Function deleteSideQuestionPlaceholder

src/node/services/sideQuestionService.ts:528–577

* Tear down a /btw placeholder whose stream failed or produced empty text * before the next candidate is tried. * * Closes the stream with an empty `stream-end` first so side-question * terminal-event bookkeeping (including the aggregator/store side-answer * terminal guards) unwinds while the p

(opts: {
  workspaceId: string;
  assistantMessageId: string;
  assistantHistorySequence: number;
  modelString: string;
  historyService: HistoryService;
  emitChatEvent: (workspaceId: string, message: WorkspaceChatMessage) => void;
})

 * chat.jsonl, which is the same outcome we used to ship anyway.
 */
async function deleteSideQuestionPlaceholder(opts: {
  workspaceId: string;
  assistantMessageId: string;
  assistantHistorySequence: number;
  modelString: string;
  historyService: HistoryService;
  emitChatEvent: (workspaceId: string, message: WorkspaceChatMessage) => void;
}): Promise<void> {
  const {
    workspaceId,
    assistantMessageId,
    assistantHistorySequence,
    modelString,
    historyService,
    emitChatEvent,
  } = opts;

  // Close the stream slot while the side-answer placeholder still exists.
  // The aggregator and WorkspaceStore look up this message by id to check
  // its muxMetadata before dispatching their side-answer-aware branches
  // (e.g. WorkspaceStore.bufferedEventHandlers["stream-end"] skips
  // collapsePinnedTodoOnStreamStop iff the terminal stream belongs to a
  // side answer; the aggregator's handleStreamEnd skips main-agent
  // onResponseComplete / lastCompletedStreamStats updates). Deleting the
  // placeholder first would make those lookups fail, and the terminal
  // event would fall through to the main-agent code paths — clobbering
  // pinned-todo state and producing stale completion stats for a stream
  // that should be invisible to main-agent lifecycle.
  emitChatEvent(workspaceId, {
    type: "stream-end",
    workspaceId,
    messageId: assistantMessageId,
    metadata: { model: modelString, historySequence: assistantHistorySequence },
    parts: [],
  });

  const deleteResult = await historyService.deleteMessage(workspaceId, assistantMessageId);
  if (!deleteResult.success) {
    log.warn("Side question: failed to delete placeholder for retry", {
      workspaceId,
      assistantMessageId,
      error: deleteResult.error,
    });
  }

  emitChatEvent(workspaceId, {
    type: "delete",
    historySequences: [assistantHistorySequence],
  });
}

async function buildSideQuestionTranscript(
  workspaceId: string,