fix(gamma): omit legacy non-binary market listings

src/polymarket/_internal/actions/gamma.py

@@ -38,6 +38,7 @@
     TagReference,
     Team,
 )
+from polymarket.models.gamma.common import parse_string_sequence
 
 CommentParentEntityType = Literal["Event", "Series"]
 TagMatch = Literal["any", "all"]
@@ -48,7 +49,7 @@
 
 def _make_keyset_parser(
     items_key: str,
-    parse_item: Callable[[object], _T],
+    parse_item: Callable[[object], _T | None],
 ) -> Callable[[object], KeysetPagePayload[_T]]:
     def parse(data: object) -> KeysetPagePayload[_T]:
         if not isinstance(data, dict):
@@ -63,7 +64,11 @@ def parse(data: object) -> KeysetPagePayload[_T]:
         if not isinstance(raw, list):
             raise UnexpectedResponseError(f"Expected '{items_key}' to be an array.")
         items_list = cast(list[Any], raw)
-        items = tuple(parse_item(item) for item in items_list)
+        items: list[_T] = []
+        for item in items_list:
+            parsed = parse_item(item)
+            if parsed is not None:
+                items.append(parsed)
 
         if "next_cursor" not in data_dict:
             server_cursor: str | None = None
@@ -82,11 +87,27 @@ def parse(data: object) -> KeysetPagePayload[_T]:
                     f"'next_cursor' must be a string when present, got {type(nc).__name__}."
                 )
 
-        return KeysetPagePayload(items=items, server_next_cursor=server_cursor)
+        return KeysetPagePayload(items=tuple(items), server_next_cursor=server_cursor)
 
     return parse
 
 
+def _parse_list_market(item: object) -> Market | None:
+    if not isinstance(item, dict):
+        return Market.parse_response(item)
+
+    item_dict = cast(dict[str, Any], item)
+    try:
+        outcomes = parse_string_sequence(item_dict.get("outcomes"))
+    except ValueError as error:
+        raise UnexpectedResponseError("Market response did not match expected shape") from error
+
+    if len(outcomes) != 2:
+        return None
+
+    return Market.parse_response(item_dict)
+
+
 def _add_optional(
     params: dict[str, QueryParamValue],
     key: str,
@@ -523,7 +544,7 @@ def list_markets_spec(
     return KeysetPaginatedSpec(
         service="gamma",
         path="/markets/keyset",
-        parse_page=_make_keyset_parser("markets", Market.parse_response),
+        parse_page=_make_keyset_parser("markets", _parse_list_market),
         base_params=params or None,
     )
 

src/polymarket/clients/async_public.py

@@ -306,7 +306,11 @@ async def get_market(
         include_tag: bool | None = None,
         locale: str | None = None,
     ) -> Market:
-        """Get a market by id, slug, or Polymarket URL."""
+        """Get a market by id, slug, or Polymarket URL.
+
+        Markets that cannot be represented by the binary Market model raise
+        UnexpectedResponseError.
+        """
         return await async_dispatch(
             self._ctx,
             _gamma_actions.get_market_spec(
@@ -858,6 +862,9 @@ def list_markets(
     ) -> AsyncPaginator[Market]:
         """List markets.
 
+        Markets that cannot be represented by the binary Market model are
+        omitted from results.
+
         Returns:
             An async paginator over matching markets.
 

src/polymarket/clients/async_secure.py

@@ -740,7 +740,11 @@ async def get_market(
         include_tag: bool | None = None,
         locale: str | None = None,
     ) -> Market:
-        """Get a market by id, slug, or Polymarket URL."""
+        """Get a market by id, slug, or Polymarket URL.
+
+        Markets that cannot be represented by the binary Market model raise
+        UnexpectedResponseError.
+        """
         return await async_dispatch(
             self._ctx,
             _gamma_actions.get_market_spec(
@@ -1292,6 +1296,9 @@ def list_markets(
     ) -> AsyncPaginator[Market]:
         """List markets.
 
+        Markets that cannot be represented by the binary Market model are
+        omitted from results.
+
         Returns:
             An async paginator over matching markets.
         """
@@ -2338,6 +2345,8 @@ async def _resolve_market_position_context(
                 ids=[parse_market_id(market_id)], page_size=1
             ).first_page()
         markets = page.items
+        if not markets:
+            raise UserInputError(f"No market found for {context}")
         if len(markets) != 1:
             raise UserInputError(f"Expected exactly one market for {context}, got {len(markets)}")
         return normalize_market_position_context(

src/polymarket/clients/public.py

@@ -151,7 +151,11 @@ def get_market(
         include_tag: bool | None = None,
         locale: str | None = None,
     ) -> Market:
-        """Get a market."""
+        """Get a market.
+
+        Markets that cannot be represented by the binary Market model raise
+        UnexpectedResponseError.
+        """
         return sync_dispatch(
             self._ctx,
             _gamma_actions.get_market_spec(
@@ -707,6 +711,9 @@ def list_markets(
     ) -> Paginator[Market]:
         """List markets.
 
