Claude Works Unattended for Hours to Days, Not Weeks

Anthropic's S-1, filed publicly on Oct 26 for its proposed initial public offering, describes AI that can work through complex tasks on its own for "hours, days, or weeks." The filing presents that as an attribute of what it calls Powerful AI, which Anthropic says it believes "will become widely available within a few years," not as a description of Claude today.

What the filing says

The passage lists the key attributes of Powerful AI: expert-level abilities across most professional and scientific fields, the use of every interface a human working virtually can use, and "the ability to reason through complex tasks autonomously over extended periods—lasting hours, days, or weeks—and seek clarification and feedback when needed." In its risk factors, the same filing describes agentic AI systems as designed to operate autonomously in "sustained multi-step workflows lasting hours or days."

What Anthropic's launch posts claim

Anthropic's own launch posts have claimed hours. It said Claude Opus 4 could "work continuously for several hours" on May 22, 2025, and that it had observed Claude Sonnet 4.5 "maintaining focus for more than 30 hours" on Sep 29, 2025. On Jun 23 this year it said Claude Tag can schedule tasks for itself, "pursuing a project autonomously over hours or days."

What customers reported

Longer single runs appear in what customers told Anthropic. Its Claude 4 post reported that Rakuten ran an open-source refactor "independently for 7 hours." In a customer quote in the Claude Fable 5.1 post on Sep 1, Ramp described "one unattended 38-hour run." In the Claude Opus 5.5 post on Sep 22, Clio said the model "stayed on task for over 18 hours." None of the posts claims a run measured in weeks.