A code model with no chat layer. JetBrains shipped Mellum2.1 Thinking on October 8, 2026: a 12.15B-total, 2.5B-active Apache 2.0 model trained for the code workflow the company’s IDEs are built around, and the official GGUF landed in the same week. 7,800 downloads on the GGUF build within a day.
What one-workflow training buys. A general 12B chat model spends its capacity on general text; Mellum’s 2.5B active slice is tuned to find, read, and complete code across a project, at the 131k context its config carries. About 7.0GB in 4-bit, it targets the same box a 16GB machine already hosts, with a 56MB-per-1,000-token cache that fits comfortably in laptop memory budgets.
Where it sits. Jetbrains’ first Mellum (April 2026, 4B) proved the focused-specialist idea; 2026’s 12B line adds the thinking variant for harder retrievals. Against qwen3 coder-line generalists it trades breadth for latency-per-answer, which is the trade an IDE needs.