fix: resolve Data type names from the SDK signature for digit-leading operationIds

src/parseOperations.mts

@@ -1,4 +1,9 @@
-import type { Project, VariableDeclaration } from "ts-morph";
+import {
+  Node,
+  type ParameterDeclaration,
+  type Project,
+  type VariableDeclaration,
+} from "ts-morph";
 import ts from "typescript";
 import {
   capitalizeFirstLetter,
@@ -68,8 +73,26 @@ function extractParameters(
 }
 
 /**
- * Get paginatable methods by checking if their Data type has the pageParam in query property.
+ * Read the operation's Data type name from the first type argument of the
+ * SDK options parameter (`Options<XData, ThrowOnError>`).
+ * See OperationInfo.dataTypeName for why the name is read from the signature
+ * instead of derived from the method name (#213).
+ */
+function getDataTypeNameFromSignature(
+  optionsParam: ParameterDeclaration | undefined,
+): string | undefined {
+  const typeNode = optionsParam?.getTypeNode();
+  if (!typeNode || !Node.isTypeReference(typeNode)) return undefined;
+  if (typeNode.getTypeName().getText() !== "Options") return undefined;
+  const [dataTypeArg] = typeNode.getTypeArguments();
+  return dataTypeArg?.getText();
+}
+
+/**
+ * Get paginatable Data types by checking if they have the pageParam in their query property.
  * Uses TypeScript compiler API for accurate AST traversal.
+ * The map is keyed by the Data type name (e.g., "FindPetsData") so callers can
+ * look it up with the name read from the SDK signature.
  */
 function getPaginatableMethods(
   project: Project,
@@ -115,18 +138,13 @@ function getPaginatableMethods(
     );
 
     if (pageParamNode) {
-      // Extract method name from Data type name (e.g., "FindPetsData" -> "findPets")
-      const methodName = key.slice(0, -4); // Remove "Data" suffix
-      // Convert first letter to lowercase
-      const methodNameLower =
-        methodName.charAt(0).toLowerCase() + methodName.slice(1);
       const pageParamType = pageParamNode.type?.getText(
         modelsFile.compilerNode,
       );
       const resolvedType = typeChecker.getTypeAtLocation(
         pageParamNode.type ?? pageParamNode,
       );
-      paginatableMethods.set(methodNameLower, {
+      paginatableMethods.set(key, {
         type: pageParamType ?? "unknown",
         typeKind: getPageParamTypeKind(resolvedType),
       });
@@ -157,12 +175,16 @@ export async function parseOperations(
     const sdkParams = getVariableArrowFunctionParameters(desc.method);
     const allParamsOptional =
       sdkParams.length === 0 || sdkParams[0].isOptional();
-    const pageParamInfo = paginatableMethods.get(methodName);
+    const dataTypeName = getDataTypeNameFromSignature(sdkParams[0]);
+    const pageParamInfo = dataTypeName
+      ? paginatableMethods.get(dataTypeName)
+      : undefined;
     const isPaginatable = httpMethod === "GET" && pageParamInfo !== undefined;
 
     return {
       methodName,
       capitalizedMethodName: capitalizeFirstLetter(methodName),
+      dataTypeName,
       httpMethod,
       jsDoc: desc.jsDoc,
       isDeprecated: desc.isDeprecated,

src/tsmorph/buildCommon.mts

@@ -5,6 +5,7 @@ import {
   type VariableStatementStructure,
 } from "ts-morph";
 import type { GenerationContext, OperationInfo } from "../types.mjs";
+import { getDataTypeName } from "./operationNames.mjs";
 
 /**
  * Build the default response type alias.
@@ -100,15 +101,8 @@ export function buildMutationKeyConst(
  * Example: export const UseFindPetsKeyFn = (clientOptions: Options<FindPetsData, true> = {}, queryKey?: Array<unknown>) =>
  *   [useFindPetsKey, ...(queryKey ?? [clientOptions])];
  */
-export function buildQueryKeyFn(
-  op: OperationInfo,
-  ctx: GenerationContext,
-): VariableStatementStructure {
-  const dataTypeName = ctx.modelNames.includes(
-    `${op.capitalizedMethodName}Data`,
-  )
-    ? `${op.capitalizedMethodName}Data`
-    : "unknown";
+export function buildQueryKeyFn(op: OperationInfo): VariableStatementStructure {
+  const dataTypeName = getDataTypeName(op);
 
