fix: pass project_root instead of checkpoint dir to initialize_service

[ChuxiJ]

init_service_wrapper was passing the checkpoint dropdown value (the full checkpoints directory path, e.g. '/checkpoints') as the project_root argument to initialize_service(). This caused initialize_service to append 'checkpoints' again, resulting in '/checkpoints/checkpoints' — triggering unnecessary model re-downloads into the nested directory.

Fix: derive project_root from file (consistent with the LLM init path that was already correct) instead of using the checkpoint dropdown value.

Adds unit tests verifying the project_root is never the checkpoints dir.

Summary by CodeRabbit

• Refactor

  • Improved initialization path computation to eliminate redundant calculations and ensure consistency.

• Tests

  • Added unit tests to validate proper path handling during service initialization.

[coderabbitai]

Caution

Review failed

The pull request is closed.

📝 Walkthrough

Walkthrough

This PR refactors path derivation in the service initialization module to compute project_root once from the file path and reuse it, eliminating duplicate "checkpoints" directory appending. A comprehensive test suite validates the corrected behavior.

Changes

Cohort / File(s)	Summary
Path Derivation Refactor acestep/ui/gradio/events/generation/service_init.py	Moved project_root computation to a single location prior to initialize_service call, removing redundant recomputation inside the init_llm block and fixing double "checkpoints" directory appending.
Checkpoint Path Tests acestep/ui/gradio/events/generation/service_init_test.py	Added new test module with InitServiceWrapperPathTests class containing two test methods validating that project_root is derived from module path (not checkpoint dropdown) and that checkpoint directory nesting is not duplicated.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 Once was a path, doubled and bent,
"Checkpoints" nested—oh what a spent!
Now single derivation, clean and pure,
Tests guard the logic, steady and sure.
Files find their home, no more confusion,
A hopper's delight, bug-free fusion! 🥕

✨ 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 fix_checkpoint_init_dir

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