diff --git a/kalshi/_contract_map.py b/kalshi/_contract_map.py
index 635c940..4514658 100644
--- a/kalshi/_contract_map.py
+++ b/kalshi/_contract_map.py
@@ -625,6 +625,14 @@ class ContractEntry:
         sdk_model="kalshi.perps.models.markets.PriceDistributionHistorical",
         spec_schema="PriceDistributionHistorical",
     ),
+    ContractEntry(
+        sdk_model="kalshi.perps.models.markets.GetMarginMarketsResponse",
+        spec_schema="GetMarginMarketsResponse",
+    ),
+    ContractEntry(
+        sdk_model="kalshi.perps.models.markets.GetMarginMarketCandlesticksResponse",
+        spec_schema="GetMarginMarketCandlesticksResponse",
+    ),
     # ── perps orders (#391) ──
     ContractEntry(
         sdk_model="kalshi.perps.models.orders.CreateMarginOrderResponse",
@@ -727,6 +735,14 @@ class ContractEntry:
         sdk_model="kalshi.perps.models.funding.MarginFundingRateEstimate",
         spec_schema="GetMarginFundingRateEstimateResponse",
     ),
+    ContractEntry(
+        sdk_model="kalshi.perps.models.funding.GetMarginHistoricalFundingRatesResponse",
+        spec_schema="GetMarginHistoricalFundingRatesResponse",
+    ),
+    ContractEntry(
+        sdk_model="kalshi.perps.models.funding.GetMarginFundingHistoryResponse",
+        spec_schema="GetMarginFundingHistoryResponse",
+    ),
     # ── perps transfers (#396) ──
     ContractEntry(
         sdk_model="kalshi.perps.models.transfers.IntraExchangeInstanceTransferResponse",
diff --git a/kalshi/perps/models/funding.py b/kalshi/perps/models/funding.py
index 9016dad..e2c947c 100644
--- a/kalshi/perps/models/funding.py
+++ b/kalshi/perps/models/funding.py
@@ -27,6 +27,8 @@
 
 from __future__ import annotations
 
+import builtins
+
 from pydantic import AliasChoices, AwareDatetime, BaseModel, Field
 
 from kalshi.types import DollarDecimal, FixedPointCount, MultiplierDecimal
@@ -97,3 +99,26 @@ class MarginFundingRateEstimate(BaseModel):
         validation_alias=AliasChoices("mark_price_dollars", "mark_price"),
     )
     next_funding_time: AwareDatetime
+
+
+class GetMarginHistoricalFundingRatesResponse(BaseModel):
+    """Spec ``GetMarginHistoricalFundingRatesResponse`` — historical-rates envelope.
+
+    ``funding_rates`` is spec-required; modeled non-optional so a missing/``null``
+    array hard-fails rather than being silently coerced to ``[]``.
+    """
+
+    funding_rates: builtins.list[MarginFundingRate]
+
+    model_config = {"extra": "allow"}
+
+
+class GetMarginFundingHistoryResponse(BaseModel):
+    """Spec ``GetMarginFundingHistoryResponse`` — funding-payment-history envelope.
+
+    ``funding_history`` is spec-required; modeled non-optional (see above).
+    """
+
+    funding_history: builtins.list[MarginFundingHistoryEntry]
+
+    model_config = {"extra": "allow"}
diff --git a/kalshi/perps/models/markets.py b/kalshi/perps/models/markets.py
index 7278977..e7d6a15 100644
--- a/kalshi/perps/models/markets.py
+++ b/kalshi/perps/models/markets.py
@@ -16,6 +16,7 @@
 
 from __future__ import annotations
 
+import builtins
 from typing import Literal
 
 from pydantic import AliasChoices, BaseModel, Field
@@ -161,3 +162,30 @@ class MarginMarketCandlestick(BaseModel):
     )
 
