fix(migration): constrain alembic targets and reset version state.

[MasakiMu319]

Link to Issue or Description of Change

• Closes: N/A
• Related: N/A

Problem:

In production, leaving Alembic unconstrained is extremely dangerous—autogenerated migrations could drop or alter unrelated business tables. The migration script also left stale alembic_version state and did not scope tables to ADK session metadata.

Solution:

Constrain Alembic to ADK session tables via targeted metadata and an include_object filter, using a dedicated alembic_version_adk as alembic version table. Rewrite the migration script to emit this safe env.py, clean backups, and reset any old version table before autogeneration—here we only need the DB tables to align with the latest Base metadata—keeping migrations isolated and idempotent.

Testing Plan

• Unit Tests: Not run (no code-level changes).
• Manual Verification: Ran the migration flow locally and confirmed the Alembic version table matched expectations.

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my changes.
• I have commented my code, particularly in hard-to-understand areas.

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[gemini-code-assist]

Summary of Changes

Hello @MasakiMu319, 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 significantly improves the safety and isolation of database migrations for ADK session tables. It addresses critical production concerns by ensuring that Alembic only interacts with its intended schema objects and by providing a robust, idempotent migration script. The changes prevent accidental data loss or schema corruption by strictly scoping migration operations and cleaning up previous states, thereby enhancing the overall stability and predictability of database updates.

Highlights

• Constrained Alembic Migrations: Alembic migrations are now strictly constrained to only operate on tables defined within the ADK session metadata. This is achieved by introducing TARGET_METADATAS and an include_object filter in env.py, preventing unintended modifications to unrelated database tables.
• Dedicated Alembic Version Table: The migration process now uses a dedicated version table named alembic_version_adk instead of the default alembic_version. This isolates ADK session migrations and prevents conflicts or confusion with other potential migration systems.
• Enhanced Migration Script Robustness: The db_migration.sh script has been significantly refactored to dynamically generate a safe env.py file, ensure proper cleanup of backup files, and proactively reset the alembic_version_adk table before autogenerating migrations. This makes the migration process more idempotent and reliable.

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[adk-bot]

Response from ADK Triaging Agent

Hello @MasakiMu319, thank you for creating this PR!

This PR is a bug fix, could you please associate a GitHub issue with this PR? If there is no existing issue, could you please create one?

In addition, could you please provide logs or a screenshot after the fix is applied?

This information will help reviewers to review your PR more efficiently. Thanks!

[gemini-code-assist]

Code Review

This pull request significantly improves the safety and reliability of the database migration script. By constraining Alembic's scope to specific tables using include_object and a dedicated version table, it effectively prevents accidental changes to unrelated business tables. The move from using sed to a cat heredoc to generate the env.py file is a much more robust and maintainable approach. Additionally, resetting the version table ensures the script is idempotent. I have a couple of suggestions to further improve the generated Python code for better adherence to best practices.