diff --git a/lib/devbase/commands/project.py b/lib/devbase/commands/project.py
index 8ce9242..771b85e 100644
--- a/lib/devbase/commands/project.py
+++ b/lib/devbase/commands/project.py
@@ -68,8 +68,6 @@ def list_projects(projects_dir: Path) -> list[dict]:
     """
     # status ロジックは commands/status.py と共有する (PLAN06 リファクタで per-entry
     # 関数 _container_status_for を分離済み)。import は循環回避のため関数内で行う。
-    from concurrent.futures import ThreadPoolExecutor
-
     from devbase.commands import status as status_mod
 
     if not projects_dir.exists():
@@ -80,31 +78,28 @@ def list_projects(projects_dir: Path) -> list[dict]:
         entry for entry in sorted(projects_dir.iterdir())
         if entry.is_symlink() or entry.is_dir()
     ]
+    if not entries:
+        return []
+
+    # コンテナ状態は docker ps 1 回で全プロジェクトぶん集計し (counts)、各 entry で
+    # 使い回す。プロジェクト数ぶん docker compose ps を起動していた旧実装の
+    # サブプロセスコストを N→1 に削減するため、並列化 (ThreadPoolExecutor) も不要。
+    counts = status_mod._running_counts_by_project()
 
     def _status_for(entry: Path) -> str:
         # is_dir() は symlink 先まで辿る。broken symlink は False → unknown のまま。
-        # _container_status_for は cwd= 引数で完結し global chdir を行わないため
-        # スレッド安全。各 `docker compose ps` は I/O バウンドで 10s timeout を
-        # 持つため、プロジェクト数が増えても並列化で総待ち時間を抑える。
         if not entry.is_dir():
             return "unknown"
-        st = status_mod._container_status_for(entry)
+        st = status_mod._container_status_for(entry, counts)
         return st["status"] if st is not None else "unknown"
 
-    # entries が空だと max_workers=0 で ValueError になるため早期 return。
-    if not entries:
-        return []
-
-    with ThreadPoolExecutor(max_workers=min(8, len(entries))) as ex:
-        statuses = list(ex.map(_status_for, entries))
-
     return [
         {
             "name": entry.name,
             "plugin": _resolve_plugin_name(entry) or "-",
-            "status": status,
+            "status": _status_for(entry),
         }
-        for entry, status in zip(entries, statuses)
+        for entry in entries
     ]
 
 
diff --git a/lib/devbase/commands/status.py b/lib/devbase/commands/status.py
index 3f3081c..55d8bb2 100644
--- a/lib/devbase/commands/status.py
+++ b/lib/devbase/commands/status.py
@@ -1,6 +1,5 @@
 """devbase status - 環境ステータスの一覧表示"""
 
-import json
 import subprocess
 from datetime import datetime
 from pathlib import Path
@@ -16,71 +15,79 @@
 logger = get_logger(__name__)
 
 
-def _container_status_for(entry: Path) -> dict | None:
-    """単一プロジェクトディレクトリのコンテナ状態を取得する。
+_COMPOSE_PROJECT_LABEL = "com.docker.compose.project"
 
-    `projects/<name>` (実ディレクトリ or plugin への symlink) を受け取り、
-    ``{"name", "status", "count"}`` を返す。対象外 (compose.yml が無い) や docker
-    コマンドが利用できない / タイムアウト / 異常終了の場合は ``None`` を返す。
+# `counts` 引数の「未指定」を docker 不在 (None) と区別するための sentinel。
+_UNSET = object()
 
-    PLAN06 で ``project list`` (commands/project.py) が同じ per-entry ロジックを
-    再利用するため、``_get_container_status`` のループ本体から分離した。挙動は
-    分離前と同一 (None を返す条件 = 旧実装で ``continue`` していた条件)。
-    """
-    compose_file = entry / "compose.yml"
-    if not compose_file.exists():
-        return None
 
