AI Excel Formula Repair Tool

AI Prompts to Build This

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1. 1. Project Setup

   Build the weekend MVP of "SheetDoctor": upload an Excel workbook and get a ranked list of structural formula defects, with a proposed fix for each that you accept one at a time. Detection is plain code; no model is involved.
   
   Stack: Next.js (App Router), TypeScript, Tailwind, Supabase (Postgres, Row Level Security, Storage, Auth with email magic link), SheetJS to read and write.xlsx, fast-formula-parser to read formulas. The audit runs in a route handler. A Vercel Cron route deletes files after 24 hours. Deploy on Vercel.
   
   Tables (Row Level Security on, each user reads only their own rows):
   - workbooks(id, user_id, filename, file_path, sheet_count, formula_count, uploaded_at, delete_after)
   - audits(id, workbook_id, status, defect_count, finished_at)
   - defects(id, audit_id, sheet, cell, kind, severity, original_formula, proposed_formula, explanation, blast_radius, status) kind is broken_ref, range_off_by_one, inconsistent_column or hardcoded_constant; status is open, accepted or rejected
   
   Screens: /login, /upload, /audit/[id] (ranked defects, show the first 25), /audit/[id]/defect/[defectId] (original and proposed side by side).
   Env vars (names only): NEXT_PUBLIC_SUPABASE_URL, NEXT_PUBLIC_SUPABASE_ANON_KEY, SUPABASE_SERVICE_ROLE_KEY (server only), CRON_SECRET.
   
   Do not build: billing, plans or seats, a model for fixes, Microsoft Graph or Google Sheets connections, circular reference or volatile function checks, firm accounts, a change log or revert.
   Done when: npm run dev starts, you can sign in, and the three tables exist with Row Level Security on.

2. 2. Core Feature

   Build the one feature that proves SheetDoctor: find the silent formula mistakes and let the user approve each fix.
   1. Upload an.xlsx to a private bucket. Set delete_after to 24 hours from now and show that on the page.
   2. Read every sheet with SheetJS. For each formula cell, extract its references. Build a map from each cell to the formulas that read it, and count the cells that depend on a formula, directly or through others. That count is blast_radius.
   3. Detect four kinds of defect. broken_ref: the formula contains #REF!. range_off_by_one: a range ends 1 or 2 rows above the last filled row of its column while sibling formulas in the column reach that row. inconsistent_column: within a column of formulas, rewrite each as relative offsets, and flag a cell whose shape differs from the majority. hardcoded_constant: a number other than 0, 1 or 100 typed inside a formula in a column whose other formulas only use references.
   4. Propose each fix in code from the majority sibling shape, or by extending the range to the last filled row. A proposal must parse with the same parser, or the defect is marked manual review.
   5. Rank by severity, then blast_radius. Show the top 25 with a Show all link. Each detail page shows original and proposed side by side, a one-sentence plain explanation and "this affects N cells".
   6. Accept and Reject buttons set the status. A Download corrected copy button applies only the accepted fixes to a new.xlsx and leaves the original untouched.
   Rules: never apply a fix the user did not accept. Never send a workbook to any outside service.
   Empty state: with no workbooks, show the upload box and one sample file to download.
   Done when: a sample workbook with a planted #REF!, a range one row short, one odd formula in a column and one typed-in number lists four defects in ranked order, accepting two and downloading changes exactly those two cells, and the cron removes files past delete_after.

3. 3. Landing Page

   Build a one-page landing site for SheetDoctor, a formula auditor for analysts and accountants.
   Hero: "You inherited this workbook. We'll tell you what's wrong with it." Sub: "Upload an Excel file and get a ranked list of broken references, ranges that stop one row short and formulas that don't match their column. You approve each fix." One button: Join the waitlist.
   Sections: a quarter-end scene (the #REF! found an hour before the board deck), a static sample defect list ranked by how many cells depend on each, the four checks in one line each (lead with the range that stops one row short, because it gives wrong numbers that look right), and a data note saying files are deleted after 24 hours.
   Waitlist: store the email in a waitlist table in Supabase. No other service.
   Style: Geist with IBM Plex Mono for every formula, off-white and near-black, one amber accent used only for severity. A precise voice with no hype.
   Done when: the page renders on a phone and a submitted email appears in the waitlist table.

4. 4. Branding Package

   Use a design or image tool for this one. A coding agent cannot draw a logo.
   Brand for SheetDoctor: a wordmark and an icon that suggest a grid with one highlighted cell.
   Colors: off-white, near-black and one amber used only for severity. Type: Geist, with IBM Plex Mono for formulas.
   Deliverables: wordmark, icon, four check icons (broken reference, range, column, constant), three severity badges that differ by shape as well as color, and one launch graphic of a defect list.
   Done when: each deliverable is saved in one folder and the severity badges are distinguishable without color.