diff --git a/core/wren/src/wren/genbi/cli.py b/core/wren/src/wren/genbi/cli.py
index 49ff47c02a..95bf8c5a97 100644
--- a/core/wren/src/wren/genbi/cli.py
+++ b/core/wren/src/wren/genbi/cli.py
@@ -204,6 +204,10 @@ def list_apps(path: ProjectPathOpt = None) -> None:
         return
 
     for name, entry in apps.items():
+        # Hand-edited non-dict entries: skip rather than AttributeError on .get
+        # (same lenient stance as get_app treating them as unregistered).
+        if not isinstance(entry, dict):
+            continue
         deploy = entry.get("deploy") or {}
         suffix = f" → {deploy['last_url']}" if deploy.get("last_url") else ""
         typer.echo(
diff --git a/core/wren/src/wren/genbi/index.py b/core/wren/src/wren/genbi/index.py
index 01b6a6fba9..8e24b39a58 100644
--- a/core/wren/src/wren/genbi/index.py
+++ b/core/wren/src/wren/genbi/index.py
@@ -80,11 +80,17 @@ def save_index(project_path: Path, index: dict) -> None:
 def register_app(project_path: Path, name: str, *, data_mode: str) -> dict:
     """Create or update the entry for ``name``. Returns the entry."""
     index = load_index(project_path)
-    entry = index["apps"].get(name) or {
-        "source": f"apps/{name}",
-        "status": "scaffolded",
-        "created_at": date.today().isoformat(),
-    }
+    existing = index["apps"].get(name)
+    # Hand-edited truthy non-dicts (e.g. a string) must not fall through the
+    # ``or`` default — assignment would raise TypeError. Treat like missing.
+    if not isinstance(existing, dict):
+        entry = {
+            "source": f"apps/{name}",
+            "status": "scaffolded",
+            "created_at": date.today().isoformat(),
+        }
+    else:
+        entry = existing
     entry["data_mode"] = data_mode
     index["apps"][name] = entry
     save_index(project_path, index)
@@ -103,13 +109,20 @@ def remove_app(project_path: Path, name: str) -> bool:
 
 def get_app(project_path: Path, name: str) -> dict | None:
     """Return the entry for ``name`` or None if not registered."""
-    return load_index(project_path)["apps"].get(name)
+    entry = load_index(project_path)["apps"].get(name)
+    # Hand-edited apps.yml may put a scalar/list under an app key; treat as
+    # unregistered rather than letting callers AttributeError on .get keys.
+    if entry is not None and not isinstance(entry, dict):
+        return None
+    return entry
 
 
 def update_app(project_path: Path, name: str, **fields) -> dict:
     """Merge ``fields`` into the entry for ``name`` and persist."""
     index = load_index(project_path)
-    entry = index["apps"][name]
+    entry = index["apps"].get(name)
+    if not isinstance(entry, dict):
+        raise KeyError(name)
     entry.update(fields)
     save_index(project_path, index)
     return entry
diff --git a/core/wren/tests/unit/test_genbi_index.py b/core/wren/tests/unit/test_genbi_index.py
index 2be768ef29..702b199bc9 100644
--- a/core/wren/tests/unit/test_genbi_index.py
+++ b/core/wren/tests/unit/test_genbi_index.py
@@ -192,3 +192,85 @@ def test_load_index_preserves_falsy_schema_version(tmp_path: Path) -> None:
 
     data = load_index(tmp_path)
     assert data["schema_version"] == 0
+
+
+def test_get_app_skips_non_dict_entry(tmp_path: Path) -> None:
+    from wren.genbi.index import get_app, save_index
+
+    idx = {
+        "schema_version": 1,
+        "apps": {"bad": "not-a-map", "good": {"source": "apps/good"}},
+    }
+    save_index(tmp_path, idx)
+    assert get_app(tmp_path, "bad") is None
+    assert get_app(tmp_path, "good") == {"source": "apps/good"}
+    assert get_app(tmp_path, "missing") is None
+
+
+def test_register_app_replaces_non_dict_entry(tmp_path: Path) -> None:
+    from wren.genbi.index import load_index, register_app, save_index
+
+    project = _make_project(tmp_path, with_app="bad")
+    save_index(
+        project,
+        {"schema_version": 1, "apps": {"bad": "not-a-map"}},
+    )
+    entry = register_app(project, "bad", data_mode="snapshot")
+    assert isinstance(entry, dict)
+    assert entry["data_mode"] == "snapshot"
+    assert entry["source"] == "apps/bad"
+    assert entry["status"] == "scaffolded"
+    assert load_index(project)["apps"]["bad"] == entry
+
+
+def test_update_app_rejects_missing_and_non_dict(tmp_path: Path) -> None:
+    from wren.genbi.index import save_index, update_app
+
+    save_index(
+        tmp_path,
+        {
+            "schema_version": 1,
+            "apps": {
+                "bad": "not-a-map",
+                "good": {"source": "apps/good", "status": "scaffolded"},
+            },
+        },
+    )
+    with pytest.raises(KeyError):
+        update_app(tmp_path, "missing", status="built")
+    with pytest.raises(KeyError):
+        update_app(tmp_path, "bad", status="built")
+    updated = update_app(tmp_path, "good", status="built")
+    assert updated["status"] == "built"
+    assert updated["source"] == "apps/good"
+    # Persistence: re-load and confirm
+    data = load_index(tmp_path)
+    assert data["apps"]["good"]["status"] == "built"
+    assert data["apps"]["bad"] == "not-a-map"
+
+
+def test_list_skips_non_dict_entries(tmp_path: Path) -> None:
+    from wren.genbi.index import save_index
+
+    project = _make_project(tmp_path, with_app="good")
+    save_index(
+        project,
+        {
+            "schema_version": 1,
+            "apps": {
+                "bad": "not-a-map",
+                "good": {
+                    "source": "apps/good",
+                    "data_mode": "snapshot",
+                    "status": "scaffolded",
+                },
+            },
+        },
+    )
+    result = runner.invoke(app, ["genbi", "list", "-p", str(project)])
+    assert result.exit_code == 0, result.output
+    assert "good" in result.output
+    assert "snapshot" in result.output
+    assert "bad" not in result.output
+    # Must not traceback; bad entry is skipped (lenient listing).
+    assert "Traceback" not in result.output