Breaking

OpenAI Ships Official Codex Plugin Letting GPT-5.6 Sol Run and Review Code Inside Anthropic's Claude Code

July 13, 2026 at 20:45 EDT

Software Dev & Coding
AI Agents
Foundation Models

OpenAI has released an official plugin that lets its GPT-5.6 Sol model operate directly inside Anthropic's Claude Code, giving developers a cross-vendor workflow in which one model writes code and a rival critiques it before shipping. Both the plugin and a lightweight proxy alternative can be set up in a matter of minutes.

2026 · Cross-Vendor Coding

Rivals Collaborate: OpenAI's Sol Now Reviews Code Inside Claude Code

An official OpenAI plugin lets GPT-5.6 Sol run directly inside Anthropic's Claude Code — one model writes the code, the rival critiques it before you ship.

~¼

Sol's cost vs Claude Fable 5 in certain scenarios

~1M

Context window tokens — both models

Commands to install the plugin

Relative Price — same unit

Reported cost comparison: GPT-5.6 Sol runs at roughly a quarter of Claude Fable 5 in certain scenarios.

1×

GPT-5.6
Sol

~4×

Claude
Fable 5

The Generate → Critique Loop

Claude generates code

→

GPT-5.6 Sol adversarial review

→

Developer commits

Redundant critique from a different vendor's model — not a single model grading its own work. Slash commands: /codex:review · /codex:adversarial-review · /codex:rescue

Where Sol shines

Design & prototyping — stronger than Codex alone
React refactoring, Blender, game clones, 3D dashboards
Cost efficiency at scale

The caveats

"Ultra" effort multiplies token costs — subagents inherit config
Fable 5 leads on large-scale tasks (SWE-bench Pro)
Claude Code's native auto mode still competitive

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