   const params: string[] = [];
   const defaultValue = op.allParamsOptional ? " = {}" : "";
@@ -158,17 +152,12 @@ export function buildMutationKeyFn(
  * Example:
  * export type FindPaginatedPetsInfiniteClientOptions = Omit<Options<FindPaginatedPetsData, true>, "query"> &
  *   { query?: Omit<NonNullable<FindPaginatedPetsData["query"]>, "page"> };
- *
- * The `<Method>Data` type is always in scope here: `parseOperations` only marks
- * an operation paginatable when it found the page parameter inside that very
- * type, and it discovers it through the same exported declarations that become
- * `ctx.modelNames`. So there is no missing-Data case to fall back on.
  */
 export function buildInfiniteClientOptionsType(
   op: OperationInfo,
   ctx: GenerationContext,
 ): TypeAliasDeclarationStructure {
-  const dataTypeName = `${op.capitalizedMethodName}Data`;
+  const dataTypeName = getDataTypeName(op);
   const type = `Omit<Options<${dataTypeName}, true>, "query"> & { query?: Omit<NonNullable<${dataTypeName}["query"]>, "${ctx.pageParam}"> }`;
 
   return {

src/tsmorph/buildMutationHooks.mts

@@ -5,21 +5,7 @@ import {
 } from "ts-morph";
 import type { GenerationContext, OperationInfo } from "../types.mjs";
 import { SDK_CALL_ARGS } from "./buildQueryHooks.mjs";
-
-/**
- * Get the error type string based on client type.
- */
-function getErrorType(op: OperationInfo, ctx: GenerationContext): string {
-  const errorTypeName = `${op.capitalizedMethodName}Error`;
-  // Operations without error responses have no generated Error type
-  const errorType = ctx.modelNames.includes(errorTypeName)
-    ? errorTypeName
-    : "unknown";
-  if (ctx.client === "@hey-api/client-axios") {
-    return `AxiosError<${errorType}>`;
-  }
-  return errorType;
-}
+import { getDataTypeName, getErrorType } from "./operationNames.mjs";
 
 /**
  * Build useMutation hook.
@@ -41,13 +27,7 @@ export function buildUseMutationHook(
   const errorType = getErrorType(op, ctx);
   const dataTypeDefault = `Common.${op.capitalizedMethodName}MutationResult`;
 
-  const dataTypeName = ctx.modelNames.includes(
-    `${op.capitalizedMethodName}Data`,
-  )
-    ? `${op.capitalizedMethodName}Data`
-    : "unknown";
-
-  const optionsType = `Options<${dataTypeName}, true>`;
+  const optionsType = `Options<${getDataTypeName(op)}, true>`;
 
   const mutationFn = `clientOptions => ${op.methodName}(${SDK_CALL_ARGS}) as unknown as Promise<TData>`;
 

src/tsmorph/buildQueryHooks.mts

@@ -4,34 +4,7 @@ import {
   type VariableStatementStructure,
 } from "ts-morph";
 import type { GenerationContext, OperationInfo } from "../types.mjs";
-
-/**
- * Get the error type string based on client type.
- */
-function getErrorType(op: OperationInfo, ctx: GenerationContext): string {
-  const errorTypeName = `${op.capitalizedMethodName}Error`;
-  // Operations without error responses have no generated Error type
-  const errorType = ctx.modelNames.includes(errorTypeName)
-    ? errorTypeName
-    : "unknown";
-  if (ctx.client === "@hey-api/client-axios") {
-    return `AxiosError<${errorType}>`;
-  }
-  return errorType;
-}
-
-/**
- * Resolve the generated Data type name for an operation, falling back to
- * unknown when the operation has no generated Data type.
- */
-export function getDataTypeName(
-  op: OperationInfo,
-  ctx: GenerationContext,
-): string {
-  return ctx.modelNames.includes(`${op.capitalizedMethodName}Data`)
-    ? `${op.capitalizedMethodName}Data`
-    : "unknown";
-}
+import { getDataTypeName, getErrorType } from "./operationNames.mjs";
 
