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The Interview Loop1 / 2

1 min lesson

State assumptions before you write

Take this case and make the call: "You're asked to write a SQL query reconciling invoiced amounts against cash received. What two mistakes most signal weakness in a finance context and how do you avoid them?"

Step 1 of 2

  1. 1State assumptions before you write. What's the grain, what's the period, are credit memos in scope - silent guessing reads as junior in a finance context.
  2. 2Key your joins to avoid double-counting. Partial payments, credit memos and true-ups all break a naive invoice_id-only join; show you know it.
  3. 3Name the control. Say what makes the result auditable - an immutable source, a reconciliation that ties to the GL, a variance threshold that triggers review.
  4. 4Connect the choice to scale. A full-table reconciliation is correct but won't hold at Cursor's volume, so watermark or partition and say why.
  5. 5Drive the deep-dive with a real retrospective. What you wrote versus configured, what failed and what you'd change - the failure is the most valuable part.
Interview move

In the implementation deep-dive, volunteer the failure before you're asked. “We configured suspension/dunning in the billing platform instead of building it and it couldn't express our usage true-up logic, so we ended up with manual credits every month - I'd have built that path.” A clean retrospective with a concrete build-vs-configure lesson is the strongest signal a staff IC can give.