refactor(app): reduce complexity in packages/app/src/components/file-tree-v2-model.ts

[mdarin60]

P1B: Starter Task: Refactoring PR

Use this pull request template to briefly answer the questions below in one to two sentences each.
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1. Issue

Link to the associated GitHub issue:
103

Full path to the refactored file:
packages/app/src/components/file-tree-v2-model.ts

What do you think this file does?
It creates functions that are used to convert lists of files paths to a file tree structure. It does not necessarily assume perfect inputs, as it removes duplicates, normalizes paths, creates parent directories, and sorts alphabetically.

What is the scope of your refactoring within that file?
The refactor moved lines 23-42 in buildFileTreeV2Model() to collectFileTreeNodes() in lines 43-62.

Which Qlty‑reported issue did you address?
Cognitive Complexity of 23 in buildFileTreeV2Model() .

2. Refactoring

How did the specific issue you chose impact the codebase’s maintainability?
Originally, in the original lines 23-42 of buildFileTreeV2Model(), it may be difficult to understand the purpose or intended behavior of the first paths.forEach. The scope of the buildFileTreeV2Model() was also too wide, in that it did the normalization, node collection, and turning this into a tree, and for future development it might be useful to view these as two seperate tasks.

What changes did you make to resolve the issue?
I moved the code that normalizes the files paths and collects nodes into a new private function, collectFileTreeNodes().

How do your changes improve maintainability? Did you consider alternatives?
The new code separates path normalization from the actual building of the tree, which makes it easier for developers to address either issue in the future. I also considered more helpers functions, but I thought the functions were well-scoped now and did not want to overcrowd the file.

3. Validation

How did you validate that the change is correct?
I validated the change is correct by using the existing tests and 5 additional tests that cover the case of empty inputs, path collisions, and verified that the function was non-mutating. The tests for this are in packages/app/src/components/file-tree-v2-model.test.ts and have 100% test coverage.

Attach a screenshot of the test coverage showing the lines were executed by the tests.

Note that both failures were in code that my changes do not touch, so I did not introduce any more lint failures.

Attach a screenshot showing the tests that cover the change passing during CI

Attach a screenshot of qlty smells --no-snippets <full/path/to/file.ts> showing fewer reported issues after the changes.