This paragraph has *constrained bold* text that requires word boundaries.
It works at the *beginning* and at the *end*.
But not in the*middle*of words without boundaries.
**Unconstrained bold with *nested constrained bold* inside**.
Edge cases: *word*.punctuation and *word*,comma and *word*!exclamation.
Multiple words: *multiple word bold phrase* with spaces.
Mixed: *bold* and _italic_ together.
Nested with italic: **Unconstrained bold with _nested constrained italic_ inside**.