+def _running_counts_by_project() -> dict[str, int] | None:
+    """全 running コンテナを単一の ``docker ps`` で取得し、compose project 名
+    ごとの running 数を返す。docker が使えない / 取得失敗時は ``None``。
+
+    プロジェクト数ぶん ``docker compose ps`` を起動する代わりに ``docker ps``
+    1 回で全コンテナのラベルを集計し、サブプロセス起動コストを N→1 に削減する。
+    compose project は ``com.docker.compose.project`` ラベル (= devbase up 時の
+    COMPOSE_PROJECT_NAME = プロジェクト名) で識別するため、呼び出し側プロセスが
+    継承する COMPOSE_PROJECT_NAME に一切影響されない (一覧が一律同一状態になる
+    回帰を構造的に回避する)。``docker ps`` は既定で running のみを列挙する。
+    """
     try:
         proc = subprocess.run(
-            ["docker", "compose", "ps", "--format", "json"],
-            cwd=str(entry),
+            ["docker", "ps",
+             "--filter", f"label={_COMPOSE_PROJECT_LABEL}",
+             "--format", f'{{{{.Label "{_COMPOSE_PROJECT_LABEL}"}}}}'],
             capture_output=True,
             text=True,
             timeout=10,
         )
         if proc.returncode != 0:
             return None
+    except (subprocess.TimeoutExpired, OSError):
+        # docker コマンドが利用できない、またはタイムアウト
+        return None
 
-        output = proc.stdout.strip()
-        if not output:
-            return {"name": entry.name, "status": "stopped", "count": 0}
-
-        # docker compose ps --format json は1行1JSONまたはJSON配列
-        containers = []
-        for line in output.splitlines():
-            line = line.strip()
-            if not line:
-                continue
-            try:
-                parsed = json.loads(line)
-                if isinstance(parsed, list):
-                    containers.extend(parsed)
-                else:
-                    containers.append(parsed)
-            except json.JSONDecodeError:
-                continue
-
-        if not containers:
-            return {"name": entry.name, "status": "stopped", "count": 0}
-
-        running = sum(
-            1 for c in containers
-            if c.get("State", "").lower() == "running"
-        )
-        total = len(containers)
+    counts: dict[str, int] = {}
+    for line in proc.stdout.splitlines():
+        name = line.strip()
+        if name:
+            counts[name] = counts.get(name, 0) + 1
+    return counts
 
-        if running > 0:
-            status = f"running ({total} containers)"
-        else:
-            status = "stopped"
 
-        return {"name": entry.name, "status": status, "count": total}
+def _container_status_for(entry: Path, counts=_UNSET) -> dict | None:
+    """単一プロジェクトディレクトリのコンテナ状態を取得する。
 
-    except (subprocess.TimeoutExpired, OSError):
-        # dockerコマンドが利用できない、またはタイムアウト
+    `projects/<name>` (実ディレクトリ or plugin への symlink) を受け取り、
+    ``{"name", "status", "count"}`` を返す。対象外 (compose.yml が無い) や docker
+    コマンドが利用できない場合は ``None`` を返す。
+
+    ``counts`` には ``_running_counts_by_project()`` の戻り値 (compose project 名
+    → running 数) を渡す。一覧表示では呼び出し側が 1 回だけ集計して全 entry で
+    使い回すことで docker サブプロセスの起動を 1 回に抑える。``counts`` を省略
+    した単発呼び出しでは本関数内で都度集計する。``None`` (docker 不在) が明示的に
+    渡された場合は再集計せず ``None`` を返す。
+    """
+    compose_file = entry / "compose.yml"
+    if not compose_file.exists():
+        return None
+
+    if counts is _UNSET:
+        counts = _running_counts_by_project()
+    if counts is None:
+        # docker が利用できない / 取得失敗
         return None
 
+    # devbase up は COMPOSE_PROJECT_NAME = entry.name でコンテナを起動するため、
+    # compose project ラベルが entry.name の running 数がこのプロジェクトの稼働数。
+    running = counts.get(entry.name, 0)
+    if running > 0:
+        status = f"running ({running} containers)"
+    else:
+        status = "stopped"
+
+    return {"name": entry.name, "status": status, "count": running}
+
 
 def _get_container_status(projects_dir: Path) -> list[dict]:
     """projects/ 配下の各プロジェクトのコンテナ状態を取得する"""
@@ -88,10 +95,13 @@ def _get_container_status(projects_dir: Path) -> list[dict]:
     if not projects_dir.exists():
         return results
 
+    # docker ps は 1 回だけ実行し、全 entry で使い回す。
+    counts = _running_counts_by_project()
+
     for entry in sorted(projects_dir.iterdir()):
         if not entry.is_dir():
             continue
-        status = _container_status_for(entry)
+        status = _container_status_for(entry, counts)
         if status is not None:
             results.append(status)
 
diff --git a/tests/cli/test_project_list.py b/tests/cli/test_project_list.py
index 881eb6f..d549d0c 100644
--- a/tests/cli/test_project_list.py
+++ b/tests/cli/test_project_list.py
@@ -144,7 +144,7 @@ def test_list_projects_enumerates_name_plugin_status(tmp_path, monkeypatch):
     _link_project(tmp_path, "beta-proj", "plugins/beta", "beta-proj")
 
