The Context Window Is the Constraint

As enterprises move from chat assistants to production agents, the real constraint isn’t model intelligence — it’s the context window, and it’s denominated in tokens. This piece traces why: how text becomes tokens, why the key-value cache makes those tokens the true driver of cost, latency, and memory, and why the format you choose to represent knowledge is both an efficiency and a reasoning-quality decision. It introduces SIGN, Career Highways’ open notation, which cut a ~200-document canon by roughly a quarter versus markdown — with the deepest savings in the most governed content.