diff --git a/lib/devbase/tui/actions_plugin.py b/lib/devbase/tui/actions_plugin.py
new file mode 100644
index 0000000..5d83541
--- /dev/null
+++ b/lib/devbase/tui/actions_plugin.py
@@ -0,0 +1,344 @@
+"""plugin カテゴリの TUI 操作フロー (PLAN31_2 PR4)。
+
+``devbase plugin`` の全サブコマンド (list/install/uninstall/update/info/sync/migrate)
+と ``plugin repo`` のサブ階層 (add/remove/list/refresh) を TUI から実行できるようにする。
+引数は ``tui.menu`` の収集ヘルパで CLI parser と同じ属性値 (plan 2.3 契約表) を集め、
+``tui.dispatch.dispatch_group`` 経由で既存ハンドラ ``cmd_plugin`` へ委譲する
+(ロジック二重実装なし)。
+
+uninstall/update/info および repo remove/refresh の ``name`` は、registry
+(``plugins.yml``) から取得した導入済み plugin / 登録済みリポジトリの一覧から
+選択させる (自由入力によるタイプミスを防ぐ)。破壊的な uninstall / repo remove は
+``menu.confirm`` で実行前確認する (plan 3.4)。
+
+ナビ規約 (actions_project と同一):
+- Esc / ← = 1 つ前のメニューへ戻る (``menu.MENU_BACK``)
+- Ctrl-C = 全体中止 (``None`` を伝搬)
+- 引数収集の中止 (``_ARG_CANCEL``) = 直前のサブメニューを再表示
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from devbase.errors import DevbaseError
+from devbase.log import get_logger
+from devbase.tui import menu
+from devbase.tui.dispatch import dispatch_group
+
+logger = get_logger(__name__)
+
+# plugin サブコマンド (表示順 = ハイライト既定順)。閲覧系の list を先頭に置き、
+# Enter 連打で安全な一覧表示へ到達できるようにする。value は cmd_plugin の subcommand 名
+# (repo のみサブ階層メニューへの分岐)。
+_PLUGIN_OPS: list[tuple[str, str]] = [
+    ("一覧表示 (list)", "list"),
+    ("インストール (install)", "install"),
+    ("アンインストール (uninstall)", "uninstall"),
+    ("更新 (update)", "update"),
+    ("詳細表示 (info)", "info"),
+    ("プロジェクトリンク再同期 (sync)", "sync"),
+    ("レガシー構成の移行 (migrate)", "migrate"),
+    ("リポジトリ管理 (repo)", "repo"),
+]
+
+# plugin repo サブ階層 (表示順 = ハイライト既定順)。value は repo_command 名。
+_REPO_OPS: list[tuple[str, str]] = [
+    ("リポジトリ一覧 (list)", "list"),
+    ("リポジトリ登録 (add)", "add"),
+    ("リポジトリ削除 (remove)", "remove"),
+    ("リポジトリ更新 (refresh)", "refresh"),
+]
+
+# 引数収集を Esc/Ctrl-C で中止したことを示す番兵 (= サブメニューへ戻る)。
+# dispatch の rc (int) や ``None`` (= 全体中止) と区別する (actions_project と同じ)。
+_ARG_CANCEL = object()
+
+
+def _dispatch(devbase_root: Path, subcommand: str, **attrs) -> int:
+    """``cmd_plugin`` へ委譲する (plan 2.3 の属性契約は呼び出し側が守る)。
+
+    import を呼び出し時まで遅延させ、テストが ``commands.plugin.cmd_plugin`` を
+    monkeypatch で差し替えられるようにする (dispatch_lifecycle と同じ流儀)。
+    """
+    from devbase.commands.plugin import cmd_plugin
+
+    return dispatch_group(cmd_plugin, devbase_root, subcommand, **attrs)
+
+
+# ---------------------------------------------------------------------------
+# 名前選択 (registry から一覧を取得して選ばせる)
+# ---------------------------------------------------------------------------
+
+def _installed_plugin_names(devbase_root: Path) -> list[str]:
+    """導入済み plugin 名の一覧を registry (plugins.yml) から取得する。"""
+    from devbase.plugin.registry import PluginRegistry
+
+    try:
+        return [p.name for p in PluginRegistry(Path(devbase_root)).list_installed()]
+    except DevbaseError as e:
+        logger.error("%s", e)
+        return []
+
+
+def _repository_names(devbase_root: Path) -> list[str]:
+    """登録済みリポジトリ名の一覧を registry (plugins.yml) から取得する。"""
+    from devbase.plugin.registry import PluginRegistry
+
+    try:
+        return [r.name for r in PluginRegistry(Path(devbase_root)).list_repositories()]
+    except DevbaseError as e:
+        logger.error("%s", e)
+        return []
+
+
+def _select_name(message: str, names: list[str], *, all_label: str | None = None):
+    """名前一覧から 1 件選ばせる共通ヘルパ。
+
+    ``all_label`` 指定時は「全対象」(value="") を先頭に置く。選択メニューの ``None``
+    (Ctrl-C) と衝突させないため空文字を番兵にし、呼び出し側へは ``None`` に変換して
+    返す (_select_build_image と同じ流儀)。
+
+    戻り値: 名前 (``str``) / ``None`` (all_label 選択 = 全対象) / ``_ARG_CANCEL``
+    (Esc・←・Ctrl-C 中止)。
+    """
+    choices: list[tuple[str, str]] = []
+    if all_label is not None:
+        choices.append((all_label, ""))
+    choices += [(n, n) for n in names]
+    sel = menu.select(
+        f"{message} (↑↓ 移動 / Enter 決定 / ←・Esc 戻る / Ctrl-C 中止):",
+        choices, back=True, search=False)
+    if sel is menu.MENU_BACK or sel is None:
+        return _ARG_CANCEL
+    return sel or None  # "" → None (全対象)
+
+
+def _select_installed_plugin(devbase_root: Path, message: str, *,
+                             all_label: str | None = None):
+    """導入済み plugin から 1 件選ばせる。対象が無ければ案内して ``_ARG_CANCEL``。"""
+    names = _installed_plugin_names(devbase_root)
+    if not names:
+        logger.info("導入済みの plugin がありません。"
+                    "`plugin install` で導入してください。")
+        return _ARG_CANCEL
+    return _select_name(message, names, all_label=all_label)
+
+
+def _select_repository(devbase_root: Path, message: str, *,
+                       all_label: str | None = None):
+    """登録済みリポジトリから 1 件選ばせる。対象が無ければ案内して ``_ARG_CANCEL``。"""
+    names = _repository_names(devbase_root)
+    if not names:
