refactor: simplify AgentConfig — effective_utility_model, unlimited iterations

- utility_model defaults to '' (empty = same as primary_model)
- effective_utility_model property returns primary if utility is empty
- effective_max_iterations: 0 = unlimited (maps to 999 practical ceiling)
- Verifier now uses effective_utility_model instead of utility_model directly

Co-Authored-By: Oz <oz-agent@warp.dev>

Author: tbitcs

src/specsmith/agents/config.py

@@ -14,7 +14,7 @@ class AgentConfig:
     """Configuration for the AG2 agent shell."""
 
     primary_model: str = "qwen2.5:14b"
-    utility_model: str = "qwen2.5:14b"  # same as primary; override in scaffold.yml
+    utility_model: str = ""  # empty = same as primary_model
     ollama_base_url: str = "http://localhost:11434"
     max_iterations: int = 10
     stream: bool = False
@@ -23,6 +23,16 @@ class AgentConfig:
         default_factory=lambda: ["filesystem", "shell", "git", "tests", "docs"]
     )
 
+    @property
+    def effective_utility_model(self) -> str:
+        """Utility model, defaulting to primary if not set."""
+        return self.utility_model or self.primary_model
+
+    @property
+    def effective_max_iterations(self) -> int:
+        """0 means unlimited (use 999 as practical ceiling)."""
+        return self.max_iterations if self.max_iterations > 0 else 999
+
     def llm_config_dict(self, model: str | None = None) -> dict[str, Any]:
         """Return an AG2-compatible LLM config dict for Ollama."""
         return {

src/specsmith/agents/roles.py

@@ -172,7 +172,7 @@ def create_verifier(config: AgentConfig, project_dir: str) -> Any:
     from specsmith.agents.tools.shell import run_project_command
     from specsmith.agents.tools.tests import run_unit_tests, summarize_failures
 
-    llm_config = LLMConfig(config.llm_config_dict(model=config.utility_model))
+    llm_config = LLMConfig(config.llm_config_dict(model=config.effective_utility_model))
     pd = project_dir
 
     def _run_tests(test_path: str = "tests/", extra_args: str = "--tb=short -q") -> str: