AI has eaten tactical programming, so juniors need strategic experience in a low-blast-radius environment.

Here's one way to make that happen:

1. Give them responsibility over a large chunk of work
2. That work must be low stakes, but not no stakes - ideally an internal tool (AI makes these kinds of projects easy to justify)
3. Let them move fast and fail fast. Give them the same AI budgets as your senior engineers.
4. When failures happen, work with them to figure out what went wrong (learnings can also be pulled upwards into the rest of the org)

In a sentence:

Hire juniors. Give them work that matters. Watch them fail. Pick them up.