+        logger.info("登録済みのリポジトリがありません。"
+                    "`plugin repo add` で登録してください。")
+        return _ARG_CANCEL
+    return _select_name(message, names, all_label=all_label)
+
+
+# ---------------------------------------------------------------------------
+# サブメニュー
+# ---------------------------------------------------------------------------
+
+def _select_operation():
+    """plugin 操作を選ぶサブメニュー。
+
+    戻り値: サブコマンド文字列 / ``MENU_BACK`` (Esc・← → トップへ戻る) / ``None``
+    (Ctrl-C 中止)。
+    """
+    return menu.select(
+        "plugin 操作を選択 (↑↓ 移動 / Enter 決定 / ←・Esc 戻る / Ctrl-C 中止):",
+        list(_PLUGIN_OPS), back=True, search=False)
+
+
+def _select_repo_operation():
+    """plugin repo 操作を選ぶサブ階層メニュー。
+
+    戻り値: repo_command 文字列 / ``MENU_BACK`` (Esc・← → plugin メニューへ戻る) /
+    ``None`` (Ctrl-C 中止)。
+    """
+    return menu.select(
+        "リポジトリ操作を選択 (↑↓ 移動 / Enter 決定 / ←・Esc 戻る / Ctrl-C 中止):",
+        list(_REPO_OPS), back=True, search=False)
+
+
+# ---------------------------------------------------------------------------
+# 各操作の引数収集 + dispatch (plan 2.3 契約)
+# ---------------------------------------------------------------------------
+
+def _run_operation(devbase_root: Path, op: str):
+    """選択された plugin 操作の引数を収集して ``cmd_plugin`` へ委譲する。
+
+    戻り値: dispatch の rc (``int``) / ``_ARG_CANCEL`` (引数収集を中止 =
+    サブメニューへ戻る)。破壊的な uninstall は ``menu.confirm`` で確認する (plan 3.4)。
+    """
+    if op == "list":
+        # --available: 導入済み一覧の代わりに未導入の利用可能 plugin を表示する。
+        available = menu.confirm(
+            "未導入の利用可能 plugin を表示しますか (--available)?", default=False)
+        if available is None:
+            return _ARG_CANCEL
+        return _dispatch(devbase_root, "list", available=available)
+
+    if op == "install":
+        source = menu.text(
+            "インストールする plugin の source (名前 / URL / パス)",
+            allow_empty=False)
+        if source is None:
+            return _ARG_CANCEL
+        link = menu.confirm(
+            "symlink としてインストールしますか (--link)?", default=False)
+        if link is None:
+            return _ARG_CANCEL
+        install_all = menu.confirm(
+            "リポジトリ内の全 plugin をインストールしますか (--all)?", default=False)
+        if install_all is None:
+            return _ARG_CANCEL
+        return _dispatch(devbase_root, "install",
+                         source=source, link=link, install_all=install_all)
+
+    if op == "uninstall":
+        name = _select_installed_plugin(
+            devbase_root, "アンインストールする plugin を選択")
+        if name is _ARG_CANCEL:
+            return _ARG_CANCEL
+        ok = menu.confirm(f"plugin '{name}' をアンインストールしますか?", default=False)
+        if not ok:                     # False (拒否) / None (中止) → 実行しない
+            return _ARG_CANCEL
+        return _dispatch(devbase_root, "uninstall", name=name)
+
+    if op == "update":
+        # name=None で全 plugin 更新 (CLI の `plugin update` 引数省略と同じ)。
+        name = _select_installed_plugin(
+            devbase_root, "更新する plugin を選択",
+            all_label="全 plugin を更新")
+        if name is _ARG_CANCEL:
+            return _ARG_CANCEL
+        return _dispatch(devbase_root, "update", name=name)
+
+    if op == "info":
+        name = _select_installed_plugin(
+            devbase_root, "詳細を表示する plugin を選択")
+        if name is _ARG_CANCEL:
+            return _ARG_CANCEL
+        return _dispatch(devbase_root, "info", name=name)
+
+    if op in ("sync", "migrate"):
+        # 引数なし (plan 2.3: sync/migrate は属性なし)。即実行。
+        return _dispatch(devbase_root, op)
+
+    # 到達しない (メニュー値は _PLUGIN_OPS に限定される)。保守的に no-op。
+    logger.error("未知の操作です: %s", op)
+    return _ARG_CANCEL
+
+
+def _run_repo_operation(devbase_root: Path, op: str):
+    """選択された plugin repo 操作の引数を収集して ``cmd_plugin`` へ委譲する。
+
+    repo 系は ``subcommand='repo'`` + ``repo_command=<op>`` の二段属性で
+    ``cmd_repo`` へ分岐する (plan 2.3 契約)。戻り値プロトコルは ``_run_operation``
+    と同じ。破壊的な remove は ``menu.confirm`` で確認する (plan 3.4)。
+    """
+    if op == "list":
+        return _dispatch(devbase_root, "repo", repo_command="list")
+
+    if op == "add":
+        url = menu.text(
+            "登録するリポジトリの URL (GitHub は owner/repo 短縮形も可)",
+            allow_empty=False)
+        if url is None:
+            return _ARG_CANCEL
+        # --name は任意 (空で URL から自動命名)。空文字は None へ変換して渡す。
+        name = menu.text("カスタム名 (--name 空で自動)", allow_empty=True)
+        if name is None:
+            return _ARG_CANCEL
+        return _dispatch(devbase_root, "repo",
+                         repo_command="add", url=url, name=name or None)
+
+    if op == "remove":
+        name = _select_repository(devbase_root, "削除するリポジトリを選択")
+        if name is _ARG_CANCEL:
+            return _ARG_CANCEL
+        ok = menu.confirm(f"リポジトリ '{name}' を削除しますか?", default=False)
