---
type: entity
subtype: tool
title: "Claude Opus 4.8"
description: "Anthropic's reasoning-heavy Claude release that owns planning, page copy, integrations, and fixes in Cole's mixed-provider frontend workflow."
tags: [llm, model]
videos: [claude-plans-gemini-designs-the-workflow-to-build-beautiful-frontends]
created: 2026-07-21
updated: 2026-07-21
---

# Claude Opus 4.8

Claude Opus 4.8 is Anthropic's reasoning-heavy flagship, introduced by Cole as "a reasoning powerhouse that just generally does really well on longer running agentic engineering tasks" ([0:00:18](../../sources/claude-plans-gemini-designs-the-workflow-to-build-beautiful-frontends.md)). His assessment is not benchmark-only: "Opus 4.8 benchmarks in my own experience and a lot of people's experiences is just way better at reasoning overall" ([0:02:01](../../sources/claude-plans-gemini-designs-the-workflow-to-build-beautiful-frontends.md)).

Its interest in this knowledge base is less "best model" than **where it is deployed**. In the mixed-provider frontend workflow, Opus 4.8 is deliberately not asked to do everything. [Gemini 3.5 Flash](./gemini-3-5-flash.md) designs the UI, because it produces unusually handcrafted-looking interfaces cheaply, and it hallucinates page copy. Opus takes the jobs where being wrong is expensive and being slow is fine: the three-section plan, the accurate site copy, the auth and API integrations, and the escalated fixes when validation fails after cheaper models have already tried twice. Sonnet handles the grind either side of it - repo exploration into a context document, then linting and unit tests.

The reason this is a workflow rather than a prompt is that no single conversation can mix providers, so each step is a separate coding-agent session that communicates only through markdown [handoff documents](../../concepts/handoff-documents.md). That constraint turns into a design advantage: every model gets a clean context window and exactly one job. It also produces one genuinely counterintuitive rule. The Opus-authored plan deliberately omits site structure, because a stronger reasoner writing detailed layout instructions would steamroll Gemini's design strength. Being the smartest model in the chain does not entitle it to every decision, and knowing what to leave out of the plan is part of using it well.

## Part of

- [Claude](./claude.md) - Anthropic's model family; Opus 4.8 is its reasoning-heavy tier.

## Realizes

- [Planning with AI](../../concepts/planning-with-ai.md) - Producing a reviewed blueprint before implementation; Opus writes the three-section spec the rest of the chain executes.
- [Two-Layer Planning](../../concepts/two-layer-planning.md) - Separating strategic planning from detailed task planning and reserving the stronger model for the former.
- [Reasoning Models](../../concepts/reasoning-models.md) - Models that think before answering, and when that extra deliberation earns its cost.
- [Model Selection](../../concepts/model-selection.md) - Assigning each step to the model that is actually best at it rather than defaulting to one everywhere.

## Contrasts with

- [Gemini 3.5 Flash](./gemini-3-5-flash.md) - Cheap, fast, and better at beautiful UIs, but hallucinates copy; the design half of the pairing Opus completes.
- [Claude Sonnet 4.5](./claude-sonnet-4-5.md) - The cheaper sibling that runs exploration, validation, and test-writing before Opus is escalated to.

## Works with

- [Claude Code](./claude-code.md) - The harness Cole drives Opus in for the planning, integration, and fix steps.
- [Pi](./pi-coding-agent.md) - The provider-agnostic harness used to run the Gemini design session the Opus plan feeds.
- [Google Antigravity](./google-antigravity.md) - The alternative surface for that same design step.
- [Archon](./archon.md) - Runs the whole multi-model chain autonomously as a workflow instead of by hand.

## Related

- [Provider Independence](../../concepts/provider-independence.md) - Architecting so the model behind any step can be swapped without a rewrite.
- [Handoff Documents](../../concepts/handoff-documents.md) - The markdown artifacts each session reads at its start and writes at its end.
- [Context Isolation](../../concepts/context-isolation.md) - Giving every step its own clean context window so no session carries unrelated tokens.
- [Phases of Work](../../concepts/phases-of-work.md) - Completing and validating one coherent chunk before starting the next.
- [Reduce Assumptions](../../concepts/reduce-assumptions.md) - Why accurate copy and verified integrations are handed to the strongest reasoner.

## Sources

- [Claude Plans, Gemini Designs: The Workflow to Build BEAUTIFUL Frontends](../../sources/claude-plans-gemini-designs-the-workflow-to-build-beautiful-frontends.md) - "[0:00:18] Anthropic drops Opus 4.8, a reasoning powerhouse that just generally does really well on longer running agentic engineering tasks."
- [Claude Plans, Gemini Designs: The Workflow to Build BEAUTIFUL Frontends](../../sources/claude-plans-gemini-designs-the-workflow-to-build-beautiful-frontends.md) - "[0:02:01] Opus 4.8 benchmarks in my own experience and a lot of people's experiences is just way better at reasoning overall."
