Clarify coarse tool invocation and repair malformed database filters

src/viano_bug_analysis/analysis/investigation_prompt.py

@@ -82,6 +82,15 @@ def output_schema(context=None, *, strict=False):
 
 
 def build_prompt(context):
+    request = _build_prompt(context)
+    from .tool_guidance import instructions, HEADER
+    guide = instructions(context)
+    if guide and HEADER not in request['messages'][0]['content']:
+        request['messages'][0]['content'] += guide
+    return request
+
+
+def _build_prompt(context):
     if context.get('lean_protocol')==2:
         from .investigation_lean_v20 import build
         return build(context)