How do I work around a touchy manager relationship as a software engineer?
The definition of "touchy" is "oversensitive and irritable," which necessarily means they are a poor manager. Good managers are calm, rational, and are empathetic to the needs of their subordinates. What you have is better called a "boss," as they allow their personality flaws to show in their managerial approach. Therefore, I read your question as, "How do I work around an oversensitive and irritable boss?"
Working for a bad boss is often cited as the #1 reason why people quit their job, and I would be remiss not to recommend that you find a new position working for an experienced manager. Touchy bosses tend to focus primarily on the mistakes you make, which can result in unconstructive criticism. After a few months of this type of treatment, you will be miserable and start looking for a job anyway, so there's little point in delaying the search. However, your question was not, "Should I quit my job?" but "How do I work around?" so I assume that you are unable to switch jobs.
Both oversensitivity and irritability point to your boss struggling with anxiety. A primary source of anxiety for a manager is - ironically - their boss. The pressure they feel from their superior can lead to them taking out their frustrations on their subordinates. As the saying goes, "You can tell the character of a person by how they treat those they do not have to treat well," and many bosses believe they do not have to treat their subordinates well. Therefore, they feel entitled to abuse their authority and use their staff as an emotional punching bag in a futile attempt to help themselves feel better. It is a profound maladaptive stress reaction that is all-to-common among managers under extreme pressure to perform.
To make them easier to deal with, helping your boss deal with the sources of their stress might help improve their managerial style. For issues in their personal life, there is not much you can do. However, managers often deal with a copious amount of pressure at work, and you might be able to alleviate some of their stress to help calm them down:
Are they overseeing a project that is behind schedule? Help to put the project back on schedule.
Are their subordinates not performing? Help them improve the performance of low-performing individuals.
Are people constantly complaining to them about work conditions? Help address the source of the complaints.
All of these are easier said than done and share the characteristic of rewarding bad behavior. Indeed, if being a bad boss gets them results, why would they change? However, reducing the ambient stress your boss deals with might improve their managerial approach. Then again, it may not. People can be so unaware of the sources of their anxiety that they need a professional therapist to help them understand why they feel the way they do. As you are not their therapist, helping them address the underlying causes of their psychology is not your responsibility.
All that I have said previously assumed your boss was touchy with everyone. If they are only irritable with you, then you must consider if you might be at fault. The good news is that if you are the source of the problem, you are in the best possible position to fix it. The bad news is, only a poor manager would isolate a single employee for mistreatment. In other words, while you may have more control over your situation if you are the cause of their bad behavior, they are still a bad boss. A good boss seeks to improve employees they feel are under-performing, not treat them poorly.
If you are aware that you are underperforming, and that is the source of your boss’s irritability towards you, the simplest solution is to improve your performance. Sadly, a bad boss is also bad at giving feedback about how you are underperforming and what you can do to improve. They may subjectively feel you are underperforming, but can't back up that claim with anything objective. You can test for this scenario by asking them, "Tell me all the things that I can do to improve." If they have no feedback for you, then their negative feelings towards you are personal. If they have a personal bias against you, then you absolutely must find a new job.
Neil writes a lot more about the softer side of software development over at neilonsoftware.com. Check it out!