impl Safe Delete #2207

[asukaminato0721]

Summary

Fixes part of #2207

Added a file-level Safe Delete code action that deletes a Python file only when no import usages are found, using a workspace edit DeleteFile operation and a new refactor.delete kind.

Implemented an AST-based import usage scan across reverse dependencies to decide safety.

note: for simplicity, I didn't impl find ref and delete anyway yet. will add in the future.

Test Plan

Added LSP interaction tests and fixtures for safe delete.

[Copilot]

Pull request overview

This PR implements the Safe Delete feature for Pyrefly, addressing part of issue #2207. The implementation provides two levels of safe deletion:

1. Symbol-level safe delete: Allows deletion of unused functions, methods, classes, variables, constants, and type aliases within a file. Uses global reference finding across all reverse dependencies to ensure the symbol is truly unused.

2. File-level safe delete: Enables deletion of entire Python files when no import usages are detected. Uses AST-based import scanning across reverse dependencies to verify safety.

Changes:

• Added symbol-level safe delete using global reference checking
• Added file-level safe delete using import usage analysis
• Introduced refactor.delete CodeActionKind for LSP clients
• Added comprehensive test coverage for both deletion types

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
pyrefly/lib/state/lsp/quick_fixes/safe_delete.rs	Implements symbol-level safe delete with reference checking
pyrefly/lib/lsp/non_wasm/safe_delete_file.rs	Implements file-level safe delete with import usage scanning
pyrefly/lib/state/lsp.rs	Adds find_global_references_from_definition and supporting methods
pyrefly/lib/lsp/non_wasm/server.rs	Integrates safe delete actions into LSP server and registers refactor.delete kind
pyrefly/lib/test/lsp/code_actions.rs	Unit tests for symbol-level safe delete
pyrefly/lib/test/lsp/lsp_interaction/safe_delete_file.rs	LSP interaction tests for file-level safe delete
Test fixtures	Example Python files for testing safe delete scenarios
Module files	Updates to module structure to include new safe delete modules

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[meta-codesync]

@jvansch1 has imported this pull request. If you are a Meta employee, you can view this in D93605267.

[stroxler]

Review automatically exported from Phabricator review in Meta.

[jvansch1]

@asukaminato0721 I am working on getting this in now. Could you just resolve the merge conflict here first?

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[github-actions]

No diffs to classify.

[meta-codesync]

@jvansch1 merged this pull request in 067c7d9.