CI: use ast-grep rule

[asukaminato0721]

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Summary

Part of #25860, add ast-grep script to auto-rewrite fields.

ref https://ast-grep.github.io/catalog/python/rewrite-sqlalchemy-mapped-column.html

Screenshots

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Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[gemini-code-assist]

Summary of Changes

Hello @asukaminato0721, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request integrates ast-grep into the project, providing a robust framework for automated code refactoring. The primary focus of this initial integration is to modernize SQLAlchemy mapped_column definitions in Python code. By introducing specific ast-grep rules, the PR automates the conversion of string field declarations to use contemporary Mapped type hints, effectively removing redundant nullable=True or nullable=False arguments. This enhancement aims to improve code consistency, readability, and maintainability by streamlining common refactoring tasks.

Highlights

• AST-grep Integration: Introduced ast-grep as a new tool for automated code refactoring, enabling semantic-aware code transformations.
• SQLAlchemy Nullable String Refactoring: Added an ast-grep rule to automatically rewrite mapped_column definitions for nullable string fields (where nullable=True) to use the modern Mapped[str | None] type hint, while removing the redundant nullable argument.
• SQLAlchemy Non-Nullable String Refactoring: Implemented an ast-grep rule to automatically refactor mapped_column definitions for non-nullable string fields (where nullable=False) to use the Mapped[str] type hint, also removing the explicit nullable argument as nullable=False is the default.
• AST-grep Configuration: Configured ast-grep to recognize and utilize the newly defined refactoring rules located in the rules directory.

Ignored Files

• Ignored by pattern: .github/workflows/** (1)
  • .github/workflows/autofix.yml

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[gemini-code-assist]

Code Review

This pull request introduces ast-grep rules to automate the refactoring of SQLAlchemy models to the modern 2.0 style, which is a good improvement for code maintainability. However, the current implementation has a few critical issues. Both new rule files use the same id, which will cause ast-grep to fail. Additionally, the rule for nullable strings contains a logical error in its rewriter that would incorrectly remove the column type definition, leading to broken code. I've provided detailed comments and code suggestions to fix these problems by ensuring unique rule IDs and correcting the rewriter logic. I also recommended more descriptive filenames for better clarity.

[asukaminato0721]

cc @QuantumGhost