feat(agent-card): add metadata field and expose list filter

src/agentex/lib/types/agent_card.py

@@ -5,7 +5,7 @@
 from enum import Enum
 from typing import TYPE_CHECKING, Any, get_args, get_origin
 
-from pydantic import BaseModel
+from pydantic import Field, BaseModel
 
 if TYPE_CHECKING:
     from agentex.lib.sdk.state_machine.state import State
@@ -31,6 +31,11 @@ class AgentCard(BaseModel):
     data_events: list[str] = []
     input_types: list[str] = []
     output_schema: dict | None = None
+    # Free-form JSON object for opt-in self-description (e.g. protocol-specific
+    # capability flags). Not interpreted by the platform, but callers can filter
+    # agents on it with ``agents.list(agent_card_metadata=...)`` -- see
+    # ``agentex.lib.utils.metadata_filters.encode_metadata_filter``.
+    metadata: dict[str, Any] = Field(default_factory=dict)
 
     @classmethod
     def from_states(
@@ -40,6 +45,7 @@ def from_states(
         output_event_model: type[BaseModel] | None = None,
         extra_input_types: list[str] | None = None,
         queries: list[str] | None = None,
+        metadata: dict[str, Any] | None = None,
     ) -> AgentCard:
         """Build an AgentCard directly from a list[State] + initial_state.
 
@@ -81,6 +87,7 @@ def from_states(
             data_events=data_events,
             input_types=sorted(derived_input_types | set(extra_input_types or [])),
             output_schema=output_schema,
+            metadata=metadata or {},
         )
 
     @classmethod
@@ -90,6 +97,7 @@ def from_state_machine(
         output_event_model: type[BaseModel] | None = None,
         extra_input_types: list[str] | None = None,
         queries: list[str] | None = None,
+        metadata: dict[str, Any] | None = None,
     ) -> AgentCard:
         """Build an AgentCard from a StateMachine instance. Delegates to from_states()."""
         lifecycle = state_machine.get_lifecycle()
@@ -125,6 +133,7 @@ def from_state_machine(
             data_events=data_events,
             input_types=sorted(derived_input_types | set(extra_input_types or [])),
             output_schema=output_schema,
+            metadata=metadata or {},
         )
 
 

src/agentex/lib/utils/metadata_filters.py

@@ -0,0 +1,53 @@
+"""Helpers for the platform's JSON-encoded metadata filter query parameters.
+
+The containment filters on ``agents.list(agent_card_metadata=...)`` and
+``tasks.list(task_metadata=...)`` carry their filter as a JSON-encoded object
+inside a single query string value, so the generated clients type them as
+``str``. Encoding by hand is easy to get subtly wrong -- Python's ``json``
+happily emits ``NaN``/``Infinity``, which the server rejects with a 400 -- so
+these helpers do it once, here, in the hand-written layer where they survive
+SDK regeneration.
+
+    from agentex.lib.utils.metadata_filters import encode_metadata_filter
+
+    client.agents.list(
+        agent_card_metadata=encode_metadata_filter({"permits_capable": True}),
+    )
+"""
+
+from __future__ import annotations
+
+import json
+from typing import Any, Mapping
+
+__all__ = ["encode_metadata_filter"]
+
+
+def encode_metadata_filter(metadata: Mapping[str, Any]) -> str:
+    """Encode a metadata filter mapping into the wire form the platform expects.
+
+    Args:
+        metadata: The key/value pairs the target's metadata object must contain.
+            Values may be any JSON type; matching is exact containment, so
+            ``{"permits_capable": True}`` matches a stored JSON ``true`` but not
+            the string ``"true"``. An empty mapping matches any target that has
+            a metadata object at all.
+
+    Returns:
+        A compact JSON object string, with keys sorted so the same filter always
+        produces the same query value.
+
+    Raises:
+        TypeError: If ``metadata`` is not a mapping, or contains a value that
+            isn't JSON-serializable.
+        ValueError: If a value is a non-finite float. ``NaN`` and ``Infinity``
+            aren't valid JSON and the server rejects them with a 400, so fail
+            here with a clearer message instead.
+    """
+    if not isinstance(metadata, Mapping):
+        raise TypeError(f"metadata must be a mapping, got {type(metadata).__name__}")
+
+    try:
+        return json.dumps(metadata, allow_nan=False, separators=(",", ":"), sort_keys=True)
+    except ValueError as exc:
+        raise ValueError(f"metadata filter is not encodable as JSON: {exc}") from exc

