/**
 * claude-sdk-sessionstore #9 (Part 2) — claude-SDK-vs-PTY routing predicate.
 *
 * Sibling to `shouldUseWarmBackend` (warm-acp-routing.ts). The warm Claude-SDK
 * backend keys its persistent `query()` on (chat_id, agent) — exactly like the
 * warm-ACP / opencode-server backends — so a task only routes to it when it carries
 * BOTH a `session_id` and a `chat_id` (a real chat tab).
 *
 * CRUCIALLY this is ALSO gated behind the `CLAUDE_SDK_BACKEND` env flag (default
 * OFF). While off — the production default — claude always falls through to the
 * existing one-shot PTY `runExternalAgent` path, UNCHANGED. The live SDK streaming
 * pump + cross-turn resume need a host smoke against the real `claude` binary, so
 * we keep the working PTY path as the default until that lands. Flip the env var
 * on a host (any truthy value) to opt a deployment into the SDK backend.
 *
 * Pure (env read injected) so it's unit-testable; the dispatcher consumes it.
 */

/** True iff the `CLAUDE_SDK_BACKEND` env flag is set to a truthy value. */
export function claudeSdkBackendEnabled(env: NodeJS.ProcessEnv = process.env): boolean {
  const v = env.CLAUDE_SDK_BACKEND;
  if (v == null) return false;
  const s = v.trim().toLowerCase();
  return s !== '' && s !== '0' && s !== 'false' && s !== 'off' && s !== 'no';
}

export function shouldUseClaudeSdk(
  task: {
    agent: string | null;
    session_id: string | null;
    chat_id: string | null;
  },
  env: NodeJS.ProcessEnv = process.env,
): boolean {
  if (!claudeSdkBackendEnabled(env)) return false;
  if (task.agent !== 'claude') return false;
  return task.session_id != null && task.chat_id != null;
}