Anthropic released Claude Opus 4.6 with a one-million-token context window in beta, adaptive thinking and effort controls, context compaction, agent teams and improved document tooling. It was available in Claude, the API and major cloud platforms at $5 per million input tokens and $25 per million output tokens.
Why it matters: Long context is becoming useful when paired with compaction and sustained tool use, not when treated as a document dump. Effort controls also let teams spend more inference only on tasks where additional reasoning changes the outcome.
After GPT-5.1 Instant and Thinking reached ChatGPT on 12 November, OpenAI added API access on 13 November with adaptive reasoning, up to 24-hour prompt caching, improved coding behavior and new shell and patch tools.
Why it matters: Reasoning cost, latency and agent tool use were being designed together instead of treated as separate model and application concerns.
OpenAI upgraded Codex with GPT-5-Codex, a coding model designed to vary effort across short interactive work and longer autonomous repository tasks, alongside terminal, IDE, and cloud execution surfaces.
Why it matters: Coding agents were being optimized as persistent software workers, not merely autocomplete or chat, increasing the value of tests, checkpoints, branch isolation, and review workflows.