/**
 * Guard against opencode's post-abort "orphan" terminal event (F.1).
 *
 * When a turn is aborted (`client.session.abort`), opencode emits one trailing
 * `session.idle` / `session.error` for the cancelled turn. Without a guard that
 * orphan settles whatever turn currently holds the session slot — which, after
 * the user immediately sends another message, is the NEXT turn, settling it early
 * as success (the v2.6.5 Stop-button bug). opencode terminal events carry only a
 * `sessionID` (no turn id), so we can't match by id; instead we swallow exactly
 * one terminal per abort, and self-heal if that orphan never arrives.
 */
export interface AbortTerminalGuard {
  /** True between an abort and the orphan terminal event that follows it. */
  swallowNextTerminal: boolean;
}

/** Arm on abort: the next terminal event for this session is the orphan. */
export function armAbortGuard(g: AbortTerminalGuard): void {
  g.swallowNextTerminal = true;
}

/**
 * A new turn produced activity (delta) → the orphan window is over. Self-heals
 * the case where opencode emits no orphan idle (e.g. abort-before-prompt), so a
 * real terminal still settles instead of being swallowed forever.
 */
export function noteTurnActivity(g: AbortTerminalGuard): void {
  g.swallowNextTerminal = false;
}

/** Decide a terminal (idle/error): swallow the post-abort orphan once, else settle. */
export function consumeTerminal(g: AbortTerminalGuard): 'swallow' | 'settle' {
  if (g.swallowNextTerminal) {
    g.swallowNextTerminal = false;
    return 'swallow';
  }
  return 'settle';
}