diff --git a/apps/docs/content/docs/environment-variables.ja.mdx b/apps/docs/content/docs/environment-variables.ja.mdx
index 9541cd920..7818ea2b6 100644
--- a/apps/docs/content/docs/environment-variables.ja.mdx
+++ b/apps/docs/content/docs/environment-variables.ja.mdx
@@ -207,6 +207,7 @@ API key と base URL の両方が空の場合、サーバーサイド LLM 生成
 | `MULTICA_DAEMON_AUTO_UPDATE_INTERVAL` | `6h` | 更新チェックの間隔 |
 | `MULTICA_DAEMON_AUTO_RELOAD` | `true` | 帯域外で置き換えられた `multica` バイナリ（`brew upgrade`、再ダウンロード、ローカルビルド）へ再起動して追従するかどうか。`MULTICA_DAEMON_AUTO_UPDATE` とは独立 |
 | `MULTICA_WORKSPACES_ROOT` | `~/multica_workspaces` | タスク作業ディレクトリのルート |
+| `MULTICA_AGENT_TEMP_BASE` | `/tmp`（Linux/macOS） | Linux/macOS 専用。作業ごとのプライベート一時ディレクトリの親ディレクトリ。既存かつ書き込み可能な絶対パスである必要があり、無効な値の場合は `/tmp` にフォールバックせず作業の開始に失敗します。短いパスを選んでください。子ツールがその配下に AF_UNIX ソケットを作成する場合があり、`sun_path` の上限は Linux で 108 バイト、macOS で 104 バイトです |
 | `MULTICA_KEEP_ENV_AFTER_TASK` | `false` | デバッグ用にタスクディレクトリを保持 |
 
 各 AI コーディングツールは `MULTICA_<PROVIDER>_PATH` と `MULTICA_<PROVIDER>_MODEL` でコマンドパスとデフォルトモデルを上書きできます。QwenPaw だけは例外で、Multica がモデルを渡さないため `MULTICA_QWENPAW_MODEL` はありません。詳しくは [AI コーディングツール比較](/providers#モデルの取得元) を参照してください。マシン全体のデフォルト引数 `MULTICA_<PROVIDER>_ARGS` は、現在 Claude Code、Codex、CodeBuddy、Qwen Code、QwenPaw の 5 ツールに対応しています。対応する変数は `MULTICA_CLAUDE_ARGS`、`MULTICA_CODEX_ARGS`、`MULTICA_CODEBUDDY_ARGS`、`MULTICA_QWEN_ARGS`、`MULTICA_QWENPAW_ARGS` です。例:
diff --git a/apps/docs/content/docs/environment-variables.ko.mdx b/apps/docs/content/docs/environment-variables.ko.mdx
index 879ae5afb..bcf0cd8e8 100644
--- a/apps/docs/content/docs/environment-variables.ko.mdx
+++ b/apps/docs/content/docs/environment-variables.ko.mdx
@@ -207,6 +207,7 @@ API key와 base URL이 모두 비어 있으면 서버 측 LLM 생성이 꺼지
 | `MULTICA_DAEMON_AUTO_UPDATE_INTERVAL` | `6h` | 업데이트 확인 간격 |
 | `MULTICA_DAEMON_AUTO_RELOAD` | `true` | 외부에서 교체된 `multica` 바이너리(`brew upgrade`, 재다운로드, 로컬 빌드)로 재시작할지 여부. `MULTICA_DAEMON_AUTO_UPDATE`와 독립적 |
 | `MULTICA_WORKSPACES_ROOT` | `~/multica_workspaces` | 실행 태스크 작업 디렉터리의 루트 |
+| `MULTICA_AGENT_TEMP_BASE` | `/tmp`(Linux/macOS) | Linux/macOS 전용. 작업별 비공개 임시 디렉터리의 상위 디렉터리입니다. 기존의 쓰기 가능한 절대 경로여야 하며, 값이 잘못되면 `/tmp`로 대체하지 않고 작업 시작에 실패합니다. 짧은 경로를 선택하세요. 하위 도구가 그 아래에 AF_UNIX 소켓을 만들 수 있으며 `sun_path` 제한은 Linux에서 108바이트, macOS에서 104바이트입니다 |
 | `MULTICA_KEEP_ENV_AFTER_TASK` | `false` | 디버깅을 위해 실행 태스크 디렉터리 유지 |
 
 각 AI 코딩 도구는 `MULTICA_<PROVIDER>_PATH`와 `MULTICA_<PROVIDER>_MODEL`로 명령 경로와 기본 모델을 덮어쓸 수 있습니다. QwenPaw만 예외로, Multica가 모델을 전달하지 않기 때문에 `MULTICA_QWENPAW_MODEL`이 없습니다. 자세한 내용은 [AI 코딩 도구 비교](/providers#모델-출처)를 참고하세요. 컴퓨터 전체 기본 인수 `MULTICA_<PROVIDER>_ARGS`는 현재 Claude Code, Codex, CodeBuddy, Qwen Code, QwenPaw 다섯 도구를 지원합니다. 해당 변수는 `MULTICA_CLAUDE_ARGS`, `MULTICA_CODEX_ARGS`, `MULTICA_CODEBUDDY_ARGS`, `MULTICA_QWEN_ARGS`, `MULTICA_QWENPAW_ARGS`입니다. 예시:
