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2026-01-05: TypeScript Conversion

Task Metadata

  • 📆 Date: 2026-01-05
  • 🚥 Status: Completed

1. Context

  • Goal: Incrementally migrate the frontend codebase from JavaScript (.js/.jsx) to TypeScript (.ts/.tsx) to improve type safety, developer experience, and code maintainability.
  • Trigger: User request to bring this task forward in the roadmap.

2. Approach

  • Technical Strategy:
    1. Initial Setup: Install TypeScript and necessary @types/* packages. Configure tsconfig.json for a React Vite project.
    2. Incremental Migration: Migrate files one by one or in logical groups, starting with leaf nodes (utilities, simple components) and moving up to complex pages and context providers.
    3. Strictness: Enable strict: true in tsconfig.json from the start but allow any temporarily if needed to unblock migration, with a plan to refine types later.
  • Key Decisions:
    • Use tsx for components and ts for logic.
    • Co-locate types with components or use a global types.d.ts for shared domain models.
    • Maintain existing functionality; this is a refactor, not a feature update.
  • Testing Strategy:
    • Must Test: Verify the build process (npm run build) passes after configuration changes. Run existing unit and visual tests to ensure no regressions.
    • Skip: Logic changes (none intended).

3. Impact Analysis

  • Files to Modify:
    • frontend/package.json (Add devDependencies)
    • frontend/tsconfig.json (Create/Update)
    • frontend/vite.config.js (Rename to .ts if needed/supported)
    • frontend/src/**/* (Renaming and editing)
  • Risks:
    • Build breakages during the transition.
    • "Type gymnastics" slowing down immediate feature work.
    • Potential for hidden runtime bugs if any is overused and incorrect assumptions are made.

4. Execution Plan

  • Install TypeScript and dependencies (typescript, @types/react, @types/react-dom, @types/node).
  • Initialize tsconfig.json.
  • Rename main.jsx to main.tsx and fix entry point errors.
  • Migrate utils/ directory.
  • Migrate hooks/ directory.
  • Migrate Leaf Components (MealItem, ProgressBar, PendingMealCard, HelpModal).
  • Migrate Complex Components (DailyTotals, SettingsModal, Header, MealList).
  • Migrate pages/ directory.
  • Verify npm run build and visual tests.

5. Execution Notes

  • Incremental Config: Enabled "allowJs": true in tsconfig.json. This was critical to allow main.tsx to import App.jsx (which hasn't been migrated yet) and to allow the build to proceed with a mix of JS and TS files.

  • Vite Types: Added frontend/src/vite-env.d.ts with /// <reference types="vite/client" /> to resolve import.meta.env type errors.

  • Legacy Compatibility: Used pragmatic typing (e.g., any for complex AWS Amplify clients) in ApiMealService to unblock migration, with plans to refine later.

  • UI Legacy Support: explicitly preserved fallback logic in MealItem.tsx (e.g., meal.MealSummary) to ensure legacy data continues to render correctly during the migration, preventing regression in the UI.

  • Pages & App Migration: Converted all main pages (Marketing, Dashboard, About, Tracker) and App.tsx to TypeScript. Added DashboardProps and User interfaces to handle strict prop typing.

  • Verification: Successfully ran bun run build and bun run test. All 21 tests passed across 4 files.

  • Tech Debt / Future Improvements:

    • Replace any in ApiMealService with proper Amplify types.
    • Remove allowJs once full migration is complete.

6. User Approval & Key Learnings

"Interesting to tease out a couple of more errors. It'll take some time to probably appreciate the Typescript conversion but it's good that we catch some data format shape errors earlier now." - User Approval, 2026-01-04

7. Context Memory (AI-Only)

Summary for Future Context

The frontend codebase has been fully migrated to TypeScript (.ts/.tsx). This included all utility functions, custom hooks, components, and pages. Configuration was updated via tsconfig.json and dependencies were added to package.json. The application was verified through a successful build and passing unit tests. Key data shape errors were caught and resolved during the conversion of the Dashboard and Tracker pages.