New Stealth Model in Cline: "Sonic"

Free stealth model is now available in Cline

Nick Baumann

19 Aug 2025 — 1 min read

We're launching a new model in stealth to Cline today. It sports a 262k context window and is entirely free to use while it's in alpha. Your usage will help refine its development.

Here's what you should know about this model:

262k context window

Built for coding - designed specifically for the kind of iterative, autonomous development that actually gets work done

Entirely free to use while in alpha - no usage limits, no tiered pricing

Access it via the Cline provider: cline:cline/sonic

-Nick

3 Seductive Traps in Agent Building

In building AI agents at Cline, we've discovered that the most dangerous ideas aren't the obviously bad ones, they're the seductive ones that sound brilliant in theory but fail in practice.

How to Think about Context Engineering in Cline

The Cline Context Playbook: when to use Deep Planning, Focus Chain, Auto Compact, /smol, /newtask, and Memory Bank

Focus: attention isn’t enough

Bigger context windows don’t stop coding agents from drifting. Cline’s new Focus Chain keeps every step anchored to the goal — so even the longest tasks finish exactly where they’re meant to.

Cline v3.25: The Coding Agent Built for Hard Problems

In v3.25, Cline never lets go of the thread.

Read more

3 Seductive Traps in Agent Building

How to Think about Context Engineering in Cline

Focus: attention isn’t enough

Cline v3.25: The Coding Agent Built for Hard Problems