     # status は docker に依存させず固定値を返す
-    def fake_status(entry: Path):
+    def fake_status(entry, counts=None):
         return {"name": entry.name, "status": "running (2 containers)", "count": 2}
 
     monkeypatch.setattr(status_mod, "_container_status_for", fake_status)
@@ -165,7 +165,7 @@ def test_list_projects_unknown_status_when_none(tmp_path, monkeypatch):
     _make_plugin_project(tmp_path, "repos/o--r/alpha", "alpha-proj")
     _link_project(tmp_path, "alpha-proj", "repos/o--r/alpha", "alpha-proj")
 
-    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry: None)
+    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry, counts=None: None)
 
     rows = project_mod.list_projects(tmp_path / "projects")
     assert rows[0]["status"] == "unknown"
@@ -179,7 +179,7 @@ def test_list_projects_real_dir_plugin_dash(tmp_path, monkeypatch):
     projects_dir.mkdir()
     (projects_dir / "standalone").mkdir()
 
-    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry: None)
+    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry, counts=None: None)
 
     rows = project_mod.list_projects(projects_dir)
     assert rows[0]["name"] == "standalone"
@@ -202,7 +202,7 @@ def test_cmd_project_list_prints_table(tmp_path, monkeypatch, capsys):
     _make_plugin_project(tmp_path, "repos/o--r/alpha", "alpha-proj")
     _link_project(tmp_path, "alpha-proj", "repos/o--r/alpha", "alpha-proj")
     monkeypatch.setattr(status_mod, "_container_status_for",
-                        lambda entry: {"name": entry.name, "status": "stopped", "count": 0})
+                        lambda entry, counts=None: {"name": entry.name, "status": "stopped", "count": 0})
 
     args = types.SimpleNamespace(interactive=False)
     rc = project_mod.cmd_project_list(tmp_path, args)
@@ -231,7 +231,7 @@ def test_cmd_project_list_non_tty_falls_back_to_table(tmp_path, monkeypatch, cap
     _make_plugin_project(tmp_path, "repos/o--r/alpha", "alpha-proj")
     _link_project(tmp_path, "alpha-proj", "repos/o--r/alpha", "alpha-proj")
     monkeypatch.setattr(status_mod, "_container_status_for",
-                        lambda entry: {"name": entry.name, "status": "stopped", "count": 0})
+                        lambda entry, counts=None: {"name": entry.name, "status": "stopped", "count": 0})
     monkeypatch.setattr(project_mod.sys.stdin, "isatty", lambda: False)
 
     called = []
@@ -256,7 +256,7 @@ def test_cmd_project_list_stdout_non_tty_falls_back_to_table(tmp_path, monkeypat
     _make_plugin_project(tmp_path, "repos/o--r/alpha", "alpha-proj")
     _link_project(tmp_path, "alpha-proj", "repos/o--r/alpha", "alpha-proj")
     monkeypatch.setattr(status_mod, "_container_status_for",
-                        lambda entry: {"name": entry.name, "status": "stopped", "count": 0})
+                        lambda entry, counts=None: {"name": entry.name, "status": "stopped", "count": 0})
     monkeypatch.setattr(project_mod.sys.stdin, "isatty", lambda: True)
     monkeypatch.setattr(project_mod.sys.stdout, "isatty", lambda: False)
 
@@ -285,7 +285,7 @@ def test_cmd_project_list_interactive_selects_and_ups(tmp_path, monkeypatch):
     _link_project(tmp_path, "alpha-proj", "repos/o--r/alpha", "alpha-proj")
     _make_plugin_project(tmp_path, "plugins/beta", "beta-proj")
     _link_project(tmp_path, "beta-proj", "plugins/beta", "beta-proj")
-    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry: None)
+    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry, counts=None: None)
 
     # 対話選択は TTY 環境でのみ起動するため isatty を True に固定する。
     monkeypatch.setattr(project_mod.sys.stdin, "isatty", lambda: True)
@@ -313,7 +313,7 @@ def test_cmd_project_list_interactive_empty_input_aborts(tmp_path, monkeypatch):
 
     _make_plugin_project(tmp_path, "repos/o--r/alpha", "alpha-proj")
     _link_project(tmp_path, "alpha-proj", "repos/o--r/alpha", "alpha-proj")
-    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry: None)
+    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry, counts=None: None)
     monkeypatch.setattr(project_mod.sys.stdin, "isatty", lambda: True)
     monkeypatch.setattr(project_mod.sys.stdout, "isatty", lambda: True)
     monkeypatch.setattr("builtins.input", lambda *a, **k: "")
@@ -335,7 +335,7 @@ def test_cmd_project_list_interactive_non_tty_eof(tmp_path, monkeypatch):
 
