Data Contract Migrations
SkillDatabases & dataDesign and verify data contracts, schema changes, migrations, rollbacks, backfills, compatibility windows, tenant isolation, and API-to-database field mapping. Use when changing database schema, event payloads, persisted documents, analytics tables, multi-tenant data boundaries, or any user-visible data contract where silent fallback or undeclared fields would be dangerous.
Available today. Use it from your connected AI after setup.
No other account needed.
Connect ahel once, and every AI you use reads what you have installed.
Then ask your AI: use the Data Contract Migrations skill
What this skill tells your AI
The instructions your AI receives, as published by majiayu000/spellbook in skills/data-contract-migrations/SKILL.md and read by ahel’s review.
Purpose
Use this skill when data shape changes can break reads, writes, reports, tenants, or integrations. The goal is an explicit compatibility and migration plan, not just a SQL diff.
Preflight
Gather these facts before proposing changes:
- Current schema, models, serializers, API contracts, and persisted samples.
- Writers and readers of each field.
- Migration tool and rollback support.
- Data volume, tenant boundaries, and backfill cost.
- Required zero-downtime or maintenance-window constraints.
- Existing tests or fixtures that prove compatibility.
If the current data does not contain a field, treat it as absent. Do not invent fallback fields.
Migration Design
Use expand-migrate-contract for production systems:
- Expand: add nullable columns, new tables, new enum values, or versioned payloads without breaking old readers.
- Dual-write or adapter: write both old and new forms when needed.
- Backfill: migrate historical data with batching, checkpoints, and retry behavior.
- Read switch: move readers to the new contract after verification.
- Contract: remove old fields only after the compatibility window and rollback risk pass.
For small systems, a direct migration is acceptable only when downtime, rollback, and data loss risks are explicitly low.
Required Checks
Every plan must include:
- Forward migration command.
- Rollback or roll-forward recovery command.
- Backfill idempotency and resume behavior.
- Data validation query before and after.
- Tenant isolation check when tenants exist.
- API/serializer compatibility test.
- Observability for migration progress and failure.
Output Shape
contract_change:
affected_readers_writers:
migration_strategy:
backfill_plan:
rollback_or_recovery:
tenant_and_security_checks:
verification_queries:
test_commands:
release_gate:
Raise errors for missing critical data rather than warning and falling back to incomplete output.
Signals
- GitHub stars
- 278
- Forks
- 26
- Last commit
- Sep 2026
Advanced
- Catalog kind
- skill
- Gateway key
data-contract-migrations- Source
- github.com/majiayu000/spellbook