chore: improve result types

Author: Mateusz Tkacz

packages/app/backend-http-client/src/client/sendByApiContract.spec.ts

@@ -180,6 +180,7 @@ describe('sendByApiContract', () => {
 
       const response = await sendByApiContract(client, contract, {}, { requestLabel: 'test' })
 
+      expectTypeOf(response.error).toEqualTypeOf<UnexpectedResponseError | undefined>()
       expect(response.error).toBeDefined()
       expect(response.result).toBeUndefined()
     })
@@ -593,6 +594,9 @@ describe('sendByApiContract', () => {
         )
 
         expect(callCount).toBe(1)
+        expectTypeOf(result.error).toEqualTypeOf<
+          UnexpectedResponseError | { statusCode: 429; headers: Record<string, string | undefined>; body: { message: string } } | undefined
+        >()
         expect(result.error).toMatchObject({ statusCode: 429 })
         expect(result.result).toBeUndefined()
       })

packages/app/backend-http-client/src/client/sendByApiContract.ts

@@ -17,10 +17,31 @@ import type { RetryConfig } from 'undici-retry'
 import type { HttpRequestContext } from './types.ts'
 import { UnexpectedResponseError } from './UnexpectedResponseError.ts'
 
-// captureAsError: true → filter to success codes only; captureAsError: false → all codes from contract
-type CaptureAsErrorFilter<T, TDoCaptureAsError extends boolean> = TDoCaptureAsError extends true
-  ? Extract<T, { statusCode: SuccessfulHttpStatusCode }>
-  : T
+type AllContractResponses<
+  TApiContract extends ApiContract,
+  TIsStreaming extends boolean,
+> = TIsStreaming extends true
+  ? InferSseClientResponse<TApiContract>
+  : InferNonSseClientResponse<TApiContract>
+
+// captureAsError: true → success codes only; captureAsError: false → all codes from contract
+type ContractResultType<
+  TApiContract extends ApiContract,
+  TIsStreaming extends boolean,
+  TDoCaptureAsError extends boolean,
+> = TDoCaptureAsError extends true
+  ? Extract<AllContractResponses<TApiContract, TIsStreaming>, { statusCode: SuccessfulHttpStatusCode }>
+  : AllContractResponses<TApiContract, TIsStreaming>
+
+// captureAsError: true → UnexpectedResponseError | <error-status-code responses from contract>
+// captureAsError: false → only UnexpectedResponseError (all contract responses go to result)
+type ContractErrorType<
+  TApiContract extends ApiContract,
+  TIsStreaming extends boolean,
+  TDoCaptureAsError extends boolean,
+> = TDoCaptureAsError extends true
+  ? UnexpectedResponseError | Exclude<AllContractResponses<TApiContract, TIsStreaming>, { statusCode: SuccessfulHttpStatusCode }>
+  : UnexpectedResponseError
 
 export type ContractRequestOptions<DoCaptureAsError extends boolean = boolean> = {
   requestLabel: string
@@ -55,13 +76,8 @@ type ReturnTypeForContract<
   TIsStreaming extends boolean,
   TDoCaptureAsError extends boolean,
 > = Either<
-  UnexpectedResponseError,
-  CaptureAsErrorFilter<
-    TIsStreaming extends true
-      ? InferSseClientResponse<TApiContract>
-      : InferNonSseClientResponse<TApiContract>,
-    TDoCaptureAsError
-  >
+  ContractErrorType<TApiContract, TIsStreaming, TDoCaptureAsError>,
+  ContractResultType<TApiContract, TIsStreaming, TDoCaptureAsError>
 >
 
 function toUndiciRetryOptions(config: RetryConfig): RetryHandler.RetryOptions {