Fixes 23 issues (addressing 13 👍). Run multiple scripts in --parallel or --sequential. bun:test mock & spyOn get Symbol.dispose support. ESM bytecode compilation. Faster Bun.markdown. Faster RegExp, String.prototype.trim, String.prototype.startsWith.

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Bun v1.3.9 introduces parallel and sequential script execution with `--parallel` and `--sequential` flags, supporting workspace filtering and Foreman-style output. Testing improvements include `Symbol.dispose` support for automatic mock cleanup. Performance enhancements include SIMD-accelerated RegExp matching, faster string operations (trim, startsWith), optimized Markdown rendering, and ESM bytecode compilation support. HTTP/2 connection upgrades via net.Server now work correctly. Bug fixes address ARM64 crashes, Windows filesystem operations, WebSocket stability, and HTTP proxy keep-alive issues.

Bun v1.3.9

bun run --parallel and bun run --sequential

HTTP/2 Connection Upgrades via net.Server

Symbol.dispose support for mock() and spyOn()

NO_PROXY now respected for explicit proxy options

Fixed: Illegal instruction (SIGILL) crashes on ARMv8.0 aarch64 CPUs

Faster AbortSignal.abort() with no listeners