diff --git a/apps/docs/content/docs/environment-variables.mdx b/apps/docs/content/docs/environment-variables.mdx
index 87d415730..e399ae1e9 100644
--- a/apps/docs/content/docs/environment-variables.mdx
+++ b/apps/docs/content/docs/environment-variables.mdx
@@ -207,6 +207,7 @@ The variables below are read on the computer that runs your agents, not in the A
 | `MULTICA_DAEMON_AUTO_UPDATE_INTERVAL` | `6h` | Update check interval |
 | `MULTICA_DAEMON_AUTO_RELOAD` | `true` | Whether to restart into a `multica` binary replaced on disk out of band (`brew upgrade`, a re-download, a local build). Independent of `MULTICA_DAEMON_AUTO_UPDATE` |
 | `MULTICA_WORKSPACES_ROOT` | `~/multica_workspaces` | Root directory for task working directories |
+| `MULTICA_AGENT_TEMP_BASE` | `/tmp` (Linux/macOS) | Linux/macOS only. Parent directory for private per-task temp dirs; must be an existing, writable absolute directory, and an invalid value fails task startup instead of falling back to `/tmp`. Pick a short path — child tools may bind AF_UNIX sockets under it, and `sun_path` is limited to 108 bytes on Linux and 104 on macOS |
 | `MULTICA_KEEP_ENV_AFTER_TASK` | `false` | Keep task directories for debugging |
 
 Each AI coding tool accepts `MULTICA_<PROVIDER>_PATH` and `MULTICA_<PROVIDER>_MODEL` to override the command path and default model. QwenPaw is the exception: it has no `MULTICA_QWENPAW_MODEL`, because Multica never sends it a model — see [AI coding tools comparison](/providers#model-sources). Machine-wide default arguments via `MULTICA_<PROVIDER>_ARGS` are currently supported for five tools: Claude Code, Codex, CodeBuddy, Qwen Code, and QwenPaw. The variables are `MULTICA_CLAUDE_ARGS`, `MULTICA_CODEX_ARGS`, `MULTICA_CODEBUDDY_ARGS`, `MULTICA_QWEN_ARGS`, and `MULTICA_QWENPAW_ARGS`. For example:
diff --git a/apps/docs/content/docs/environment-variables.zh.mdx b/apps/docs/content/docs/environment-variables.zh.mdx
index 3f0f6c111..4b63bdd05 100644
--- a/apps/docs/content/docs/environment-variables.zh.mdx
+++ b/apps/docs/content/docs/environment-variables.zh.mdx
@@ -207,6 +207,7 @@ API key 与 base URL 都为空时，服务端 LLM 生成关闭，调用方会使
 | `MULTICA_DAEMON_AUTO_UPDATE_INTERVAL` | `6h` | 检查更新的间隔 |
 | `MULTICA_DAEMON_AUTO_RELOAD` | `true` | 是否在 `multica` 二进制被带外替换（`brew upgrade`、重新下载、本地构建）后重启到新二进制。与 `MULTICA_DAEMON_AUTO_UPDATE` 相互独立 |
 | `MULTICA_WORKSPACES_ROOT` | `~/multica_workspaces` | 执行任务工作目录的根目录 |
+| `MULTICA_AGENT_TEMP_BASE` | `/tmp`（Linux/macOS） | 仅适用于 Linux/macOS。私有 task 临时目录的父目录；必须是现有、可写的绝对路径，无效值会使 task 启动失败，不会回退到 `/tmp`。请选择较短的路径——子工具可能会在其中绑定 AF_UNIX socket；Linux 的 `sun_path` 上限为 108 字节，macOS 为 104 字节 |
 | `MULTICA_KEEP_ENV_AFTER_TASK` | `false` | 保留执行任务目录用于调试 |
 
