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Case 03

Formula and pricing calculator

A business puts pricing, tax, eligibility, scoring, or planning logic behind a JavaScript tool so answers calculate the same way every time.

JavaScript toolsJintFormula logicDeterministic output
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Case 03

An AI app that talks naturally, calls a controlled JavaScript function, and explains the deterministic result.

A business puts pricing, tax, eligibility, scoring, or planning logic behind a JavaScript tool so answers calculate the same way every time.

Audience Consultants, accountants, agencies, operations teams, and SaaS teams with repeatable formulas.
Outcome An AI app that talks naturally, calls a controlled JavaScript function, and explains the deterministic result.
Build stack JavaScript tools · Jint · Formula logic · Deterministic output

Case 03

Formula and pricing calculator

A business puts pricing, tax, eligibility, scoring, or planning logic behind a JavaScript tool so answers calculate the same way every time.

01

Before Prostir, the formula sits outside the chat

The business already has the formula in a spreadsheet, SOP, pricing sheet, or consultant habit, but customers still ask the assistant for the answer.

  • The danger is letting the model improvise math when the result controls price, eligibility, scoring, tax, or planning.
  • Prostir moves the rule into a named JavaScript tool with input descriptions and guardrails for missing, out-of-range, or forbidden cases.
02

What changes in the calculation

The customer asks a natural question, but the answer depends on exact inputs and a stable business rule.

  • Scene
  • Intervention
  • After-state
01 Scene

The customer asks a natural question, but the answer depends on exact inputs and a stable business rule.

02 Intervention

The app asks for missing numbers, validates ranges, and calls JavaScript instead of doing fragile mental math in chat.

03 After-state

The customer gets the number, assumptions, and next steps in the creator's language, with the calculation living in a reviewable tool.

03

After Prostir, the answer is deterministic

Creators can ship deterministic calculations, not only knowledge answers.

  • Teams with spreadsheets or pricing logic can expose the result through conversation without losing control of the formula.
  • The business can review and improve the named tool without rewriting the whole app.
04

Case roadmap

Now: encode the formula as a named JavaScript tool with parameter examples.

  • Next: add validation, missing-input questions, assumptions, and error messages.
  • Later: reuse the tool across pricing, scoring, planning, or eligibility apps with quotas.

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Build this pattern

An AI app that talks naturally, calls a controlled JavaScript function, and explains the deterministic result.

A business puts pricing, tax, eligibility, scoring, or planning logic behind a JavaScript tool so answers calculate the same way every time.

Build a calculator app → Docs