Zospend — Smart Daily Expense Tracker (Android)

A full-featured expense module for small business owners to quickly capture, review, and report daily spend. Built with Jetpack Compose and MVVM, with local persistence via Room.

AI Usage Summary

I used Gemini (Android Studio agent) and ChatGPT-5 Thinking as pair-programmers to scaffold the module, generate MVVM/Compose boilerplate, and iterate quickly on UI/UX. They helped diagnose build issues (KSP, missing test deps), improved performance via targeted recomposition fixes (remember, derivedStateOf, @Stable), and added accessibility + haptics with minimal patches. I leaned on the agents for small, verifiable diffs (one feature per prompt), then immediately compiled and fed back errors for precise fix-ups. They also drafted README/usage docs and produced a concise compliance checklist against the brief.

Prompt Log (Key Prompts & Outcomes)

1. Prompt: “Add a calendar icon to the expense list screen. On click, it should open a date picker that allows selection up to today.” Outcome: Implemented a DatePickerDialog launched from a new calendar icon, disabling future dates and updating the ViewModel on selection.

2. Prompt: “I’m getting the following error while building my project: KSP failed with exit code: PROCESSING_ERROR.” Outcome: Root-caused annotation processing issues and provided a checklist (versions, kapt/ksp setup, incremental flags), plus a minimal Gradle/config patch.

3. Prompt: “Review Entry/List/Report composables for recomposition issues; introduce remember/ derivedStateOf where appropriate.” Outcome: Produced a focused diff using remember, derivedStateOf, and @Stable data holders to reduce unnecessary recompositions.

4. Prompt: “Refactor the chart to calculate its Y-axis scale automatically. Also, replace the hardcoded category colors with theme-aware ones.” Outcome: Made the line chart’s Y-axis dynamic by calculating intervals based on the data. Decoupled colors from the data model and used theme-aware colors in the UI.

5. Prompt: “Add content descriptions for actionable icons/images, error semantics for validation, and haptic feedback on successful add.” Outcome: Inserted accessibility modifiers, announced validation errors via semantics, and added light haptics on success.

6. Prompt: “Add category icons in enum.” Outcome: Extended Category enum with icon refs and updated UI (List/Report) to render icons next to labels.

7. Prompt: “Add Material icons.” Outcome: Verified BOM and material-icons-extended dependency; exposed icons for immediate use.

8. Prompt: “Add unit tests for InMemoryExpenseRepository and a simple Compose UI test for EntryScreen.” Outcome: Added repository tests (success, duplicate rejection, per-day totals) and a Compose test for validation/success flow; included kotlinx-coroutines-test.

9. Prompt: “mock is unresolved.” Outcome: Identified missing Mockito Kotlin dependency; added minimal Gradle entry and imports.

10. Prompt: “Compare current code to the Zobaze brief and output a checklist with Pass/Fail per requirement.” Outcome: Generated a gap report with file/line pointers to close misses (export action, empty states, grouping behavior).

11. Prompt: “Generate README.md for the module (features, architecture, how to run, decisions/trade-offs, ‘How I used AI’).” Outcome: Produced a concise README tailored to the current codebase.

12. Prompt: “Show receipt thumbnail in today’s list item; on click open dialog with full image.” Outcome: Added a thumbnail to the list item that, when clicked, opens a dialog showing the full-sized receipt image.

Notes: Prompts were consolidated and outcomes were tightened for clarity.

Feature Checklist

• Expense Entry: Add new expenses with title, amount, category, notes, and an optional receipt image.
• Daily Expense List: View expenses for any selected day using a calendar picker.
• Daily Totals: See the total amount and count of expenses for the selected day.
• 7-Day Report: Visualize category spending trends over the last week with a line chart.
• CSV Export: Share daily and category totals via the Android share sheet.
• Dynamic Chart Scaling: The report chart's Y-axis automatically adjusts to the data.
• Theme-Aware UI: Colors adapt to the system's light or dark theme.
• Image Previews: View receipt thumbnails in the list and tap to see the full image.
• Search & Filter: Search for expenses by title or filter by category.
• Monthly Reports: View aggregated expense data on a monthly basis.
• Cloud Sync: Back up and sync expenses across multiple devices.

APK Download Link

APK Drive Link

Screenshots

Expense List	Expense Entry	Report

Architecture & Tech

• Architecture: MVVM with ViewModel + StateFlow.
• UI: Jetpack Compose (Material 3), Navigation-Compose.
• Data: Room database as single source of truth; repository abstraction.
• Time/Money: java.time (Instant/LocalDate); amounts stored in paise/cents (Long) for accuracy.
• Charts: Compose Canvas (no external chart libs).
• Export: CSV string → Android share intent.

Module Structure

app/
  ui/
    entry/          # EntryScreen, EntryViewModel
    list/           # ExpenseListScreen, ExpenseListViewModel
    report/         # ReportScreen, ReportViewModel
    components/     # Reusable UI bits (dropdowns, dialogs, chart etc.)
    navigation/     # NavGraph
    theme/          # Material theme
    main/           # Main screen, Wrapper screen
  domain/
    model/          # Expense, Category
    repo/           # ExpenseRepository, implementations
  data/
    local/          # Entities, DAO, Database
    mock/           # Mock data creation 
  util/             # Formatting, CSV builder, share helpers
  tests/            # Unit + UI tests

Navigation

• Bottom Nav: List (Today by Default) Report
• FAB: Add → Entry (bottom sheet form)
• Update Expense: Full screen update expense form
• Back: Entry → List; Report → List

How to Run

1. Open in Android Studio (latest stable).
2. Use AGP 8+, Kotlin 2.x, JDK 17 recommended.
3. Sync Gradle, then Run on device/emulator (minSdk 30, compileSdk 36).

If you must stay on Java 11, ensure Gradle toolchain and jvmTarget are aligned across Kotlin/Java.

Decisions & Trade-offs

• Room vs In-Memory: Chose Room to satisfy persistence and mirror real usage.
• Date UX: A calendar picker allows for quick navigation to any date, providing more flexibility than simple next/previous day buttons.
• Charts: Kept to Canvas for zero dependencies and full control.
• Money type: Paise/Cents (Long) to avoid floating point rounding issues.