IBM's Hugging Face[1][6] announcement 'Granite 4.2 LLMs: How They're Built' and the ibm-granite/granite-4.2-8b model card both give the release as August 25, 2026; OpenRouter[3] lists the 8B on 31 August, which is when the router added it.
IBM releases Granite 4.2, three open Apache 2.0 reasoning models (3B, 8B and 30B) with a switchable thinking mode; the 8B scores 47.67 on SWE-bench Verified and 86.67 on AIME25 in IBM's own runs.