API

Fable 5 ships with safety classifiers that route flagged requests away from the model. In production you need to handle this, and Anthropic shipped three ways to do it. Here's how each one works, with code, plus the billing rules nobody has written up.

Anthropic's Claude Fable 5 mandates 30-day data retention on every platform, overriding existing Zero Data Retention contracts for enterprise API customers. Here is what compliance teams and developers need to audit before their next deployment.

12 days out from the Fable 5 promotional window closing on claude.ai, here is the practical checklist for Pro users, Max subscribers, teams, and API developers - what to decide, what to test, and what not to worry about.

Claude Fable 5 routes blocked queries to Opus 4.8 rather than refusing outright - but the fallback is not automatic for API users and requires explicit configuration. Here is the complete developer guide to the refusal architecture.

Fable 5 is mostly a drop-in replacement for Opus 4.8, but 'mostly' is doing real work in that sentence. Here's every breaking change, what to delete from your code, and the prompt audit you should run before flipping the model ID.

OpenRouter gives you one API key for 300+ models, automatic fallbacks, and intelligent provider routing. Here is what it actually costs, how to set it up in five minutes, and when you should skip it entirely.

10 min read

DeepSeek V4 splits into Flash and Pro, ships a 1M context window, and undercuts every closed model on price. Here's how to wire it up with the OpenAI SDK, when to pick it over Claude or GPT, and what changed since V3 and R1.

10 min read

A hands-on developer guide to Mercury 2 from Inception Labs. OpenAI-compatible API, reasoning levels, tool use, structured outputs, and when a diffusion LLM beats an autoregressive one in real apps.

13 min read

OpenAI is sunsetting the Assistants API in 2026. Here is a tested migration plan to the Responses API - code, state, threads, tools, every cliff I hit, in order.