Function buildSideQuestionFallbackParams

src/utils/queryContext.ts:88–179

({
  tools,
  commands,
  mcpClients,
  messages,
  readFileState,
  getAppState,
  setAppState,
  customSystemPrompt,
  appendSystemPrompt,
  thinkingConfig,
  agents,
}: {
  tools: Tools
  commands: Command[]
  mcpClients: MCPServerConnection[]
  messages: Message[]
  readFileState: FileStateCache
  getAppState: () => AppState
  setAppState: (f: (prev: AppState) => AppState) => void
  customSystemPrompt: string | undefined
  appendSystemPrompt: string | undefined
  thinkingConfig: ThinkingConfig | undefined
  agents: AgentDefinition[]
})

 * the alternative is returning null and failing the side question entirely.
 */
export async function buildSideQuestionFallbackParams({
  tools,
  commands,
  mcpClients,
  messages,
  readFileState,
  getAppState,
  setAppState,
  customSystemPrompt,
  appendSystemPrompt,
  thinkingConfig,
  agents,
}: {
  tools: Tools
  commands: Command[]
  mcpClients: MCPServerConnection[]
  messages: Message[]
  readFileState: FileStateCache
  getAppState: () => AppState
  setAppState: (f: (prev: AppState) => AppState) => void
  customSystemPrompt: string | undefined
  appendSystemPrompt: string | undefined
  thinkingConfig: ThinkingConfig | undefined
  agents: AgentDefinition[]
}): Promise<CacheSafeParams> {
  const mainLoopModel = getMainLoopModel()
  const appState = getAppState()

  const { defaultSystemPrompt, userContext, systemContext } =
    await fetchSystemPromptParts({
      tools,
      mainLoopModel,
      additionalWorkingDirectories: Array.from(
        appState.toolPermissionContext.additionalWorkingDirectories.keys(),
      ),
      mcpClients,
      customSystemPrompt,
    })

  const systemPrompt = asSystemPrompt([
    ...(customSystemPrompt !== undefined
      ? [customSystemPrompt]
      : defaultSystemPrompt),
    ...(appendSystemPrompt ? [appendSystemPrompt] : []),
  ])

  // Strip in-progress assistant message (stop_reason === null) — same guard
  // as btw.tsx. The SDK can fire side_question mid-turn.
  const last = messages.at(-1)
  const forkContextMessages =
    last?.type === 'assistant' && last.message!.stop_reason === null
      ? messages.slice(0, -1)
      : messages

  const toolUseContext: ToolUseContext = {
    options: {
      commands,
      debug: false,