ThinCtx by thinletter. ThinCtx-Qwen3.5-0.8B is the ThinCtx conversion of Qwen3.5-0.8B that keeps the GPU memory for the context small: it grows 20 to 30 times more slowly than the base model's cache (0.43 GB instead of 6.0 GB at half a million tokens). The part of the context kept on the GPU is small and grows slowly with the length of the conversation or document; the full context is kept in ordinary system memory. ThinCtx trades some speed for this (see Speed below). Chat and tool calling use the Qwen3.5 chat template. Runtime required. ThinCtx models run on the thinctx runtime (pip install thinctx, below). The runtime is what keeps the context memory small; other inference libraries do…