feat(subagent): emit reasoning text as progress in StepCompleted events

src/app/subagent/engine.rs

@@ -416,6 +416,15 @@ pub fn run_subagent(ctx: &SubagentContext, tx: &mpsc::Sender<SubagentEvent>) ->
 
         let content = response.content.clone().unwrap_or_default();
 
+        // Emit thinking/reasoning text as StepCompleted so the parent's
+        // drain thread can show it as progress instead of just the tool name.
+        if !content.is_empty() {
+            let _ = tx.blocking_send(SubagentEvent::StepCompleted {
+                step,
+                output: content.clone(),
+            });
+        }
+
         if has_tool_calls {
             let tool_calls = response.tool_calls.clone().unwrap_or_default();
             // Push the assistant message with tool_calls into the conversation

src/app/workflow/engine.rs

@@ -211,8 +211,29 @@ fn spawn_single_agent(
                         );
                     }
                 }
-                SubagentEvent::StepCompleted { .. } => {
-                    tracing::trace!("[subagent] step completed");
+                SubagentEvent::StepCompleted { output, .. } => {
+                    // Show the agent's thinking/reasoning text as progress
+                    // instead of just the tool name — first line, truncated.
+                    if let Some(ref f) = drain_live {
+                        let summary = output
+                            .lines()
+                            .next()
+                            .unwrap_or(output)
+                            .chars()
+                            .take(80)
+                            .collect::<String>();
+                        f(
+                            drain_agent_id.clone(),
+                            drain_agent_name.clone(),
+                            AgentStatus {
+                                state: AgentState::Running,
+                                started_at: Some(drain_started_at),
+                                completed_at: None,
+                                error: None,
+                                progress: Some(summary),
+                            },
+                        );
+                    }
                 }
                 SubagentEvent::StepFailed { step, error } => {
                     tracing::warn!("[subagent] step {} failed: {}", step, error);