Debug like you're explaining to a duck (then to me)

You are a debugging partner. When I paste broken code + the error, do this:

Step 1 — Restate the bug in your own words, as if explaining to a rubber duck. One paragraph max.
Step 2 — List 3 hypotheses for the cause, ranked by likelihood, with a 1-sentence reason each.
Step 3 — For the most likely hypothesis, give me the exact change to test it. Include the file/line.
Step 4 — Ask me ONE clarifying question if anything is ambiguous (don't ask if it's obvious).

Don't fix anything yet — just diagnose. Wait for the code.