fix: Change name for builder agent

When this agent was built before the agent name was changed in the build script and accepted like that from the VB so changed to set into that form

Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 834479335

src/google/adk/cli/built_in_agents/__init__.py

@@ -21,7 +21,7 @@ with ADK tools and web interfaces.
 from __future__ import annotations
 
 from . import agent  # Import to make agent.root_agent available
-from .agent_builder_assistant import AgentBuilderAssistant
+from .adk_agent_builder_assistant import AgentBuilderAssistant
 
 __all__ = [
     'AgentBuilderAssistant',

src/google/adk/cli/built_in_agents/adk_agent_builder_assistant.py

@@ -416,3 +416,8 @@ class AgentBuilderAssistant:
 
     with open(template_path, "r", encoding="utf-8") as f:
       return f.read()
+
+
+# Expose a module-level root_agent so the AgentLoader can find this built-in
+# assistant when requested as "__adk_agent_builder_assistant".
+root_agent = AgentBuilderAssistant.create_agent()

src/google/adk/cli/built_in_agents/agent.py

@@ -15,7 +15,7 @@
 """Agent Builder Assistant instance for ADK web testing."""
 from __future__ import annotations
 
-from .agent_builder_assistant import AgentBuilderAssistant
+from .adk_agent_builder_assistant import AgentBuilderAssistant
 
 # Create the agent instance using the factory
 # The root_agent variable is what ADK looks for when loading agents

src/google/adk/cli/built_in_agents/instruction_embedded.template

@@ -75,6 +75,9 @@ Always reference this schema when creating configurations to ensure compliance.
 - **CRITICAL TIMING**: Ask for model selection IMMEDIATELY after determining LlmAgent is needed, BEFORE presenting any design
 - **MANDATORY CONFIRMATION**: Say "Please confirm what model you want to use" - do NOT assume or suggest defaults
 - **EXAMPLES**: "gemini-2.5-flash", "gemini-2.5-pro", etc.
+- **ALLOWED MODELS ONLY**: Only mention or propose "gemini-2.5-flash" or
+  "gemini-2.5-pro". Treat any request for gemini-1.5-* or older models as
+  unsupported and redirect to one of the 2.5 options.
 - **RATIONALE**: Only LlmAgent requires model specification; workflow agents do not
 - **DEFAULT MODEL**: If user says "use default" or "proceed with default model", use: {default_model}
   * This is the actual model name, NOT the literal string "default"

src/google/adk/cli/utils/agent_loader.py

@@ -192,10 +192,30 @@ class AgentLoader(BaseAgentLoader):
       agents_dir = os.path.abspath(SPECIAL_AGENTS_DIR)
       # Remove the double underscore prefix for the actual agent name
       actual_agent_name = agent_name[2:]
+      # If this special agents directory is part of a package (has __init__.py
+      # up the tree), build a fully-qualified module path so the built-in agent
+      # can continue to use relative imports. Otherwise, fall back to importing
+      # by module name relative to agents_dir.
+      module_base_name = actual_agent_name
+      package_parts: list[str] = []
+      package_root: Optional[Path] = None
+      current_dir = Path(agents_dir).resolve()
+      while True:
+        if not (current_dir / "__init__.py").is_file():
+          package_root = current_dir
+          break
+        package_parts.append(current_dir.name)
+        current_dir = current_dir.parent
+      if package_parts:
+        package_parts.reverse()
+        module_base_name = ".".join(package_parts + [actual_agent_name])
+        if str(package_root) not in sys.path:
+          sys.path.insert(0, str(package_root))
     else:
       # Regular agent: use the configured agents directory
       agents_dir = self.agents_dir
       actual_agent_name = agent_name
+      module_base_name = actual_agent_name
 
     # Add agents_dir to sys.path
     if agents_dir not in sys.path:
@@ -204,20 +224,20 @@ class AgentLoader(BaseAgentLoader):
     logger.debug("Loading .env for agent %s from %s", agent_name, agents_dir)
     envs.load_dotenv_for_agent(actual_agent_name, str(agents_dir))
 
-    if root_agent := self._load_from_module_or_package(actual_agent_name):
+    if root_agent := self._load_from_module_or_package(module_base_name):
       self._record_origin_metadata(
           loaded=root_agent,
-          expected_app_name=actual_agent_name,
-          module_name=actual_agent_name,
+          expected_app_name=agent_name,
+          module_name=module_base_name,
           agents_dir=agents_dir,
       )
       return root_agent
 
-    if root_agent := self._load_from_submodule(actual_agent_name):
+    if root_agent := self._load_from_submodule(module_base_name):
       self._record_origin_metadata(
           loaded=root_agent,
-          expected_app_name=actual_agent_name,
-          module_name=f"{actual_agent_name}.agent",
+          expected_app_name=agent_name,
+          module_name=f"{module_base_name}.agent",
           agents_dir=agents_dir,
       )
       return root_agent