Use a larger context window with a clear plan

Anthropic announced Claude Opus 4.6 on February 5, 2026, including a one-million-token context window in beta. The release also described improvements to planning, code review and longer agent tasks. These are the vendor's release claims, not a guarantee for every codebase. ^[1]

A larger context window lets a model receive more material in one request. It does not tell the model which files matter or resolve contradictions between old documentation and current code.

Give the task a boundary

Start with the desired behavior, the files likely to own it and the checks that define success. Add related modules when the agent identifies a dependency. Keep generated files and unrelated logs out unless they help answer a specific question.

For a large change, ask for a plan that names the affected interfaces before implementation. Review one working slice before expanding the task. Record cost and time alongside correctness when evaluating the larger window.

Check current model availability and context limits in your selected product. A beta limit from a February announcement should not silently become a permanent assumption in your tooling.