+        if not ok:                     # False (拒否) / None (中止) → 実行しない
+            return _ARG_CANCEL
+        force = menu.confirm(
+            "未 commit / 未 push の変更があっても強制削除しますか (--force)?",
+            default=False)
+        if force is None:
+            return _ARG_CANCEL
+        return _dispatch(devbase_root, "repo",
+                         repo_command="remove", name=name, force=force)
+
+    if op == "refresh":
+        # name=None で全リポジトリを refresh (CLI の引数省略と同じ)。
+        name = _select_repository(
+            devbase_root, "更新するリポジトリを選択",
+            all_label="全リポジトリを更新")
+        if name is _ARG_CANCEL:
+            return _ARG_CANCEL
+        return _dispatch(devbase_root, "repo", repo_command="refresh", name=name)
+
+    # 到達しない (メニュー値は _REPO_OPS に限定される)。保守的に no-op。
+    logger.error("未知のリポジトリ操作です: %s", op)
+    return _ARG_CANCEL
+
+
+# ---------------------------------------------------------------------------
+# メニューループ
+# ---------------------------------------------------------------------------
+
+def _repo_menu(devbase_root: Path):
+    """plugin repo のサブ階層メニューを回す。
+
+    戻り値プロトコル (``is`` 同一性判定):
+    - dispatch の rc (``int``): 操作を実行 → 呼び出し元へ (最終的にトップへ復帰)。
+    - ``menu.MENU_BACK``: Esc/← で plugin メニューへ戻る。
+    - ``None``: Ctrl-C で全体中止。
+
+    引数収集を中止 (``_ARG_CANCEL``) した場合はサブ階層メニューを再表示する。
+    """
+    while True:
+        op = _select_repo_operation()
+        if op is menu.MENU_BACK:
+            return menu.MENU_BACK
+        if op is None:
+            return None
+        rc = _run_repo_operation(devbase_root, op)
+        if rc is _ARG_CANCEL:
+            continue                   # 引数収集を中止 → サブ階層メニューへ戻る
+        return rc                      # 実行 rc → 呼び出し元へ
+
+
+def run(devbase_root: Path):
+    """プラグイン操作カテゴリ。操作選択 → 引数収集 → ``cmd_plugin`` へ委譲。
+
+    戻り値プロトコル (トップループが ``is`` 同一性で判定する。actions_project と同じ):
+    - **操作を実行した場合**: dispatch の rc (``int``) を返す。失敗 (非0) は
+      ``devbase list`` の終了コードへ伝搬する。
+    - ``menu.MENU_BACK``: 操作なしでトップメニューへ戻る (Esc/←)。
+    - ``None``: Ctrl-C による全体中止。
+
+    repo はサブ階層メニュー (``_repo_menu``) へ分岐し、Esc/← で plugin メニューへ
+    戻れる。引数収集を中止した場合は plugin メニューを再表示する。
+    操作完了後はトップメニューへ復帰する (plan 3.5 状態遷移: Exec → Top)。
+    """
+    while True:
+        op = _select_operation()
+        if op is menu.MENU_BACK:
+            return menu.MENU_BACK
+        if op is None:
+            return None
+
+        if op == "repo":
+            rc = _repo_menu(devbase_root)
+            if rc is menu.MENU_BACK:
+                continue              # plugin メニューへ戻る
+            return rc                 # 実行 rc (int) / None (Ctrl-C) を伝搬
+        rc = _run_operation(devbase_root, op)
+        if rc is _ARG_CANCEL:
+            continue                  # 引数収集を中止 → plugin メニューへ戻る
+
+        # 操作完了 → トップメニューへ復帰。rc は呼び出し側 (top loop) が記憶し
+        # 最終的な devbase の終了コードへ伝搬させる。
+        return rc
diff --git a/lib/devbase/tui/app.py b/lib/devbase/tui/app.py
index 9a62158..b0103dd 100644
--- a/lib/devbase/tui/app.py
+++ b/lib/devbase/tui/app.py
@@ -4,8 +4,8 @@
 プロジェクト一覧の選択だけだった旧挙動を、全カテゴリ
 (project / env / plugin / snapshot / status) を束ねるトップ階層メニューへ拡張する。
 
-PR1 では **project カテゴリのみ配線**し、env/plugin/snapshot/status は後続 PR
-(PR3〜PR5) で各 ``actions_*`` を ``_route`` に足すまでプレースホルダ案内を出す。
+PR1 で project、PR4 で plugin カテゴリを配線済み。env/snapshot/status は後続 PR
+(PR3/PR5) で各 ``actions_*`` を ``_route`` に足すまでプレースホルダ案内を出す。
 
 後方互換 (plan 3.2):
 - ``--no-interactive`` / ``--plain`` (interactive=False) と非 TTY は従来どおり一覧
@@ -26,7 +26,7 @@
 
 from devbase.commands.project import _print_table, list_projects
 from devbase.log import get_logger
-from devbase.tui import actions_project, menu
+from devbase.tui import actions_plugin, actions_project, menu
 
 logger = get_logger(__name__)
 
@@ -56,7 +56,9 @@ def _route(category: str, devbase_root: Path):
     """
     if category == "project":
         return actions_project.run(devbase_root)
-    # PR3: env, PR4: plugin, PR5: snapshot/status をここに追加する。
+    if category == "plugin":
+        return actions_plugin.run(devbase_root)
+    # PR3: env, PR5: snapshot/status をここに追加する。
     logger.info("「%s」は後続 PR で実装予定です。", _LABELS.get(category, category))
     return menu.MENU_BACK
 
diff --git a/tests/cli/tui/test_actions_plugin.py b/tests/cli/tui/test_actions_plugin.py
new file mode 100644
index 0000000..a92d5a5
--- /dev/null
+++ b/tests/cli/tui/test_actions_plugin.py
@@ -0,0 +1,554 @@
+"""PLAN31_2 PR4: tui.actions_plugin (plugin カテゴリ操作) のテスト。
+
+test_actions_project.py のパターンを踏襲し、`menu.*` を monkeypatch して選択値を
+注入、`cmd_plugin` を mock して **plan 2.3 の契約どおりの属性を持つ Namespace** で
+呼ばれることを各サブコマンド (repo 系含む) で検証する。破壊的操作 (uninstall /
+repo remove) の confirm 拒否で未実行になること、Esc/←/Ctrl-C の遷移も検証する。
+"""
+
+from __future__ import annotations
+
+import pytest
+import yaml
+
+from devbase.tui import actions_plugin, menu
