Feat/issue 12 manifest metadata

src/agentpool/models/manifest.py

@@ -375,6 +375,7 @@ class AgentsManifest(Schema):
     """
 
     model_config = ConfigDict(
+        extra="allow",
         json_schema_extra={
             "x-icon": "octicon:file-code-16",
             "x-doc-title": "Manifest Overview",
@@ -777,6 +778,31 @@ def get_output_type(self, agent_name: str) -> type[Any] | None:
             return response_def.response_schema.get_schema()
         return agent_config.output_type.response_schema.get_schema()
 
+    @model_validator(mode="after")
+    def validate_extra_fields(self) -> Self:
+        """Validate and warn about unknown extra fields.
+
+        Allowed prefixes:
+        - `.` (dot): YAML anchors
+        - `_` (underscore): Internal metadata
+        - `x-` (x-prefix): Custom extensions
+
+        Unknown fields trigger a WARNING but do not raise ValidationError.
+        """
+        if hasattr(self, "model_extra") and self.model_extra:
+            for key in self.model_extra:
+                # Check if key starts with allowed prefixes
+                if key.startswith((".", "_", "x-")):
+                    continue  # Silently allow these
+
+                # Warn about unknown fields
+                logger.warning(
+                    "Unknown field '%s' in manifest. This field will be IGNORED.",
+                    key,
+                    stacklevel=2,
+                )
+        return self
+
 
 if __name__ == "__main__":
     from llmling_models_config import InputModelConfig

tests/manifest/test_metadata_fields.py

@@ -0,0 +1,114 @@
+"""Tests for manifest metadata fields (YAML anchors and extensions)."""
+
+from __future__ import annotations
+
+from llmling_models_config import StringModelConfig
+import yamling
+
+from agentpool import AgentsManifest
+from agentpool.models.agents import NativeAgentConfig
+
+
+# Valid config with allowed metadata fields
+MANIFEST_WITH_ALLOWED_METADATA = """\
+agents:
+  test_agent:
+    type: native
+    model: openai:gpt-4o
+    system_prompt: "You are a test agent"
+
+.anchor: &default_settings
+  timeout: 30
+  retries: 3
+
+_meta:
+  version: "1.0.0"
+  author: "Test User"
+
+x-custom:
+  environment: "production"
+  feature_flags:
+    - feature_a
+    - feature_b
+"""
+
+# Valid config with unknown field (typo)
+MANIFEST_WITH_UNKNOWN_FIELD = """\
+agents:
+  test_agent:
+    type: native
+    model: openai:gpt-4o
+    system_prompt: "You are a test agent"
+
+random_field: "this is a typo/unknown field"
+"""
+
+# Valid config with both allowed and unknown fields
+MANIFEST_WITH_MIXED_FIELDS = """\
+agents:
+  test_agent:
+    type: native
+    model: openai:gpt-4o
+    system_prompt: "You are a test agent"
+
+_meta:
+  version: "1.0.0"
+
+random_field: "should trigger warning"
+"""
+
+
+def test_allowed_metadata_fields_succeed():
+    """Test that metadata fields starting with ., _, x- are allowed.
+
+    RED PHASE: This test will FAIL because currently extra fields
+    are forbidden. After implementation, this test will PASS.
+    """
+    config = yamling.load_yaml(MANIFEST_WITH_ALLOWED_METADATA)
+    manifest = AgentsManifest.model_validate(config)
+
+    # Verify that manifest loaded successfully
+    assert "test_agent" in manifest.agents
+    agent = manifest.agents["test_agent"]
+    assert isinstance(agent, NativeAgentConfig)
+    assert isinstance(agent.model, StringModelConfig)
+    assert agent.model.identifier == "openai:gpt-4o"
+
+
+def test_unknown_field_generates_warning():
+    """Test that unknown fields generate a warning but don't raise ValidationError.
+
+    RED PHASE: This test will FAIL because currently unknown fields
+    raise ValidationError. After implementation, this test will PASS.
+    """
+    config = yamling.load_yaml(MANIFEST_WITH_UNKNOWN_FIELD)
+
+    # After implementation, this should NOT raise ValidationError
+    # It should log a warning instead
+    manifest = AgentsManifest.model_validate(config)
+
+    # Verify agents loaded correctly
+    assert "test_agent" in manifest.agents
+    agent = manifest.agents["test_agent"]
+    assert isinstance(agent, NativeAgentConfig)
+    assert isinstance(agent.model, StringModelConfig)
+    assert agent.model.identifier == "openai:gpt-4o"
+
+
+def test_mixed_allowed_and_unknown_fields():
+    """Test manifest with both allowed and unknown fields.
+
+    RED PHASE: This test will FAIL because currently unknown fields
+    raise ValidationError. After implementation, this test will PASS.
+    """
+    config = yamling.load_yaml(MANIFEST_WITH_MIXED_FIELDS)
+
+    # After implementation, this should succeed with warning for 'random_field'
+    manifest = AgentsManifest.model_validate(config)
+
+    # Verify allowed metadata fields are accessible
+    assert "test_agent" in manifest.agents
+    agent = manifest.agents["test_agent"]
+    assert isinstance(agent, NativeAgentConfig)
+    assert isinstance(agent.model, StringModelConfig)
+    assert agent.model.identifier == "openai:gpt-4o"

tests/manifest/test_models.py

@@ -36,11 +36,16 @@
 """
 
 INVALID_RESPONSE_CONFIG = """\
-responses: {}
-agent:
-  name: Test Agent
-  model: test
-  output_type: NonExistentResponse
+responses:
+  InvalidResponse:
+    type: object
+
+agents:
+  test_agent:
+    type: native
+    model: "openai:gpt-4o"
+    system_prompt: "test"
+    output_type: NonExistentResponse
 """