Upstage's Solar Pro 4: a 512K-context agent model, $0.30 per million
The Korean lab's flagship runs multi-step shell jobs, scores 70.6 on SWE-bench Verified, and launches 90% off — plus a Japanese Kimi-based API from Sakana.
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An agent tuned to finish the job
Solar Pro 4 is Upstage's flagship, built for agentic work — reading docs, running shell tools, and shipping the deliverable rather than chatting. It posts 70.6 on SWE-bench Verified, 57 on Terminal-Bench v2.1, and 71 on the AA-LCR long-document benchmark, with a February 2026 knowledge cutoff.
512K in, 128K out
It accepts a 524,288-token context and emits up to 131,072 tokens per call — enough to drop an entire repo plus its docs into one request and get a full patch back. It's OpenAI-compatible, so pointing an existing client at it is a base_url swap.
The price is the pitch
List is $0.30 / $1.20 per million tokens in/out ($0.06 cached), but a launch promo runs it 90% off — roughly $0.03 / $0.12 — through September 10. It's live now on OpenRouter, the Upstage Console, and SolarChat.
Elsewhere: Sakana routes a Japanese-tuned Kimi
Sakana AI's Namazu — Moonshot's Kimi K2.6 fine-tuned for Japanese and business norms, with built-in web search and code execution — is now callable on OpenRouter at about $0.95 per million tokens. It's OpenAI-compatible but blocked in the EU.