src/agentex/resources/agents/agents.py

@@ -116,6 +116,7 @@ def retrieve(
     def list(
         self,
         *,
+        agent_card_metadata: Optional[str] | Omit = omit,
         limit: int | Omit = omit,
         order_by: Optional[str] | Omit = omit,
         order_direction: str | Omit = omit,
@@ -132,6 +133,10 @@ def list(
         List all registered agents, optionally filtered by query parameters.
 
         Args:
+          agent_card_metadata: JSON-encoded object used to filter agents on
+              `registration_metadata.agent_card.metadata` via JSONB containment. Example:
+              {"permits_capable": true}.
+
           limit: Limit
 
           order_by: Field to order by
@@ -159,6 +164,7 @@ def list(
                 timeout=timeout,
                 query=maybe_transform(
                     {
+                        "agent_card_metadata": agent_card_metadata,
                         "limit": limit,
                         "order_by": order_by,
                         "order_direction": order_direction,
@@ -777,6 +783,7 @@ async def retrieve(
     async def list(
         self,
         *,
+        agent_card_metadata: Optional[str] | Omit = omit,
         limit: int | Omit = omit,
         order_by: Optional[str] | Omit = omit,
         order_direction: str | Omit = omit,
@@ -793,6 +800,10 @@ async def list(
         List all registered agents, optionally filtered by query parameters.
 
         Args:
+          agent_card_metadata: JSON-encoded object used to filter agents on
+              `registration_metadata.agent_card.metadata` via JSONB containment. Example:
+              {"permits_capable": true}.
+
           limit: Limit
 
           order_by: Field to order by
@@ -820,6 +831,7 @@ async def list(
                 timeout=timeout,
                 query=await async_maybe_transform(
                     {
+                        "agent_card_metadata": agent_card_metadata,
                         "limit": limit,
                         "order_by": order_by,
                         "order_direction": order_direction,

src/agentex/types/agent_list_params.py

@@ -9,6 +9,13 @@
 
 
 class AgentListParams(TypedDict, total=False):
+    agent_card_metadata: Optional[str]
+    """
+    JSON-encoded object used to filter agents on
+    `registration_metadata.agent_card.metadata` via JSONB containment. Example:
+    {"permits_capable": true}.
+    """
+
     limit: int
     """Limit"""
 

tests/api_resources/test_agents.py

@@ -75,6 +75,7 @@ def test_method_list(self, client: Agentex) -> None:
     @parametrize
     def test_method_list_with_all_params(self, client: Agentex) -> None:
         agent = client.agents.list(
+            agent_card_metadata="agent_card_metadata",
             limit=1,
             order_by="order_by",
             order_direction="order_direction",
@@ -469,6 +470,7 @@ async def test_method_list(self, async_client: AsyncAgentex) -> None:
     @parametrize
     async def test_method_list_with_all_params(self, async_client: AsyncAgentex) -> None:
         agent = await async_client.agents.list(
+            agent_card_metadata="agent_card_metadata",
             limit=1,
             order_by="order_by",
             order_direction="order_direction",

tests/lib/test_agent_card.py

@@ -189,13 +189,42 @@ def test_defaults(self):
         assert card.data_events == []
         assert card.input_types == []
         assert card.output_schema is None
+        assert card.metadata == {}
 
     def test_serialization_roundtrip(self):
         card = AgentCard(input_types=["text"], data_events=["result"])
         dumped = card.model_dump()
         restored = AgentCard.model_validate(dumped)
         assert restored == card
 