 各 AI 编程工具可以使用 `MULTICA_<PROVIDER>_PATH` 和 `MULTICA_<PROVIDER>_MODEL` 覆盖命令路径与默认模型。QwenPaw 是例外：它没有 `MULTICA_QWENPAW_MODEL`，因为 Multica 不会向它传模型，详见 [AI 编程工具对比](/providers#模型来源)。全机默认参数 `MULTICA_<PROVIDER>_ARGS` 目前支持 Claude Code、Codex、CodeBuddy、Qwen Code 和 QwenPaw 五款工具。对应变量是 `MULTICA_CLAUDE_ARGS`、`MULTICA_CODEX_ARGS`、`MULTICA_CODEBUDDY_ARGS`、`MULTICA_QWEN_ARGS` 和 `MULTICA_QWENPAW_ARGS`。例如：
diff --git a/server/internal/daemon/daemon.go b/server/internal/daemon/daemon.go
index 2824b9fad..bd6a314c3 100644
--- a/server/internal/daemon/daemon.go
+++ b/server/internal/daemon/daemon.go
@@ -7626,16 +7626,45 @@ func ensureTaskTempDir(envRoot string, workspaceID string, taskID string) (strin
 	if taskID == "" {
 		return "", errors.New("task id is empty")
 	}
-	dir, err := os.MkdirTemp(socketSafeTempBaseDir(), "multica-task-")
+	base, overrideConfigured, err := taskTempBaseDir()
 	if err != nil {
 		return "", err
 	}
+	dir, err := os.MkdirTemp(base, "multica-task-")
+	if err != nil {
+		if overrideConfigured {
+			return "", fmt.Errorf("MULTICA_AGENT_TEMP_BASE: create task temp dir: %w", err)
+		}
+		return "", err
+	}
 	if err := os.Chmod(dir, 0o700); err != nil {
 		return "", err
 	}
 	return dir, nil
 }
 
+// taskTempBaseDir resolves the parent directory for private per-task temp
+// dirs on Linux and macOS. The daemon operator can relocate it with
+// MULTICA_AGENT_TEMP_BASE, which must be an absolute path to an existing,
+// writable directory; an invalid value fails task startup instead of silently
+// falling back. Windows ignores the variable. Unset keeps the platform default
+// exactly as before, down to the syscalls made.
+// Operators should pick a short path: child tools may bind AF_UNIX sockets
+// under $TMPDIR (sun_path is 108 bytes on Linux, 104 on macOS).
+func taskTempBaseDir() (string, bool, error) {
+	if runtime.GOOS == "windows" {
+		return socketSafeTempBaseDir(), false, nil
+	}
+	base := strings.TrimSpace(os.Getenv("MULTICA_AGENT_TEMP_BASE"))
+	if base == "" {
+		return socketSafeTempBaseDir(), false, nil
+	}
+	if !filepath.IsAbs(base) {
+		return "", true, fmt.Errorf("MULTICA_AGENT_TEMP_BASE must be an absolute path, got %q", base)
+	}
+	return base, true, nil
+}
+
 func socketSafeTempBaseDir() string {
 	if os.PathSeparator == '/' {
 		if info, err := os.Stat("/tmp"); err == nil && info.IsDir() {
diff --git a/server/internal/daemon/workdir_race_test.go b/server/internal/daemon/workdir_race_test.go
index 5624e8fb4..6b7e294a9 100644
--- a/server/internal/daemon/workdir_race_test.go
+++ b/server/internal/daemon/workdir_race_test.go
@@ -272,6 +272,300 @@ printf '%s\n' '{"type":"result","subtype":"success","is_error":false,"session_id
 	}
 }
 
+// TestTaskTempBaseDir covers the MULTICA_AGENT_TEMP_BASE validation contract:
+// Windows ignores it, while Unix honors a valid absolute directory and reports
+// unusable configured bases from the real task-directory creation instead of
+// silently falling back to /tmp.
