coderabbitai Google Sheets Formula Builder
Use this skill when the formula itself is the task.
Read ./references/formula-patterns.md before drafting the first formula. The point is not to relearn Sheets from scratch. It is to refresh exact syntax and a few high-value function constraints before writing.
Workflow
- Ground the formula in the live sheet first: exact input columns, target output cell or column, and a few representative rows.
- Choose the formula shape deliberately:
- row formula when the logic is local to one row and should copy down
- spill formula when one formula should populate a whole output range
- lookup formula when the task is key-to-value retrieval
- filter/query formula when the task is to derive a subset or summary table
- named function only when the same logic is conceptually reusable
- Draft the formula in one helper cell or a scratch location first.
- Test on a small representative slice, including likely edge cases.
- Iterate until the sample output is correct, then roll the formula out to the intended target range.
Output Conventions
- Name the exact target cell or output column.
- Return the final formula exactly as it should be entered.
- If rollout matters, say whether the formula should be filled down, spilled from one anchor cell, or turned into a named function.
References
- For syntax reminders, formula-shape heuristics, and official Google Sheets docs links, read
./references/formula-patterns.md.