Workflows in Claude Code, shipped with Opus 4.8: hundreds of subagents at once

TL;DR Put the word workflow in your prompt (or run the bundled /deep-research) and Claude writes a JavaScript script that orchestrates up to hundreds of subagents in the background — with the plan and intermediate results outside its context, and agents that refute each other until they converge before reporting back. It's a research preview, needs Claude Code v2.1.154+, ships on all paid plans (on Pro you enable it in /config), and burns meaningfully more tokens: start on a scoped task.

Opus 4.8 dropped today (same price as 4.7, ~4× less likely to let code flaws pass unremarked). But the thing that actually changes how you work in Claude Code shipped the same day and isn't the model: dynamic workflows. It runs on whatever model you've got selected.

The problem it solves: until now, if you wanted to delegate a huge task to many subagents, Claude was the orchestrator — it decided turn by turn what to spawn, and every intermediate result landed in its context. That's why it didn't scale past a handful of agents.

The shift: the plan moves into code

A workflow moves the plan — the loop, the branching, the state — into a JavaScript script Claude writes on the fly. A runtime executes it in the background, isolated from your conversation. Your context only gets the final answer. That buys two things: running hundreds of agents without blowing context, and a repeatable quality pattern — agents that adversarially review each other's findings before reporting them.

Try it today without writing anything: /deep-research

The zero-cost on-ramp is a workflow that already ships built in:

/deep-research What changed in the Node.js permission model between v20 and v22?

It fans out searches across several angles, cross-checks the sources, votes on each claim, and returns a cited report with claims that didn't survive the cross-check already filtered out. Your session stays free while it runs. Track progress with /workflows.

The three ways to launch one

# 1. The word "workflow" in your prompt (Claude writes the script)
Run a workflow to audit every endpoint under src/routes/ for missing auth checks

# 2. A bundled workflow
/deep-research <question>

# 3. Let Claude decide (opt-in)
/effort ultracode

With ultracode, Claude decides on its own whether each task warrants a workflow — opt-in, lasts the session, drop back with /effort high for routine work. By default it does not spin up agent fleets unless you ask.

The control: before anything runs, Claude shows you the planned phases and you can read the raw script (Ctrl+G). It's not a black box. And if a run does what you wanted, press s in /workflows and it's saved as /your-command forever — on every branch, for every teammate who pulls. This is the "skills 2.0" feel.

What it's actually for

Migrations across hundreds of files, security or bug audits across a whole codebase, research with cross-checked sources. The extreme case: Jarred Sumner ported Bun from Zig to Rust with workflows — 750,000 lines, 99.8% of the test suite passing, 11 days from first commit to merge, hundreds of agents in parallel with two reviewers per file.

What to know first (honest)

• Research preview · needs v2.1.154+ · all paid plans (on Pro, enable in /config)
• Limits: max 16 concurrent agents, 1,000 total per run
• Cost: a run burns meaningfully more tokens than doing the task in conversation. Anthropic says it plainly: start on a scoped task to get a feel for it
• Subagents run in acceptEdits and inherit your allowlist; file edits are auto-approved

If you came from parallel worktrees or the background agents map, workflows are the next rung: not several of your own sessions, but one that orchestrates hundreds of agents with the plan held in code.

Official docs: Orchestrate subagents at scale with dynamic workflows