fix: stream Codex reasoning + drop swarm agents on their own completion

internal/providers/openai/codex_responses.go

@@ -59,6 +59,7 @@ const (
 	responsesEventOutputItemAdded   = "response.output_item.added"
 	responsesEventContentPartAdded  = "response.content_part.added"
 	responsesEventOutputTextDelta   = "response.output_text.delta"
+	responsesEventReasoningDelta    = "response.reasoning_summary_text.delta"
 	responsesEventOutputTextDone    = "response.output_text.done"
 	responsesEventFunctionArgsDelta = "response.function_call_arguments.delta"
 	responsesEventContentPartDone   = "response.content_part.done"
@@ -86,6 +87,10 @@ type responsesRequest struct {
 // here; omitted entirely when the caller requests no (or an unsupported) effort.
 type responsesReasoning struct {
 	Effort string `json:"effort,omitempty"`
+	// Summary requests a streamed reasoning summary ("auto" lets the API pick a
+	// level). Without it the backend emits no reasoning events, so a long thinking
+	// phase produces zero visible output and reads as a hang in the UI.
+	Summary string `json:"summary,omitempty"`
 }
 
 // inputItem is one element of the Responses `input` array. The Type field
@@ -256,7 +261,9 @@ func (p *CodexProvider) buildResponsesRequest(request zeroruntime.CompletionRequ
 	// and an empty or unsupported effort simply omits the field — without this the
 	// caller's chosen effort was silently dropped for every Codex model.
 	if effort := openAIReasoningEffort(request.ReasoningEffort); effort != "" {
-		req.Reasoning = &responsesReasoning{Effort: effort}
+		// Summary "auto" makes the backend stream reasoning_summary_text deltas so a
+		// long thinking phase shows live progress instead of looking hung.
+		req.Reasoning = &responsesReasoning{Effort: effort, Summary: "auto"}
 	}
 	return req, nil
 }
@@ -501,6 +508,17 @@ func (p *CodexProvider) emitResponsesEvent(
 			})
 		}
 		return true
+	case responsesEventReasoningDelta:
+		// Reasoning summary deltas: surface as live "thinking" so a long reasoning
+		// phase shows progress (and keeps the activity clock fresh) instead of
+		// looking like a hang. Requested via reasoning.summary="auto".
+		if event.Delta != "" {
+			providerio.SendEvent(ctx, events, zeroruntime.StreamEvent{
+				Type:    zeroruntime.StreamEventReasoning,
+				Content: event.Delta,
+			})
+		}
+		return true
 	case responsesEventFunctionArgsDelta:
 		p.handleFunctionArgsDelta(ctx, &event, state, events)
 		return true

internal/providers/openai/codex_test.go

@@ -485,6 +485,58 @@ func TestCodexProviderForwardsReasoningEffort(t *testing.T) {
 	if reasoning["effort"] != "high" {
 		t.Fatalf("body.reasoning.effort = %#v, want high", reasoning["effort"])
 	}
+	// A reasoning summary must be requested so the backend streams
+	// reasoning_summary_text deltas — otherwise a long think shows no live output.
+	if reasoning["summary"] != "auto" {
+		t.Fatalf("body.reasoning.summary = %#v, want auto", reasoning["summary"])
+	}
+}
+
+func TestCodexProviderStreamsReasoningSummaryDeltas(t *testing.T) {
+	// reasoning_summary_text deltas must surface as StreamEventReasoning (live
+	// "thinking"), in order, alongside the normal text output. Without this a long
+	// reasoning phase produces zero visible output and reads as a hang.
+	var rec codexRequest
+	srv := newCodexResponsesServer(t, &rec,
+		`{"type":"response.created","response":{"id":"resp-1","status":"in_progress"}}`,
+		`{"type":"response.reasoning_summary_text.delta","delta":"Thinking. "}`,
+		`{"type":"response.reasoning_summary_text.delta","delta":"Planning."}`,
+		`{"type":"response.output_text.delta","delta":"done"}`,
+		`{"type":"response.completed","response":{"id":"resp-1","status":"completed"}}`,
+	)
+	defer srv.Close()
+
+	provider, err := NewCodexProvider(CodexOptions{
+		Options:   Options{APIKey: "sk-test", BaseURL: srv.URL, Model: "gpt-5"},
+		AccountID: "acc-x",
+	})
+	if err != nil {
+		t.Fatalf("NewCodexProvider: %v", err)
+	}
+	stream, err := provider.StreamCompletion(context.Background(), zeroruntime.CompletionRequest{
+		Messages:        []zeroruntime.Message{{Role: zeroruntime.MessageRoleUser, Content: "solve it"}},
+		ReasoningEffort: "high",
+	})
+	if err != nil {
+		t.Fatalf("StreamCompletion: %v", err)
+	}
+	var reasoning, text []string
+	for ev := range stream {
+		switch ev.Type {
+		case zeroruntime.StreamEventReasoning:
+			reasoning = append(reasoning, ev.Content)
+		case zeroruntime.StreamEventText:
+			text = append(text, ev.Content)
+		case zeroruntime.StreamEventError:
+			t.Fatalf("unexpected error event: %q", ev.Error)
+		}
+	}
+	if got := strings.Join(reasoning, ""); got != "Thinking. Planning." {
+		t.Fatalf("reasoning deltas = %q, want %q", got, "Thinking. Planning.")
+	}
+	if got := strings.Join(text, ""); got != "done" {
+		t.Fatalf("text deltas = %q, want %q", got, "done")
+	}
 }
 
