fix(config): preserve env refs when save_config rewrites config (#11892)

Co-authored-by: binhnt92 <84617813+binhnt92@users.noreply.github.com>

tests/hermes_cli/test_config_env_refs.py

@@ -0,0 +1,169 @@
+import textwrap
+
+from hermes_cli.config import load_config, save_config
+
+
+def _write_config(tmp_path, body: str):
+    (tmp_path / "config.yaml").write_text(textwrap.dedent(body), encoding="utf-8")
+
+
+def _read_config(tmp_path) -> str:
+    return (tmp_path / "config.yaml").read_text(encoding="utf-8")
+
+
+def test_save_config_preserves_env_refs_on_unrelated_change(monkeypatch, tmp_path):
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+    monkeypatch.setenv("TU_ZI_API_KEY", "sk-realsecret")
+    monkeypatch.setenv("ALT_SECRET", "alt-secret")
+    _write_config(
+        tmp_path,
+        """\
+        custom_providers:
+          - name: tuzi
+            base_url: https://api.tu-zi.com
+            api_key: ${TU_ZI_API_KEY}
+            headers:
+              Authorization: Bearer ${ALT_SECRET}
+            model: claude-opus-4-6
+        model:
+          default: claude-opus-4-6
+        """,
+    )
+
+    config = load_config()
+    config["model"]["default"] = "doubao-pro"
+    save_config(config)
+
+    saved = _read_config(tmp_path)
+    assert "api_key: ${TU_ZI_API_KEY}" in saved
+    assert "Authorization: Bearer ${ALT_SECRET}" in saved
+    assert "sk-realsecret" not in saved
+    assert "alt-secret" not in saved
+
+
+def test_save_config_preserves_unresolved_env_refs(monkeypatch, tmp_path):
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+    monkeypatch.delenv("MISSING_SECRET", raising=False)
+    _write_config(
+        tmp_path,
+        """\
+        custom_providers:
+          - name: unresolved
+            api_key: ${MISSING_SECRET}
+            model: claude-opus-4-6
+        model:
+          default: claude-opus-4-6
+        """,
+    )
+
+    config = load_config()
+    config["display"]["compact"] = True
+    save_config(config)
+
+    assert "api_key: ${MISSING_SECRET}" in _read_config(tmp_path)
+
+
+def test_save_config_allows_intentional_secret_value_change(monkeypatch, tmp_path):
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+    monkeypatch.setenv("TU_ZI_API_KEY", "sk-old-secret")
+    _write_config(
+        tmp_path,
+        """\
+        custom_providers:
+          - name: tuzi
+            api_key: ${TU_ZI_API_KEY}
+            model: claude-opus-4-6
+        model:
+          default: claude-opus-4-6
+        """,
+    )
+
+    config = load_config()
+    config["custom_providers"][0]["api_key"] = "sk-new-secret"
+    save_config(config)
+
+    saved = _read_config(tmp_path)
+    assert "api_key: sk-new-secret" in saved
+    assert "${TU_ZI_API_KEY}" not in saved
+
+
+def test_save_config_preserves_template_when_env_rotates_after_load(monkeypatch, tmp_path):
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+    monkeypatch.setenv("TU_ZI_API_KEY", "sk-old-secret")
+    _write_config(
+        tmp_path,
+        """\
+        custom_providers:
+          - name: tuzi
+            api_key: ${TU_ZI_API_KEY}
+            model: claude-opus-4-6
+        model:
+          default: claude-opus-4-6
+        """,
+    )
+
+    config = load_config()
+    monkeypatch.setenv("TU_ZI_API_KEY", "sk-rotated-secret")
+    config["model"]["default"] = "doubao-pro"
+    save_config(config)
+
+    saved = _read_config(tmp_path)
+    assert "api_key: ${TU_ZI_API_KEY}" in saved
+    assert "sk-old-secret" not in saved
+    assert "sk-rotated-secret" not in saved
+
+
+def test_save_config_keeps_edited_partial_template_strings_literal(monkeypatch, tmp_path):
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+    monkeypatch.setenv("ALT_SECRET", "alt-secret")
+    _write_config(
+        tmp_path,
+        """\
+        custom_providers:
+          - name: tuzi
+            headers:
+              Authorization: Bearer ${ALT_SECRET}
+            model: claude-opus-4-6
+        model:
+          default: claude-opus-4-6
+        """,
+    )
+
+    config = load_config()
+    config["custom_providers"][0]["headers"]["Authorization"] = "Token alt-secret"
+    save_config(config)
+
+    saved = _read_config(tmp_path)
+    assert "Authorization: Token alt-secret" in saved
+    assert "Authorization: Bearer ${ALT_SECRET}" not in saved
+
+
+def test_save_config_falls_back_to_positional_matching_for_duplicate_names(monkeypatch, tmp_path):
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+    monkeypatch.setenv("FIRST_SECRET", "first-secret")
+    monkeypatch.setenv("SECOND_SECRET", "second-secret")
+    _write_config(
+        tmp_path,
+        """\
+        custom_providers:
+          - name: duplicate
+            api_key: ${FIRST_SECRET}
+            model: claude-opus-4-6
+          - name: duplicate
+            api_key: ${SECOND_SECRET}
+            model: doubao-pro
+        model:
+          default: claude-opus-4-6
+        """,
+    )
+
+    config = load_config()
+    config["display"]["compact"] = True
+    save_config(config)
+
+    saved = _read_config(tmp_path)
+    assert saved.count("name: duplicate") == 2
+    assert "api_key: ${FIRST_SECRET}" in saved
+    assert "api_key: ${SECOND_SECRET}" in saved
+    assert "first-secret" not in saved
+    assert "second-secret" not in saved