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#0004 draft contrarian 2026-05-07 #claude-code#model-routing#haiku#sonnet

Sonnet for new decisions. Haiku for established implementation.

The model routing rule in one sentence. After your first sprint, 80% of sessions are implementation against decisions already made. Those sessions do not need frontier reasoning. They need frontier context.

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Sonnet for new decisions.
Haiku for established implementation.

That is the whole rule.

After your first sprint, roughly 80% of your sessions are implementation against decisions you have already made. Those sessions do not need frontier reasoning. They need frontier context.
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