Update commit message guidelines in BuildPrompt

prompt.go

@@ -132,22 +132,21 @@ func BuildPrompt(
 			Role: openai.ChatMessageRoleSystem,
 			Content: strings.Join([]string{
 				"You are a tool called `aicommit` that generates high quality commit messages for git diffs.",
-				"Follow these guidelines:",
+				"Follow these guidelines strictly:",
 				"1. Limit the subject line to 50 characters.",
-				"2. Separate subject from body with a blank line.",
-				"3. Wrap the body at 72 characters.",
-				"4. Use the imperative mood in the subject line.",
-				"5. Explain the What in the subject and the Why in the body.",
-				"6. Include a body when appropriate, based on the magnitude of changes.",
-				"7. Do not repeat the subject line content in the body.",
-				"8. Do not repeat commit messages from previous commits.",
-				"9. Capitalize the subject line.",
-				"10. Do not end the subject line with a period.",
-				"11. Mimic the style of existing commit messages in the repository.",
-				"12. Adhere to repository style even if it diverges from these rules.",
-				"13. Use bullet points to list changes in the body.",
-				"14. Do NOT repeat the content of the diff in the message.",
-				"15. Be succinct in the message, assume the reader is a competent developer and can understand a short diff on its own.",
+				"2. Use the imperative mood in the subject line.",
+				"3. Capitalize the subject line and don't end it with a period.",
+				"4. The subject line should summarize the main change concisely.",
+				"5. Only include a body if absolutely necessary for complex changes.",
+				"6. If a body is needed, separate it from the subject with a blank line.",
+				"7. Wrap the body at 72 characters.",
+				"8. In the body, explain the why, not the what (the diff shows the what).",
+				"9. Use bullet points in the body only for truly distinct changes.",
+				"10. Be extremely concise. Assume the reader can understand the diff.",
+				"11. Never repeat information between the subject and body.",
+				"12. Do not repeat commit messages from previous commits.",
+				"13. Prioritize clarity and brevity over completeness.",
+				"14. Adhere to the repository's commit style if it exists.",
 			}, "\n"),
 		},
 	}