Opus 4.8 ships Dynamic Workflows — hundreds of parallel subagents per session. Read this before you wire it into prod.

Opus 4.8 ships Dynamic Workflows — hundreds of parallel subagents per session. Read this before you wire it into prod. Anthropic's Opus 4.8 announcement on May 28 spent most of its word count on benchmarks. CursorBench up. Terminal-Bench 2.1 beats GPT-5.5. OSWorld-Verified at 82.3%. Online-Mind2Web at 84%. The legal-agent benchmark broke 10% on all-pass for the first time. Those are the numbers the headline writers grabbed. Buried under the benchmark table is the line that actually changes how you ship agents: Dynamic Workflows. Run hundreds of parallel subagents. Handle codebase-scale migrations spanning hundreds of thousands of lines. That is not a benchmark. That is a new programming model. And it is shipping as a preview, which means the defaults are not what they will be in 90 days. If you are running agents in production and you do not pin your config before the next minor release, your bill is going to surprise you. Here is what the preview actually does. Three tasks it eats alive. One class of work where it loses you money. And the exact config to pin before the dynamic-workflow defaults move under you. What Dynamic Workflows actually changed Before 4.8, parallel subagents on the Anthropic stack meant one of two things. Either you called the Agent tool from inside Claude Code and got a fixed number of side-task subagents — usually capped somewhere around four or eight concurrent. Or you wrote your own orchestrator in TypeScript or Python, called the Messages API in a Promise.all , and handled the queueing yourself. The Agent path was ergonomic but capped. The DIY path was uncapped but the orchestration was your problem — retries, structured output validation, cache invalidation, all of it. Dynamic Workflows in 4.8 collapses both. You write a script — JavaScript, not a separate orchestrator binary — that calls agent() , parallel() , pipeline() , and phase() as primitives. The runtime handles concurrency, structured output validation against JSON Schema, retri