Microsoft Build 2026

Use the Expensive Model to Plan, the Cheap One to Build

原演讲者: Harald Kirschner, Product Manager, Visual Studio Code · Microsoft

来源已核验演讲日期待核实presentation9:34EN2 分钟阅读

Model selection per phase within one task beats selection per task, and the team's admission that context switching between agents remains unsolved names the cost nobody prices when demonstrating parallel agents.

The recommendation buried at the end of this nine-minute segment is the most immediately usable advice from Build: use the larger model for planning, and a cheaper automatic selection for implementation (8:11).

The reasoning is economic and specific. Having analysed the cost of their own conversations (7:32), the team found the expensive model earns its price during planning — where a wrong decision propagates through everything after it — and stops earning it during implementation, where the work is largely mechanical once the plan is settled.

Most guidance about model selection is per-task. This is per-phase within one task, which is a finer distinction and produces a much larger saving.

The problem they admit they have not solved

The candid moment is worth more than the feature.

Context switching between agents, they say, is an unsolved problem — visible in user testing and in their own experience, and it burns you out (5:19).

This is the cost nobody prices when demonstrating parallel agents. Running six agents concurrently sounds like six times the throughput. What it produces is six streams of work in different states, each requiring you to reconstruct where it was, what it decided and whether it is on track before you can usefully intervene. The reconstruction is the expensive part, and it happens every time you switch.

Human working memory does not multiply. An interface that dispatches many agents easily has solved the cheap half of the problem and made the expensive half worse — which is precisely what the VS Code team is describing about their own users, and their own working days.

Why the admission matters

An agents window that collects concurrent sessions in one place is a reasonable response, and the team is clear that it is a partial one.

The unsolved part is not display. It is that supervising parallel work requires holding parallel context, and no arrangement of panels changes what a person can hold. The eventual answer probably looks less like a better dashboard and more like agents that summarise their own state well enough that reconstruction is unnecessary — which is a model capability rather than an interface feature.

Until then, the honest position is the one they take: here is a place to see them all, and switching between them still costs you something no tool currently removes.

演讲章节

关键要点

  1. 01

    Their recommendation from analysing their own conversation costs: the larger model for planning, a cheaper automatic selection for implementation. 8:11

  2. 02

    The saving comes from selecting per phase within a task rather than per task, since the expensive model stops earning its price once the plan is settled. 7:32

  3. 03

    They name context switching between agents as an unsolved problem, visible in user testing and in their own working days. 5:19

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