Fable is not really for planning — did you know that, or am I wrong? From what I understand, Opus is stronger for planning and architecture, Sonnet is better for executing clear tasks, and Fable is better for long, difficult, or ambiguous execution where the model needs to investigate, test, review, and close the loop. So Fable can plan during execution, but it is not mainly “the planning model.” The confusion is thinking that Fable is the planning model and Sonnet is the execution model. That is not quite right. The practical rule is: Opus is best for planning. Sonnet is best for executing well-defined tasks. Fable is better for difficult, long, or ambiguous work because it tends to investigate, test, review, and close the loop more carefully. Use Opus when you need to design the architecture, write a spec, define phases, or think through the strategy before touching the code. Use Sonnet when the plan is already clear and the task is to implement, edit files, run tests, and fix clear issues. Use Fable when the project is still unclear, has hidden bugs, requires investigation, involves multiple steps, or needs more autonomous execution. There is also an important difference in Claude Code: Using `/model opus` means using Opus for everything: planning, execution, and review. Using `/model opusplan` means using Opus for planning and Sonnet for execution. So, simply telling Opus “I want to plan” does not automatically activate `opusplan`. To use that hybrid flow, you need to explicitly select `/model opusplan`. Final summary: Opus thinks through the plan. Sonnet executes the plan. Fable handles the work when it is difficult, long, or ambiguous. `opusplan` combines Opus for planning with Sonnet for execution. https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5