46 lines
3.2 KiB
Markdown
46 lines
3.2 KiB
Markdown
# Working Spec
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## Overview
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SDLC SIMPCALC3 — Simple Calculator 3 is a browser-based web application that provides the four fundamental arithmetic operations: addition, subtraction, multiplication, and division. The application is delivered as a single-page web app through the AI-SDLC pipeline. It is intended to be lightweight, accessible, and easy to use without any installation or account creation.
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## Actors
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| Actor | Description |
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|---|---|
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| **End User** | Any person who opens the web app in a browser to perform arithmetic calculations. No authentication or account is required. |
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## Functional Requirements
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1. **Addition** — The user can enter two numeric operands and compute their sum.
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2. **Subtraction** — The user can enter two numeric operands and compute their difference.
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3. **Multiplication** — The user can enter two numeric operands and compute their product.
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4. **Division** — The user can enter two numeric operands and compute their quotient.
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5. **Division by zero handling** — When the divisor is zero, the application displays a clear error message rather than crashing or displaying `Infinity`/`NaN`.
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6. **Result display** — The computed result is displayed prominently on screen immediately after the user triggers the calculation.
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7. **Clear / reset** — The user can clear the current inputs and result to start a new calculation.
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8. **Keyboard input** — The user can enter operands and trigger calculations using a standard keyboard.
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9. **Decimal number support** — The application accepts and correctly computes floating-point (decimal) operands.
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10. **Operator selection** — The user can select the desired arithmetic operator via the UI (e.g., buttons or a dropdown).
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## Non-Functional Requirements
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| ID | Category | Requirement |
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| NFR-1 | Performance | The result must appear within 100 ms of user action on any modern browser. |
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| NFR-2 | Usability | The UI must be usable on desktop and mobile screen sizes (responsive design). |
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| NFR-3 | Accessibility | The app must meet WCAG 2.1 Level AA contrast and keyboard-navigation requirements. |
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| NFR-4 | Compatibility | The app must function correctly in the latest stable versions of Chrome, Firefox, Safari, and Edge. |
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| NFR-5 | Maintainability | Code must be modular and covered by unit tests for all arithmetic logic. |
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| NFR-6 | Deployability | The app must be deployable as a static site (no server-side runtime required). |
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## Assumptions
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1. The target user base requires no server-side persistence; all computation is performed client-side in the browser.
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2. No user authentication, account management, or history/logging feature is in scope for this version.
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3. The calculator operates on two operands per operation (binary operations only); chained multi-step expression input (e.g., a full expression parser) is out of scope.
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4. Numeric precision follows standard IEEE 754 double-precision floating-point; no arbitrary-precision arithmetic is required.
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5. The application will be delivered as a static web app (HTML/CSS/JavaScript); a specific front-end framework will be determined during technical architecture.
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6. Internationalisation (i18n) and localisation (l10n) are out of scope for this version.
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7. Offline (PWA/service-worker) support is not required for this version.
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