polish(types): retype count/size/volume fields to FixedPointCount (#90)

CHANGELOG.md

@@ -15,6 +15,19 @@ All notable changes to kalshi-sdk will be documented in this file.
 
 ### Changed
 
+- **Count/size/volume response fields retyped from `DollarDecimal` to
+  `FixedPointCount` (#90).** Fields with `_fp` wire aliases were annotated
+  as `DollarDecimal` — the type that signals "dollar amount." Runtime
+  behavior is unchanged (both validators are byte-identical and parse the
+  same wire strings into `Decimal`), but the annotation now communicates
+  the correct semantics and prevents silent corruption if either parser
+  ever diverges. Affected: `Market.{yes_bid_size, yes_ask_size, no_bid_size,
+  no_ask_size, volume, volume_24h, open_interest}`, `Candlestick.{volume,
+  open_interest}`, `OrderbookLevel.quantity`, `Fill.count`, `Trade.count`,
+  `MarketPosition.position`, `EventPosition.total_cost_shares`,
+  `Settlement.{yes_count, no_count}`, `Series.volume`. Both types resolve
+  to `Decimal` at the type level, so user code that handles these fields
+  as `Decimal` is unaffected.
 - **`*_all()` methods are now unbounded by default.** Previously, internal
   `_list_all` had an invisible 1000-page safety cap that silently truncated
   callers iterating beyond ~100k items. The cap is gone; the cursor-repeat

kalshi/models/historical.py

@@ -7,7 +7,7 @@
 
 from pydantic import AliasChoices, BaseModel, Field
 
-from kalshi.types import DollarDecimal
+from kalshi.types import DollarDecimal, FixedPointCount
 
 # Single-value enum per spec (MveHistoricalFilterQuery). mypy rejects plain
 # `str` here even if it holds "exclude" at runtime — pass the literal directly.
@@ -30,7 +30,7 @@ class Trade(BaseModel):
 
     trade_id: str
     ticker: str | None = None
-    count: DollarDecimal | None = Field(
+    count: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("count_fp", "count"),
     )

kalshi/models/markets.py

@@ -8,7 +8,7 @@
 
 from pydantic import AliasChoices, BaseModel, Field
 
-from kalshi.types import DollarDecimal, NullableList
+from kalshi.types import DollarDecimal, FixedPointCount, NullableList
 
 MarketStatusLiteral = Literal["unopened", "open", "paused", "closed", "settled"]
 """Market status filter for GET /markets. Spec: MarketStatusQuery enum."""
@@ -81,31 +81,31 @@ class Market(BaseModel):
     )
 
     # Size/volume fields (FixedPointCount)
-    yes_bid_size: DollarDecimal | None = Field(
+    yes_bid_size: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("yes_bid_size_fp", "yes_bid_size"),
     )
-    yes_ask_size: DollarDecimal | None = Field(
+    yes_ask_size: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("yes_ask_size_fp", "yes_ask_size"),
     )
-    no_bid_size: DollarDecimal | None = Field(
+    no_bid_size: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("no_bid_size_fp", "no_bid_size"),
     )
-    no_ask_size: DollarDecimal | None = Field(
+    no_ask_size: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("no_ask_size_fp", "no_ask_size"),
     )
-    volume: DollarDecimal | None = Field(
+    volume: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("volume_fp", "volume"),
     )
-    volume_24h: DollarDecimal | None = Field(
+    volume_24h: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("volume_24h_fp", "volume_24h"),
     )
-    open_interest: DollarDecimal | None = Field(
+    open_interest: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("open_interest_fp", "open_interest"),
     )
@@ -141,12 +141,12 @@ class Market(BaseModel):
 class OrderbookLevel(BaseModel):
     """A single price level in the orderbook.
 
-    Quantity is DollarDecimal to support fractional contracts
-    (FixedPointCount strings like ``"100.50"`` from the API).
+    Quantity is FixedPointCount — fractional contract counts are sent as
+    FixedPointCount strings like ``"100.50"`` from the API.
     """
 
     price: DollarDecimal
-    quantity: DollarDecimal
+    quantity: FixedPointCount
 
 
 class Orderbook(BaseModel):
@@ -217,11 +217,11 @@ class Candlestick(BaseModel):
     yes_bid: BidAskDistribution | None = None
     yes_ask: BidAskDistribution | None = None
     price: PriceDistribution | None = None
-    volume: DollarDecimal | None = Field(
+    volume: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("volume_fp", "volume"),
     )
-    open_interest: DollarDecimal | None = Field(
+    open_interest: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("open_interest_fp", "open_interest"),
     )

kalshi/models/orders.py

@@ -115,7 +115,7 @@ class Fill(BaseModel):
     side: str | None = None
     action: str | None = None
     is_taker: bool | None = None
-    count: DollarDecimal | None = Field(
+    count: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("count_fp", "count"),
     )

kalshi/models/portfolio.py

@@ -7,7 +7,7 @@
 
 from pydantic import AliasChoices, BaseModel, Field
 
-from kalshi.types import DollarDecimal, NullableList
+from kalshi.types import DollarDecimal, FixedPointCount, NullableList
 
 SettlementStatusLiteral = Literal["all", "unsettled", "settled"]
 """Position settlement status filter for GET /fcm/positions. Spec: settlement_status query enum."""
@@ -43,7 +43,7 @@ class MarketPosition(BaseModel):
         default=None,
         validation_alias=AliasChoices("total_traded_dollars", "total_traded"),
     )
-    position: DollarDecimal | None = Field(
+    position: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("position_fp", "position"),
     )
@@ -73,7 +73,7 @@ class EventPosition(BaseModel):
         default=None,
         validation_alias=AliasChoices("total_cost_dollars", "total_cost"),
     )
-    total_cost_shares: DollarDecimal | None = Field(
+    total_cost_shares: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("total_cost_shares_fp", "total_cost_shares"),
     )
@@ -113,15 +113,15 @@ class Settlement(BaseModel):
     ticker: str
     event_ticker: str | None = None
     market_result: str | None = None
-    yes_count: DollarDecimal | None = Field(
+    yes_count: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("yes_count_fp", "yes_count"),
     )
     yes_total_cost: DollarDecimal | None = Field(
         default=None,
         validation_alias=AliasChoices("yes_total_cost_dollars", "yes_total_cost"),
     )
-    no_count: DollarDecimal | None = Field(
+    no_count: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("no_count_fp", "no_count"),
     )

kalshi/models/series.py

@@ -8,7 +8,7 @@
 from pydantic import AliasChoices, BaseModel, Field
 
 from kalshi.models.markets import Candlestick
-from kalshi.types import DollarDecimal, NullableList
+from kalshi.types import FixedPointCount, NullableList
 
 # Fee type constants (use str fields, not StrEnum, for forward-compat)
 FEE_TYPE_QUADRATIC = "quadratic"
@@ -31,7 +31,7 @@ class Series(BaseModel):
     fee_type: str = ""
     fee_multiplier: float = 0.0
     additional_prohibitions: NullableList[str] = []
-    volume: DollarDecimal | None = Field(
+    volume: FixedPointCount | None = Field(
         default=None,
         validation_alias=AliasChoices("volume_fp", "volume"),
     )