1.31.0 Releaase

Debugging

• The VS Code debugger now sets breakpoints inside concurrent worker bodies:
  async.run / async.all / async.race workers, generator bodies, and
  network request handlers, in addition to the main script. Each running
  worker appears as its own thread in the Call Stack pane; hitting a
  breakpoint stops all threads, Continue resumes them, and a step advances
  only the selected thread.

Performance

• String index (s[i]), substring / slice, and length() now cache rune
  offsets for strings longer than 256 bytes, making each access amortized O(1)
  and a character-scanning loop O(n) instead of O(n^2). Shorter strings are
  rescanned per access with a maximum scan of 256 bytes. The cache is
  concurrency-safe and memory-bounded, with no API change.