+        Markets that cannot be represented by the binary Market model are
+        omitted from results.
+
         Returns:
             A paginator over matching markets.
 

src/polymarket/clients/secure.py

@@ -473,7 +473,11 @@ def get_market(
         include_tag: bool | None = None,
         locale: str | None = None,
     ) -> Market:
-        """Get a market by id, slug, or Polymarket URL."""
+        """Get a market by id, slug, or Polymarket URL.
+
+        Markets that cannot be represented by the binary Market model raise
+        UnexpectedResponseError.
+        """
         return sync_dispatch(
             self._ctx,
             _gamma_actions.get_market_spec(
@@ -1025,6 +1029,9 @@ def list_markets(
     ) -> Paginator[Market]:
         """List markets.
 
+        Markets that cannot be represented by the binary Market model are
+        omitted from results.
+
         Returns:
             A paginator over matching markets.
         """
@@ -2291,6 +2298,8 @@ def _resolve_market_position_context(
             context = f"market {market_id}"
             page = self.list_markets(ids=[parse_market_id(market_id)], page_size=1).first_page()
         markets = page.items
+        if not markets:
+            raise UserInputError(f"No market found for {context}")
         if len(markets) != 1:
             raise UserInputError(f"Expected exactly one market for {context}, got {len(markets)}")
         return normalize_market_position_context(

tests/integration/test_gamma_paginated.py

@@ -62,6 +62,16 @@ def test_list_markets_returns_paginator() -> None:
         assert all(isinstance(market, Market) for market in first.items)
 
 
+@pytest.mark.integration
+def test_list_closed_markets_omits_legacy_multi_outcome_markets() -> None:
+    with PublicClient() as client:
+        first = client.list_markets(closed=True, page_size=100).first_page()
+
+        assert first.items
+        assert all(isinstance(market, Market) for market in first.items)
+        assert all(market.outcomes.yes.label and market.outcomes.no.label for market in first.items)
+
+
 @pytest.mark.integration
 def test_async_list_markets_returns_paginator() -> None:
     async def run() -> None:

tests/integration/test_markets.py

@@ -3,9 +3,11 @@
 import pytest
 
 from polymarket import AsyncPublicClient, Market, PublicClient, TagReference
+from polymarket.errors import UnexpectedResponseError
 
 MARKET_ID = "540816"
 MARKET_SLUG = "russia-ukraine-ceasefire-before-gta-vi-554"
+LEGACY_MULTI_OUTCOME_MARKET_SLUG = "who-will-the-world-s-richest-person-be-on-february-27-2021"
 
 
 @pytest.mark.integration
@@ -44,6 +46,12 @@ def test_get_market_by_url_returns_canonical_market() -> None:
         assert market.outcomes.no.label
 
 
+@pytest.mark.integration
+def test_get_market_rejects_legacy_multi_outcome_market_with_typed_error() -> None:
+    with PublicClient() as client, pytest.raises(UnexpectedResponseError):
+        client.get_market(slug=LEGACY_MULTI_OUTCOME_MARKET_SLUG)
+
+
 @pytest.mark.integration
 def test_get_market_tags_returns_tags() -> None:
     with PublicClient() as client:

tests/unit/test_gamma_paginated_specs.py

@@ -6,7 +6,20 @@
     OffsetPaginatedSpec,
     PageBasedSpec,
 )
-from polymarket.errors import UserInputError
+from polymarket.errors import UnexpectedResponseError, UserInputError
+
+
+def _minimal_market_payload(**overrides: object) -> dict[str, object]:
+    payload: dict[str, object] = {
+        "id": "MARKET-1",
+        "outcomes": ["Yes", "No"],
+        "outcomePrices": ["0.6", "0.4"],
+        "clobTokenIds": ["TOKEN-YES", "TOKEN-NO"],
+        "positionIds": ["POSITION-YES", "POSITION-NO"],
+        "marketMakerAddress": "0xMM",
+    }
+    payload.update(overrides)
+    return payload
 
 
 def test_list_events_spec_defaults_to_open_events() -> None:
@@ -72,6 +85,39 @@ def test_list_markets_spec_collects_array_params() -> None:
     }
 
 
+def test_list_markets_parser_skips_non_binary_markets_and_keeps_cursor() -> None:
+    spec = gamma_actions.list_markets_spec()
+
+    payload = spec.parse_page(
+        {
+            "markets": [
+                _minimal_market_payload(id="MARKET-1"),
+                _minimal_market_payload(
+                    id="MARKET-2",
+                    outcomes=["Jeff Bezos", "Elon Musk", "Other"],
+                ),
+            ],
+            "next_cursor": "cursor-1",
+        }
+    )
+
+    assert [market.id for market in payload.items] == ["MARKET-1"]
+    assert payload.server_next_cursor == "cursor-1"
+
+
+def test_list_markets_parser_rejects_malformed_outcomes() -> None:
+    spec = gamma_actions.list_markets_spec()
+
+    with pytest.raises(UnexpectedResponseError, match="Market response"):
+        spec.parse_page(
+            {
+                "markets": [
+                    _minimal_market_payload(outcomes=["Yes", 1]),
+                ]
+            }
+        )
+
+
 def test_list_series_spec_default_has_no_params() -> None:
     spec = gamma_actions.list_series_spec()
 

tests/unit/test_relayer_split_position.py

@@ -115,7 +115,7 @@ async def run() -> None:
         client = await make_deposit_client()
         client.list_markets = lambda **_: _StubPaginator(())  # type: ignore[method-assign]
         try:
-            with pytest.raises(UserInputError, match="exactly one market"):
+            with pytest.raises(UserInputError, match="No market found"):
                 await client.split_position(condition_id=_CONDITION_ID, amount=1)
         finally:
             await client.close()