Better Auth Package Exports#

Both better-auth and @better-auth/oauth-provider use a fully explicit Node.js exports map with ESM-only output built by tsdown. Every subpath is listed individually — there is no wildcard catch-all — and each entry carries three conditions: dev-source, types, and default.

better-auth Export Map#

packages/better-auth/package.json (current version: 1.6.25) publishes only the dist/ folder and exposes 40+ named subpaths. Key ones:

All compiled types use .d.mts declarations matching .mjs runtime files. 1

A parallel typesVersions block maps the same subpaths for older TypeScript versions that don't read exports.types.

The package is declared "type": "module" and "sideEffects": false. 2

@better-auth/oauth-provider Export Map#

packages/oauth-provider/package.json exposes three subpaths:

3

The root src/index.ts re-exports everything from ./types via export type * from "./types". 4

./client entry#

oauthProviderClient 5 is a BetterAuthClientPlugin that injects an oauth_query body field into non-GET/DELETE requests when window.location.search is present. It infers the server plugin's types via $InferServerPlugin: {} as ReturnType<typeof oauthProvider>. 6

The dev-source Export Condition#

Every subpath in both packages includes a dev-source condition pointing to the original .ts source file (e.g., "dev-source": "./src/index.ts"). 7 This is a custom TypeScript customConditions entry (set in the workspace-level tsconfig.base.json) that lets IDEs and TypeScript resolve "jump-to-definition" directly to source rather than compiled declarations. It has no effect at runtime or during normal consumer builds.

Non-Portable Type Export Fix (PR #9406)#

Problem: Downstream projects that re-export oauthProvider and ran tsc --emitDeclarationOnly received TS2742 errors — TypeScript could not portably reference helper types (AuthMethod, BearerMethodsSupported, GrantType, TokenEndpointAuthMethod) because they were used inside the public OAuthOptions interface but not re-exported from the package entrypoint. 8

Fix: PR #9406 added explicit export type { ... } re-exports for those four types from src/types/index.ts 9:

export type {
  AuthMethod,
  AuthServerMetadata,
  BearerMethodsSupported,
  GrantType,
  OAuthClient,
  OIDCMetadata,
  ResourceServerMetadata,
  TokenEndpointAuthMethod,
} from "./oauth";

Regression guard: The PR also converted the e2e smoke fixture from noEmit: true to emitDeclarationOnly: true so CI actually exercises declaration emission rather than just type-checking. 8

General rule: Any type that appears in a public API's function signature or interface must be re-exported from the package entrypoint. If it is only reachable through internal imports, TypeScript's declaration emitter will generate non-portable references that break consumers in composite/project-reference setups.

Key References#

• packages/better-auth/package.json — full exports map and typesVersions
• packages/oauth-provider/package.json — oauth-provider exports map
• packages/oauth-provider/src/index.ts — root re-export barrel
• packages/oauth-provider/src/types/index.ts — public type surface
• packages/oauth-provider/src/client.ts — client plugin
• PR #9406 — non-portable type export fix