The Model Pulse

Issue archive.

A weekly read on the software side of the AI stack: model lineage, architecture, benchmarks, and vendor signals.

Each issue runs to about six minutes and is anchored to the LLM Evolutionary Tree, which the brief annotates each week. The cross-stack flywheel (capital, hardware, networking) lives in The AI Stack Weekly.

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Published issues.

Issue 01/April 2026 Recap/April 25, 2026
April rewrote the floor: open weights crossed the closed frontier, and the safety-gated frontier became a procurement criterion.
April 2026 was the most productive month in frontier model history. Eleven model rows landed in the LLM Evolutionary Tree across eight vendors, including the first open-weights MoE to score frontier-class on SWE-Bench Pro coding (Kimi K2.6 at 58.6 and GLM-5.1 at 58.4, both above GPT-5.4 at 57.7 and Claude Opus 4.6 at 57.3). DeepSeek V4 shipped in two configurations under MIT license with 1M-token context and 1.6T total parameters, moving on-prem coding from 'can we?' to 'which workload first?' Anthropic withheld its Mythos flagship on cyber-capability grounds after UK AISI confirmed autonomous offensive capability — an inflection that turns capability gating from a research-org concern into a procurement diligence requirement. The closed frontier responded: GPT-5.5 (Apr 23) and Claude Opus 4.7 (Apr 16) reset the closed-source ceiling, with adaptive-thinking and ultra-long-context as the new defaults. Read together, April was the month the canopy widened on three axes at once: open-vs-closed parity on coding, reasoning-as-default at every tier, and capability gating as a market signal.
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The methodology.

— Every issue starts with the tree delta — the model rows added or updated in content/llm-tree/models.yaml since the prior issue.
— Frontier and open-weights releases are tagged by tier and architecture so procurement reads can scan to the relevant class.
— Architecture watch names patterns that crossed multiple vendors. One pattern, several exemplars, what it changes.
— Benchmark moves cite public leaderboards and vendor model cards as of publish date.
— Vendor signals cover the non-release moves: pricing, gating, deprecation, license changes.
— All sources are public. Independent analysis only.

Operate. Publish. Teach.

Published issues.

April rewrote the floor: open weights crossed the closed frontier, and the safety-gated frontier became a procurement criterion.

The methodology.