refactor(translate): clarify assistant-turn replay ownership

packages/protocols/src/openai-chat-completions/history.ts

@@ -0,0 +1,16 @@
+import type { OpenAIChatCompletionsAssistantMessageEx, OpenAIChatCompletionsAssistantOutputMessageEx } from './index.ts';
+
+export const toOpenAIChatCompletionsInputAssistantMessage = (outputTurn: OpenAIChatCompletionsAssistantOutputMessageEx): OpenAIChatCompletionsAssistantMessageEx => {
+  // The SDK serializes supplied message fields directly; prior audio input uses an ID reference.
+  // https://github.com/openai/openai-node/blob/f57c9651c8d22ae82cacca27317cfa7126491011/src/resources/chat/completions/completions.ts#L195-L210
+  // https://github.com/openai/openai-node/blob/f57c9651c8d22ae82cacca27317cfa7126491011/src/client.ts#L637-L637
+  // https://github.com/openai/openai-node/blob/f57c9651c8d22ae82cacca27317cfa7126491011/src/internal/request-options.ts#L115-L144
+  // The response object also carries audio bytes, expiry, and transcript.
+  // https://github.com/openai/openai-node/blob/f57c9651c8d22ae82cacca27317cfa7126491011/src/resources/chat/completions/completions.ts#L884-L935
+  // https://github.com/openai/openai-node/blob/f57c9651c8d22ae82cacca27317cfa7126491011/src/resources/chat/completions/completions.ts#L962-L984
+  const { audio, ...message } = outputTurn;
+  return {
+    ...message,
+    ...(Object.hasOwn(outputTurn, 'audio') ? { audio: audio === null || audio === undefined ? audio : { id: audio.id } } : {}),
+  };
+};

packages/protocols/src/openai-chat-completions/index.ts

@@ -180,3 +180,5 @@ export { parseOpenAIChatCompletionsStream, type ParseOpenAIChatCompletionsStream
 export { collectOpenAIChatCompletionsProtocolEventsToResult } from './to-result.ts';
 export { createOpenAIChatCompletionsEventAccumulator, reassembleOpenAIChatCompletionsEvents, type OpenAIChatCompletionsEventAccumulator } from './reassemble.ts';
 export { openaiChatCompletionsProtocolFrameToSSEFrame } from './to-sse.ts';
+
+export { toOpenAIChatCompletionsInputAssistantMessage } from './history.ts';

packages/protocols/src/openai-responses/history.ts

@@ -0,0 +1,52 @@
+import type { CanonicalOpenAIResponsesInputItem, OpenAIResponsesOutputItemEx } from './index.ts';
+
+// Match the official SDK's history normalization for SDK-owned fields and replay-only item transforms.
+// https://github.com/openai/openai-node/blob/f57c9651c8d22ae82cacca27317cfa7126491011/src/lib/responses/ResponseInputItems.ts#L41-L67
+// https://github.com/openai/openai-node/blob/f57c9651c8d22ae82cacca27317cfa7126491011/src/lib/responses/ResponseInputItems.ts#L115-L160
+type OpenAIResponsesOutputMessage = Extract<OpenAIResponsesOutputItemEx, { type: 'message' }>;
+type OpenAIResponsesOutputContent = OpenAIResponsesOutputMessage['content'][number];
+
+const stripCreatedBy = (item: OpenAIResponsesOutputItemEx): OpenAIResponsesOutputItemEx => {
+  if (!('created_by' in item)) return item;
+  const { created_by: _createdBy, ...historyItem } = item;
+  return historyItem;
+};
+
+const outputContentToHistoryContent = (part: OpenAIResponsesOutputContent): OpenAIResponsesOutputContent => {
+  if ((part.type !== 'output_text' && part.type !== 'refusal') || !('parsed' in part)) return part;
+  const { parsed: _parsed, ...historyContent } = part;
+  return historyContent;
+};
+
+// OpenAI defines output and replayable input items as separate unions. After the
+// SDK's documented output-only fields and variants are removed below, the wire
+// object is an input item even though TypeScript cannot encode that union relation.
+const asInputItem = (item: OpenAIResponsesOutputItemEx): CanonicalOpenAIResponsesInputItem => item as CanonicalOpenAIResponsesInputItem;
+
+export const toOpenAIResponsesInputItem = (item: OpenAIResponsesOutputItemEx): CanonicalOpenAIResponsesInputItem | null => {
+  const historyItem = stripCreatedBy(item);
+  if (historyItem.type === 'message') {
+    const content = historyItem.content.map(part => outputContentToHistoryContent(part));
+    return asInputItem(content.every((part, index) => part === historyItem.content[index]) ? historyItem : { ...historyItem, content });
+  }
+  if (historyItem.type === 'function_call') {
+    if (!('parsed_arguments' in historyItem)) return asInputItem(historyItem);
+    const { parsed_arguments: _parsedArguments, ...withoutParsedArguments } = historyItem;
+    return asInputItem(withoutParsedArguments);
+  }
+  if (historyItem.type === 'shell_call_output') {
+    return asInputItem({ ...historyItem, output: historyItem.output.map(({ created_by: _createdBy, ...output }) => output) });
+  }
+  if (historyItem.type === 'computer_call_output') return historyItem.status === 'failed' ? null : asInputItem(historyItem);
+  if (historyItem.type === 'custom_tool_call_output') {
+    if ('status' in historyItem && historyItem.status !== 'completed') return null;
+    const { status: _status, ...inputItem } = historyItem;
+    return asInputItem(inputItem);
+  }
+  return asInputItem(historyItem);
+};
+
+export const toOpenAIResponsesInputItems = (output: readonly OpenAIResponsesOutputItemEx[]): CanonicalOpenAIResponsesInputItem[] => output.flatMap(item => {
+  const input = toOpenAIResponsesInputItem(item);
+  return input === null ? [] : [input];
+});

packages/protocols/src/openai-responses/index.ts

@@ -1450,3 +1450,4 @@ export { reassembleOpenAIResponsesEvents } from './reassemble.ts';
 export { openaiResponsesProtocolFrameToSSEFrame } from './to-sse.ts';
 
 export { canonicalizeOpenAIResponsesPayload } from './canonicalize-payload.ts';
+export { toOpenAIResponsesInputItem, toOpenAIResponsesInputItems } from './history.ts';

packages/translate/AGENTS.md

@@ -29,7 +29,8 @@ Protocol-native request normalization and Part data classification belong to
 6. **Assistant-turn round trips** — keep owner-specific sidecar validation, replay
    validation, and native stream coordination under `round-trip/`. Source replay
    inspection and carriers belong in `as-source/round-trip.ts`; native assistant-turn
-   shapes and output-to-input converters belong in `as-target/assistant-turn.ts`.
+   reference shapes and state alignment belong in `as-target/assistant-turn.ts`.
+   Native output-to-input payload normalization belongs in `@floway-dev/protocols`.
    Transport encoding is injected through `TranslateOptions.sidecarCodec`.
 7. **Protocol-independent utility** — keep it in `shared/`, with tests under
    `__tests__/shared/`. Protocol behavior belongs in its owning protocol directory.