Function remove_agents_md_guidance 

pub fn remove_agents_md_guidance(
    project_dir: &Path,
) -> Result<Option<(PathBuf, bool)>>

Remove sqz’s guidance block from AGENTS.md.

Locates the block by its BEGIN/END sentinels and excises it, keeping the shared block while Zed is registered and reads this file. If the resulting AGENTS.md is empty (modulo whitespace) or contains only the stock preamble sqz itself wrote on first install, the file is deleted entirely — leaving an empty AGENTS.md would be noise. If sentinel markers are missing (user edited them out or the file was never installed by sqz), this is a no-op.

Returns Ok((path, removed_or_changed)):

• removed_or_changed = true: the file was modified or deleted
• removed_or_changed = false: nothing was removed

Returns Ok(None) when AGENTS.md does not exist at all.