+    def test_metadata_accepts_arbitrary_json_object(self):
+        card = AgentCard(
+            metadata={
+                "permits_capable": True,
+                "supported_workflows": ["submit", "review"],
+                "limits": {"max_batch": 5},
+            }
+        )
+        assert card.metadata == {
+            "permits_capable": True,
+            "supported_workflows": ["submit", "review"],
+            "limits": {"max_batch": 5},
+        }
+
+    def test_metadata_serialization_roundtrip(self):
+        card = AgentCard(metadata={"permits_capable": True})
+        dumped = card.model_dump()
+        assert dumped["metadata"] == {"permits_capable": True}
+        restored = AgentCard.model_validate(dumped)
+        assert restored == card
+
+    def test_metadata_default_instances_are_independent(self):
+        """Each default metadata is its own dict, not a shared class-level object."""
+        card_a = AgentCard()
+        card_b = AgentCard()
+        card_a.metadata["mutated"] = True
+        assert card_b.metadata == {}
+
 
 # --- AgentCard.from_states ---
 
@@ -247,6 +276,14 @@ def test_state_fields(self, sample_states):
         assert waiting.accepts == ["text", "doc_upload"]
         assert waiting.transitions == ["processing"]
 
+    def test_metadata_forwarded(self, sample_states):
+        card = AgentCard.from_states(
+            initial_state=SampleState.WAITING,
+            states=sample_states,
+            metadata={"permits_capable": True},
+        )
+        assert card.metadata == {"permits_capable": True}
+
     def test_matches_from_state_machine(self, sample_states, sample_sm):
         """from_states and from_state_machine should produce identical cards."""
         card_states = AgentCard.from_states(
@@ -315,6 +352,13 @@ def test_no_output_model(self, sample_sm):
         assert card.data_events == []
         assert card.output_schema is None
 
+    def test_metadata_forwarded(self, sample_sm):
+        card = AgentCard.from_state_machine(
+            state_machine=sample_sm,
+            metadata={"permits_capable": True},
+        )
+        assert card.metadata == {"permits_capable": True}
+
 
 # --- register_agent agent_card merging ---
 
@@ -370,6 +414,20 @@ async def test_agent_card_merged_into_metadata(self, mock_env_vars):
             assert metadata["agent_card"]["input_types"] == ["text"]
             assert metadata["agent_card"]["data_events"] == ["result"]
 
+    async def test_agent_card_metadata_propagates_through_registration(self, mock_env_vars):
+        card = AgentCard(metadata={"permits_capable": True})
+        mock_client = self._make_mock_client()
+
+        with patch("agentex.lib.utils.registration.httpx.AsyncClient", return_value=mock_client):
+            from agentex.lib.utils.registration import register_agent
+
+            await register_agent(mock_env_vars, agent_card=card)
+
+            sent_data = mock_client.post.call_args.kwargs["json"]
+            metadata = sent_data["registration_metadata"]
+
+            assert metadata["agent_card"]["metadata"] == {"permits_capable": True}
+
     async def test_none_preserved_when_no_card(self, mock_env_vars):
         mock_client = self._make_mock_client()
 