 func TestCodexProviderOmitsReasoningWhenUnset(t *testing.T) {

internal/tui/sidebar.go

@@ -261,13 +261,11 @@ func (m model) swarmSpawnedAgents() []swarmAgent {
 			switch a.state {
 			case "done", "failed", "completed", "cancelled":
 				a.finishing = true
-				if m.pending {
-					// Run still going: keep it visible and clickable, no fade.
-					a.finishedAt = time.Time{}
-					live = append(live, a)
-					continue
-				}
-				// Turn ended: fade out over the linger window, then drop.
+				// A member drops once ITS OWN task completes — not when the whole turn
+				// ends: fade out over the linger window from when it was first seen
+				// finished (stamped each tick by stampSwarmDone), then remove. This
+				// holds whether or not the overall run is still in flight, mirroring
+				// how finished specialists drop (sidebarSpecialists).
 				doneAt, stamped := m.swarmDoneAt[a.id]
 				if stamped && m.now().Sub(doneAt) >= sidebarAgentLinger {
 					continue // past the linger window — remove

internal/tui/sidebar_test.go

@@ -391,32 +391,32 @@ func TestSidebarShowsSwarmSpawnedAgents(t *testing.T) {
 // row (e.g. a resumed transcript that dropped the call): the member is still
 // A finished member stays visible (and clickable) while the run is still in
 // flight, so the user can inspect it; only once the turn ends does it drop.
-func TestSwarmAgentsPersistWhileRunInFlight(t *testing.T) {
+func TestSwarmAgentDropsOnOwnCompletionEvenMidRun(t *testing.T) {
 	base := time.Date(2026, 6, 24, 12, 0, 0, 0, time.UTC)
 	m := sidebarTestModel()
 	m.now = func() time.Time { return base }
-	m.pending = true  // run still going
+	m.pending = true  // run STILL going — a member must still drop on its OWN completion
 	m.activeRunID = 7 // exercise the run-scoped filter with a non-zero id
 	m.transcript = append(m.transcript,
 		transcriptRow{kind: rowToolCall, tool: "swarm_spawn", detail: "build homepage", runID: 7},
 		transcriptRow{kind: rowToolResult, tool: "swarm_spawn", detail: "Spawned subagent as task subagent-1 on team default.", runID: 7},
 		transcriptRow{kind: rowToolResult, tool: "swarm_collect", detail: "Results: 1 task(s)\n- subagent-1 [done] build homepage", runID: 7},
 	)
-	// Long past the linger window — but it must still show while pending.
-	m.swarmDoneAt = map[string]time.Time{"subagent-1": base.Add(-10 * sidebarAgentLinger)}
-
+	// Just finished, still within the linger window: shows briefly with a fading ✓.
+	m.swarmDoneAt = map[string]time.Time{"subagent-1": base.Add(-sidebarAgentLinger / 2)}
 	agents := m.swarmSpawnedAgents()
 	if len(agents) != 1 {
-		t.Fatalf("a finished member must stay while the run is in flight, got %d: %+v", len(agents), agents)
+		t.Fatalf("within the linger window a finished member should still show (fading), got %d: %+v", len(agents), agents)
 	}
 	if !agents[0].finishing {
 		t.Fatalf("a finished member should render done (✓), got %+v", agents[0])
 	}
 
-	// Once the turn ends, the long-finished member fades out and drops.
-	m.pending = false
+	// Past the linger window: it drops — even though the overall run is still in
+	// flight (previously a finished member lingered until the whole turn ended).
+	m.swarmDoneAt = map[string]time.Time{"subagent-1": base.Add(-2 * sidebarAgentLinger)}
 	if got := len(m.swarmSpawnedAgents()); got != 0 {
-		t.Fatalf("after the turn ends a long-finished member should drop, got %d", got)
+		t.Fatalf("a member past its linger window must drop on its own completion mid-run, got %d", got)
 	}
 }