     model_config = {"extra": "allow", "populate_by_name": True}
+
+
+class GetMarginMarketsResponse(BaseModel):
+    """Spec ``GetMarginMarketsResponse`` — the ``GET /margin/markets`` envelope.
+
+    ``markets`` is spec-required, so it is modeled non-optional: a missing or
+    ``null`` array surfaces as a ``ValidationError`` rather than being silently
+    coerced to ``[]`` (which would mask server-side spec drift).
+    """
+
+    markets: builtins.list[MarginMarket]
+
+    model_config = {"extra": "allow"}
+
+
+class GetMarginMarketCandlesticksResponse(BaseModel):
+    """Spec ``GetMarginMarketCandlesticksResponse`` — the candlesticks envelope.
+
+    Both ``ticker`` and ``candlesticks`` are spec-required; validating the
+    envelope keeps the required ``ticker`` from being silently dropped and
+    hard-fails on a missing/``null`` ``candlesticks`` array.
+    """
+
+    ticker: str
+    candlesticks: builtins.list[MarginMarketCandlestick]
+
+    model_config = {"extra": "allow"}
diff --git a/kalshi/perps/resources/funding.py b/kalshi/perps/resources/funding.py
index 3d334fe..4913db1 100644
--- a/kalshi/perps/resources/funding.py
+++ b/kalshi/perps/resources/funding.py
@@ -19,6 +19,8 @@
 from typing import Any
 
 from kalshi.perps.models.funding import (
+    GetMarginFundingHistoryResponse,
+    GetMarginHistoricalFundingRatesResponse,
     MarginFundingHistoryEntry,
     MarginFundingRate,
     MarginFundingRateEstimate,
@@ -77,7 +79,7 @@ def historical_rates(
         data = self._get(
             "/margin/funding_rates/historical", params=params, extra_headers=extra_headers
         )
-        return [MarginFundingRate.model_validate(r) for r in data.get("funding_rates", [])]
+        return GetMarginHistoricalFundingRatesResponse.model_validate(data).funding_rates
 
     def history(
         self,
@@ -96,9 +98,7 @@ def history(
             subaccount=subaccount,
         )
         data = self._get("/margin/funding_history", params=params, extra_headers=extra_headers)
-        return [
-            MarginFundingHistoryEntry.model_validate(e) for e in data.get("funding_history", [])
-        ]
+        return GetMarginFundingHistoryResponse.model_validate(data).funding_history
 
 
 class AsyncFundingResource(AsyncResource):
@@ -126,7 +126,7 @@ async def historical_rates(
         data = await self._get(
             "/margin/funding_rates/historical", params=params, extra_headers=extra_headers
         )
-        return [MarginFundingRate.model_validate(r) for r in data.get("funding_rates", [])]
+        return GetMarginHistoricalFundingRatesResponse.model_validate(data).funding_rates
 
     async def history(
         self,
@@ -147,6 +147,4 @@ async def history(
         data = await self._get(
             "/margin/funding_history", params=params, extra_headers=extra_headers
         )
-        return [
-            MarginFundingHistoryEntry.model_validate(e) for e in data.get("funding_history", [])
-        ]
+        return GetMarginFundingHistoryResponse.model_validate(data).funding_history
diff --git a/kalshi/perps/resources/markets.py b/kalshi/perps/resources/markets.py
index bef3856..787e318 100644
--- a/kalshi/perps/resources/markets.py
+++ b/kalshi/perps/resources/markets.py
@@ -16,6 +16,8 @@
 from typing import Any
 
 from kalshi.perps.models.markets import (
+    GetMarginMarketCandlesticksResponse,
+    GetMarginMarketsResponse,
     MarginMarket,
     MarginMarketCandlestick,
     MarginMarketStatusLiteral,
@@ -67,8 +69,7 @@ def list(
         """
         params = _params(status=status)
         data = self._get("/margin/markets", params=params, extra_headers=extra_headers)
-        raw = data.get("markets") or []
-        return [MarginMarket.model_validate(m) for m in raw]
+        return GetMarginMarketsResponse.model_validate(data).markets
 
     def get(self, ticker: str, *, extra_headers: dict[str, str] | None = None) -> MarginMarket:
         data = self._get(
@@ -114,8 +115,7 @@ def candlesticks(
             params=params,
             extra_headers=extra_headers,
         )
-        raw = data.get("candlesticks") or []
-        return [MarginMarketCandlestick.model_validate(c) for c in raw]
+        return GetMarginMarketCandlesticksResponse.model_validate(data).candlesticks
 