+
+
+def _seed_registry(root, plugins=(), repos=()):
+    """plugins.yml を生成して導入済み plugin / 登録済みリポジトリを注入する。"""
+    data = {
+        "repositories": [
+            {"name": r, "url": f"https://github.com/o/{r}",
+             "added_at": "2026-01-01T00:00:00+00:00", "plugins": []}
+            for r in repos
+        ],
+        "installed_plugins": [
+            {"name": p, "version": "1.0", "source": "o--r",
+             "installed_at": "2026-01-01T00:00:00+00:00",
+             "path": f"repos/o--r/{p}", "linked": False}
+            for p in plugins
+        ],
+    }
+    (root / "plugins.yml").write_text(yaml.safe_dump(data, allow_unicode=True))
+
+
+def _capture_dispatch(monkeypatch):
+    """cmd_plugin の呼び出し引数を全属性キャプチャするヘルパ。"""
+    from devbase.commands import plugin as plugin_mod
+    captured = {}
+
+    def _spy(devbase_root, args):
+        captured["devbase_root"] = devbase_root
+        captured["subcommand"] = args.subcommand
+        for k in ("available", "source", "link", "install_all", "name",
+                  "repo_command", "url", "force"):
+            if hasattr(args, k):
+                captured[k] = getattr(args, k)
+        return 0
+
+    monkeypatch.setattr(plugin_mod, "cmd_plugin", _spy)
+    return captured
+
+
+def _no_dispatch(monkeypatch):
+    """cmd_plugin が呼ばれないことを検証するためのスパイ (呼び出しを記録)。"""
+    from devbase.commands import plugin as plugin_mod
+    called = []
+    monkeypatch.setattr(plugin_mod, "cmd_plugin",
+                        lambda root, args: called.append(1) or 0)
+    return called
+
+
+# ---------------------------------------------------------------------------
+# run(): plugin メニューのループと戻り値プロトコル
+# ---------------------------------------------------------------------------
+
+def test_run_executes_and_returns_rc(monkeypatch, tmp_path):
+    """操作を実行したら dispatch の rc を返してトップへ復帰する。"""
+    captured = _capture_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_operation", lambda: "sync")
+    assert actions_plugin.run(tmp_path) == 0
+    assert captured["subcommand"] == "sync"
+    assert captured["devbase_root"] == tmp_path
+
+
+def test_run_propagates_nonzero_dispatch_rc(monkeypatch, tmp_path):
+    """dispatch が非0 (失敗) を返したら run() もその rc を返す (終了コード伝搬)。"""
+    from devbase.commands import plugin as plugin_mod
+    monkeypatch.setattr(plugin_mod, "cmd_plugin", lambda root, args: 1)
+    monkeypatch.setattr(actions_plugin, "_select_operation", lambda: "sync")
+    assert actions_plugin.run(tmp_path) == 1
+
+
+def test_run_back_returns_menu_back(monkeypatch, tmp_path):
+    """plugin メニューで Esc/← (MENU_BACK) を押すとトップへ戻る (何も起動しない)。"""
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_operation", lambda: menu.MENU_BACK)
+    assert actions_plugin.run(tmp_path) is menu.MENU_BACK
+    assert called == []
+
+
+def test_run_ctrl_c_aborts(monkeypatch, tmp_path):
+    """plugin メニューで Ctrl-C (None) を押すと全体中止 (None を返す)。"""
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_operation", lambda: None)
+    assert actions_plugin.run(tmp_path) is None
+    assert called == []
+
+
+def test_run_arg_cancel_reshows_menu(monkeypatch, tmp_path):
+    """引数収集を中止 (_ARG_CANCEL) すると plugin メニューを再表示し、再選択で実行する。"""
+    select_calls = []
+    # 1 回目: install (→ 引数収集中止) / 2 回目: sync (→ 実行)
+    monkeypatch.setattr(actions_plugin, "_select_operation",
+                        lambda: (select_calls.append(1),
+                                 "install" if len(select_calls) == 1 else "sync")[1])
+
+    run_calls = []
+
+    def fake_run_op(root, op):
+        run_calls.append(op)
+        return actions_plugin._ARG_CANCEL if op == "install" else 0
+
+    monkeypatch.setattr(actions_plugin, "_run_operation", fake_run_op)
+
+    assert actions_plugin.run(tmp_path) == 0
+    assert run_calls == ["install", "sync"]
+    assert len(select_calls) == 2, "引数中止で plugin メニューが再表示される"
+
+
+def test_run_repo_back_reshows_plugin_menu(monkeypatch, tmp_path):
+    """repo サブ階層で Esc/← (MENU_BACK) を押すと plugin メニューへ戻る。"""
+    select_calls = []
+    monkeypatch.setattr(actions_plugin, "_select_operation",
+                        lambda: (select_calls.append(1),
+                                 "repo" if len(select_calls) == 1 else menu.MENU_BACK)[1])
+    monkeypatch.setattr(actions_plugin, "_repo_menu", lambda root: menu.MENU_BACK)
+
+    assert actions_plugin.run(tmp_path) is menu.MENU_BACK
+    assert len(select_calls) == 2, "repo から戻ると plugin メニューが再表示される"
+
+
+def test_run_repo_rc_propagates(monkeypatch, tmp_path):
+    """repo サブ階層で操作を実行したらその rc を返してトップへ復帰する。"""
+    monkeypatch.setattr(actions_plugin, "_select_operation", lambda: "repo")
+    monkeypatch.setattr(actions_plugin, "_repo_menu", lambda root: 1)
+    assert actions_plugin.run(tmp_path) == 1
+
+
+def test_run_repo_ctrl_c_aborts(monkeypatch, tmp_path):
