Prepend base.yaml only when a real base config is named

src/webwright/skill_factory/route.py

@@ -21,6 +21,7 @@
 import os
 import subprocess
 import sys
+from pathlib import Path
 
 from .execute import run_skill
 from .gate import gate
@@ -61,7 +62,7 @@ def agent_cfg(cfg: list[str]) -> list[str]:
         # -c REPLACES the defaults; base.yaml carries the agent's system/instance templates, so
         # re-add it unless a base was named — otherwise `-c model.yaml` alone yields an agent with
         # no template (a cryptic pydantic ValidationError, not a helpful message).
-        if not any("base" in c for c in cfg):
+        if not any(Path(c).name == "base.yaml" for c in cfg):
             cfg = ["base.yaml", *cfg]
         return cfg
     over = [f"model.{key}={val}" for key, val in

tests/skill_factory/test_build_init.py

@@ -364,6 +364,14 @@ def test_bare_model_config_gets_base_prepended():
         ["base.yaml", "m.yaml", "model.max_output_tokens=16000"]
 
 
+def test_base_is_matched_on_the_filename_not_a_substring():
+    """`base` in `database.yaml` is not a base config. Prepend base.yaml so the agent
+    still gets system/instance templates."""
+    assert agent_cfg(["database.yaml"]) == ["base.yaml", "database.yaml"]
+    assert agent_cfg(["my_base_model.yaml"]) == ["base.yaml", "my_base_model.yaml"]
+    assert agent_cfg(["configs/base.yaml", "mine.yaml"]) == ["configs/base.yaml", "mine.yaml"]
+
+
 def test_the_env_path_carries_a_usable_output_budget(monkeypatch):
     """The env path stands in for a model yaml, which set max_output_tokens: 16000. base.yaml's
     4000 truncates the agent mid-script when it reuses a big skill, and the run loops re-emitting