From 0c031d60b0fdbb28925970622434721f3fd631db Mon Sep 17 00:00:00 2001
From: Bartok <danielrpike9@gmail.com>
Date: Mon, 29 Jun 2026 05:56:49 -0400
Subject: [PATCH] fix(genbi): normalise null apps/schema_version in app index
 (#2406)

---
 core/wren/src/wren/genbi/index.py        | 20 +++++++++-
 core/wren/tests/unit/test_genbi_index.py | 47 ++++++++++++++++++++++++
 2 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/core/wren/src/wren/genbi/index.py b/core/wren/src/wren/genbi/index.py
index 3032b00ee..01b6a6fba 100644
--- a/core/wren/src/wren/genbi/index.py
+++ b/core/wren/src/wren/genbi/index.py
@@ -50,8 +50,24 @@ def load_index(project_path: Path) -> dict:
             f"{path} is malformed — expected a mapping at the top level, "
             f"got {type(data).__name__}."
         )
-    data.setdefault("schema_version", INDEX_SCHEMA_VERSION)
-    data.setdefault("apps", {})
+    # Normalise explicit null values (``apps:`` / ``schema_version:`` with no
+    # value, e.g. from a hand-edit or a truncated write). ``setdefault`` is a
+    # no-op when the key already exists, which left ``apps: None`` in place and
+    # made every accessor crash with an opaque ``AttributeError`` deep in a
+    # command. We check ``is None`` specifically rather than truthiness so a
+    # valid falsy value is preserved and surfaced for validation instead of
+    # being silently coerced to a default.
+    if data.get("schema_version") is None:
+        data["schema_version"] = INDEX_SCHEMA_VERSION
+    apps = data.get("apps")
+    if apps is None:
+        apps = {}
+    if not isinstance(apps, dict):
+        raise MalformedIndexError(
+            f"{path} is malformed — 'apps' must be a mapping, "
+            f"got {type(apps).__name__}."
+        )
+    data["apps"] = apps
     return data
 
 
diff --git a/core/wren/tests/unit/test_genbi_index.py b/core/wren/tests/unit/test_genbi_index.py
index 2d1d8dad2..2be768ef2 100644
--- a/core/wren/tests/unit/test_genbi_index.py
+++ b/core/wren/tests/unit/test_genbi_index.py
@@ -145,3 +145,50 @@ def test_register_rejects_path_traversal_name(tmp_path: Path) -> None:
     result = runner.invoke(app, ["genbi", "register", "../evil", "-p", str(project)])
     assert result.exit_code != 0
     assert "invalid app name" in result.output
+
+
+def test_load_index_normalises_null_apps(tmp_path: Path) -> None:
+    # Regression: an explicit ``apps:`` with no value (hand-edit / truncated
+    # write) is valid YAML and parses to None. setdefault() was a no-op since
+    # the key existed, leaving ``apps: None`` so every accessor crashed with an
+    # opaque AttributeError. load_index must normalise it to an empty dict.
+    path = index_path(tmp_path)
+    path.parent.mkdir(parents=True)
+    path.write_text("schema_version: 1\napps:\n")
+
+    data = load_index(tmp_path)
+    assert data["apps"] == {}
+    assert data["schema_version"] == 1
+    # And the normal accessor must not crash on it.
+    from wren.genbi.index import get_app
+
+    assert get_app(tmp_path, "missing") is None
+
+
+def test_load_index_normalises_null_schema_version(tmp_path: Path) -> None:
+    path = index_path(tmp_path)
+    path.parent.mkdir(parents=True)
+    path.write_text("schema_version:\napps: {}\n")
+
+    data = load_index(tmp_path)
+    assert data["schema_version"] == 1
+
+
+def test_load_index_raises_on_non_mapping_apps(tmp_path: Path) -> None:
+    path = index_path(tmp_path)
+    path.parent.mkdir(parents=True)
+    path.write_text("apps:\n  - one\n  - two\n")  # apps is a list, not a mapping
+
+    with pytest.raises(MalformedIndexError):
+        load_index(tmp_path)
+
+
+def test_load_index_preserves_falsy_schema_version(tmp_path: Path) -> None:
+    # A literal 0 is a real value, not a missing one — it must be preserved
+    # rather than coerced to the default, so only explicit null normalises.
+    path = index_path(tmp_path)
+    path.parent.mkdir(parents=True)
+    path.write_text("schema_version: 0\napps: {}\n")
+
+    data = load_index(tmp_path)
+    assert data["schema_version"] == 0