Function buildFetch

src/services/api/client.ts:381–422

(
  fetchOverride: ClientOptions['fetch'],
  source: string | undefined,
)

export const CLIENT_REQUEST_ID_HEADER = 'x-client-request-id'

function buildFetch(
  fetchOverride: ClientOptions['fetch'],
  source: string | undefined,
): ClientOptions['fetch'] {
  // eslint-disable-next-line eslint-plugin-n/no-unsupported-features/node-builtins
  const inner = fetchOverride ?? globalThis.fetch
  // Only send to the first-party API — Bedrock/Vertex/Foundry don't log it
  // and unknown headers risk rejection by strict proxies (inc-4029 class).
  const injectClientRequestId =
    getAPIProvider() === 'firstParty' && isFirstPartyAnthropicBaseUrl()
  return async (input, init) => {
    // eslint-disable-next-line eslint-plugin-n/no-unsupported-features/node-builtins
    const headers = new Headers(init?.headers)
    if (injectClientRequestId && !headers.has(CLIENT_REQUEST_ID_HEADER)) {
      headers.set(CLIENT_REQUEST_ID_HEADER, randomUUID())
    }

    let body = init?.body
    try {
      // eslint-disable-next-line eslint-plugin-n/no-unsupported-features/node-builtins
      const url = input instanceof Request ? input.url : String(input)
      const id = headers.get(CLIENT_REQUEST_ID_HEADER)
      logForDebugging(
        `[API REQUEST] ${new URL(url).pathname}${id ? ` ${CLIENT_REQUEST_ID_HEADER}=${id}` : ''} source=${source ?? 'unknown'}`,
      )

      if (
        url.includes('/v1/messages') &&
        headers.has('anthropic-version') &&
        typeof body === 'string' &&
        hasCchPlaceholder(body)
      ) {
        const cch = await computeCch(body)
        body = replaceCchPlaceholder(body, cch)
        logForDebugging(`[CCH] signed request cch=${cch}`)
      }
    } catch {
      // never let logging crash the fetch
    }
    return inner(input, { ...init, headers, body })
  }
}