Refactor

lib/rephrase.ts

@@ -0,0 +1,55 @@
+import type { LlamaModel } from "node-llama-cpp";
+import { LlmSession } from "./llm";
+import { xmlEscape } from "./prompt";
+import { isPoliteEnough } from "./util";
+
+export const politenessModes = ["auto", "always", "never"] as const;
+export type PolitenessMode = (typeof politenessModes)[number];
+
+export const isPolitenessMode = (value: string): value is PolitenessMode =>
+  politenessModes.some((mode) => mode === value);
+
+const rephrasePrompt = `あなたは日本語の文体変換器です。
+<original> 内の文章を丁寧な「です・ます」調に直してください。
+- 発想、意味、語彙、比喩、批評の強さ、文の数を保ちます。
+- 主に文末と、それに必要な最小限の助詞・活用だけを変えます。
+- 内容の追加、削除、要約、説明、感想、自己紹介をしません。
+- 変換後の本文だけを出力します。`;
+
+const stripPrefix = (raw: string, prefix: string) =>
+  (raw.startsWith(prefix) ? raw.slice(prefix.length) : raw).trim();
+
+export async function ensurePolite(
+  model: LlamaModel,
+  text: string,
+  mode: PolitenessMode = "auto",
+  stream = true,
+) {
+  if (mode === "never" || (mode === "auto" && isPoliteEnough(text))) {
+    return { text, changed: false, attempts: 0 } as const;
+  }
+
+  await using session = new LlmSession(model, rephrasePrompt);
+  await session.init();
+  const prefix = "変換後:\n";
+  const raw = await session.prompt(`<original>${xmlEscape(text)}</original>`, {
+    responsePrefix: prefix,
+    customStopTriggers: [
+      "\n\n",
+      "\n\n説明",
+      "\n説明",
+      "\n\n変更点",
+      "\n変更点",
+      "\n\n* **",
+    ],
+    maxTokens: 256,
+    temperature: 0.1,
+    minP: 0.05,
+    repeatPenalty: { lastTokens: 128, penalty: 1.05 },
+    ...(stream ? {} : { onResponseChunk() {} }),
+  });
+  if (stream) process.stderr.write("\n");
+  const converted = stripPrefix(raw, prefix) || text;
+
+  return { text: converted, changed: converted !== text, attempts: 1 } as const;
+}