+    """repo サブ階層で Ctrl-C (None) を受けたら全体中止を伝搬する。"""
+    monkeypatch.setattr(actions_plugin, "_select_operation", lambda: "repo")
+    monkeypatch.setattr(actions_plugin, "_repo_menu", lambda root: None)
+    assert actions_plugin.run(tmp_path) is None
+
+
+# ---------------------------------------------------------------------------
+# _select_operation / _select_repo_operation: menu.select への委譲
+# ---------------------------------------------------------------------------
+
+def test_select_operation_lists_all_ops(monkeypatch):
+    captured = {}
+
+    def fake_select(message, choices, *, back, search):
+        captured.update(back=back, search=search,
+                        values=[c[1] for c in choices])
+        return "list"
+
+    monkeypatch.setattr(menu, "select", fake_select)
+    assert actions_plugin._select_operation() == "list"
+    assert captured["back"] is True
+    assert captured["search"] is False
+    # 閲覧系の list を先頭にしつつ全 8 操作 (repo 含む) を提示する。
+    assert captured["values"] == [
+        "list", "install", "uninstall", "update", "info", "sync", "migrate", "repo"]
+
+
+def test_select_repo_operation_lists_all_ops(monkeypatch):
+    captured = {}
+
+    def fake_select(message, choices, *, back, search):
+        captured.update(back=back, values=[c[1] for c in choices])
+        return "add"
+
+    monkeypatch.setattr(menu, "select", fake_select)
+    assert actions_plugin._select_repo_operation() == "add"
+    assert captured["back"] is True
+    assert captured["values"] == ["list", "add", "remove", "refresh"]
+
+
+# ---------------------------------------------------------------------------
+# _run_operation: 各操作の引数収集 + dispatch 契約 (plan 2.3)
+# ---------------------------------------------------------------------------
+
+@pytest.mark.parametrize("available", [True, False])
+def test_run_operation_list_available_flag(monkeypatch, tmp_path, available):
+    captured = _capture_dispatch(monkeypatch)
+    monkeypatch.setattr(menu, "confirm", lambda *a, **k: available)
+    assert actions_plugin._run_operation(tmp_path, "list") == 0
+    assert captured["subcommand"] == "list"
+    assert captured["available"] is available
+
+
+def test_run_operation_list_cancel(monkeypatch, tmp_path):
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(menu, "confirm", lambda *a, **k: None)   # Esc/Ctrl-C
+    assert actions_plugin._run_operation(tmp_path, "list") is actions_plugin._ARG_CANCEL
+    assert called == []
+
+
+def test_run_operation_install_collects_source_link_all(monkeypatch, tmp_path):
+    captured = _capture_dispatch(monkeypatch)
+    monkeypatch.setattr(menu, "text", lambda *a, **k: "owner/repo")
+    confirms = iter([True, False])           # link=True, install_all=False
+    monkeypatch.setattr(menu, "confirm", lambda *a, **k: next(confirms))
+    assert actions_plugin._run_operation(tmp_path, "install") == 0
+    assert captured["subcommand"] == "install"
+    assert captured["source"] == "owner/repo"
+    assert captured["link"] is True and captured["install_all"] is False
+
+
+def test_run_operation_install_source_cancel(monkeypatch, tmp_path):
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(menu, "text", lambda *a, **k: None)      # Esc/Ctrl-C
+    assert actions_plugin._run_operation(tmp_path, "install") is actions_plugin._ARG_CANCEL
+    assert called == []
+
+
+def test_run_operation_install_confirm_cancel_midway(monkeypatch, tmp_path):
+    """install の途中 (install_all) で中止したら実行しない。"""
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(menu, "text", lambda *a, **k: "owner/repo")
+    confirms = iter([True, None])            # link=True, install_all で中止
+    monkeypatch.setattr(menu, "confirm", lambda *a, **k: next(confirms))
+    assert actions_plugin._run_operation(tmp_path, "install") is actions_plugin._ARG_CANCEL
+    assert called == []
+
+
+def test_run_operation_uninstall_confirmed(monkeypatch, tmp_path):
+    """uninstall は一覧から選んだ name で confirm=True のとき実行する (plan 3.4)。"""
+    captured = _capture_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_installed_plugin",
+                        lambda root, msg, **k: "ndf")
+    monkeypatch.setattr(menu, "confirm", lambda *a, **k: True)
+    assert actions_plugin._run_operation(tmp_path, "uninstall") == 0
+    assert captured["subcommand"] == "uninstall" and captured["name"] == "ndf"
+
+
+@pytest.mark.parametrize("confirm_ret", [False, None])
+def test_run_operation_uninstall_cancelled_does_not_dispatch(
+        monkeypatch, tmp_path, confirm_ret):
+    """uninstall の confirm を拒否 (False) / 中止 (None) したら実行しない。"""
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_installed_plugin",
+                        lambda root, msg, **k: "ndf")
+    monkeypatch.setattr(menu, "confirm", lambda *a, **k: confirm_ret)
