Wresrg

Does your company have a clear/clean desk policy? i.e. no sensitive documents to be left on the desk/"out" when the employee is away (usually overnight, but it depends on the company). Put your notebook in the desk drawer and lock it.

Years ago I had a similar problem where an office junior would take our ideas to a senior manager who would burst into the office the following day with a great idea "he had just come up with".

It's unprofessional (although very funny), but my colleague's solution was to invent plausible sounding garbage solutions, then watch the manager's face when asked what the benefits would be or how it could be implemented. Eg we should store all dates in hex to avoid the Office 2016 problem and leapfrog our competition.

Make your notes publicly available (within your organization or team).

Securing your notebook will be an easier option, but as you've asked for other approaches you might consider this one.

This will be varyingly convenient depending on how your workplace operates, but if you have something like a Sharepoint site or internal blogging service you can keep your future project notes there instead of on a notepad in your desk. Alternatively you can meet regularly with your boss and go through your ideas for new projects. As long as it's only accessible to the appropriate people in your company or workgroup you shouldn't have to worry about confidential information leaking as a result of this practice.

You can be more creative as well, making things like ranked-choice surveys for executives to vote on which projects they think should have the highest priority, etc.

In any case you are creating a contemporaneous record of your ideas in a manner which identifies them as yours-- update histories, your boss' notes, and so on put ideas "out there" but still identify those ideas as your own.

I, personally, would also include a note in my notebook outlining that I know what the snooping coworker has been up to and am not pleased about it, ideally with some kind of tamper-evident countermeasure (like a thread taped across the drawer which will be broken if the drawer is opened). A change in your practices will be obvious to the snoop anyways, so there's little reason not to be a pointed in making sure they know why those changes are happening.

I once had a coworker who copied my code. It was brought to my attention after a QA person asked why both our codes looked so similar. At first, I thought it was merely a coincidence because after all there's so many ways to do something.

What I found out is each night I would push to my Github account with all my branches I worked on the day. Just as a backup. I named each branch by the issue ticket I'm working on and you can easily see each commit I made. The Git account is private but anyone within the company can view anyone else's account except outside the company.

I decided to go in deeper. I'd name things a certain unique way, even putting hashtags into variable names and so forth. I checked the released code and sure enough my code with my unique hashtag was on it. I'm not sure why this person did this but the issue with my coworker was due to shyness and aversion to speaking with others. This person would go to extreme lengths to not talk to people and working with this individual became very frustrating. After a while the boss figured it out.

This is what I think you should do. While your coworker might see the same problems you're seeing and arriving to the same conclusion, you have to be sure. Put something unique in your journal that you know someone can't just come up. That way you can have proof before seeing the boss.

If I was you, I would be having a chat with the boss about this, and I'd obviously want to be reasonably sure on my suspicions.

The reason I'm complaining to the boss, of course, is because this dishonest conduct defrauds the company and makes me feel less inclined to jot down my ideas.

Also, my notes would contain an incomplete picture of different ideas. Maybe there are some important elements that is getting missed because it's still in my head. Maybe by running behind my back with my ideas, you'll be running with a good idea, instead of a great idea.

What I would say about your situation however, is you have notes, he has actions. Maybe it's time to start taking those notes, and turning them into initiatives. You should from time to time mention these ideas to your boss, flesh them out, write plans. Good ideas are of no use on paper, they need to be acted on.