PrismFacet/plugin/hooks/before-prompt-build.ts

import { resolveInjection } from "../core/prompt-injector.js";

const _G = globalThis as Record<string, unknown>;
const DEDUP_KEY = "_prismFacetBPBDedup";

export function registerBeforePromptBuild(api: {
  on(hook: string, handler: (...args: any[]) => any): void;
  logger: { info(msg: string): void; warn(msg: string): void };
}): void {
  if (!(_G[DEDUP_KEY] instanceof WeakSet)) _G[DEDUP_KEY] = new WeakSet<object>();
  const dedup = _G[DEDUP_KEY] as WeakSet<object>;

  api.on("before_prompt_build", async (event: unknown, ctx: { agentId?: string }) => {
    if (dedup.has(event as object)) return;
    dedup.add(event as object);

    const agentId = ctx.agentId || "";
    if (!agentId) return;

    const result = await resolveInjection({ agentId }, api.logger);
    if (result.appendSystemContext) {
      return { appendSystemContext: result.appendSystemContext };
    }
  });
}