+    assert actions_plugin._run_operation(tmp_path, "uninstall") is actions_plugin._ARG_CANCEL
+    assert called == [], "確認を拒否/中止したら uninstall しない"
+
+
+def test_run_operation_uninstall_name_cancel(monkeypatch, tmp_path):
+    """name 選択を中止したら confirm も dispatch もしない。"""
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_installed_plugin",
+                        lambda root, msg, **k: actions_plugin._ARG_CANCEL)
+    confirms = []
+    monkeypatch.setattr(menu, "confirm",
+                        lambda *a, **k: confirms.append(1) or True)
+    assert actions_plugin._run_operation(tmp_path, "uninstall") is actions_plugin._ARG_CANCEL
+    assert called == [] and confirms == []
+
+
+def test_run_operation_update_named(monkeypatch, tmp_path):
+    captured = _capture_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_installed_plugin",
+                        lambda root, msg, **k: "ndf")
+    assert actions_plugin._run_operation(tmp_path, "update") == 0
+    assert captured["subcommand"] == "update" and captured["name"] == "ndf"
+
+
+def test_run_operation_update_all_is_name_none(monkeypatch, tmp_path):
+    """「全 plugin を更新」は name=None で委譲する (CLI の引数省略と同じ)。"""
+    captured = _capture_dispatch(monkeypatch)
+    seen = {}
+    monkeypatch.setattr(actions_plugin, "_select_installed_plugin",
+                        lambda root, msg, **k: seen.update(k) or None)
+    assert actions_plugin._run_operation(tmp_path, "update") == 0
+    assert captured["subcommand"] == "update" and captured["name"] is None
+    assert seen.get("all_label"), "update では全 plugin 選択肢を提示する"
+
+
+def test_run_operation_update_cancel(monkeypatch, tmp_path):
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_installed_plugin",
+                        lambda root, msg, **k: actions_plugin._ARG_CANCEL)
+    assert actions_plugin._run_operation(tmp_path, "update") is actions_plugin._ARG_CANCEL
+    assert called == []
+
+
+def test_run_operation_info(monkeypatch, tmp_path):
+    captured = _capture_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_installed_plugin",
+                        lambda root, msg, **k: "ndf")
+    assert actions_plugin._run_operation(tmp_path, "info") == 0
+    assert captured["subcommand"] == "info" and captured["name"] == "ndf"
+
+
+def test_run_operation_info_cancel(monkeypatch, tmp_path):
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_installed_plugin",
+                        lambda root, msg, **k: actions_plugin._ARG_CANCEL)
+    assert actions_plugin._run_operation(tmp_path, "info") is actions_plugin._ARG_CANCEL
+    assert called == []
+
+
+@pytest.mark.parametrize("op", ["sync", "migrate"])
+def test_run_operation_sync_migrate_no_attrs(monkeypatch, tmp_path, op):
+    """sync/migrate は引数収集なしで即委譲する (plan 2.3: 属性なし)。"""
+    captured = _capture_dispatch(monkeypatch)
+    assert actions_plugin._run_operation(tmp_path, op) == 0
+    assert captured == {"devbase_root": tmp_path, "subcommand": op}, \
+        "subcommand 以外の属性を載せない"
+
+
+def test_run_operation_unknown_is_noop(monkeypatch, tmp_path):
+    called = _no_dispatch(monkeypatch)
+    assert actions_plugin._run_operation(tmp_path, "bogus") is actions_plugin._ARG_CANCEL
+    assert called == []
+
+
+# ---------------------------------------------------------------------------
+# _run_repo_operation: repo 系の引数収集 + dispatch 契約 (plan 2.3)
+# ---------------------------------------------------------------------------
+
+def test_run_repo_operation_list(monkeypatch, tmp_path):
+    """repo list は repo_command='list' のみで委譲する。"""
+    captured = _capture_dispatch(monkeypatch)
+    assert actions_plugin._run_repo_operation(tmp_path, "list") == 0
+    assert captured == {"devbase_root": tmp_path, "subcommand": "repo",
+                        "repo_command": "list"}
+
+
+def test_run_repo_operation_add_with_custom_name(monkeypatch, tmp_path):
+    captured = _capture_dispatch(monkeypatch)
+    texts = iter(["https://github.com/o/r", "myrepo"])  # url, name
+    monkeypatch.setattr(menu, "text", lambda *a, **k: next(texts))
+    assert actions_plugin._run_repo_operation(tmp_path, "add") == 0
+    assert captured["subcommand"] == "repo"
+    assert captured["repo_command"] == "add"
+    assert captured["url"] == "https://github.com/o/r"
+    assert captured["name"] == "myrepo"
+
+
+def test_run_repo_operation_add_empty_name_is_none(monkeypatch, tmp_path):
+    """カスタム名を空にすると name=None (URL から自動命名) で委譲する。"""
+    captured = _capture_dispatch(monkeypatch)
+    texts = iter(["o/r", ""])                # url, name(空)
+    monkeypatch.setattr(menu, "text", lambda *a, **k: next(texts))
+    assert actions_plugin._run_repo_operation(tmp_path, "add") == 0
+    assert captured["url"] == "o/r" and captured["name"] is None
+
+
