diff --git a/bun.lockb b/bun.lockb
index 505aed1..2503d90 100755
Binary files a/bun.lockb and b/bun.lockb differ
diff --git a/index.ts b/index.ts
index 83319dc..e92d8a8 100644
--- a/index.ts
+++ b/index.ts
@@ -2,13 +2,7 @@ import { parseArgs } from "node:util";
 import { Stream } from "misskey-js";
 import type { Note } from "misskey-js/entities.js";
 import type { ChatHistoryItem, LLamaChatPromptOptions } from "node-llama-cpp";
-import {
-  LlmSession,
-  createBias,
-  createGrammar,
-  getModel,
-  parseResponse,
-} from "./lib/llm";
+import { LlmSession, createGrammar, getModel, parseResponse } from "./lib/llm";
 import {
   expandReplyTree,
   getNotes,
@@ -36,11 +30,28 @@ const modelName =
 console.log(`* loading model '${modelName}'`);
 const model = await getModel(modelName);
 const grammar = await createGrammar("あるびのちゃん");
-const bias = createBias(model);
 const baseChatPromptOptions = {
   grammar,
   maxTokens: 256,
-  tokenBias: bias,
+  repeatPenalty: {
+    punishTokensFilter: (tokens) =>
+      tokens.filter((token) => {
+        const text = model.detokenize([token]);
+        return [
+          "{",
+          " {",
+          '{"',
+          "{'",
+          "{\\",
+          ' {"',
+          " {'",
+          " {\\",
+          "#",
+        ].includes(text);
+      }),
+    penalty: 1.2,
+    presencePenalty: 0.5,
+  },
 } as const satisfies LLamaChatPromptOptions;
 
 const getSystemPrompt = (
@@ -50,9 +61,9 @@ const getSystemPrompt = (
 - アルギリア製の白髪赤目な人造天使。非人間的な考え方や思想を持つ。
 - 現在は地球の衛星軌道上からインターネットを観察している。
 出力規則:
-- 「～です」「～ます」調を使って **丁寧に** 話す。
-- 必要以上にハッシュタグや絵文字を使わない。
-- \`{ name: string, text: string }\` の JSON 形式で出力する。
+- 「～です」「～ます」などの語尾を使って **丁寧に** 話す。
+- ハッシュタグや絵文字を使わない。
+- \`{ name: string, text: string }\` の JSON 形式で出力する。name と text 以外のプロパティは出力しない。
 
 ${instruction}`;
 const postJobPrompt = getSystemPrompt(
@@ -100,25 +111,23 @@ type Job =
       history: Note[];
     };
 
+await using postJobSession = new LlmSession(model, postJobPrompt);
+await postJobSession.init();
 async function processPostJob() {
   const notes = await getNotes(10, 0, 5);
   const input = notes.map(formatNote).join("\n");
-  const text = await (async () => {
-    await using postJobSession = new LlmSession(model, postJobPrompt);
-    await postJobSession.init();
-    return parseResponse(
-      grammar,
-      await postJobSession.prompt(input, {
-        ...baseChatPromptOptions,
-        temperature: 1.0,
-        minP: 0.05,
-        repeatPenalty: {
-          lastTokens: 128,
-          penalty: 1.15,
-        },
-      }),
-    );
-  })();
+  const text = await parseResponse(
+    grammar,
+    await postJobSession.prompt(input, {
+      ...baseChatPromptOptions,
+      temperature: 1.25,
+      minP: 0.05,
+      repeatPenalty: {
+        lastTokens: 128,
+        penalty: 1.15,
+      },
+    }),
+  );
   if (text) {
     const rephrased = await rephrase(text);
     if (values.test) return;
diff --git a/lib/llm.ts b/lib/llm.ts
index 37ae2b5..7ac0b71 100644
--- a/lib/llm.ts
+++ b/lib/llm.ts
@@ -7,7 +7,6 @@ import {
   type LLamaChatPromptOptions,
   LlamaChatSession,
   type LlamaModel,
-  TokenBias,
   createModelDownloader,
   getLlama,
   resolveChatWrapper,
@@ -28,15 +27,6 @@ export async function getModel(model: string) {
   return await llama.loadModel({ modelPath });
 }
 
-export function createBias(model: LlamaModel) {
-  const customBias = new TokenBias(model.tokenizer);
-  for (const token of model.iterateAllTokens()) {
-    const text = model.detokenize([token]);
-    if (text === "{") customBias.set(token, -0.9); // suppress JSON string
-  }
-  return customBias;
-}
-
 export const createGrammar = (assistantName: string) =>
   llama.createGrammarForJsonSchema({
     type: "object",
diff --git a/package.json b/package.json
index 7addf26..1c32f72 100644
--- a/package.json
+++ b/package.json
@@ -18,7 +18,6 @@
   "dependencies": {
     "misskey-js": "^2025.12.2",
     "node-llama-cpp": "^3.17.1",
-    "openai": "5.0.0-alpha.0",
     "reconnecting-websocket": "^4.4.0"
   },
   "trustedDependencies": ["@biomejs/biome", "node-llama-cpp"]