     _make_plugin_project(tmp_path, "repos/o--r/alpha", "alpha-proj")
     _link_project(tmp_path, "alpha-proj", "repos/o--r/alpha", "alpha-proj")
-    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry: None)
+    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry, counts=None: None)
 
     def raise_eof(*a, **k):
         raise EOFError
@@ -360,7 +360,7 @@ def test_cmd_project_list_interactive_keyboard_interrupt_aborts(tmp_path, monkey
 
     _make_plugin_project(tmp_path, "repos/o--r/alpha", "alpha-proj")
     _link_project(tmp_path, "alpha-proj", "repos/o--r/alpha", "alpha-proj")
-    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry: None)
+    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry, counts=None: None)
 
     def raise_interrupt(*a, **k):
         raise KeyboardInterrupt
@@ -385,7 +385,7 @@ def test_cmd_project_list_interactive_out_of_range_reprompts(tmp_path, monkeypat
 
     _make_plugin_project(tmp_path, "repos/o--r/alpha", "alpha-proj")
     _link_project(tmp_path, "alpha-proj", "repos/o--r/alpha", "alpha-proj")
-    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry: None)
+    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry, counts=None: None)
 
     monkeypatch.setattr(project_mod.sys.stdin, "isatty", lambda: True)
     monkeypatch.setattr(project_mod.sys.stdout, "isatty", lambda: True)
@@ -410,7 +410,7 @@ def test_cmd_project_list_interactive_non_numeric_reprompts(tmp_path, monkeypatc
 
     _make_plugin_project(tmp_path, "repos/o--r/alpha", "alpha-proj")
     _link_project(tmp_path, "alpha-proj", "repos/o--r/alpha", "alpha-proj")
-    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry: None)
+    monkeypatch.setattr(status_mod, "_container_status_for", lambda entry, counts=None: None)
 
     monkeypatch.setattr(project_mod.sys.stdin, "isatty", lambda: True)
     monkeypatch.setattr(project_mod.sys.stdout, "isatty", lambda: True)
@@ -559,7 +559,7 @@ def test_get_container_status_uses_per_entry(tmp_path, monkeypatch):
     (projects_dir / "b").mkdir()
 
