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

Two agent-visibility fixes surfaced diagnosing a 20-minute gpt-5.5 step and an
'agents never disappear' report.

A) Codex Responses path streamed no reasoning, so a long thinking phase produced
   zero visible output and read as a hang (the activity clock never advanced).
   Root cause: the request never asked for a reasoning summary and the parser had
   no case for reasoning deltas. Now request reasoning.summary="auto" and forward
   response.reasoning_summary_text.delta as StreamEventReasoning — the existing TUI
   handler renders it live and refreshes the activity clock.

B) A finished swarm member stayed in the AGENTS panel until the whole turn ended.
   Now it drops once ITS OWN task completes (fade over the linger window, then
   remove), independent of the overall run — matching how finished specialists
   already behave. Running members and mid-flight collect are unaffected.

README.md

@@ -82,6 +82,18 @@ If you are testing before the first public release, build from source:
 go build -o zero ./cmd/zero
 ```
 
+On Linux, build the sandbox helper too if you want native sandboxing:
+
+```bash
+go build -o zero-linux-sandbox ./cmd/zero-linux-sandbox
+go build -o zero-seccomp ./cmd/zero-seccomp   # optional compatibility wrapper
+```
+
+Put `zero` and `zero-linux-sandbox` in the same directory on `PATH`
+(`~/.local/bin` is a good default). macOS does not need an extra helper binary.
+Windows source builds can use the main `zero.exe` as their sandbox helper; release
+archives still ship standalone Windows helper executables.
+
 More install details: [docs/INSTALL.md](docs/INSTALL.md).
 
 ## First Run

docs/INSTALL.md

@@ -108,6 +108,36 @@ go build -o zero ./cmd/zero
 
 Source builds require Go 1.25+.
 
+### Sandbox Helpers For Source Builds
+
+Release archives include the platform sandbox helpers. If you build directly
+from source, build the helpers you need:
+
+Linux:
+
+```bash
+go build -o zero ./cmd/zero
+go build -o zero-linux-sandbox ./cmd/zero-linux-sandbox
+go build -o zero-seccomp ./cmd/zero-seccomp
+```
+
+Put `zero` and `zero-linux-sandbox` in the same directory on `PATH`, for example
+`~/.local/bin`. `zero-seccomp` is kept as a compatibility wrapper; the sandbox
+helper applies the Unix-socket filter itself when that sandbox option is enabled.
+Linux native sandboxing also requires Bubblewrap to be installed.
+
+macOS uses the system sandbox and does not need an extra helper binary.
+
+Windows source builds can use the main `zero.exe` as the command runner and setup
+helper through Zero's built-in self-dispatch path. If you want a release-style
+layout anyway, build the standalone helper executables next to `zero.exe`:
+
+```powershell
+go build -o zero.exe ./cmd/zero
+go build -o zero-windows-command-runner.exe ./cmd/zero-windows-command-runner
+go build -o zero-windows-sandbox-setup.exe ./cmd/zero-windows-sandbox-setup
+```
+
 ## Release Archive Format
 
 Release archives are named:

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/providers/openai/provider.go

@@ -385,6 +385,14 @@ func sendBufferedEvent(events chan<- zeroruntime.StreamEvent, event zeroruntime.
 func (provider *Provider) openAIRequest(request zeroruntime.CompletionRequest) chatCompletionRequest {
 	messages := make([]chatMessage, 0, len(request.Messages))
 	for _, message := range request.Messages {
+		// Drop a degenerate assistant turn that carries neither text nor tool calls
+		// (e.g. a sub-agent that failed with no output). The Anthropic/Gemini mappers
+		// already skip empty turns; without this, the contentless message reaches
+		// strict OpenAI-compatible servers and is rejected.
+		if message.Role == zeroruntime.MessageRoleAssistant &&
+			strings.TrimSpace(message.Content) == "" && len(message.ToolCalls) == 0 {
+			continue
+		}
 		messages = append(messages, mapMessage(message))
 	}
 
@@ -445,11 +453,12 @@ func mapMessage(message zeroruntime.Message) chatMessage {
 	// message that happens to carry Images keeps the plain string/nil content
