The Code Mode Issue

A quarterly about machines that think — and the substrates that hold them

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Contents · MARCH 2026

In this issue.

Editor's Note The agent has always been writing Large language models possess extensive training on production code bu… p. 01
Feature 01 The Code Mode Thesis Two tools only. search and execute. A 99.9% reduction from naive imple… p. 06
Feature 02 Inside the Dynamic Worker V8 isolates start in milliseconds, consume single-digit megabytes, and… p. 11
Feature 03 Project Think An ephemeral agent is a tool. A durable agent is infrastructure. The e… p. 16
Feature 04 Memory as Infrastructure Agent knowledge accumulation typically disappears after sessions end. … p. 21

From the Editor · MARCH 2026

The agent has always been writing.

The industry has operated under a flawed assumption — that AI agents fundamentally work by calling tools from a menu. Cloudflare's 2025-26 releases demonstrate this model was misguided. The actual primitive is code itself.

RUNTIME is a quarterly about machines that think and the substrates that hold them. This issue is about code mode: what it is, why isolates matter more than containers, and how agent infrastructure becomes persistent rather than ephemeral.

Features:

The Code Mode Thesis — ~1,000-token footprint regardless of endpoint count
Inside the Dynamic Worker — an isolate, not a container
Project Think — an ephemeral agent is a tool; a durable agent is infrastructure
Memory as Infrastructure

— Runtime Editorial