Complex Multi-File Refactors: Claude Opus 4.8 Owns the Messy Stuff
When a refactor touches forty files and the codebase is held together with duct tape, Claude Opus 4.8 is the pick. Alex Finn, Brian Casel, and AI Master all converge on Opus 4.8 as the best coding model for complex, multi-file repository work. The model alone isn't enough: Maximilian Schwarzmüller and Brian Casel argue Claude Code is the best harness for Opus because the same company built both, a tight integration that third-party tools can't replicate.
Opus's price premium is the live debate. Alex Finn calls Opus "10× smarter than Sonnet," while Nate Herk says Sonnet handles most work fine and Opus quota on the Max plan evaporates fast. The working pattern in practice: Opus for planning, then switch to Sonnet for execution. Claude Code's plan mode is what makes that work: it explores the codebase and asks clarifying questions before it touches a single file.