 /**
  * SDK call arguments shared by every generated queryFn/mutationFn.
@@ -53,11 +26,8 @@ export function getPageParamType(op: OperationInfo): string {
 /**
  * Build the client options parameter string.
  */
-export function buildClientOptionsParam(
-  op: OperationInfo,
-  ctx: GenerationContext,
-): string {
-  const dataTypeName = getDataTypeName(op, ctx);
+export function buildClientOptionsParam(op: OperationInfo): string {
+  const dataTypeName = getDataTypeName(op);
 
   const hasParams = op.parameters.length > 0;
   if (!hasParams) {
@@ -94,15 +64,12 @@ export function getPageType(op: OperationInfo): string {
  * TQueryFnData the infinite options are instantiated with (#203). Spelled as
  * a cast rather than `!` because generated code is linted downstream, and a
  * non-null assertion trips biome's noNonNullAssertion.
- *
- * Only ever called for paginatable operations, so the `<Method>Data` type is
- * guaranteed to exist — see buildInfiniteClientOptionsType for why.
  */
 export function buildPagedQueryFn(
   op: OperationInfo,
   ctx: GenerationContext,
 ): string {
-  const dataTypeName = `${op.capitalizedMethodName}Data`;
+  const dataTypeName = getDataTypeName(op);
   const thenClause = `.then(response => response.data as ${getPageType(op)})`;
   const pageParamType = getPageParamType(op);
   // When the initial page param is omitted, the first request must send no
@@ -208,7 +175,7 @@ export function buildUseQueryHook(
   const hookName = `use${op.capitalizedMethodName}`;
   const errorType = getErrorType(op, ctx);
   const dataTypeDefault = `Common.${op.capitalizedMethodName}DefaultResponse`;
-  const clientOptionsParam = buildClientOptionsParam(op, ctx);
+  const clientOptionsParam = buildClientOptionsParam(op);
 
   const queryFn = `({ signal }) => ${op.methodName}(${QUERY_SDK_CALL_ARGS}).then(response => response.data as TData) as TData`;
 
@@ -239,7 +206,7 @@ export function buildUseSuspenseQueryHook(
   const hookName = `use${op.capitalizedMethodName}Suspense`;
   const errorType = getErrorType(op, ctx);
   const dataTypeDefault = `NonNullable<Common.${op.capitalizedMethodName}DefaultResponse>`;
-  const clientOptionsParam = buildClientOptionsParam(op, ctx);
+  const clientOptionsParam = buildClientOptionsParam(op);
 
   const queryFn = `({ signal }) => ${op.methodName}(${QUERY_SDK_CALL_ARGS}).then(response => response.data as TData) as TData`;
 
@@ -339,10 +306,7 @@ export function buildUseSuspenseInfiniteQueryHook(
  *     ...options
  *   });
  */
-export function buildPrefetchFn(
-  op: OperationInfo,
-  ctx: GenerationContext,
-): VariableStatementStructure {
+export function buildPrefetchFn(op: OperationInfo): VariableStatementStructure {
   const fnName = `prefetchUse${op.capitalizedMethodName}`;
 
   const queryFn = `({ signal }) => ${op.methodName}(${QUERY_SDK_CALL_ARGS}).then(response => response.data)`;
@@ -359,7 +323,7 @@ export function buildPrefetchFn(
     declarations: [
       {
         name: fnName,
-        initializer: `(queryClient: QueryClient, ${buildClientOptionsParam(op, ctx)}, ${optionsParam}) => ${body}`,
+        initializer: `(queryClient: QueryClient, ${buildClientOptionsParam(op)}, ${optionsParam}) => ${body}`,
       },
     ],
   };
@@ -428,7 +392,6 @@ export function buildPrefetchInfiniteQueryFn(
  */
 export function buildEnsureQueryDataFn(
   op: OperationInfo,
-  ctx: GenerationContext,
 ): VariableStatementStructure {
   const fnName = `ensureUse${op.capitalizedMethodName}Data`;
 
@@ -446,7 +409,7 @@ export function buildEnsureQueryDataFn(
     declarations: [
       {
         name: fnName,
-        initializer: `(queryClient: QueryClient, ${buildClientOptionsParam(op, ctx)}, ${optionsParam}) => ${body}`,
+        initializer: `(queryClient: QueryClient, ${buildClientOptionsParam(op)}, ${optionsParam}) => ${body}`,
       },
     ],
   };

src/tsmorph/buildQueryOptions.mts

@@ -28,10 +28,9 @@ import {
  */
 export function buildQueryOptionsFn(
   op: OperationInfo,
-  ctx: GenerationContext,
 ): VariableStatementStructure {
   const fnName = `${op.methodName}Options`;
-  const clientOptionsParam = buildClientOptionsParam(op, ctx);
+  const clientOptionsParam = buildClientOptionsParam(op);
 