+def test_run_repo_operation_add_url_cancel(monkeypatch, tmp_path):
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(menu, "text", lambda *a, **k: None)      # Esc/Ctrl-C
+    assert actions_plugin._run_repo_operation(tmp_path, "add") is actions_plugin._ARG_CANCEL
+    assert called == []
+
+
+@pytest.mark.parametrize("force", [True, False])
+def test_run_repo_operation_remove_confirmed(monkeypatch, tmp_path, force):
+    """repo remove は confirm=True のとき force フラグ付きで実行する (plan 3.4)。"""
+    captured = _capture_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_repository",
+                        lambda root, msg, **k: "r1")
+    confirms = iter([True, force])           # 削除確認=True, force
+    monkeypatch.setattr(menu, "confirm", lambda *a, **k: next(confirms))
+    assert actions_plugin._run_repo_operation(tmp_path, "remove") == 0
+    assert captured["subcommand"] == "repo"
+    assert captured["repo_command"] == "remove"
+    assert captured["name"] == "r1" and captured["force"] is force
+
+
+@pytest.mark.parametrize("confirm_ret", [False, None])
+def test_run_repo_operation_remove_cancelled_does_not_dispatch(
+        monkeypatch, tmp_path, confirm_ret):
+    """repo remove の confirm を拒否 (False) / 中止 (None) したら実行しない。"""
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_repository",
+                        lambda root, msg, **k: "r1")
+    monkeypatch.setattr(menu, "confirm", lambda *a, **k: confirm_ret)
+    assert actions_plugin._run_repo_operation(tmp_path, "remove") is actions_plugin._ARG_CANCEL
+    assert called == [], "確認を拒否/中止したら remove しない"
+
+
+def test_run_repo_operation_remove_force_cancel(monkeypatch, tmp_path):
+    """force の確認を中止 (None) したら実行しない。"""
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_repository",
+                        lambda root, msg, **k: "r1")
+    confirms = iter([True, None])            # 削除確認=True, force で中止
+    monkeypatch.setattr(menu, "confirm", lambda *a, **k: next(confirms))
+    assert actions_plugin._run_repo_operation(tmp_path, "remove") is actions_plugin._ARG_CANCEL
+    assert called == []
+
+
+def test_run_repo_operation_remove_name_cancel(monkeypatch, tmp_path):
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_repository",
+                        lambda root, msg, **k: actions_plugin._ARG_CANCEL)
+    assert actions_plugin._run_repo_operation(tmp_path, "remove") is actions_plugin._ARG_CANCEL
+    assert called == []
+
+
+def test_run_repo_operation_refresh_named(monkeypatch, tmp_path):
+    captured = _capture_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_repository",
+                        lambda root, msg, **k: "r1")
+    assert actions_plugin._run_repo_operation(tmp_path, "refresh") == 0
+    assert captured["subcommand"] == "repo"
+    assert captured["repo_command"] == "refresh" and captured["name"] == "r1"
+
+
+def test_run_repo_operation_refresh_all_is_name_none(monkeypatch, tmp_path):
+    """「全リポジトリを更新」は name=None で委譲する (CLI の引数省略と同じ)。"""
+    captured = _capture_dispatch(monkeypatch)
+    seen = {}
+    monkeypatch.setattr(actions_plugin, "_select_repository",
+                        lambda root, msg, **k: seen.update(k) or None)
+    assert actions_plugin._run_repo_operation(tmp_path, "refresh") == 0
+    assert captured["repo_command"] == "refresh" and captured["name"] is None
+    assert seen.get("all_label"), "refresh では全リポジトリ選択肢を提示する"
+
+
+def test_run_repo_operation_refresh_cancel(monkeypatch, tmp_path):
+    called = _no_dispatch(monkeypatch)
+    monkeypatch.setattr(actions_plugin, "_select_repository",
+                        lambda root, msg, **k: actions_plugin._ARG_CANCEL)
+    assert actions_plugin._run_repo_operation(tmp_path, "refresh") is actions_plugin._ARG_CANCEL
+    assert called == []
+
+
+# ---------------------------------------------------------------------------
+# _repo_menu: サブ階層メニューのループ
+# ---------------------------------------------------------------------------
+
+def test_repo_menu_back_returns_menu_back(monkeypatch, tmp_path):
+    monkeypatch.setattr(actions_plugin, "_select_repo_operation",
+                        lambda: menu.MENU_BACK)
+    assert actions_plugin._repo_menu(tmp_path) is menu.MENU_BACK
+
+
+def test_repo_menu_ctrl_c_aborts(monkeypatch, tmp_path):
+    monkeypatch.setattr(actions_plugin, "_select_repo_operation", lambda: None)
+    assert actions_plugin._repo_menu(tmp_path) is None
+
+
+def test_repo_menu_arg_cancel_reshows_submenu(monkeypatch, tmp_path):
+    """引数収集を中止 (_ARG_CANCEL) するとサブ階層メニューを再表示し、再選択で実行する。"""
+    select_calls = []
+    # 1 回目: add (→ 引数収集中止) / 2 回目: list (→ 実行)
+    monkeypatch.setattr(actions_plugin, "_select_repo_operation",
+                        lambda: (select_calls.append(1),
+                                 "add" if len(select_calls) == 1 else "list")[1])
+
