feat(config): config 디렉터리 기반 설정 관리 (--config-path/--env-file, trex-orb-v1 정합, BAT-026)

REQ-048/010 change-req. `--config` 를 이름으로 해석 + `--config-path <dir>`
(기본 ./config) + resolve_config_toml(슬래시 포함 값은 하위호환 명시 경로).
`.env` 를 config-dir 결정적 해석(--env-file 우선, 없으면 <config_dir>/.env,
CWD 무관) + config/.env.example + .gitignore config/* 허용목록. 운영자 CLI 도
--config-path/--env-file 동일 적용. from_env() legacy 루트 .env 폴백 유지로
완전 하위호환.

단위 23 + 전체 375 passed, ruff clean, 라이브 스모크(name·path 동일).
REQ-048/010 → Implemented.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/runtime/test_config_resolution.py

@@ -0,0 +1,87 @@
+"""config-dir resolution + config-dir/.env loading (REQ-048/010 CHG-20260609-01)."""
+from __future__ import annotations
+
+import os
+
+import pytest
+
+from trex_core.runtime.config import _load_dotenv, resolve_config_toml
+
+_K = "TREX_TEST_RESOLVE_KEY"
+
+
+@pytest.fixture(autouse=True)
+def _clean(monkeypatch):
+    monkeypatch.delenv(_K, raising=False)
+
+
+# --- resolve_config_toml (REQ-048 AC-7/8) ---------------------------------- #
+def test_resolve_name_default_dir():
+    assert resolve_config_toml("test") == os.path.join("config", "test.toml")
+
+
+def test_resolve_appends_toml():
+    assert resolve_config_toml("test.toml") == os.path.join("config", "test.toml")
+
+
+def test_resolve_with_config_path():
+    assert resolve_config_toml("prod", "/etc/trex") == os.path.join("/etc/trex", "prod.toml")
+
+
+def test_resolve_path_form_passthrough():
+    # AC-8: a slash-bearing value is an explicit path (backward-compat).
+    assert resolve_config_toml("config/test.toml") == "config/test.toml"
+    assert resolve_config_toml("config/test.toml", "/etc/trex") == "config/test.toml"
+
+
+# --- _load_dotenv config-dir resolution (REQ-010 AC-6/7) ------------------- #
+def test_dotenv_loaded_from_config_dir_cwd_independent(tmp_path, monkeypatch):
+    cfgdir = tmp_path / "cfg"
+    cfgdir.mkdir()
+    (cfgdir / ".env").write_text(f"{_K}=from_config_dir\n")
+    toml = str(cfgdir / "inst.toml")
+    # chdir somewhere with no .env to prove CWD-independence.
+    other = tmp_path / "elsewhere"
+    other.mkdir()
+    monkeypatch.chdir(other)
+    _load_dotenv(toml)
+    assert os.environ[_K] == "from_config_dir"
+
+
+def test_dotenv_env_file_wins(tmp_path, monkeypatch):
+    cfgdir = tmp_path / "cfg"
+    cfgdir.mkdir()
+    (cfgdir / ".env").write_text(f"{_K}=from_config_dir\n")
+    explicit = tmp_path / "explicit.env"
+    explicit.write_text(f"{_K}=from_env_file\n")
+    monkeypatch.chdir(tmp_path)
+    _load_dotenv(str(cfgdir / "inst.toml"), env_file=str(explicit))
+    assert os.environ[_K] == "from_env_file"
+
+
+def test_dotenv_os_env_takes_precedence(tmp_path, monkeypatch):
+    cfgdir = tmp_path / "cfg"
+    cfgdir.mkdir()
+    (cfgdir / ".env").write_text(f"{_K}=from_config_dir\n")
+    monkeypatch.setenv(_K, "from_os_env")
+    _load_dotenv(str(cfgdir / "inst.toml"))
+    assert os.environ[_K] == "from_os_env"  # override=False
+
+
+def test_dotenv_absent_is_noop(tmp_path):
+    # config dir has no .env -> no crash, key stays unset.
+    _load_dotenv(str(tmp_path / "inst.toml"))
+    assert _K not in os.environ
+
+
+# --- CLI --config-path instance routing (REQ-048 AC-9) --------------------- #
+def test_cli_resolve_instance_honors_config_path(tmp_path):
+    from types import SimpleNamespace
+
+    from trex_core.runtime.cli import _resolve_instance
+
+    cfgdir = tmp_path / "cfg"
+    cfgdir.mkdir()
+    (cfgdir / "inst.toml").write_text('instance_key = "inst-xyz"\n')
+    args = SimpleNamespace(instance=None, config="inst", config_path=str(cfgdir))
+    assert _resolve_instance(args) == "inst-xyz"

tests/runtime/test_instance_config.py

@@ -83,7 +83,9 @@ def test_config_required_cli_exits_nonzero():
 
 
 def test_gitignore_excludes_instance_toml():
-    """AC-5: .gitignore excludes instance TOML but keeps the example."""
+    """AC-5 (CHG-20260609-01): .gitignore ignores config/* but keeps example
+    templates (*.example.toml covers instance.example.toml) and .env.example."""
     gi = (_REPO / ".gitignore").read_text()
-    assert "/config/*.toml" in gi
-    assert "!/config/instance.example.toml" in gi
+    assert "/config/*" in gi
+    assert "!/config/*.example.toml" in gi
+    assert "!/config/.env.example" in gi