chore: import upstream snapshot with attribution

open-sse/utils/responsesStatePolicy.ts

@@ -0,0 +1,75 @@
+import { isOpenAIResponsesStoreEnabled } from "@/lib/providers/requestDefaults";
+import {
+  DEFAULT_RESPONSES_PREVIOUS_RESPONSE_ID_MODE,
+  RESPONSES_PREVIOUS_RESPONSE_ID_MODES,
+  type ResponsesPreviousResponseIdMode,
+} from "@/shared/constants/responsesPreviousResponseId";
+import { FORMATS } from "../translator/formats.ts";
+
+type JsonRecord = Record<string, unknown>;
+
+type ApplyResponsesPreviousResponseIdPolicyOptions = {
+  mode: unknown;
+  sourceFormat?: unknown;
+  targetFormat?: unknown;
+  credentials?: unknown;
+};
+
+const MODE_SET = new Set<string>(RESPONSES_PREVIOUS_RESPONSE_ID_MODES);
+
+function toRecord(value: unknown): JsonRecord {
+  return value && typeof value === "object" && !Array.isArray(value) ? (value as JsonRecord) : {};
+}
+
+export function normalizeResponsesPreviousResponseIdMode(
+  value: unknown
+): ResponsesPreviousResponseIdMode {
+  if (typeof value === "string" && MODE_SET.has(value)) {
+    return value as ResponsesPreviousResponseIdMode;
+  }
+  return DEFAULT_RESPONSES_PREVIOUS_RESPONSE_ID_MODE;
+}
+
+export function shouldStripPreviousResponseId({
+  mode,
+  sourceFormat,
+  targetFormat,
+  credentials,
+}: ApplyResponsesPreviousResponseIdPolicyOptions): boolean {
+  const normalizedMode = normalizeResponsesPreviousResponseIdMode(mode);
+  if (normalizedMode === "preserve") return false;
+  if (normalizedMode === "strip") return true;
+
+  const isResponsesSource = sourceFormat === FORMATS.OPENAI_RESPONSES;
+  const isResponsesTarget = targetFormat === FORMATS.OPENAI_RESPONSES;
+  if (!isResponsesSource && !isResponsesTarget) return false;
+
+  // `previous_response_id` is only safe when the upstream actually keeps
+  // Responses state. OmniRoute defaults to stateless upstream calls, so auto
+  // strips unless the connection explicitly opts into OpenAI Responses storage.
+  const providerSpecificData = toRecord(toRecord(credentials).providerSpecificData);
+  return !isOpenAIResponsesStoreEnabled(providerSpecificData);
+}
+
+export function applyResponsesPreviousResponseIdPolicy(
+  body: unknown,
+  options: ApplyResponsesPreviousResponseIdPolicyOptions
+): { body: unknown; stripped: boolean; mode: ResponsesPreviousResponseIdMode } {
+  const mode = normalizeResponsesPreviousResponseIdMode(options.mode);
+  if (!body || typeof body !== "object" || Array.isArray(body)) {
+    return { body, stripped: false, mode };
+  }
+
+  const record = body as JsonRecord;
+  if (!Object.hasOwn(record, "previous_response_id")) {
+    return { body, stripped: false, mode };
+  }
+
+  if (!shouldStripPreviousResponseId({ ...options, mode })) {
+    return { body, stripped: false, mode };
+  }
+
+  const next = { ...record };
+  delete next.previous_response_id;
+  return { body: next, stripped: true, mode };
+}