 
 class AsyncPerpsMarketsResource(AsyncResource):
@@ -134,8 +134,7 @@ async def list(
         """
         params = _params(status=status)
         data = await self._get("/margin/markets", params=params, extra_headers=extra_headers)
-        raw = data.get("markets") or []
-        return [MarginMarket.model_validate(m) for m in raw]
+        return GetMarginMarketsResponse.model_validate(data).markets
 
     async def get(
         self, ticker: str, *, extra_headers: dict[str, str] | None = None
@@ -183,5 +182,4 @@ async def candlesticks(
             params=params,
             extra_headers=extra_headers,
         )
-        raw = data.get("candlesticks") or []
-        return [MarginMarketCandlestick.model_validate(c) for c in raw]
+        return GetMarginMarketCandlesticksResponse.model_validate(data).candlesticks
diff --git a/kalshi/perps/resources/order_groups.py b/kalshi/perps/resources/order_groups.py
index 537a873..f0e5a07 100644
--- a/kalshi/perps/resources/order_groups.py
+++ b/kalshi/perps/resources/order_groups.py
@@ -83,7 +83,9 @@ def list(
         self._require_auth()
         params = _params(subaccount=subaccount)
         data = self._get("/margin/order_groups", params=params, extra_headers=extra_headers)
-        raw = data.get("order_groups", [])
+        # order_groups is OPTIONAL per spec (no `required` block), so stay
+        # tolerant of a missing OR null array — `or []` covers both (#404).
+        raw = data.get("order_groups") or []
         return [OrderGroup.model_validate(item) for item in raw]
 
     def get(
@@ -236,7 +238,9 @@ async def list(
         self._require_auth()
         params = _params(subaccount=subaccount)
         data = await self._get("/margin/order_groups", params=params, extra_headers=extra_headers)
-        raw = data.get("order_groups", [])
+        # order_groups is OPTIONAL per spec (no `required` block), so stay
+        # tolerant of a missing OR null array — `or []` covers both (#404).
+        raw = data.get("order_groups") or []
         return [OrderGroup.model_validate(item) for item in raw]
 
     async def get(
diff --git a/tests/perps/test_funding.py b/tests/perps/test_funding.py
index 0e00b0a..5d0b0f7 100644
--- a/tests/perps/test_funding.py
+++ b/tests/perps/test_funding.py
@@ -167,11 +167,15 @@ def test_edge_empty_array(self, perps_client: PerpsClient) -> None:
         assert perps_client.funding.historical_rates() == []
 
     @respx.mock
-    def test_edge_missing_key(self, perps_client: PerpsClient) -> None:
-        respx.get(f"{BASE}/margin/funding_rates/historical").mock(
-            return_value=httpx.Response(200, json={})
-        )
-        assert perps_client.funding.historical_rates() == []
+    def test_edge_missing_or_null_key_raises(self, perps_client: PerpsClient) -> None:
+        # #404: `funding_rates` is spec-required — missing/null hard-fails.
+        route = respx.get(f"{BASE}/margin/funding_rates/historical")
+        route.mock(return_value=httpx.Response(200, json={}))
+        with pytest.raises(ValidationError):
+            perps_client.funding.historical_rates()
+        route.mock(return_value=httpx.Response(200, json={"funding_rates": None}))
+        with pytest.raises(ValidationError):
+            perps_client.funding.historical_rates()
 
     @respx.mock
     def test_error_500_maps(self, perps_client: PerpsClient) -> None:
@@ -220,6 +224,15 @@ def _entry(*, funding_amount: str, subaccount_number: int | None) -> dict[str, o
 
 
 class TestHistory:
+    @respx.mock
+    def test_missing_or_null_funding_history_raises(self, perps_client: PerpsClient) -> None:
+        # #404: funding_history is spec-required — missing/null hard-fails.
+        route = respx.get(f"{BASE}/margin/funding_history")
+        for payload in ({}, {"funding_history": None}):
+            route.mock(return_value=httpx.Response(200, json=payload))
+            with pytest.raises(ValidationError):
+                perps_client.funding.history(start_date="2026-06-01", end_date="2026-06-04")
+
     @respx.mock
     def test_happy(self, perps_client: PerpsClient) -> None:
         route = respx.get(f"{BASE}/margin/funding_history").mock(
diff --git a/tests/perps/test_markets.py b/tests/perps/test_markets.py
index eed7363..ac63039 100644
--- a/tests/perps/test_markets.py
+++ b/tests/perps/test_markets.py
@@ -12,6 +12,7 @@
 import httpx
 import pytest
 import respx
+from pydantic import ValidationError
 
