What
The internal functions that decide which Anthropic API beta headers to send (covering things like interleaved thinking, per-turn timing, and context management) were rewritten. Instead of long if-chains, they now use two arrays of {beta, when} rules, one for the main request path and one for per-turn timing.
Why
This is an internal restructuring; the behavior for each existing rule appears to be preserved, so it shouldn't change what you see, but it makes the header logic easier to maintain going forward.