Anthropic launched mid-conversation system messages for Claude Opus 4.8, without a beta header.

Instruction changes during long-running sessions no longer have to break prompt cache hits.

For builders, instruction changes now sit after a user turn in messages, subject to placement rules.

• Jun 11, 2026OpenAI modelcard diff shows the API docs navigation content removed.
• Jun 11, 2026OpenAI pricing page removed visible API pricing content for GPT-5.5, GPT-5.4, and realtime.
• Jun 11, 2026Anthropic launched Claude Fable 5 and Claude Mythos 5 with 1M context and 128k max output.

This is the world we build in. It moves this fast. We move with it.