v5 megathread

[pranaygp]

Now that 4.x is a stable release, it opens up v5 to start shipping the new features we've been waiting for. The v5 roadmap is focussed on performance and parity on basic functionality we've been lacking like concurrency contorls and idempotency

Features:

• Concurrency Controls #301
• VM Snapshot Runtime — Replace Event Replay with WASM Snapshot/Restore #1298
• feat: serializable AbortController/AbortSignal #1301
• Cancellation RFC #537
  • via feat: serializable AbortController/AbortSignal #1301
• Attributes - A unified solution for idempotency and observability #132
• Crons #1649
• [core] Combine flow+step bundle and process steps eagerly #1338
• Unified workflow.config.ts configuration file to replace env variables and independent builder configs
• Observability V2 - Featuring a redesigned trace viewer

Minor changes:

• [world] Restructure stream interface, require run ID for all step and stream operations #1293
• [builders] Switch Vercel Build Output API from CJS to ESM #1562

Vercel World:

• Globally distributed (remove the iad1 single region limitation)