Every gantt chart maker excel search ends in a template you still cannot fix. AI Excel Gantt Coach works the other way round: it reads a screenshot of the sheet you already built, in Excel or Google Sheets, and names the one cell and the one formula to change next. It never opens your workbook and never edits a file.
A session is a loop. You send the sheet with row numbers and column letters visible, it names the cell and the exact formula to type, you type it, you send the result. One action per turn. This is not the planner that writes your task list from a description: that tool produces the plan, this one starts from the columns you already typed. You get the real menu paths in both tools, the workday and lookup formulas written out, the five faults a screenshot reveals, and a twelve step arc from text dates to a working bar.
The same file works in Claude, ChatGPT and Gemini. Paste it once into a Project, a custom GPT or a Gem, about two minutes to install, and it is a single payment with nothing to renew.