A renamed file created a duplicate post

The reassuring news first: renaming a markdown file does not normally create a duplicate. Specter identifies each post by a ghost_id value stored in the file’s frontmatter, not by the filename. So you can rename a file freely — the post is matched by its id, and Specter updates the existing Ghost post rather than making a new one.

A duplicate appears in one specific situation: a file reaches Specter without a ghost_id in its frontmatter. When Specter sees a local file that has no id, it has no way to know which existing post it belongs to, so it treats it as brand new and creates a fresh post on Ghost. That usually happens if the frontmatter got stripped during a rename or move, if you copied a post’s body into a new file by hand, or if a tool rewrote the file and dropped the metadata block.

To avoid it, keep the whole frontmatter block — including the ghost_id line — intact whenever you move or rename a post. If a duplicate has already been created, the fix is straightforward: delete the unwanted copy in your Ghost admin, and make sure the file you are keeping still has its original ghost_id so it continues to map to the right post on the next sync.