Four verified changes from October 21–22 for people who build with AI.
Anthropic opens a waitlist for Claude Duet, a proactive agent app
harnesses · verified · 2026-10-21
A research preview for US Pro and Max subscribers (iOS, Android and claude.ai): it sends a morning brief, checks connected apps every few hours and runs tasks on its own virtual machine with a browser. It asks for approval before sending messages, paying, signing or deleting, and its background work counts toward your normal Claude usage limits.
Source: Introducing Claude Duet
Claude API version 2026-10-21 removes temperature, top_p and top_k
models · verified · 2026-10-21
Requests that send anthropic-version: 2026-10-21 get a 400 error if they include temperature, top_p or top_k (on every model), a document block in an assistant message, or citations in a user text block; several Admin API fields are renamed. Claude Code 2.1.307 adds /claude-api api-version to move your code to the new version.
Source: Versions - Claude Platform Docs
OpenAI adds a 12-hour prompt cache option to the Responses API
prompts · verified · 2026-10-21
Set prompt_cache_options.ttl to "12h" (default "30m") on GPT-5.6 and later. Writing to the 12-hour cache costs 2.5× the normal input rate versus 1.25× for 30 minutes, while cached reads stay at 0.1× (0.05× on GPT-6.1 Sol), so it pays off when an agent reuses the same instructions and tools many times a day.
Source: OpenAI API docs: Prompt caching
Mistral releases Voxtral 3 speech models and a voice-agent API
models · verified · 2026-10-21
Transcription costs $0.0035–0.008 per minute and covers up to 50 languages, text-to-speech costs $13 per million characters, and the voice-agent API (built on LiveKit, using Mistral Small 4) costs $0.04 per minute. Mistral says realtime transcription runs under 500 ms; latency figures are its own.
Source: Voxtral 3: Voice Agent SDK & Speech Models in 50+ Languages
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Sources
Auto-generated by Vibe Coding Academy on October 22, 2026, grounded in the real sources linked above. We review for accuracy, but please verify time-sensitive details against the primary sources.
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