DB Migration

DB Migration Workflow

Purpose

Use this workflow to safely create and validate database migrations in DeadTrees with MCP-first database operations.

Core Rules

• Never connect to the database directly with Python; use MCP tools.
• Use local DB MCP (user-deadtrees-local) for schema changes and validation.
• Before any change, verify local and production DB are in sync using MCP-only checks.
• Keep test scope fast first: run only relevant, quick tests before broader checks.
• Ask before committing; do not commit automatically.
• Never push/apply migrations to production from the agent; production migration application is manual by the user.

Required Workflow

Follow these steps in order.

1) Verify local and production are in sync (MCP-only)

• Compare local and production schemas via MCP (user-deadtrees-local and user-deadtrees-prod) before making changes.
• Validate critical objects involved in the migration (tables, views, functions, policies, indexes, triggers).
• If drift is found, stop and report it before proceeding.

2) Make local dev DB changes via MCP

• Apply schema/function/policy changes using MCP SQL execution against local DB.
• Prefer safe SQL patterns:
  • Start with small, targeted statements.
  • Validate affected objects immediately after each change.
• If view dependencies exist, handle drop/alter/recreate order explicitly.

3) Validate with fast tests and MCP checks

• Run relevant fast tests only (smallest affected scope first).
• Follow project testing rules:
  • Use deadtrees CLI for tests.
  • Prefer focused test paths instead of full suites.
• Review DB behavior with MCP:
  • Check updated schema objects.
  • Run validation queries that prove expected behavior.
  • Confirm no unintended side effects in related tables/views/functions.

4) Fix breakages if found

• If tests or MCP validation fail, fix code/SQL and re-run step 2.
• Continue until fast tests pass and MCP validation confirms expected behavior.

5) Export migration

Run:

PGSSLMODE=disable supabase db diff -f name-of-migration-file

• Use a descriptive migration file name.
• Ensure generated migration reflects only intended schema changes.

6) Review migration file

• Verify SQL ordering and dependency safety.
• Confirm idempotence expectations and rollback safety where applicable.
• Ensure no accidental changes are included.

7) Ask to commit

• Summarize what changed, what was tested, and MCP validation results.
• Ask user for approval before git add/git commit.
• Explicitly remind: do not apply/push migration to production; user applies it manually.

Fast-Path Test Selection Guidance

When selecting tests, prefer this order:

1. Direct unit/integration tests for changed module.
2. Closely related API/processor test file via --test-path.
3. Broader suite only if targeted tests indicate cross-cutting impact.

MCP Validation Checklist

Use this checklist before exporting migration:

• Local object exists and has expected definition.
• Key queries against changed object return expected results.
• Related policies/views/functions still work.
• No obvious regressions in dependent paths.

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