
+fn subtask_failure_detail(locale: Locale, error: &str) -> String {
+    let compact = error.split_whitespace().collect::<Vec<_>>().join(" ");
+    if compact.is_empty() {
+        return op_i18n::translate(locale, "ai.designProgress.detail.noDiagnostic").into();
+    }
+    let mut visible: String = compact.chars().take(220).collect();
+    if compact.chars().count() > 220 {
+        visible.push('…');
+    }
+    op_i18n::translate(locale, "ai.designProgress.detail.failureReason")
+        .replace("{{reason}}", &visible)
+}
+
 fn planned_narration(locale: Locale, count: usize) -> String {
     let key = if count == 1 {
         "ai.designProgress.narration.plannedOne"

crates/op-host-desktop/src/design_session_terminal_tests.rs

@@ -151,6 +151,17 @@ fn companion_chat_disconnect_cannot_drop_validation_completion_or_retry_payload(
             .status,
         ChatActivityStatus::Error
     );
+    assert_eq!(
+        message
+            .activities
+            .iter()
+            .find(|activity| activity.id == "sun_arc")
+            .unwrap()
+            .detail
+            .as_deref(),
+        Some("Reason: self-check failed"),
+        "the terminal summary must preserve the concrete subtask failure"
+    );
     assert_eq!(message.failed_subtasks.len(), 1);
     assert_eq!(message.failed_subtasks[0].subtask_id, "sun_arc");
     assert_eq!(