+func TestTaskTempBaseDir(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Setenv("MULTICA_AGENT_TEMP_BASE", `C:\configured-but-ignored`)
+		got, configured, err := taskTempBaseDir()
+		if err != nil {
+			t.Fatalf("taskTempBaseDir(): %v", err)
+		}
+		if configured {
+			t.Fatal("taskTempBaseDir() marked Windows override as configured")
+		}
+		if got != socketSafeTempBaseDir() {
+			t.Fatalf("taskTempBaseDir() = %q, want platform default %q", got, socketSafeTempBaseDir())
+		}
+		return
+	}
+
+	validBase := t.TempDir()
+	cases := []struct {
+		name           string
+		value          string
+		set            bool
+		want           string
+		wantConfigured bool
+		wantErr        bool
+	}{
+		{name: "unset keeps platform default", set: false, want: socketSafeTempBaseDir()},
+		{name: "empty keeps platform default", set: true, value: "  ", want: socketSafeTempBaseDir()},
+		{name: "valid absolute dir is honored", set: true, value: validBase, want: validBase, wantConfigured: true},
+		{name: "relative path rejected", set: true, value: "relative/base", wantConfigured: true, wantErr: true},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			// Register the restore hook in both branches: t.Setenv remembers
+			// whether the variable was originally set and undoes either case.
+			t.Setenv("MULTICA_AGENT_TEMP_BASE", tc.value)
+			if !tc.set {
+				if err := os.Unsetenv("MULTICA_AGENT_TEMP_BASE"); err != nil {
+					t.Fatalf("unset MULTICA_AGENT_TEMP_BASE: %v", err)
+				}
+			}
+			got, configured, err := taskTempBaseDir()
+			if configured != tc.wantConfigured {
+				t.Fatalf("taskTempBaseDir() configured = %v, want %v", configured, tc.wantConfigured)
+			}
+			if tc.wantErr {
+				if err == nil {
+					t.Fatalf("taskTempBaseDir() = %q, want error", got)
+				}
+				// The message must name the variable the operator set, so the
+				// failure is actionable rather than a bare mkdir/stat error.
+				if !strings.Contains(err.Error(), "MULTICA_AGENT_TEMP_BASE") {
+					t.Fatalf("error %q does not mention MULTICA_AGENT_TEMP_BASE", err)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("taskTempBaseDir(): %v", err)
+			}
+			if got != tc.want {
+				t.Fatalf("taskTempBaseDir() = %q, want %q", got, tc.want)
+			}
+		})
+	}
+
+	t.Run("configured base creates private 0700 task dir", func(t *testing.T) {
+		t.Setenv("MULTICA_AGENT_TEMP_BASE", validBase)
+		dir, err := ensureTaskTempDir("root", "ws", "task")
+		if err != nil {
+			t.Fatalf("ensureTaskTempDir(): %v", err)
+		}
+		t.Cleanup(func() { _ = os.RemoveAll(dir) })
+		info, err := os.Stat(dir)
+		if err != nil {
+			t.Fatalf("stat task temp dir: %v", err)
+		}
+		if info.Mode().Perm() != 0o700 {
+			t.Fatalf("task temp dir mode = %o, want 0700", info.Mode().Perm())
+		}
+	})
+
+	notDir := filepath.Join(t.TempDir(), "file")
+	if err := os.WriteFile(notDir, []byte("x"), 0o600); err != nil {
+		t.Fatalf("write notDir fixture: %v", err)
+	}
+	readOnlyBase := filepath.Join(t.TempDir(), "read-only")
+	if err := os.Mkdir(readOnlyBase, 0o500); err != nil {
+		t.Fatalf("mkdir readOnlyBase fixture: %v", err)
+	}
+	// t.TempDir cleanup needs to descend into it again.
