@anthropic-ai/sdk/src/internal/stainless-helper-header.ts

The official TypeScript library for the Anthropic API

/**
 * Single source of truth for the `x-stainless-helper` telemetry header — the
 * key, the closed value vocabulary, and per-object helper tagging. The
 * append-don't-clobber merge for the header itself lives in
 * {@link import('../internal/headers').buildHeaders} via `APPEND_HEADERS`.
 */

/**
 * Telemetry header naming the SDK helper(s) a request came from. Always this
 * lowercase form; `buildHeaders` matches it case-insensitively for its append
 * semantics, but a single canonical casing keeps every call site greppable.
 */
export const STAINLESS_HELPER_HEADER = 'x-stainless-helper';

/** Telemetry header naming the SDK method (e.g. `stream`) in use. */
export const STAINLESS_HELPER_METHOD_HEADER = 'x-stainless-helper-method';

/**
 * The closed set of helper telemetry tags, shared verbatim across SDKs. A
 * typo at any call site is a type error rather than silently mistagged
 * telemetry. Existing values keep their original spellings — telemetry
 * consumers match on them, so renames lose history. New tags are hyphenated
 * lowercase.
 */
export type StainlessHelperHeaderValue =
  | 'BetaToolRunner'
  | 'betaZodTool'
  | 'compaction'
  | 'environments-work-poller'
  | 'environments-worker'
  | 'fallback-refusal-middleware'
  | 'mcpContent'
  | 'mcpMessage'
  | 'mcpResourceToContent'
  | 'mcpResourceToFile'
  | 'mcpTool'
  | 'session-tool-runner';

/**
 * The `{ 'x-stainless-helper': value }` header dict, for passing into
 * `buildHeaders` (which comma-appends `x-stainless-helper` across sources)
 * or as `defaultHeaders`/per-request `headers`.
 */
export function helperHeader(value: StainlessHelperHeaderValue): { [STAINLESS_HELPER_HEADER]: string } {
  return { [STAINLESS_HELPER_HEADER]: value };
}

/**
 * Symbol used to mark objects created by SDK helpers for tracking.
 * The value is the helper name (e.g., 'mcpTool', 'betaZodTool').
 */
export const SDK_HELPER_SYMBOL = Symbol('anthropic.sdk.stainlessHelper');

type StainlessHelperObject = { [SDK_HELPER_SYMBOL]: string };

export function wasCreatedByStainlessHelper(value: unknown): value is StainlessHelperObject {
  return typeof value === 'object' && value !== null && SDK_HELPER_SYMBOL in value;
}

/**
 * Collects helper names from tools and messages arrays.
 * Returns a deduplicated array of helper names found.
 */
export function collectStainlessHelpers(
  tools: readonly unknown[] | undefined,
  messages: readonly unknown[] | undefined,
): string[] {
  const helpers = new Set<string>();

  // Collect from tools
  if (tools) {
    for (const tool of tools) {
      if (wasCreatedByStainlessHelper(tool)) {
        helpers.add(tool[SDK_HELPER_SYMBOL]);
      }
    }
  }

  // Collect from messages and their content blocks
  if (messages) {
    for (const message of messages) {
      if (wasCreatedByStainlessHelper(message)) {
        helpers.add(message[SDK_HELPER_SYMBOL]);
      }

      const content = (message as { content?: unknown }).content;
      if (Array.isArray(content)) {
        for (const block of content) {
          if (wasCreatedByStainlessHelper(block)) {
            helpers.add(block[SDK_HELPER_SYMBOL]);
          }
        }
      }
    }
  }

  return Array.from(helpers);
}

/**
 * Builds x-stainless-helper header value from tools and messages.
 * Returns an empty object if no helpers are found.
 */
export function stainlessHelperHeader(
  tools: readonly unknown[] | undefined,
  messages: readonly unknown[] | undefined,
): { 'x-stainless-helper'?: string } {
  const helpers = collectStainlessHelpers(tools, messages);
  if (helpers.length === 0) return {};
  return { [STAINLESS_HELPER_HEADER]: helpers.join(', ') };
}

/**
 * Builds x-stainless-helper header value from a file object.
 * Returns an empty object if the file is not marked with a helper.
 */
export function stainlessHelperHeaderFromFile(file: unknown): { 'x-stainless-helper'?: string } {
  if (wasCreatedByStainlessHelper(file)) {
    return { [STAINLESS_HELPER_HEADER]: file[SDK_HELPER_SYMBOL] };
  }
  return {};
}