export function getStatusPluginMessagePreviewSource(): string[] {
  return [
    '',
    'function capMessagePartText(text) {',
    '  return text.length > MESSAGE_PART_MAX_CHARS ? text.slice(0, MESSAGE_PART_MAX_CHARS) : text;',
    '}',
    '',
    'async function postMessagePart(properties, factoryID) {',
    '  while (messagePartPostInFlight) await messagePartPostInFlight;',
    '  const delivery = post("MessagePart", properties);',
    '  messagePartPostInFlight = delivery;',
    '  try {',
    '    const delivered = await delivery;',
    '    if (delivered) deliveredMessagePartFactoryID = factoryID;',
    '  } finally {',
    '    if (messagePartPostInFlight === delivery) messagePartPostInFlight = null;',
    '  }',
    '}',
    '',
    'async function flushPendingAssistantPart(force = false) {',
    '  if (assistantPartFlushTimer) {',
    '    clearTimeout(assistantPartFlushTimer);',
    '    assistantPartFlushTimer = null;',
    '  }',
    '  // Why: an idle/waiting transition must wait for every older preview;',
    '  // keep one post in flight while later snapshots coalesce in memory.',
    '  while (messagePartPostInFlight) await messagePartPostInFlight;',
    '  const pending = pendingAssistantPart;',
    '  pendingAssistantPart = null;',
    '  if (!pending) return;',
    '  if (',
    '    !activeFactoryIDs.has(pending.factoryID) ||',
    '    disposingFactoryIDs.has(pending.factoryID)',
    '  ) return;',
    '  if (!force && pending.authorityRevision !== stateArrivalRevision) return;',
    '  lastAssistantPartPostAt = Date.now();',
    '  await postMessagePart({',
    '    role: pending.role,',
    '    text: capMessagePartText(pending.text),',
    '    messageID: pending.messageID,',
    '    sessionID: pending.sessionID,',
    '  }, pending.factoryID);',
    '}',
    '',
    'function queueAssistantPart(part) {',
    '  // Why: keep only the latest snapshot — each event already contains the',
    '  // full accumulated text, so intermediate snapshots are pure waste.',
    '  pendingAssistantPart = part;',
    '  const sinceLastPost = Date.now() - lastAssistantPartPostAt;',
    '  if (sinceLastPost >= MESSAGE_PART_THROTTLE_MS) {',
    '    void flushPendingAssistantPart();',
    '    return;',
    '  }',
    '  if (!assistantPartFlushTimer) {',
    '    assistantPartFlushTimer = setTimeout(() => {',
    '      void flushPendingAssistantPart();',
    '    }, MESSAGE_PART_THROTTLE_MS - sinceLastPost);',
    '    if (assistantPartFlushTimer.unref) assistantPartFlushTimer.unref();',
    '  }',
    '}',
    '',
    '// Why: message.part.updated fires for every Part (text, tool, reasoning)',
    '// but does not include the message role — that lives on the parent',
    '// message.updated event. Cache the role per messageID so the plugin can',
    '// tag a TextPart as user vs assistant when POSTing. Capped at 128 entries',
    '// so long-running sessions do not grow this map unboundedly.',
    'const messageRoleById = new Map();',
    'function rememberMessageRole(messageID, role) {',
    '  if (!messageID || !role) return;',
    '  if (messageRoleById.size >= 128) {',
    '    const first = messageRoleById.keys().next().value;',
    '    if (first !== undefined) messageRoleById.delete(first);',
    '  }',
    '  messageRoleById.set(messageID, role);',
    '}',
    ''
  ]
}