Building a Good Vertical Agent: Context as a Cache Hierarchy
The article argues that a good vertical agent is a faithful compression of its task distribution, and its context should be organized as L1/L2/L3 cache tiers. Using their Shortcut spreadsheet agent as example, they detail extreme optimizations: reading a range compresses 500 formulas into a single legend line via R1C1 normalization and aliasing; after writing, a structured diff groups, samples, and triages changes, flagging #REF! errors under MUST FIX. L2 provides curated English specs fetched on demand, like the pivot table recipe that bakes in gotchas (suspendLayout/resumeLayout, raw integer 8 for aggregation). L3 is the raw API reference plus a 100-line grep skill that lets the model mine tens of thousands of lines in bounded steps. The prompt budget mirrors the frequency curve, and the hierarchy moves as models improve. Practical, transferable advice for engineers building reliable agents in any domain.