 	// path (its images are simply not serialized).
 	if len(message.Images) == 0 || message.Role != zeroruntime.MessageRoleUser {
-		// Preserve the legacy behavior: only non-empty text is serialized, so
-		// empty content is omitted by the `omitempty` tag.
-		if message.Content != "" {
-			mapped.Content = message.Content
-		}
+		// Always set content (to "" when empty) so it serializes as `"content":""`
+		// rather than being dropped. Strict OpenAI-compatible servers reject a
+		// message with no content field; tool results and assistant-with-tool-calls
+		// turns must still carry an (empty) content. Truly empty assistant turns are
+		// dropped upstream in openAIRequest.
+		mapped.Content = message.Content
 	} else {
 		parts := make([]contentPart, 0, len(message.Images)+1)
 		if message.Content != "" {

internal/providers/openai/provider_test.go

@@ -1000,57 +1000,6 @@ func TestStreamCompletionEmitsDroppedOnNamelessToolCall(t *testing.T) {
 	}
 }
 
-func TestOpenAIRequestTextOnlyOmitsEmptyContent(t *testing.T) {
-	provider, err := New(Options{Model: "gpt-test"})
-	if err != nil {
-		t.Fatalf("New returned error: %v", err)
-	}
-
-	got, err := json.Marshal(provider.openAIRequest(zeroruntime.CompletionRequest{
-		Messages: []zeroruntime.Message{
-			{Role: zeroruntime.MessageRoleSystem, Content: "system"},
-			{Role: zeroruntime.MessageRoleUser, Content: "hello"},
-			{
-				Role:    zeroruntime.MessageRoleAssistant,
-				Content: "", // assistant turn that is *only* a tool call -> empty content must drop
-				ToolCalls: []zeroruntime.ToolCall{{
-					ID:        "call_1",
-					Name:      "read_file",
-					Arguments: `{"path":"README.md"}`,
-				}},
-			},
-			{Role: zeroruntime.MessageRoleTool, Content: "contents", ToolCallID: "call_1"},
-		},
-	}))
-	if err != nil {
-		t.Fatalf("marshal request: %v", err)
-	}
-
-	// String content round-trips as a JSON string, and empty content is omitted.
-	if !strings.Contains(string(got), `"content":"hello"`) {
-		t.Fatalf("user content not serialized as string: %s", got)
-	}
-	if strings.Contains(string(got), `"content":""`) {
-		t.Fatalf("empty assistant content must be omitted, got: %s", got)
-	}
-
-	// Decode the assistant message and assert no content key at all.
-	var decoded chatCompletionRequest
-	var raw struct {
-		Messages []map[string]any `json:"messages"`
-	}
-	if err := json.Unmarshal(got, &raw); err != nil {
-		t.Fatalf("unmarshal request: %v", err)
-	}
-	_ = decoded
-	if _, present := raw.Messages[2]["content"]; present {
-		t.Fatalf("assistant (tool-only) message must omit content key, got: %#v", raw.Messages[2])
-	}
-	if raw.Messages[1]["content"] != "hello" {
-		t.Fatalf("user content = %#v, want \"hello\"", raw.Messages[1]["content"])
-	}
-}
-
 func TestContentPartImageURLMarshalsDataURI(t *testing.T) {
 	parts := []contentPart{
 		{Type: "text", Text: "look"},
@@ -1076,38 +1025,6 @@ func TestContentPartImageURLMarshalsDataURI(t *testing.T) {
 	}
 }
 
-func TestOpenAIRequestEmptyContentStaysOmittedAfterAnyRefactor(t *testing.T) {
-	provider, err := New(Options{Model: "gpt-test"})
-	if err != nil {
-		t.Fatalf("New returned error: %v", err)
-	}
-	got, err := json.Marshal(provider.openAIRequest(zeroruntime.CompletionRequest{
-		Messages: []zeroruntime.Message{
-			{
-				Role:    zeroruntime.MessageRoleAssistant,
-				Content: "",
-				ToolCalls: []zeroruntime.ToolCall{{
-					ID:        "call_1",
-					Name:      "read_file",
-					Arguments: `{}`,
-				}},
-			},
-		},
-	}))
-	if err != nil {
-		t.Fatalf("marshal: %v", err)
-	}
-	var raw struct {
-		Messages []map[string]any `json:"messages"`
-	}
-	if err := json.Unmarshal(got, &raw); err != nil {
-		t.Fatalf("unmarshal: %v", err)
-	}
-	if _, present := raw.Messages[0]["content"]; present {
-		t.Fatalf("empty content boxed in any must stay omitted, got: %#v", raw.Messages[0])
-	}
-}
-
 func TestMapMessageBuildsImageURLContentParts(t *testing.T) {
 	msg := mapMessage(zeroruntime.Message{
 		Role:    zeroruntime.MessageRoleUser,
@@ -1165,8 +1082,8 @@ func TestMapMessageTextOnlyKeepsStringContent(t *testing.T) {
