Can an idea be patented?

An idea itself cannot be patented: “Only the technical means used to implement it can be,” as stated by the INPI (French National Institute of Industrial Property) in the article: https://www.inpi.fr/fr/comprendre-la-propriete-intellectuelle/le-brevet/ce-qui-est-brevetable-ou-pas

The best practice is therefore to ask the question, after the idea has been submitted and during the analysis and decision phase:
“Can the implementation of this idea lead to a patent?”
If the answer is yes, the idea should at the very least be marked as confidential. It should then follow a dedicated handling process, either within the application or outside of it.