1
Understanding Classifier Refusals
How Fable 5's safety classifiers work, what stop_reason 'refusal' and categories like 'cyber' and 'bio' mean, and how to handle refusals in application code.
Start lessonRefusals, Fallbacks & Production Reliability
Handle safety-classifier refusals gracefully, wire up server-side fallbacks to Opus 4.8, and run Fable 5 within its retention and latency constraints.
Lessons in this module
Follow the lessons sequentially for best understanding
2
Server-Side Fallbacks: The Recommended Pattern
Wire up the server-side-fallback beta so refused Fable 5 requests automatically fail over to Opus 4.8 — no client-side reroute code, no second round-trip.
Start lesson3
The Production Envelope: Retention, Timeouts, Monitoring
Run Fable 5 inside its operational constraints — the 30-day retention requirement, ZDR exclusion, per-effort timeout budgets, and the four metrics every deployment needs.
Start lessonKey skills
What you'll master in this module
Practical knowledge
Gain practical experience you can apply immediately
Expertise
Develop deeper domain expertise
Communication
Learn to communicate your knowledge effectively
Documentation
Create your own notes and documentation
Problem analysis
Learn systematic approaches to complex problems
Optimization
Optimize for performance and efficiency
Tips for success
How to get the most out of this module
1
Proceed step by step
Don't move on until you fully understand the previous lesson
2
Practice regularly
Spend daily time on the practical lesson exercises
3
Take notes
Write down key insights and your own thoughts
4
Ask questions
If something is unclear, ask the community for help
5
Test knowledge
Validate learning with exercises and quizzes
6
Share insights
Teach concepts to others to reinforce retention