   const queryFn = `({ signal }) => ${op.methodName}(${QUERY_SDK_CALL_ARGS}).then(response => response.data)`;
   const body = `queryOptions({ queryKey: Common.Use${op.capitalizedMethodName}KeyFn(clientOptions, queryKey), queryFn: ${queryFn} })`;

src/tsmorph/generateFiles.mts

@@ -93,7 +93,7 @@ function generateCommonFile(
     sourceFile.addTypeAlias(buildDefaultResponseType(op));
     sourceFile.addTypeAlias(buildQueryResultType(op));
     sourceFile.addVariableStatement(buildQueryKeyConst(op));
-    sourceFile.addVariableStatement(buildQueryKeyFn(op, ctx));
+    sourceFile.addVariableStatement(buildQueryKeyFn(op));
   }
 
   // Add dedicated infinite query types and keys for paginatable operations
@@ -170,7 +170,7 @@ function generateQueryOptionsFile(
   const getOperations = operations.filter((op) => op.httpMethod === "GET");
 
   for (const op of getOperations) {
-    sourceFile.addVariableStatement(buildQueryOptionsFn(op, ctx));
+    sourceFile.addVariableStatement(buildQueryOptionsFn(op));
   }
 
   // Add infiniteQueryOptions factories
@@ -264,7 +264,7 @@ function generatePrefetchFile(
 
   // Add prefetch functions
   for (const op of getOperations) {
-    sourceFile.addVariableStatement(buildPrefetchFn(op, ctx));
+    sourceFile.addVariableStatement(buildPrefetchFn(op));
   }
 
   // Add prefetchInfiniteQuery functions
@@ -297,7 +297,7 @@ function generateEnsureQueryDataFile(
 
   // Add ensureQueryData functions
   for (const op of getOperations) {
-    sourceFile.addVariableStatement(buildEnsureQueryDataFn(op, ctx));
+    sourceFile.addVariableStatement(buildEnsureQueryDataFn(op));
   }
 
   return sourceFile.getFullText();

src/tsmorph/operationNames.mts

@@ -0,0 +1,35 @@
+import type { GenerationContext, OperationInfo } from "../types.mjs";
+
+/**
+ * Resolve the generated Data type name for an operation, falling back to
+ * unknown when the SDK signature exposes no Data type.
+ * See OperationInfo.dataTypeName for why the name is read from the signature
+ * instead of derived from the method name (#213).
+ */
+export function getDataTypeName(op: OperationInfo): string {
+  return op.dataTypeName ?? "unknown";
+}
+
+/**
+ * Get the error type string based on client type.
+ * The Error type shares its stem with the Data type — hey-api mints both from
+ * the operationId (see OperationInfo.dataTypeName, #213) — so the stem comes
+ * from `dataTypeName` rather than the method name. The modelNames probe stays
+ * because operations without error responses have no generated Error type.
+ */
+export function getErrorType(
+  op: OperationInfo,
+  ctx: GenerationContext,
+): string {
+  const stem = op.dataTypeName
+    ? op.dataTypeName.replace(/Data$/, "")
+    : op.capitalizedMethodName;
+  const errorTypeName = `${stem}Error`;
+  const errorType = ctx.modelNames.includes(errorTypeName)
+    ? errorTypeName
+    : "unknown";
+  if (ctx.client === "@hey-api/client-axios") {
+    return `AxiosError<${errorType}>`;
+  }
+  return errorType;
+}

src/types.mts

@@ -7,6 +7,20 @@ export interface OperationInfo {
   methodName: string;
   /** Capitalized method name (e.g., "FindPets") */
   capitalizedMethodName: string;
+  /**
+   * Generated Data type name read from the SDK function's own
+   * `Options<XData, ThrowOnError>` signature (e.g., "FindPetsData").
+   * Not derivable from the method name: for digit-leading operationIds
+   * hey-api prefixes the function but strips the digits from the type (#213).
+   * Undefined when the SDK signature exposes no Data type.
+   *
+   * The rule this encodes: names hey-api owns (Data, Error) must be read from
+   * the SDK signature or share this field's stem; names this codegen mints
+   * itself (DefaultResponse, MutationResult, key fns) may be derived from
+   * capitalizedMethodName because they anchor back to the SDK via
+   * `typeof methodName`.
+   */
+  dataTypeName?: string;
   /** HTTP method (e.g., "GET", "POST", "PUT", "PATCH", "DELETE") */
   httpMethod: string;
   /** JSDoc comment string (if present) */