[3.1.1] HTML/XML tags are getting stripped from prompt

[marcopixel]

Describe the bug

When saving a prompt that contains structured tags (e.g. <instructions>, <context>), the editor removes these tags, resulting in a flattened, unstructured prompt. This happens either in Rich-Text editor mode and Source editor mode. This is probably a side effect of the new editor implemented at #5988, reverting back to 3.1.0 fixed the issue for me.

This is problematic because major LLM providers explicitly recommend structured prompting with XML-style tags. Removing them breaks the intended structure, reduces model reliability, and undermines best practices for clear instruction separation and predictable outputs.

Guidelines:

• https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/claude-prompting-best-practices#structure-prompts-with-xml-tags
• https://developers.openai.com/api/docs/guides/prompt-engineering?prompt-example=prompt#message-formatting-with-markdown-and-xml

To Reproduce

1. Open Agentflow V2
2. Create a new LLM/Agent node
3. Open any prompt input
4. Enter the following text:

<question>
{{question}}
</question>
<current_date_time>
{{current_date_time}}
</current_date_time>

5. Save and reopen

Expected behavior

The tags should be retained in the prompt output and not being removed.

Screenshots

Before saving:

After saving:

Flow

No response

Use Method

Docker

Flowise Version

3.1.1

Operating System

Linux

Browser

Chrome

Additional context

No response

[Hetsavani]

I would like to work on this issue. Please assign it to me.

[jocelynlin-wd]

PR #6095