Cartridges vs OpenMythos

Cartridges is an open-source single-GPU PyTorch reproduction of two recent papers on KV-cache compaction for long-context LLM inference: "Cartridges" (lightweight long-context representations via self-study condensation) and "STILL." Both methods address the same bottleneck — KV caches grow linearly with context length and quickly become the dominant memory consumer in long-context inference, making extended context windows impractical on consumer hardware. The Cartridges paper proposes condensing long contexts into compact "cartridge" representations through a self-study phase, trading some context fidelity for dramatic memory reduction. STILL uses a different approach focused on selective layer-wise compression. This repository makes both reproducible on a single consumer GPU — previously these required multi-GPU setups accessible mainly to research labs. KV-cache memory is one of the primary bottlenecks preventing long-context models from running efficiently on local hardware. A working single-GPU reproduction of these techniques is directly useful to anyone building long-context applications outside of cloud environments, and may accelerate community development of hybrid compaction strategies not in the original papers.

OpenMythos is a PyTorch reconstruction of the suspected architecture underlying Anthropic's Claude Mythos model, built entirely from published research. Creator Kye Gomez hypothesizes that Mythos uses a Recurrent-Depth Transformer (RDT) — where a subset of transformer layers loops multiple times per forward pass with shared weights rather than stacking unique layers. This allows the model to simulate "thinking" by iterating over the same compute graph, giving it emergent chain-of-thought behavior without explicit CoT prompting. At 770M parameters, the OpenMythos implementation reportedly matches the downstream quality of a 1.3B standard transformer on benchmarks. The architecture combines Multi-Latent Attention for memory compression, LTI (Linear Time-Invariant) stability constraints to prevent training instability during recurrence, Mixture of Experts routing for specialization, and Adaptive Computation Time (ACT) halting to decide when to stop looping per token. The project exploded on GitHub within days — 6.2k stars, 1.2k forks — and Kye's X announcement drove massive engagement (4.1k likes, 4.5k reposts). Community reaction is genuinely divided: AI researchers calling it "the most sophisticated reverse-engineering of an LLM architecture I've seen" while Anthropic has not confirmed or denied any of the architectural claims. This is an educated speculation backed by real engineering, not a marketing exercise.