export type Side = "left" | "right";

export type SerializedMessage = Record<string, unknown>;

export interface StreamUpdate {
  text?: string;
  reasoning?: string;
  status?: string;
}

export interface RunRequest {
  history: SerializedMessage[];
  prompt: string;
  branchId: string;
  onUpdate?: (update: StreamUpdate) => void;
}

export interface RunResult {
  branchId: string;
  messages: SerializedMessage[];
  response: string;
  reasoning: string;
  startedAt: string;
  completedAt: string;
  model: {
    provider: string;
    id: string;
    checkpoint?: string;
  };
  events: Array<Record<string, unknown>>;
}

export interface BranchBackend {
  readonly name: string;
  readonly displayName: string;
  readonly systemPrompt: string;
  run(request: RunRequest): Promise<RunResult>;
}

export interface ForkResult {
  turnId: string;
  createdAt: string;
  prompt: string;
  parentHistory: SerializedMessage[];
  parentHistoryHash: string;
  left: RunResult;
  right: RunResult;
}

export interface CandidateRecord {
  id: string;
  source: "left" | "right" | "revision";
  response: string;
  reasoning: string;
  messages: SerializedMessage[];
  model: RunResult["model"];
}

export interface PreferenceRecord {
  schema: "branch-preference/v1";
  id: string;
  createdAt: string;
  backend: string;
  systemPrompt: string;
  systemPromptHash: string;
  parentHistory: SerializedMessage[];
  parentHistoryHash: string;
  prompt: string;
  candidates: CandidateRecord[];
  preferredCandidateId: string;
  rejectedCandidateIds: string[];
  selection: "left" | "right" | "revise-left" | "revise-right";
  correction?: {
    feedback: string;
    originalCandidateId: string;
    revisionPrompt: string;
  };
}