Few-shot and reasoning — examples that work, and the CoT trap on reasoning models (step 6/9) · prompting cursor and claude code effectively

This build_prompt function unconditionally appends "Think step by step." to every prompt — even when the model is a reasoning model (o3, Claude with thinking, etc.). On reasoning models, this is at best wasted tokens and at worst hurts answer quality.

Fix the function to ONLY append the CoT prefix when the model is NOT in REASONING_MODELS.

Expected output:

o3            cot? False
claude-haiku  cot? True

The break is on line 5 — but read the whole snippet first.

⌘↵ runs the editor.read, then continue.

Fix the function to ONLY append the CoT prefix when the model is NOT in REASONING_MODELS.

Expected output:

o3            cot? False
claude-haiku  cot? True

The break is on line 5 — but read the whole snippet first.

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Few-shot and reasoning — examples that work, and the CoT trap on reasoning models — step 6 of 9

this step needs the editor