Feat/progressive inbox scan

[Vamsiindugu]

Summary

This PR resolves the performance issue where the extension would freeze when scanning very large inboxes (~500k emails).

It replaces the "all-at-once" email fetching mechanism with a progressive loading system that processes emails in batches.

This provides a much better user experience by preventing the UI from freezing and giving the user real-time feedback and control over the scanning process.

✨ Key Changes

• Batched Processing: The BrowserEmailService now fetches emails in configurable batches to avoid blocking the main thread.
• Progress UI: A new FetchProgressBar component has been added, which displays:
  • Current page vs. total pages
  • Number of processed emails
  • A percentage completion bar
• Cancellation Support: Users can now cancel an in-progress scan via a "Cancel" button.
• State Management: The AppProvider now manages the state for fetch progress and cancellation.
• Incremental Aggregation: Sender data is aggregated incrementally, improving memory efficiency.

✅ Verification

All 37 existing Playwright UI tests were executed and passed successfully, confirming that these changes do not break existing functionality.

[Copilot]

Pull Request Overview

This PR adds progressive loading functionality to display real-time progress when fetching email senders from Gmail, improving user experience during long-running operations.

Key changes:

• Introduces a visual progress bar UI with cancellation support
• Implements batch processing with progress reporting in the email fetching logic
• Adds comprehensive Playwright tests for progressive loading behavior

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
test/ui/sidebar/progressiveLoading.spec.ts	New test suite with 10 tests covering progress bar display, cancellation, transitions, and edge cases
test/ui/sidebar/helpers.ts	Added helper functions for waiting on progress completion and retrieving progress state
src/presentation/providers/app_provider.tsx	Updated context to manage fetch progress state and cancellation, integrated progress callbacks with MockEmailRepo
src/presentation/apps/sidebar/components/sendersContainer.tsx	Modified rendering logic to show progress bar when fetchProgress is available
src/presentation/apps/sidebar/components/fetchProgress.tsx	New component rendering the progress bar UI with stats and cancel button
src/presentation/apps/sidebar/components/fetchProgress.css	Styling for the progress bar component
src/data/services/browser_email_service.ts	Refactored to support batch processing, progress callbacks, and cancellation via AbortSignal
src/data/repositories/mocks/mock_email_repo.ts	Added progress simulation with configurable progressive loading and cancellation
src/data/repositories/browser_email_repo.ts	Added progress callback support and cancel method, listens for progress messages from content script
src/data/content_scripts/content.ts	Refactored to support cancellation with AbortController and send progress updates to side panel

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