     monkeypatch.setattr(status_mod, "_container_status_for",
-                        lambda entry: {"name": entry.name, "status": "stopped", "count": 0})
+                        lambda entry, counts=None: {"name": entry.name, "status": "stopped", "count": 0})
     results = status_mod._get_container_status(projects_dir)
     names = sorted(r["name"] for r in results)
     assert names == ["a", "b"]
diff --git a/tests/plugin/test_container_status_for.py b/tests/plugin/test_container_status_for.py
new file mode 100644
index 0000000..67efa72
--- /dev/null
+++ b/tests/plugin/test_container_status_for.py
@@ -0,0 +1,154 @@
+"""Regression tests for コンテナ状態取得 (status.py)。
+
+`devbase list` / `status` の状態取得は当初プロジェクト数ぶん `docker compose ps`
+をサブプロセス起動しており、(1) `bin/devbase` が常に export する
+`COMPOSE_PROJECT_NAME` を継承して全プロジェクトが同一状態になる回帰、
+(2) N サブプロセス起動の重さ、の二点があった。
+
+現在は `_running_counts_by_project()` が単一の `docker ps` で全 running コンテナ
+を `com.docker.compose.project` ラベルごとに集計し、`_container_status_for()` は
+その counts マップを参照するだけ。docker ps はラベルで識別するため
+`COMPOSE_PROJECT_NAME` の継承に一切影響されない。
+"""
+
+from __future__ import annotations
+
+import subprocess
+from pathlib import Path
+
+from devbase.commands import status as status_mod
+from devbase.commands.status import (
+    _container_status_for,
+    _running_counts_by_project,
+)
+
+
+def _make_entry(tmp_path: Path, name: str) -> Path:
+    entry = tmp_path / "projects" / name
+    entry.mkdir(parents=True)
+    (entry / "compose.yml").write_text("services:\n  dev:\n    image: busybox\n")
+    return entry
+
+
+# --- _running_counts_by_project ------------------------------------------
+
+
+def test_counts_aggregates_single_docker_ps(monkeypatch):
+    """docker ps 1 回でラベルごとの running 数を集計する (N 回起動しない)。"""
+    calls: list[list[str]] = []
+
+    def fake_run(cmd, **kwargs):
+        calls.append(cmd)
+
+        class R:
+            returncode = 0
+            # 9 個のうち carmo-system-console が複数 (複数コンテナ project)
+            stdout = "carmo-ai\ncarmo-system-console\ncarmo-system-console\n"
+
+        return R()
+
+    monkeypatch.setattr(subprocess, "run", fake_run)
+    # 継承 COMPOSE_PROJECT_NAME があっても集計に影響しないこと
+    monkeypatch.setenv("COMPOSE_PROJECT_NAME", "some-other-project")
+
+    counts = _running_counts_by_project()
+
+    assert counts == {"carmo-ai": 1, "carmo-system-console": 2}
+    # 1 回しか docker を起動していない
+    assert len(calls) == 1
+    # docker compose ps ではなく docker ps をラベル filter で叩いている
+    assert calls[0][:2] == ["docker", "ps"]
+    assert any("label=com.docker.compose.project" in a for a in calls[0])
+
+
+def test_counts_none_when_docker_unavailable(monkeypatch):
+    """docker コマンドが無い (OSError) なら None。"""
+
+    def fake_run(cmd, **kwargs):
+        raise FileNotFoundError("docker not found")
+
+    monkeypatch.setattr(subprocess, "run", fake_run)
+    assert _running_counts_by_project() is None
+
+
+# --- _container_status_for -----------------------------------------------
+
+
+def test_status_uses_counts_and_ignores_env(tmp_path, monkeypatch):
+    """counts マップを参照し、継承 COMPOSE_PROJECT_NAME に影響されない。"""
+    entry = _make_entry(tmp_path, "myproj")
+    monkeypatch.setenv("COMPOSE_PROJECT_NAME", "some-other-project")
+
+    result = _container_status_for(entry, {"myproj": 3, "other": 9})
+
+    assert result == {"name": "myproj", "status": "running (3 containers)", "count": 3}
+
+
+def test_status_stopped_when_not_in_counts(tmp_path):
+    """counts に居なければ stopped (count=0)。"""
+    entry = _make_entry(tmp_path, "myproj")
+
+    result = _container_status_for(entry, {"other": 1})
+
+    assert result == {"name": "myproj", "status": "stopped", "count": 0}
+
+
+def test_status_none_without_compose(tmp_path):
+    """compose.yml が無ければ対象外 (None)。"""
+    entry = tmp_path / "projects" / "noncompose"
+    entry.mkdir(parents=True)
+
+    assert _container_status_for(entry, {"noncompose": 1}) is None
+
+
+def test_status_none_when_counts_none(tmp_path, monkeypatch):
+    """docker 不在 (counts=None) を明示的に渡したら None (再集計しない)。"""
+    entry = _make_entry(tmp_path, "myproj")
+
+    def fake_run(cmd, **kwargs):  # 呼ばれてはいけない
+        raise AssertionError("counts=None なら再集計してはならない")
+
+    monkeypatch.setattr(subprocess, "run", fake_run)
+
+    assert _container_status_for(entry, None) is None
+
+
+def test_distinct_projects_distinct_counts(tmp_path):
+    """同じ counts から各 entry が自分の名前ぶんだけ拾う。"""
+    a = _make_entry(tmp_path, "proj-a")
+    b = _make_entry(tmp_path, "proj-b")
+    counts = {"proj-a": 2, "proj-b": 5}
+
+    assert _container_status_for(a, counts)["count"] == 2
+    assert _container_status_for(b, counts)["count"] == 5
+
+
+def test_get_container_status_runs_docker_ps_once(tmp_path, monkeypatch):
+    """_get_container_status は docker ps を 1 回だけ実行し全 entry に使い回す。"""
+    projects_dir = tmp_path / "projects"
+    for name in ("a", "b", "c"):
+        d = projects_dir / name
+        d.mkdir(parents=True)
+        (d / "compose.yml").write_text("services:\n  dev:\n    image: busybox\n")
+
+    calls = []
+
+    def fake_run(cmd, **kwargs):
+        calls.append(cmd)
+
+        class R:
+            returncode = 0
+            stdout = "a\nb\nb\n"
+
+        return R()
+
+    monkeypatch.setattr(subprocess, "run", fake_run)
+
+    results = status_mod._get_container_status(projects_dir)
+    by_name = {r["name"]: r for r in results}
+
+    assert by_name["a"]["status"] == "running (1 containers)"
+    assert by_name["b"]["status"] == "running (2 containers)"
+    assert by_name["c"]["status"] == "stopped"
+    # entry が 3 つでも docker 起動は 1 回
+    assert len(calls) == 1