+	t.Cleanup(func() { _ = os.Chmod(readOnlyBase, 0o700) })
+
+	for _, tc := range []struct {
+		name string
+		base string
+	}{
+		{name: "missing dir rejected", base: filepath.Join(validBase, "missing")},
+		{name: "non-directory rejected", base: notDir},
+		{name: "non-writable dir rejected", base: readOnlyBase},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Setenv("MULTICA_AGENT_TEMP_BASE", tc.base)
+			dir, err := ensureTaskTempDir("root", "ws", "task")
+			if err == nil {
+				_ = os.RemoveAll(dir)
+				if tc.base == readOnlyBase {
+					t.Skip("process can write to the read-only fixture")
+				}
+				t.Fatalf("ensureTaskTempDir() = %q with unusable MULTICA_AGENT_TEMP_BASE, want error", dir)
+			}
+			if !strings.Contains(err.Error(), "MULTICA_AGENT_TEMP_BASE") {
+				t.Fatalf("error %q does not mention MULTICA_AGENT_TEMP_BASE", err)
+			}
+		})
+	}
+}
+
+// TestRunTask_TaskTempBaseOverride is the MULTICA_AGENT_TEMP_BASE counterpart
+// of TestRunTask_InjectsPrivateTaskTempDir: with the variable set, all three
+// temp vars point at one fresh private dir under the configured base, agent
+// custom_env still cannot override them, and the dir is removed on task exit.
+func TestRunTask_TaskTempBaseOverride(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("shell-script agent fixture is POSIX-only")
+	}
+
+	tempBase := t.TempDir()
+	t.Setenv("MULTICA_AGENT_TEMP_BASE", tempBase)
+
+	workspacesRoot := t.TempDir()
+	workspaceID := "ws-temp-base"
+	taskID := "task-temp-base"
+
+	captureFile := filepath.Join(t.TempDir(), "agent-env.txt")
+	fakeBin := filepath.Join(t.TempDir(), "claude")
+	script := `#!/bin/sh
+printf 'TMPDIR=%s\nTMP=%s\nTEMP=%s\n' "$TMPDIR" "$TMP" "$TEMP" > "$CAPTURE_FILE"
+IFS= read -r _
+printf '%s\n' '{"type":"system","session_id":"sess-temp-base"}'
+printf '%s\n' '{"type":"result","subtype":"success","is_error":false,"session_id":"sess-temp-base","result":"done"}'
+`
+	if err := os.WriteFile(fakeBin, []byte(script), 0o755); err != nil {
+		t.Fatalf("write fake agent: %v", err)
+	}
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+	t.Cleanup(srv.Close)
+
+	d := &Daemon{
+		client:         NewClient(srv.URL),
+		logger:         slog.New(slog.NewTextHandler(io.Discard, nil)),
+		workspaces:     make(map[string]*workspaceState),
+		runtimeIndex:   map[string]Runtime{"rt-1": {ID: "rt-1", Provider: "claude"}},
+		activeEnvRoots: make(map[string]int),
+		cfg: Config{
+			WorkspacesRoot: workspacesRoot,
+			AgentTimeout:   5 * time.Second,
+			ServerBaseURL:  srv.URL,
+			Agents: map[string]AgentEntry{
+				"claude": {Path: fakeBin, Model: ""},
+			},
+		},
+	}
+
+	task := Task{
+		ID:          taskID,
+		WorkspaceID: workspaceID,
+		RuntimeID:   "rt-1",
+		IssueID:     "issue-temp-base",
+		AuthToken:   "mat_temp_base",
+		Agent: &AgentData{
+			ID:   "agent-temp-base",
+			Name: "test-agent",
+			CustomEnv: map[string]string{
+				"CAPTURE_FILE": captureFile,
+				"TMPDIR":       "/shared/tmp",
+				"TMP":          "/shared/tmp",
+				"TEMP":         "/shared/tmp",
+			},
+		},
+	}
+
+	taskLog := slog.New(slog.NewTextHandler(io.Discard, nil))
+	result, err := d.runTask(context.Background(), task, "claude", 0, taskLog)
+	if err != nil {
+		t.Fatalf("runTask(): %v", err)
+	}
+	if result.Status != "completed" {
+		t.Fatalf("runTask status = %q, want completed (comment=%q)", result.Status, result.Comment)
+	}
+
+	raw, err := os.ReadFile(captureFile)
+	if err != nil {
