From 081dc594b6a16e1876ce9c0ef5295672a08a2c69 Mon Sep 17 00:00:00 2001
From: Bartok9 <danielrpike9@gmail.com>
Date: Mon, 20 Jul 2026 02:07:39 -0400
Subject: [PATCH 1/2] fix(genbi): guard non-dict models/columns in inventory
 format

_format_model_inventory assumed dict rows; junk MDL entries raised
AttributeError while composing build instructions.
---
 core/wren/src/wren/genbi/composer.py          | 13 ++++++--
 .../unit/test_genbi_format_model_inventory.py | 30 +++++++++++++++++++
 2 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 core/wren/tests/unit/test_genbi_format_model_inventory.py

diff --git a/core/wren/src/wren/genbi/composer.py b/core/wren/src/wren/genbi/composer.py
index 726b8d5860..6bcff8061f 100644
--- a/core/wren/src/wren/genbi/composer.py
+++ b/core/wren/src/wren/genbi/composer.py
@@ -51,14 +51,23 @@ def _data_mode_guidance(data_mode: str) -> str:
     raise ValueError(f"unknown data-mode {data_mode!r}; expected one of {DATA_MODES}")
 
 
-def _format_model_inventory(models: list[dict]) -> str:
+def _format_model_inventory(models: list[dict] | None) -> str:
     """One markdown bullet per model with its column names."""
     if not models:
         return "- (no models found — run `wren context build` first)"
     lines = []
     for model in models:
-        cols = ", ".join(c.get("name", "?") for c in model.get("columns", []))
+        if not isinstance(model, dict):
+            continue
+        raw_cols = model.get("columns") or []
+        if not isinstance(raw_cols, list):
+            raw_cols = []
+        cols = ", ".join(
+            c.get("name", "?") for c in raw_cols if isinstance(c, dict)
+        )
         lines.append(f"- **{model.get('name', '?')}**: {cols}")
+    if not lines:
+        return "- (no models found — run `wren context build` first)"
     return "\n".join(lines)
 
 
diff --git a/core/wren/tests/unit/test_genbi_format_model_inventory.py b/core/wren/tests/unit/test_genbi_format_model_inventory.py
new file mode 100644
index 0000000000..b8415d81ed
--- /dev/null
+++ b/core/wren/tests/unit/test_genbi_format_model_inventory.py
@@ -0,0 +1,30 @@
+from wren.genbi.composer import _format_model_inventory
+
+
+def test_formats_clean_models():
+    text = _format_model_inventory(
+        [{"name": "orders", "columns": [{"name": "id"}, {"name": "total"}]}]
+    )
+    assert "orders" in text
+    assert "id" in text
+
+
+def test_skips_non_dict_models_and_columns():
+    text = _format_model_inventory(
+        [
+            None,
+            "x",
+            {
+                "name": "t",
+                "columns": [None, {"name": "a"}, "bad"],
+            },
+        ]
+    )
+    assert "t" in text
+    assert "a" in text
+    assert "None" not in text
+
+
+def test_all_junk_falls_back_to_empty_message():
+    text = _format_model_inventory([None, "x", 1])
+    assert "no models found" in text

From 87bcf4db6229647fa997c7944a02577b0de2a34e Mon Sep 17 00:00:00 2001
From: Bartok9 <danielrpike9@gmail.com>
Date: Mon, 20 Jul 2026 12:06:18 -0400
Subject: [PATCH 2/2] style(genbi): ruff format composer model inventory guards

---
 core/wren/src/wren/genbi/composer.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/core/wren/src/wren/genbi/composer.py b/core/wren/src/wren/genbi/composer.py
index 6bcff8061f..f4afc11c11 100644
--- a/core/wren/src/wren/genbi/composer.py
+++ b/core/wren/src/wren/genbi/composer.py
@@ -62,9 +62,7 @@ def _format_model_inventory(models: list[dict] | None) -> str:
         raw_cols = model.get("columns") or []
         if not isinstance(raw_cols, list):
             raw_cols = []
-        cols = ", ".join(
-            c.get("name", "?") for c in raw_cols if isinstance(c, dict)
-        )
+        cols = ", ".join(c.get("name", "?") for c in raw_cols if isinstance(c, dict))
         lines.append(f"- **{model.get('name', '?')}**: {cols}")
     if not lines:
         return "- (no models found — run `wren context build` first)"