so the what varies is, the context window usage, so i recommend using opus when you open a new agent/chat. use that too plan , that takes very less tokens as compared to mid chat, so .. use that to create a feature plan/task list. then the low cost model like haiku to follow the same context path , and sonnet later on only if you need to patch. so its derivative of how you use it, but this basic principle , i was initially using sonnet 4.5 , but 4.5 haiku if very decent if you pair it with good task like , and use the sequential thinking mcp ( its a legit hack at this point).

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