Function stripSignatureBlocks

src/utils/messages.ts:5066–5099

(messages: Message[])

 * the API rejects them with a 400.
 */
export function stripSignatureBlocks(messages: Message[]): Message[] {
  let changed = false
  const result = messages.map(msg => {
    if (msg.type !== 'assistant') return msg

    const content = msg.message.content
    if (!Array.isArray(content)) return msg

    const filtered = content.filter(block => {
      if (isThinkingBlock(block)) return false
      if (feature('CONNECTOR_TEXT')) {
        if (isConnectorTextBlock(block)) return false
      }
      return true
    })
    if (filtered.length === content.length) return msg

    // Strip to [] even for thinking-only messages. Streaming yields each
    // content block as a separate same-id AssistantMessage (claude.ts:2150),
    // so a thinking-only singleton here is usually a split sibling that
    // mergeAssistantMessages (2232) rejoins with its text/tool_use partner.
    // If we returned the original message, the stale signature would survive
    // the merge. Empty content is absorbed by merge; true orphans are handled
    // by the empty-content placeholder path in normalizeMessagesForAPI.

    changed = true
    return {
      ...msg,
      message: { ...msg.message, content: filtered },
    } as typeof msg
  })

  return changed ? result : messages
}

/**
 * Creates a tool use summary message for SDK emission.