+    run_calls = []
+
+    def fake_run_op(root, op):
+        run_calls.append(op)
+        return actions_plugin._ARG_CANCEL if op == "add" else 0
+
+    monkeypatch.setattr(actions_plugin, "_run_repo_operation", fake_run_op)
+
+    assert actions_plugin._repo_menu(tmp_path) == 0
+    assert run_calls == ["add", "list"]
+    assert len(select_calls) == 2, "引数中止でサブ階層メニューが再表示される"
+
+
+def test_repo_menu_returns_rc(monkeypatch, tmp_path):
+    monkeypatch.setattr(actions_plugin, "_select_repo_operation", lambda: "list")
+    monkeypatch.setattr(actions_plugin, "_run_repo_operation", lambda root, op: 1)
+    assert actions_plugin._repo_menu(tmp_path) == 1
+
+
+# ---------------------------------------------------------------------------
+# 名前選択ヘルパ (_select_name / _select_installed_plugin / _select_repository)
+# ---------------------------------------------------------------------------
+
+def test_select_name_lists_names(monkeypatch):
+    captured = {}
+
+    def fake_select(message, choices, *, back, search):
+        captured.update(back=back, search=search,
+                        values=[c[1] for c in choices])
+        return "b"
+
+    monkeypatch.setattr(menu, "select", fake_select)
+    assert actions_plugin._select_name("選択", ["a", "b"]) == "b"
+    assert captured["back"] is True
+    assert captured["values"] == ["a", "b"]
+
+
+def test_select_name_all_label_first_and_maps_to_none(monkeypatch):
+    """all_label は value='' で先頭に置き、選択時は None に変換する。"""
+    captured = {}
+
+    def fake_select(message, choices, *, back, search):
+        captured["values"] = [c[1] for c in choices]
+        return ""
+
+    monkeypatch.setattr(menu, "select", fake_select)
+    assert actions_plugin._select_name("選択", ["a"], all_label="全対象") is None
+    assert captured["values"] == ["", "a"]
+
+
+@pytest.mark.parametrize("sel", [None, "BACK"])
+def test_select_name_back_or_ctrl_c_is_cancel(monkeypatch, sel):
+    ret = menu.MENU_BACK if sel == "BACK" else None
+    monkeypatch.setattr(menu, "select", lambda *a, **k: ret)
+    assert actions_plugin._select_name("選択", ["a"]) is actions_plugin._ARG_CANCEL
+
+
+def test_select_installed_plugin_reads_registry(monkeypatch, tmp_path):
+    """plugins.yml の導入済み plugin が選択肢に並ぶ (registry 結合)。"""
+    _seed_registry(tmp_path, plugins=("ndf", "carmo"))
+    captured = {}
+
+    def fake_select(message, choices, *, back, search):
+        captured["values"] = [c[1] for c in choices]
+        return "ndf"
+
+    monkeypatch.setattr(menu, "select", fake_select)
+    assert actions_plugin._select_installed_plugin(tmp_path, "選択") == "ndf"
+    assert captured["values"] == ["ndf", "carmo"]
+
+
+def test_select_installed_plugin_empty_is_cancel(monkeypatch, tmp_path):
+    """導入済み plugin が無ければ選択メニューを出さず中止する。"""
+    selects = []
+    monkeypatch.setattr(menu, "select", lambda *a, **k: selects.append(1) or None)
+    assert actions_plugin._select_installed_plugin(tmp_path, "選択") \
+        is actions_plugin._ARG_CANCEL
+    assert selects == []
+
+
+def test_select_repository_reads_registry(monkeypatch, tmp_path):
+    """plugins.yml の登録済みリポジトリが選択肢に並ぶ (registry 結合)。"""
+    _seed_registry(tmp_path, repos=("r1", "r2"))
+    captured = {}
+
+    def fake_select(message, choices, *, back, search):
+        captured["values"] = [c[1] for c in choices]
+        return "r2"
+
+    monkeypatch.setattr(menu, "select", fake_select)
+    assert actions_plugin._select_repository(tmp_path, "選択") == "r2"
+    assert captured["values"] == ["r1", "r2"]
+
+
+def test_select_repository_empty_is_cancel(monkeypatch, tmp_path):
+    selects = []
+    monkeypatch.setattr(menu, "select", lambda *a, **k: selects.append(1) or None)
+    assert actions_plugin._select_repository(tmp_path, "選択") \
+        is actions_plugin._ARG_CANCEL
+    assert selects == []
diff --git a/tests/cli/tui/test_app.py b/tests/cli/tui/test_app.py
index eeae959..8ffd3d2 100644
--- a/tests/cli/tui/test_app.py
+++ b/tests/cli/tui/test_app.py
@@ -8,7 +8,7 @@
 
 import types
 
-from devbase.tui import actions_project, app, menu
+from devbase.tui import actions_plugin, actions_project, app, menu
 
 
 def _make_plugin_project(root, plugin_path, proj):
@@ -213,5 +213,12 @@ def test_route_project_delegates(monkeypatch, tmp_path):
     assert app._route("project", tmp_path) == "RESULT"
 
 
+def test_route_plugin_delegates(monkeypatch, tmp_path):
+    """PR4: plugin カテゴリは actions_plugin.run へ routing される。"""
+    monkeypatch.setattr(actions_plugin, "run", lambda root: "RESULT")
+    assert app._route("plugin", tmp_path) == "RESULT"
+
+
 def test_route_unimplemented_returns_menu_back(tmp_path):
-    assert app._route("plugin", tmp_path) is menu.MENU_BACK
+    # snapshot は PR5 で配線されるまでプレースホルダ (MENU_BACK)。
+    assert app._route("snapshot", tmp_path) is menu.MENU_BACK