[Bug] Anthropic API: Fable 5 safety classifier incorrectly flags all new sessions

Bug Description
▎ Fable 5 safety classifier flags ALL fresh sessions from my account, regardless of content. A
▎ bare "hello" in an empty directory gets flagged as cybersecurity/biology — reproduced 7/7 with
▎ no MCP servers (--strict-mcp-config), no memory, no CLAUDE.md, no hooks, scrubbed env (env -i),
▎ on both claude-fable-5 and claude-fable-5[1m]. Opus 4.8 works fine every time. Claude Code
▎ 2.1.175, macOS.
▎
▎ Evidence request IDs: req_011Cby2FQhV717jYYamrm5eA ("hello", scrubbed env, empty dir),
▎ req_011Cby1yCRMK5oqsc6bE9Wss ("hey mate", clean dir).

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.175
• Feedback ID: f010f88a-356e-4dbd-a45b-f9393d4191ee

Errors

[]