tests/lib/test_metadata_filters.py

@@ -0,0 +1,112 @@
+from __future__ import annotations
+
+import json
+
+import httpx
+import respx
+import pytest
+
+from agentex import Agentex, AsyncAgentex
+from agentex.lib.utils.metadata_filters import encode_metadata_filter
+
+BASE_URL = "http://127.0.0.1:4010"
+API_KEY = "My API Key"
+
+
+class TestEncodeMetadataFilter:
+    def test_encodes_a_json_object(self) -> None:
+        assert encode_metadata_filter({"permits_capable": True}) == '{"permits_capable":true}'
+
+    def test_empty_mapping_encodes_to_an_empty_object(self) -> None:
+        assert encode_metadata_filter({}) == "{}"
+
+    def test_key_order_is_stable(self) -> None:
+        assert (
+            encode_metadata_filter({"region": "us", "permits_capable": True})
+            == encode_metadata_filter({"permits_capable": True, "region": "us"})
+            == '{"permits_capable":true,"region":"us"}'
+        )
+
+    def test_preserves_json_types_and_nesting(self) -> None:
+        encoded = encode_metadata_filter({"flag": True, "count": 3, "ratio": 1.5, "nested": {"a": [1, "two", None]}})
+        assert json.loads(encoded) == {
+            "flag": True,
+            "count": 3,
+            "ratio": 1.5,
+            "nested": {"a": [1, "two", None]},
+        }
+
+    @pytest.mark.parametrize("value", [float("nan"), float("inf"), float("-inf")])
+    def test_rejects_non_finite_floats(self, value: float) -> None:
+        # The server rejects these with a 400; fail locally with a clearer message.
+        with pytest.raises(ValueError, match="not encodable as JSON"):
+            encode_metadata_filter({"x": value})
+
+    def test_rejects_a_non_mapping(self) -> None:
+        with pytest.raises(TypeError, match="must be a mapping"):
+            encode_metadata_filter([("permits_capable", True)])  # type: ignore[arg-type]
+
+    def test_rejects_a_non_serializable_value(self) -> None:
+        with pytest.raises(TypeError):
+            encode_metadata_filter({"x": object()})
+
+
+class TestAgentCardMetadataOnTheWire:
+    """The encoded filter has to survive the client's query-string serialization.
+
+    The generated `agents.list` parameter is a plain `str` (the platform spec
+    declares a JSON-encoded string, matching the shipped `task_metadata`
+    filter), so these assert the exact query value the server will parse.
+    """
+
+    @respx.mock(base_url=BASE_URL)
+    def test_sync_client_sends_the_encoded_object(self, respx_mock: respx.MockRouter) -> None:
+        route = respx_mock.get("/agents").mock(return_value=httpx.Response(200, json=[]))
+
+        with Agentex(base_url=BASE_URL, api_key=API_KEY, _strict_response_validation=True) as client:
+            client.agents.list(
+                agent_card_metadata=encode_metadata_filter({"permits_capable": True, "region": "us"}),
+                limit=5,
+            )
+
+        params = route.calls.last.request.url.params
+        raw = params["agent_card_metadata"]
+        assert raw == '{"permits_capable":true,"region":"us"}'
+        assert json.loads(raw) == {"permits_capable": True, "region": "us"}
+        assert params["limit"] == "5"
+
+    @respx.mock(base_url=BASE_URL)
+    async def test_async_client_sends_the_encoded_object(self, respx_mock: respx.MockRouter) -> None:
+        route = respx_mock.get("/agents").mock(return_value=httpx.Response(200, json=[]))
+
+        async with AsyncAgentex(base_url=BASE_URL, api_key=API_KEY, _strict_response_validation=True) as client:
+            await client.agents.list(
+                agent_card_metadata=encode_metadata_filter({"permits_capable": True, "region": "us"}),
+                limit=5,
+            )
+
+        params = route.calls.last.request.url.params
+        raw = params["agent_card_metadata"]
+        assert raw == '{"permits_capable":true,"region":"us"}'
+        assert json.loads(raw) == {"permits_capable": True, "region": "us"}
+        assert params["limit"] == "5"
+
+    @respx.mock(base_url=BASE_URL)
+    def test_omitted_filter_is_absent_from_the_query(self, respx_mock: respx.MockRouter) -> None:
+        route = respx_mock.get("/agents").mock(return_value=httpx.Response(200, json=[]))
+
+        with Agentex(base_url=BASE_URL, api_key=API_KEY, _strict_response_validation=True) as client:
+            client.agents.list()
+
+        assert "agent_card_metadata" not in route.calls.last.request.url.params
+
+    @respx.mock(base_url=BASE_URL)
+    def test_empty_object_filter_is_sent_verbatim(self, respx_mock: respx.MockRouter) -> None:
+        """`{}` is a meaningful filter server-side (agent must have card metadata),
+        so it must reach the wire rather than being dropped as falsy."""
+        route = respx_mock.get("/agents").mock(return_value=httpx.Response(200, json=[]))
+
+        with Agentex(base_url=BASE_URL, api_key=API_KEY, _strict_response_validation=True) as client:
+            client.agents.list(agent_card_metadata=encode_metadata_filter({}))
+
+        assert route.calls.last.request.url.params["agent_card_metadata"] == "{}"