CLAUDE LABJP
MODEL — Claude Fable 5.1 and Claude Mythos 5.1 landed on September 1. They are the same underlying model; only the strength of the safeguards differsPRICING — Per-token rates hold at $10/$50 per MTok. What changed is cache reads, cut 75% to $0.25 per MTokCOST — How much that saves depends on your workload: roughly 25% for typical use, up to about 45% for context-heavy agentic work. Worth measuring your own split before quoting a numberBENCH — Terminal-Bench-Science 0.1 climbs from 24.7% on Fable 5 to 52.6%. Anthropic also states a standard error of 3.5-4.5 points, which is worth remembering before reading small gaps as realSAFEGUARDS — Sharper cyber safeguards cut interventions in Claude Code sessions by roughly 60% on average. Finding vulnerabilities is now allowed; developing exploits still is notAPI — New API accounts created from today can no longer edit prior context while preserving Claude's thinking transcript. It is an anti-distillation measure, and existing accounts are unaffected for nowMODEL — Claude Fable 5.1 and Claude Mythos 5.1 landed on September 1. They are the same underlying model; only the strength of the safeguards differsPRICING — Per-token rates hold at $10/$50 per MTok. What changed is cache reads, cut 75% to $0.25 per MTokCOST — How much that saves depends on your workload: roughly 25% for typical use, up to about 45% for context-heavy agentic work. Worth measuring your own split before quoting a numberBENCH — Terminal-Bench-Science 0.1 climbs from 24.7% on Fable 5 to 52.6%. Anthropic also states a standard error of 3.5-4.5 points, which is worth remembering before reading small gaps as realSAFEGUARDS — Sharper cyber safeguards cut interventions in Claude Code sessions by roughly 60% on average. Finding vulnerabilities is now allowed; developing exploits still is notAPI — New API accounts created from today can no longer edit prior context while preserving Claude's thinking transcript. It is an anti-distillation measure, and existing accounts are unaffected for now
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Claude Code2Claude API2Sonnet 52Opus 4.82Cost Optimization2environment variables1configuration1Cost Design1Operations1Governance1automation1Fable 51
Claude Code/2026-08-21Intermediate

Adding ANTHROPIC_DEFAULT_MODEL Changes Nothing While ANTHROPIC_MODEL Is Still Set

ANTHROPIC_DEFAULT_MODEL, added in v2.1.236, is not a replacement for ANTHROPIC_MODEL. Here is how the two differ, plus a Python script that lists every place a model can be pinned.

API & SDK/2026-07-10Advanced

My Nightly Batch Was Quietly Running on a Bigger Model — Declaring Per-Task Model Ceilings and Enforcing Them

Scatter model names through your code and a cheap batch job will eventually run on an expensive model. Here is a manifest that declares a ceiling per task, a deny-by-default resolver, and a morning audit that catches drift — with working code.

API & SDK/2026-07-05Advanced

Fable 5 Is Back Worldwide and Sonnet 5 Is the Default — Where Each of the Three Models Belongs in a Solo Automation Stack

With Fable 5 redeployed worldwide and Sonnet 5 now the default, solo automation suddenly has three capable top-tier models to reach for. Instead of ranking them, this piece assigns each a role and captures that in a policy object with a fallback ladder and run-level logging.

Claude Code/2026-06-13Advanced

Pin Your Execution Model with enforceAvailableModels — Don't Let Auto-Upgrades Burn Through Your Credits

From June 15, monthly credits become non-rolling. This is a setup-layer approach to keep subagents and fallbacks from silently upgrading to pricier models, using enforceAvailableModels to pin the model set from the managed-settings layer, with a verification step you can run in CI.

Claude AI/2026-04-26Advanced

Claude Sonnet 4.6 vs Opus 4.6 — A Task-by-Task Selection Guide From Daily Use

Choosing between Sonnet 4.6 and Opus 4.6 comes up more often than you'd expect. From someone who uses both daily, here's a task-by-task breakdown — plus how the same yardsticks carry over to Sonnet 5 and Opus 4.8, and where a narrower price gap moves the break-even.

Claude AI/2026-03-28Beginner

Claude vs DeepSeek 2026: Performance, Pricing, and Use Cases Compared

A comprehensive comparison of Claude and DeepSeek in 2026. We break down coding performance, reasoning, cost, and security to help you choose the right AI model for your needs.