You have awesome engineers, and they want to advance in their career. Their team is growing because of advancements they've made, and you want to recognize the work they've done with something. The obvious answer is to put them in charge of the team they've built, especially as they're the de-facto leader of the team already. But is this what they want? Or just what they believe they're supposed to want?
People Management Is A Different Skill
It's well known in the engineering world that engineers often will reach a technical peak, only to be asked to learn an entirely new set of skills, revolving around social and soft skills that they've spent the past chunk of their career probably ignoring. Building these skills involves a lot of trial and error, and above all, most of their time. Their time is now spent not coding, which is what they were originally rewarded for. Suddenly, they go from being good at their job to bad at it, which destroys confidence and job satisfaction.
The problem here is that people management is a different skill than technical leadership. What you want is to reward someone with recognition that they are a thought leader, an exceptional performer- to make them an example of what others should strive to be. Everyone can't strive to be a manager, who would do the work? Additionally, you don't want to send the message that management, as a career, is somehow "better" than coding or anything else in the company, for that matter.
What Is Technical Leadership?
Technical Leadership is composed of several aspects of purview over parts of job responsibility. Think about the day of a typical engineer- many decisions have to be made, problems have to be prioritized, solutions need to be found. Those are the fun parts of any engineer's job, and indeed all engineers must exercise some degree of technical leadership.
The rest of the job involves answering questions about how a thing you made works or doesn't work. Bugs need to be found and fixed. Documentation has to be written. Code has to be reviewed. Estimations must be made. Most of all, the longer an engineer remains at a company, the harder it is to find a few hours of isolation, free from interruption, to get work done. These parts, they are the worst parts of the job.
All of the fun work happens in these uninterrupted times, and these uninterrupted times happen only when your disappearance doesn't materially slow down someone else's work. Innovation happens when you have the bandwidth to hold the entire problem in your head- most of the time that takes a great deal of "load time" - research and contemplation about the problem. For introverts this means quiet, for extroverts this means dedicated time in a room of other people you work well with, thinking about the problem.
So what gets in the way? Why can't exceptional engineers have more fun work, and have someone who is yet to be recognized do more of the less fun things? The key is in empowerment, and an engineer's ability to say "No". This isn't a function of courage, it's a function of empowerment - most exceptional engineers can't just let problems go unsolved, and if they feel responsible for a product or service, they end up chained to the project forever. Engineers often feel responsible for a project for the rest of its life, and this is exacerbated by the tendency for information to "silo" in one person, rather than distributing across a team.
How To Empower Your Technical Leaders
As a project grows, a technical leader might naturally accrue team members, and accidentally transform into a people manager. This is the biggest risk. The way to empower your technical leaders is to set expectations early and often, encouraging them to be clear about their ultimate goals, without sending the message that they will be less respected if they don't transition into people management. If their goal is to be the best programmer imaginable, or to create a system that scales to 10 million users, or to understand deep processes in the operating system, then finding ways to help them reach their goals is rewarding for everyone.
Technical goals are easy to meet - there will be plenty of opportunities as a company grows to reward engineers with "fun" projects, and the ability to learn and grow as an engineer. Identify when someone will have to learn a lot for a role, these roles are rewarding and coveted. Also find opportunities to allow for professional development outside of your company, such as encouraging engineers to go to conferences and give talks, and become thought leaders in their field. Most engineers don't have an actionable plan for their own professional development, and so can benefit from advice on how to celebrate their accomplishments by putting them in a favorable position. This also will help you make the case for raises and bonuses, and will increase the esteem of your engineering department in general, which in turn attracts more talent. Seeing someone speak on something that interests them is the number one reason why mid-to-senior level engineers seek employment in an organization, rather than being recruited. Developing a strategy for positioning your technical thought leaders as the technical thought leaders is empowering, and it helps them empower themselves.
The ability to say "No" is the second component of a technical leader - develop a strategy around handoffs. The objective here is to reward innovators by not chaining them to their innovations forever - it encourages those who create to continue creating. Junior developers are perfect to hand off smaller creations to, it helps them develop a sense of ownership without having to understand deeply the best practices that created the idea. Handoffs create opportunities in both directions- both for the person with more time, as well as the person accepting the responsibility. The incentives align well, but make sure there are expectations for the person receiving the responsibility- be honest about what it means for their career, and set up a strategy around them getting help with the project.
I came up with these ideas by helping Simple activate and reward their talent with things they actually want, rather than taking the obvious-but-wrong path. If you need help developing strategies for creating opportunities for your technical leaders, email me. I'm a consultant and I'm also an engineer myself, so I can provide insights into how to keep engineers happy and productive.