 		t.Fatalf("Content = %#v, want string \"hi\"", msg.Content)
 	}
 	empty := mapMessage(zeroruntime.Message{Role: zeroruntime.MessageRoleAssistant, Content: ""})
-	if empty.Content != nil {
-		t.Fatalf("empty text content = %#v, want nil so omitempty drops it", empty.Content)
+	if got, ok := empty.Content.(string); !ok || got != "" {
+		t.Fatalf("empty text content = %#v, want \"\" so it serializes as content:\"\" (strict servers reject a missing/null content)", empty.Content)
 	}
 }
 
@@ -1246,3 +1163,66 @@ func TestStreamCompletionSerializesImageContentParts(t *testing.T) {
 		t.Fatalf("image url = %#v, want data:image/png;base64,QUJD", imageURL["url"])
 	}
 }
+
+// TestOpenAIRequestEmptyContentHandling locks in the fix for strict OpenAI-
+// compatible servers (e.g. glm-* on Ollama-cloud) that reject a message whose
+// `content` is absent/null with "invalid message content type: <nil>": a
+// contentless assistant turn with no tool calls is dropped, and every other
+// message serializes an explicit `"content"` field (empty string when there is
+// no text) instead of omitting it.
+func TestOpenAIRequestEmptyContentHandling(t *testing.T) {
+	provider, err := New(Options{Model: "gpt-test"})
+	if err != nil {
+		t.Fatalf("New returned error: %v", err)
+	}
+
+	req := provider.openAIRequest(zeroruntime.CompletionRequest{
+		Messages: []zeroruntime.Message{
+			{Role: zeroruntime.MessageRoleUser, Content: "hi"},
+			// Degenerate empty assistant turn (e.g. a sub-agent that failed with no
+			// output): must be dropped, not sent.
+			{Role: zeroruntime.MessageRoleAssistant, Content: "   "},
+			// Assistant with tool calls but no text: kept, content present as "".
+			{Role: zeroruntime.MessageRoleAssistant, Content: "", ToolCalls: []zeroruntime.ToolCall{{
+				ID: "call_1", Name: "read_file", Arguments: "{}",
+			}}},
+			// Tool result with empty content: kept, content present as "".
+			{Role: zeroruntime.MessageRoleTool, Content: "", ToolCallID: "call_1"},
+		},
+	})
+
+	if len(req.Messages) != 3 {
+		t.Fatalf("empty assistant turn should be dropped; got %d messages: %#v", len(req.Messages), req.Messages)
+	}
+
+	// No message may serialize with an absent/null content field.
+	for i, message := range req.Messages {
+		if message.Content == nil {
+			t.Fatalf("message %d has nil content (would serialize as null/omitted): %#v", i, message)
+		}
+		data, err := json.Marshal(message)
+		if err != nil {
+			t.Fatalf("marshal message %d: %v", i, err)
+		}
+		if !strings.Contains(string(data), `"content":`) {
+			t.Fatalf("message %d omits the content field: %s", i, data)
+		}
+	}
+
+	if req.Messages[0].Content != "hi" {
+		t.Fatalf("user content = %#v, want \"hi\"", req.Messages[0].Content)
+	}
+	// The kept-but-textless messages must send content as an explicit empty string.
+	for _, idx := range []int{1, 2} {
+		data, err := json.Marshal(req.Messages[idx])
+		if err != nil {
+			t.Fatalf("marshal message %d: %v", idx, err)
+		}
+		if !strings.Contains(string(data), `"content":""`) {
+			t.Fatalf("message %d should send content:\"\", got %s", idx, data)
+		}
+	}
+	if len(req.Messages[1].ToolCalls) != 1 {
+		t.Fatalf("assistant tool calls dropped: %#v", req.Messages[1])
+	}
+}

internal/providers/openai/types.go

@@ -18,8 +18,13 @@ type streamOptions struct {
 }
 
 type chatMessage struct {
-	Role       string            `json:"role"`
-	Content    any               `json:"content,omitempty"`
+	Role string `json:"role"`
+	// Content has no omitempty: strict OpenAI-compatible servers (e.g. some
+	// Ollama-cloud models like glm-*) reject a message whose `content` is absent
+	// or null with "invalid message content type: <nil>". mapMessage always sets
+	// this (to "" when there's no text), so a contentless message serializes as
+	// `"content":""` rather than being dropped.
+	Content    any               `json:"content"`
 	ToolCalls  []requestToolCall `json:"tool_calls,omitempty"`
 	ToolCallID string            `json:"tool_call_id,omitempty"`
 }

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)
 	}
 }