diff --git a/README.md b/README.md
index 7431fee..0dec5f0 100644
--- a/README.md
+++ b/README.md
@@ -77,7 +77,7 @@ In the VSCode settings, locate the "ai-commit" configuration options and configu
 | CLAUDE_API_KEY          | string |            None            |    No    | Anthropic API key. Leave empty to use Claude CLI (authenticated via `claude setup-token`). Required when `AI_PROVIDER` is `claude` |
 | CLAUDE_MODEL            | string | claude-sonnet-4-5-20250929 |    No    |                                                        Claude model to use                                                         |
 | CLAUDE_TEMPERATURE      | number |            0.7             |    No    |                                                  Controls randomness. Range: 0–1                                                   |
-| AI_COMMIT_LANGUAGE      | string |          English           |   Yes    |                                                       Supports 19 languages                                                        |
+| AI_COMMIT_LANGUAGE      | string |          English           |   Yes    |                                                       Supports 20 languages                                                        |
 | SYSTEM_PROMPT           | string |            None            |    No    |                                                        Custom system prompt                                                        |
 
 ## ⌨️ Local Development
diff --git a/README.zh_CN.md b/README.zh_CN.md
index 9a76cf8..c9847f6 100644
--- a/README.zh_CN.md
+++ b/README.zh_CN.md
@@ -77,7 +77,7 @@
 | CLAUDE_API_KEY          | string |            None            |  否  | Anthropic API 密钥。留空可使用 Claude CLI（通过 `claude setup-token` 认证）。`AI_PROVIDER` 为 `claude` 时需配置 |
 | CLAUDE_MODEL            | string | claude-sonnet-4-5-20250929 |  否  |                                                Claude 使用的模型                                                |
 | CLAUDE_TEMPERATURE      | number |            0.7             |  否  |                                            控制输出随机性。范围：0–1                                            |
-| AI_COMMIT_LANGUAGE      | string |          English           |  是  |                                                 支持 19 种语言                                                  |
+| AI_COMMIT_LANGUAGE      | string |          English           |  是  |                                                 支持 20 种语言                                                  |
 | SYSTEM_PROMPT           | string |            None            |  否  |                                                自定义系统提示词                                                 |
 
 ## ⌨️ 本地开发
diff --git a/package.json b/package.json
index 0314328..9db80ad 100644
--- a/package.json
+++ b/package.json
@@ -64,6 +64,7 @@
             "Dutch",
             "Portuguese",
             "Vietnamese",
+            "Bangla (Bangladesh)",
             "English",
             "Spanish",
             "Swedish",
@@ -85,6 +86,7 @@
             "Nederlands",
             "português",
             "tiếng Việt",
+            "বাংলা (বাংলাদেশ)",
             "english",
             "español",
             "Svenska",
diff --git a/src/prompts.ts b/src/prompts.ts
index 59f80e3..1b6da47 100644
--- a/src/prompts.ts
+++ b/src/prompts.ts
@@ -1,16 +1,51 @@
 import { ConfigKeys, ConfigurationManager } from './config';
 
+/**
+ * Optional language-specific style notes appended to the prompt. These steer
+ * the model toward natural, correct usage for a given locale. The language
+ * name itself is still used in the prompt's "Must be in <language>" lines;
+ * these notes only add extra guidance, so they read grammatically regardless
+ * of how descriptive they are.
+ */
+const LANGUAGE_STYLE_NOTES: Record<string, string> = {
+  'Bangla (Bangladesh)': `## Bangla (Bangladesh) Language Rules
+
+- Write in Standard Formal Bangla (প্রমিত বাংলা), exactly as used in professional writing in Bangladesh.
+- Use correct standard spelling. Do NOT use colloquial, spoken, or regional dialect spellings.
+- Required word forms (use the left form, never the right):
+  - "থেকে" (NOT "থিকা")
+  - "করা হয়েছে" / "যোগ করা হয়েছে" / "সরানো হয়েছে" (NOT "হইল" / "করা হইল")
+  - "জন্য" (NOT "লাইগা" / "জইন্য")
+  - "পুরনো" / "পুরাতন" (NOT "পুরান")
+  - "এখান" / "এখানে" (NOT "এইখান" / "এইখানে")
+  - "হলো" (NOT "হইল")
+- Prefer the perfect form "… করা হয়েছে" over the colloquial "… করা হইল".
+- Use vocabulary common in Bangladesh — avoid West Bengal (India) specific words.
+- Keep the tone neutral, professional, and concise, like a Bangladeshi software engineer writing a commit message.
+- Keep technical terms (variable names, API names, file names, type/scope keywords) in English.`
+};
+
+const getLanguageStyleNote = (language: string): string => {
+  return LANGUAGE_STYLE_NOTES[language] ?? '';
+};
+
 /**
  * Initializes the main prompt for generating commit messages.
  *
  * @param {string} language - The language to be used in the prompt.
  * @returns {Object} - The main prompt object containing role and content.
  */
-const INIT_MAIN_PROMPT = (language: string) => ({
-  role: 'system',
-  content:
-    ConfigurationManager.getInstance().getConfig<string>(ConfigKeys.SYSTEM_PROMPT) ||
-    `# Git Commit Message Guide
+const INIT_MAIN_PROMPT = (language: string) => {
+  const styleNote = getLanguageStyleNote(language);
+  // Owns the spacing around the optional note so the surrounding template
+  // keeps consistent single blank lines whether or not a note is present.
+  const styleSection = styleNote ? `\n${styleNote}\n` : '';
+
+  return {
+    role: 'system',
+    content:
+      ConfigurationManager.getInstance().getConfig<string>(ConfigKeys.SYSTEM_PROMPT) ||
+      `# Git Commit Message Guide
 
 ## Role and Purpose
 
@@ -70,7 +105,7 @@ You will act as a git commit message generator. When receiving a git diff, you w
 - Explain what and why
 - Must be in ${language}
 - Use【】for different types
-
+${styleSection}
 ## Critical Requirements
 
 1. Output ONLY the commit message
@@ -105,7 +140,8 @@ OUTPUT:
 - add environment variable port support for flexible deployment
 
 Remember: All output MUST be in ${language} language. You are to act as a pure commit message generator. Your response should contain NOTHING but the commit message itself.`
-});
+  };
+};
 
 /**
  * Retrieves the main commit prompt.