NLP Lineage

17 February 2026 · Efficiency and infrastructure

Claude Sonnet 4.6

Claude Sonnet 4.6

Anthropic

Date
17 February 2026
What the date marks
Model release
Kind
Model
Organisation
Anthropic
Access
API only
Threads
In the guided tour
Chapter 14. Where the threads meet now
Learning phases
7. Agents

Too recent for its influence to be judged: no later milestone in the data descends from it yet. How levels are decided

Figures quoted here are reported by the organisation that built it, not independently verified.

Full summary in progress. Until then, this page shows the milestone's record from the research data.

What it changed

Before it

Long context on the mid tier was capped at 200K tokens.

The problem

Agents working across large repositories exhaust that quickly.

What it introduced

A mid-tier model with a million-token context in beta.

Why it matters

Long context reached the price tier that agents actually run on.

What modern models inherit

Very long context at mid-tier prices.

What came next

The Claude 5 generation mid-year.

Before and after

The milestones it descends from, and the milestones that descend from it. Work developed alongside it is not counted. Weak links are left out unless you include them.

Before: where it came from

No documented ancestors are recorded for Claude Sonnet 4.6 without weak links.

No documented ancestors are recorded for Claude Sonnet 4.6 without weak links.

No recorded ancestors are recorded for Claude Sonnet 4.6.

No recorded ancestors are recorded for Claude Sonnet 4.6.

After: what it led to

No documented descendants are recorded for Claude Sonnet 4.6 without weak links.

No documented descendants are recorded for Claude Sonnet 4.6 without weak links.

No recorded descendants are recorded for Claude Sonnet 4.6.

No recorded descendants are recorded for Claude Sonnet 4.6.

Direct links and their sources

Where it came from

Developed alongside

What it led to

None recorded in the sources used.