/**
 * Read `<TRANSPORT>_BRIDGE_*` and `BRIDGE_*` env vars into a
 * lowerCamelCase-keyed bag ready to hand to `createBridgeClient`.
 *
 * Precedence when the same key resolves from both forms:
 * transport-specific wins over shared.
 *
 * Transport ids with dashes (`google-chat`, `line-works`,
 * `twilio-sms`, …) are normalised to underscores when building the
 * env prefix: `google-chat` → `GOOGLE_CHAT_BRIDGE_*`. Dashes in env
 * var names break shells, so `_` is the portable convention.
 *
 * Example:
 *   SLACK_BRIDGE_DEFAULT_ROLE=slack
 *   BRIDGE_DEFAULT_ROLE=general
 *   → `{ defaultRole: "slack" }`
 *
 *   GOOGLE_CHAT_BRIDGE_DEFAULT_ROLE=support
 *   (with transportId="google-chat")
 *   → `{ defaultRole: "support" }`
 */
export declare function readBridgeEnvOptions(transportId: string, env: Readonly<Record<string, string | undefined>>): Record<string, string>;