[WordService] Refactor RestoreFrontierWords

[imnasnainaec]

A less important piece of #4146

---

This change is 

Summary by CodeRabbit

• New Features

  • Added batch word retrieval by IDs for faster multi-word operations.

• Bug Fixes

  • Prevented deleted words from being restored to the frontier.

• Refactor

  • Optimized frontier restoration with deduplication, batch validation/checks, and immediate no-op for empty requests for improved reliability and performance.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

---

📝 Walkthrough

Walkthrough

Adds a batch word retrieval method to the repository and mock, and refactors RestoreFrontierWords to deduplicate inputs, perform batched frontier and repository checks, reject deleted or missing words, and batch-add valid words to the Frontier.

Changes

Cohort / File(s)	Summary
Interface & Mock Backend/Interfaces/IWordRepository.cs, Backend.Tests/Mocks/WordRepositoryMock.cs	Added GetWords(string projectId, List<string> wordIds) to the interface; mock now filters by projectId and wordId list and returns cloned results.
Repository Implementation Backend/Repositories/WordRepository.cs	Implemented GetWords(projectId, wordIds) with filter/query and telemetry span; minor XML doc cleanup in Create overloads.
Service Logic Backend/Services/WordService.cs	Refactored RestoreFrontierWords to deduplicate inputs, use batched AreInFrontier and GetWords, validate no Deleted words and matching counts, then batch-adds to Frontier.

Sequence Diagram(s)

sequenceDiagram
  participant Client as Client
  participant Service as WordService
  participant Repo as WordRepository
  participant Frontier as FrontierStore

  Client->>Service: RestoreFrontierWords(projectId, wordIds)
  Note right of Service: deduplicate wordIds
  Service->>Frontier: AreInFrontier(projectId, wordIds)
  Frontier-->>Service: noneInFrontier / someInFrontier
  alt someInFrontier
    Service-->>Client: return false
  else noneInFrontier
    Service->>Repo: GetWords(projectId, wordIds)
    Repo-->>Service: List<Word> (may be incomplete)
    alt count mismatch or contains Deleted
      Service-->>Client: return false
    else valid words
      Service->>Frontier: AddFrontier(projectId, words)
      Frontier-->>Service: success
      Service-->>Client: return true
    end
  end

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

Suggested labels

refactor

Suggested reviewers

• jasonleenaylor

Poem

🐰 I hopped through code with eager paws,

Gathered IDs and trimmed the claws,
Batched the checks, no duplicates kept,
Deleted words politely leapt,
Frontier filled — a tidy cause! ✨

🚥 Pre-merge checks | ✅ 3 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 43.75% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main change: refactoring RestoreFrontierWords method in WordService with batch operations and improved validation logic.
Merge Conflict Detection	✅ Passed	✅ No merge conflicts detected when merging into master

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch restore-frontier-words-refactor

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[codecov]

Codecov Report

❌ Patch coverage is 69.23077% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.03%. Comparing base (21b27bf) to head (285abe1).
⚠️ Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
Backend/Services/WordService.cs	69.23%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4147       +/-   ##
===========================================
+ Coverage   74.76%   86.03%   +11.27%     
===========================================
  Files         302       56      -246     
  Lines       11068     4834     -6234     
  Branches     1389      600      -789     
===========================================
- Hits         8275     4159     -4116     
+ Misses       2390      528     -1862     
+ Partials      403      147      -256     

Flag	Coverage Δ
backend	86.03% <69.23%> (-0.09%)	⬇️
frontend	?

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@Backend/Services/WordService.cs`:
- Around line 101-122: The method processes wordIds and currently can call
_wordRepo.AddFrontier(words) with an empty list, which triggers
MongoDB/InsertManyAsync ArgumentException; add an explicit guard after
deduplication (wordIds = wordIds.Distinct().ToList()) or after fetching words to
return false / no-op when wordIds (or words) is empty so AddFrontier is never
invoked with an empty collection — update the logic around wordIds / words
checks in WordService (references: wordIds, _wordRepo.AreInFrontier,
_wordRepo.GetWords, _wordRepo.AddFrontier) to short-circuit when empty.

[imnasnainaec]

Replaced by #4161