refactor: restructure PrismFacet per OpenClaw plugin spec

- plugin/ directory structure: hooks/, tools/, core/
- export default { id, name, register } entry format
- globalThis state management with lifecycle protection
- WeakSet dedup on before_prompt_build hook
- Tool uses inputSchema + execute (not parameters + handler)
- additionalProperties: false in config schema
- Core logic in plugin/core/ (no plugin-sdk dependency)
- Install/uninstall script (scripts/install.mjs)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

plugin/index.ts

@@ -0,0 +1,66 @@
+import path from "node:path";
+import { loadRouters } from "./core/router-loader.js";
+import { initRuleStore } from "./core/rule-store.js";
+import { registerBeforePromptBuild } from "./hooks/before-prompt-build.js";
+import { registerPromptRulesTool } from "./tools/prompt-rules.js";
+
+interface PluginConfig {
+  routersDir?: string;
+  rulesFile?: string;
+}
+
+interface OpenClawPluginApi {
+  logger: {
+    info(msg: string): void;
+    warn(msg: string): void;
+    error(msg: string): void;
+  };
+  on(hook: string, handler: (...args: any[]) => any): void;
+  registerTool(def: any): void;
+  config?: PluginConfig;
+}
+
+const _G = globalThis as Record<string, unknown>;
+const LIFECYCLE_KEY = "_prismFacetGatewayLifecycleRegistered";
+
+function normalizeConfig(api: OpenClawPluginApi): PluginConfig {
+  const raw = (api as any).config ?? {};
+  return {
+    routersDir: typeof raw.routersDir === "string" ? raw.routersDir : undefined,
+    rulesFile: typeof raw.rulesFile === "string" ? raw.rulesFile : undefined,
+  };
+}
+
+export default {
+  id: "prism-facet",
+  name: "PrismFacet",
+
+  register(api: OpenClawPluginApi) {
+    const config = normalizeConfig(api);
+    const pluginDir = path.dirname(new URL(import.meta.url).pathname);
+    const routersDir = config.routersDir || path.resolve(pluginDir, "..", "routers");
+    const rulesFile = config.rulesFile || path.resolve(pluginDir, "..", "rules.json");
+
+    // Gateway lifecycle: init once
+    if (!_G[LIFECYCLE_KEY]) {
+      _G[LIFECYCLE_KEY] = true;
+
+      initRuleStore(rulesFile);
+      loadRouters(routersDir, api.logger).catch((err) => {
+        api.logger.error(`[prism-facet] failed to load routers: ${String(err)}`);
+      });
+
+      api.on("gateway_stop", () => {
+        _G[LIFECYCLE_KEY] = false;
+      });
+    }
+
+    // Agent session hooks: register every time (dedup inside handler)
+    registerBeforePromptBuild(api);
+
+    // Tools
+    registerPromptRulesTool(api, routersDir);
+
+    api.logger.info("[prism-facet] plugin registered");
+  },
+};