A Claude Opus 5 model string showed up in Google’s Vertex catalog

Per Testing Catalog, prep for Claude Opus 5 has spread past internal testing to some partners. Earlier this month, a research build briefly surfaced in one coding tool’s model list: early access with per-command control, a safety fallback, a 1 million token context window, and a high-compute mode. The same identifier later turned up in Google Vertex’s quota catalog.

There’s no pricing, system card, or public model name yet, so the spec list is preliminary. The fallback points to Opus 4.8, matching earlier Honeycomb testing.

Testing Catalog figures that at launch Opus 5 would replace Opus 4.8 across the paid Claude apps, Claude Code, the Claude Platform, and three cloud partners. Anthropic hasn’t commented.