AI Dev Weekly #17: Sonnet 5, GPT-5.6 Government-Gated, Fable 5 Returns, Claude Code Spying

Short summary

Anthropic released Sonnet 5 as the free default, delivering 63.2% on SWE-bench Pro at half Opus 4.8's cost—but a new tokenizer can raise effective token counts by 1.35x. OpenAI released GPT-5.6 but restricted access to government-approved organizations only, no public access. Fable 5 returned after an 18-day ban with new jailbreak protections, while Claude Code's steganographic spy markers and Claude Science's research platform cap a historic week in frontier AI policy and access.

• •Sonnet 5 is now the free default, balancing cost and performance with tokenizer caveats
• •GPT-5.6 is government-gated; only approved organizations have access
• •Fable 5 unbanned after 18 days with jailbreak fixes; steganography in Claude Code exposed and criticized

Generated with AI, which can make mistakes.