+		t.Fatalf("read captured agent env: %v", err)
+	}
+	got := make(map[string]string)
+	for _, line := range strings.Split(strings.TrimSpace(string(raw)), "\n") {
+		key, value, ok := strings.Cut(line, "=")
+		if !ok {
+			t.Fatalf("malformed captured env line %q", line)
+		}
+		got[key] = value
+	}
+	taskTempDir := got["TMPDIR"]
+	if taskTempDir == "" {
+		t.Fatal("TMPDIR was not captured")
+	}
+	for _, key := range []string{"TMP", "TEMP"} {
+		if got[key] != taskTempDir {
+			t.Fatalf("%s = %q, want same private task temp dir %q", key, got[key], taskTempDir)
+		}
+	}
+	if filepath.Dir(taskTempDir) != tempBase {
+		t.Fatalf("task temp dir %q is not directly under configured base %q", taskTempDir, tempBase)
+	}
+	if _, err := os.Stat(taskTempDir); !os.IsNotExist(err) {
+		t.Fatalf("expected task temp dir %q to be cleaned after run, stat err=%v", taskTempDir, err)
+	}
+}
+
+// TestRunTask_TaskTempBaseInvalidFailsStartup pins the "no silent fallback"
+// half of the contract at the level operators experience it: an unusable
+// MULTICA_AGENT_TEMP_BASE fails the task with a message naming the variable,
+// and the agent never starts against a /tmp dir it did not ask for.
+func TestRunTask_TaskTempBaseInvalidFailsStartup(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("shell-script agent fixture is POSIX-only")
+	}
+
+	missingBase := filepath.Join(t.TempDir(), "does-not-exist")
+	t.Setenv("MULTICA_AGENT_TEMP_BASE", missingBase)
+
+	workspacesRoot := t.TempDir()
+	captureFile := filepath.Join(t.TempDir(), "agent-env.txt")
+	fakeBin := filepath.Join(t.TempDir(), "claude")
+	script := `#!/bin/sh
+printf 'ran\n' > "$CAPTURE_FILE"
+`
+	if err := os.WriteFile(fakeBin, []byte(script), 0o755); err != nil {
+		t.Fatalf("write fake agent: %v", err)
+	}
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+	t.Cleanup(srv.Close)
+
+	d := &Daemon{
+		client:         NewClient(srv.URL),
+		logger:         slog.New(slog.NewTextHandler(io.Discard, nil)),
+		workspaces:     make(map[string]*workspaceState),
+		runtimeIndex:   map[string]Runtime{"rt-1": {ID: "rt-1", Provider: "claude"}},
+		activeEnvRoots: make(map[string]int),
+		cfg: Config{
+			WorkspacesRoot: workspacesRoot,
+			AgentTimeout:   5 * time.Second,
+			ServerBaseURL:  srv.URL,
+			Agents: map[string]AgentEntry{
+				"claude": {Path: fakeBin, Model: ""},
+			},
+		},
+	}
+
+	task := Task{
+		ID:          "task-temp-base-invalid",
+		WorkspaceID: "ws-temp-base-invalid",
+		RuntimeID:   "rt-1",
+		IssueID:     "issue-temp-base-invalid",
+		AuthToken:   "mat_temp_base_invalid",
+		Agent: &AgentData{
+			ID:        "agent-temp-base-invalid",
+			Name:      "test-agent",
+			CustomEnv: map[string]string{"CAPTURE_FILE": captureFile},
+		},
+	}
+
+	taskLog := slog.New(slog.NewTextHandler(io.Discard, nil))
+	_, err := d.runTask(context.Background(), task, "claude", 0, taskLog)
+	if err == nil {
+		t.Fatal("runTask() succeeded with an unusable MULTICA_AGENT_TEMP_BASE, want failure")
+	}
+	if !strings.Contains(err.Error(), "MULTICA_AGENT_TEMP_BASE") {
+		t.Fatalf("runTask() error = %v, want it to name MULTICA_AGENT_TEMP_BASE", err)
+	}
+	if _, statErr := os.Stat(captureFile); !os.IsNotExist(statErr) {
+		t.Fatalf("agent ran despite the temp-base failure, stat err=%v", statErr)
+	}
+}
+
 func TestRunTask_ExtendsPrepareLeaseDuringStartTask(t *testing.T) {
 	oldRefresh := taskPrepareLeaseRefresh
 	oldTimeout := taskPrepareLeaseTimeout