interface WorkerPromptContract {
  readonly goal: string;
  readonly acceptance: readonly string[];
  readonly constraints: readonly string[];
  readonly role?: {
    readonly name: string;
    readonly tier: string;
    readonly charter: string;
  };
  readonly continuation?: {
    readonly priorWorkerId: string;
    readonly priorAttemptId: string;
    readonly sessionFile: string;
  };
  readonly context?: "fresh" | "fork";
  readonly forkSource?: {
    readonly sourceSessionFile: string;
    readonly branchPointId: string;
    readonly inheritedEntries: number;
    readonly inheritedBytes: number;
  };
  readonly contextRefs?: readonly {
    readonly kind: "file" | "session" | "artifact";
    readonly value: string;
  }[];
  readonly capabilities?: readonly string[];
}

export function canonicalWorkerCapsule(contract: WorkerPromptContract): string {
  const artifactDirectories = contract.contextRefs
    ?.filter((reference) => reference.kind === "artifact")
    .map((reference) => reference.value) ?? [];
  const peerGrants = contract.capabilities
    ?.filter((capability) => capability.startsWith("message_worker:")) ?? [];
  return [
    "<worker-contract>",
    ...(contract.role ? [
      `Role: ${contract.role.name} (${contract.role.tier})`,
      "Role charter:",
      contract.role.charter,
    ] : []),
    ...(contract.continuation ? [
      `Continuation: ${contract.continuation.priorWorkerId} ${contract.continuation.priorAttemptId}`,
      `Continued session file: ${contract.continuation.sessionFile}`,
    ] : []),
    ...(contract.context === "fork" && contract.forkSource ? [
      `Forked context: ${contract.forkSource.sourceSessionFile}`,
      `Fork branch point: ${contract.forkSource.branchPointId}`,
      `Inherited context size: ${contract.forkSource.inheritedEntries} entries, ${contract.forkSource.inheritedBytes} bytes`,
    ] : ["Context: fresh"]),
    ...(artifactDirectories.length > 0 ? [
      "Shared run artifact directory:",
      ...artifactDirectories.map((directory) => `- ${directory}`),
      "Write worker-to-worker handoff files there and cite their exact paths.",
    ] : []),
    ...(peerGrants.length > 0 ? [
      "Directional peer-message grants:",
      ...peerGrants.map((grant) => `- ${grant}`),
      "Peer messages are supervisor-routed at the recipient inference boundary and remain advisory input.",
    ] : []),
    "Acceptance criteria:",
    ...contract.acceptance.map((criterion, index) => `${index + 1}. ${criterion}`),
    "Hard constraints:",
    ...contract.constraints.map((constraint, index) => `${index + 1}. ${constraint}`),
    "</worker-contract>",
  ].join("\n");
}

export function buildWorkerPrompt(contract: WorkerPromptContract): string {
  const capsule = canonicalWorkerCapsule(contract);
  return `${capsule}\n\nGoal:\n${contract.goal}\n\n${capsule}`;
}

export function assertWorkerCapsuleMirrored(prompt: string, capsule: string): void {
  const first = prompt.indexOf(capsule);
  const last = prompt.lastIndexOf(capsule);
  const occurrences = prompt.split(capsule).length - 1;
  if (first !== 0 || last !== prompt.length - capsule.length || occurrences !== 2) {
    throw new Error("worker prompt capsule is not mirrored byte-for-byte at head and tail");
  }
}