 from kalshi.errors import KalshiNotFoundError, KalshiServerError
 from kalshi.perps import AsyncPerpsClient, PerpsClient, PerpsConfig
@@ -135,9 +136,16 @@ def test_empty_list(self, perps_client: PerpsClient) -> None:
         assert perps_client.markets.list() == []
 
     @respx.mock
-    def test_missing_markets_key(self, perps_client: PerpsClient) -> None:
-        respx.get(f"{BASE}/margin/markets").mock(return_value=httpx.Response(200, json={}))
-        assert perps_client.markets.list() == []
+    def test_missing_or_null_markets_raises(self, perps_client: PerpsClient) -> None:
+        # #404: `markets` is spec-required — a missing/null array hard-fails
+        # (surfacing drift) instead of being silently coerced to [].
+        route = respx.get(f"{BASE}/margin/markets")
+        route.mock(return_value=httpx.Response(200, json={}))
+        with pytest.raises(ValidationError):
+            perps_client.markets.list()
+        route.mock(return_value=httpx.Response(200, json={"markets": None}))
+        with pytest.raises(ValidationError):
+            perps_client.markets.list()
 
     @respx.mock
     def test_server_error_maps(self, perps_client: PerpsClient) -> None:
@@ -351,6 +359,18 @@ def test_all_null_trade_prices(self, perps_client: PerpsClient) -> None:
         # bid/ask OHLC are still required + present.
         assert c.bid.open == Decimal("0.5500")
 
+    @respx.mock
+    def test_missing_ticker_or_candlesticks_raises(self, perps_client: PerpsClient) -> None:
+        # #404: both `ticker` and `candlesticks` are spec-required on this
+        # response — the envelope validates the previously-discarded `ticker`.
+        route = respx.get(f"{BASE}/margin/markets/BTC-PERP/candlesticks")
+        route.mock(return_value=httpx.Response(200, json={"candlesticks": []}))  # no ticker
+        with pytest.raises(ValidationError):
+            perps_client.markets.candlesticks("BTC-PERP", start_ts=1, end_ts=2, period_interval=1)
+        route.mock(return_value=httpx.Response(200, json={"ticker": "BTC-PERP"}))  # no array
+        with pytest.raises(ValidationError):
+            perps_client.markets.candlesticks("BTC-PERP", start_ts=1, end_ts=2, period_interval=1)
+
     @respx.mock
     def test_required_and_optional_params(self, perps_client: PerpsClient) -> None:
         route = respx.get(f"{BASE}/margin/markets/BTC-PERP/candlesticks").mock(
diff --git a/tests/perps/test_order_groups.py b/tests/perps/test_order_groups.py
index dffed5e..8499c41 100644
--- a/tests/perps/test_order_groups.py
+++ b/tests/perps/test_order_groups.py
@@ -74,10 +74,13 @@ def test_happy(self, perps_client: PerpsClient) -> None:
         assert _signed(route.calls.last.request)
 
     @respx.mock
-    def test_empty_when_absent(self, perps_client: PerpsClient) -> None:
-        respx.get(f"{BASE}/margin/order_groups").mock(
-            return_value=httpx.Response(200, json={})
-        )
+    def test_empty_when_absent_or_null(self, perps_client: PerpsClient) -> None:
+        # #404: order_groups is spec-OPTIONAL, so it stays tolerant — a missing
+        # OR null array yields [] (unlike the spec-required perps list endpoints).
+        route = respx.get(f"{BASE}/margin/order_groups")
+        route.mock(return_value=httpx.Response(200, json={}))
+        assert perps_client.order_groups.list() == []
+        route.mock(return_value=httpx.Response(200, json={"order_groups": None}))
         assert perps_client.order_groups.list() == []
 
     @respx.mock