Solar Pro 4 vs Solar Pro 3: What Changed and How to Migrate

Solar Pro 4 is the generation where the focus moves from answering to finishing. The API surface stays familiar, so the migration is mostly about what you can now hand over in one task — and about re-checking the assumptions you built around a shorter context window.

What changed

• Agentic completion. Solar Pro 4 is tuned for multi-step jobs that end in a deliverable: reading documents, running terminal tasks, and chaining tool calls. The published scores — Terminal-Bench v2.1 57, τ³-Banking 23, AA-LCR 71 — are each a several-fold step over Solar Pro 3, and the benchmark guide explains what each one measures.
• Reasoning by default. Responses carry the reasoning trace, and reasoning effort is adjustable from real-time interaction to deep analysis.
• Longer work in one session. A 512K context with up to 128K output tokens means several contracts, reports, and data files can stay in a single conversation.
• Evidence discipline. Solar Pro 4 is built to say it cannot verify rather than fill the gap — useful when the deliverable has to survive review.

What stays the same

• The endpoint is OpenAI-compatible: change the endpoint and the model name (solar-pro4) and your existing code runs.
• Pricing stays token-based: $0.30 per 1M input tokens, $0.06 per 1M cached input tokens, $1.20 per 1M output tokens.
• English, Korean, and Japanese are supported for both input and output.

Migration checklist

1. Swap the model name. Set solar-pro4 and keep the rest of your request shape; see the API guide for the setup.
2. Re-check your context budget. Prompts that were trimmed for a smaller window can now carry whole document sets — and output limits up to 128K change how much a single call can return.
3. Re-test your tool schemas. Multi-turn tool use is where the generation gap shows; run the same bank of tool-calling conversations you use today.
4. Handle reasoning traces. If you parse responses strictly, account for the reasoning trace the response carries by default.
5. Re-run your evaluations. Keep the tasks, change the model, and compare completion — not tone.

When Solar Pro 3 is still fine

If your workload is single-turn generation with a short prompt, the newer agentic behavior buys you little. The migration pays off where tasks are long, tools are involved, and completion is the metric.

FAQ

Is the migration a rewrite?

No. The endpoint is OpenAI-compatible, so the change is the endpoint, the model name, and any context or output assumptions in your code.

Does the pricing change between generations?

The published token rates for Solar Pro 4 are on the pricing page, alongside the plan options.

How do I know whether completion actually improved?

Run a fixed set of multi-step tasks and grade the final deliverable, the way the benchmarks do. The benchmark guide describes the task shapes to copy.