Planetscale Vitess Safety Review Agent Skill

Vitess safety review

Purpose

Recommend best practices for a PlanetScale Vitess database. Focus on production safety, deployability, observability, and agent-safe automation. Do not apply any changes.

Primary safety features to evaluate

Safe migrations

Check whether safe migrations are enabled on production and staging branches.

Recommend enabling safe migrations when:

• The branch receives production traffic.
• The team runs DDL outside deploy requests.
• There is no protected branch workflow.
• The application is expected to evolve schema frequently.

Explain the tradeoff: safe migrations reject direct DDL on protected branches and force schema changes through deploy requests. That is a feature, but it can break teams relying on direct production DDL. Treat enablement as a behavior-changing change requiring approval.

Deploy requests

Check:

• Whether deploy requests are used for schema changes.
• Whether administrator approval is required.
• Whether deploy requests are reviewed for data loss, conflicts, lint errors, foreign key problems, charset issues, and shard impact.
• Whether teams use gated deployments for cutover control.
• Whether “deploy instantly” is used and whether the team understands it removes the gated-deployment/revert shape.
• Whether cutover is regularly delayed by long-running transactions.
• Whether deploy request events are subscribed to via webhooks.

Recommend:

• Require deploy requests for production schema changes.
• Enable administrator approval for production deploy requests when there is more than one administrator.
• In a single-admin organization, administrator approval does not stop an agent that acts as that admin:

the admin who opens a deploy request can also approve it. If the goal is to keep agents from

self-approving, give the agent a separate user, or a service token without deploy request

approval permission.

• Prefer normal safe deployments over instant deployments unless the migration is known to be instant-safe and the rollback story is acceptable.
• Use gated deployment when cutover timing matters.
• Treat “force cutover now” as an operator-controlled action for delayed

cutovers: it aggressively stops running transactions to complete schema

cutover. Recommend reviewing the blocking workload and incident context

before use, and only recommend the database-level aggressive cutover default

when frequent cutover blocking is understood and accepted.

Schema revert

Check whether the team knows the revert window and whether their incident runbook includes it.

Recommend documenting:

• How to identify a bad schema migration.
• How to revert within the supported window.
• Who is authorized to revert.
• Which application deploy should be rolled back together with the schema revert.

Branch strategy

Recommend a branch topology:

• main or equivalent production branch with safe migrations enabled.
• staging branch based from production with safe migrations enabled.
• Short-lived development branches based from staging.
• Deploy requests from development to staging, then staging to production when appropriate.

Do not create branches without approval.

Query Insights

Review Insights for:

• Slow queries.
• Queries reading too many rows.
• Erroring queries.
• Queries with poor index usage.
• For sharded databases, whether query patterns use relevant vindexes and how

vindex usage changes after index or routing changes.

• Unusual query volume.
• Missing SQL comment tags.
• Tag breakdowns when built-in metadata or SQLCommenter tags are present:

tag:key:value filtering in the dashboard, and the insights/tags and

insights/tags/summaries API endpoints for programmatic breakdowns.

• Deploy correlation data.

Recommend enabling or improving application query tagging so Insights can attribute queries to app, route, controller, action, job, deployment SHA, and feature.

Anomalies

Review active and recent anomalies.

Recommend:

• Subscribe branch.anomaly webhooks to the team’s alerting or automation system.
• Route anomaly payloads to a triage workflow that opens an issue or agent task.
• Correlate anomalies with deploy requests, application deploys, and query tags.
• Do not automatically apply schema or code changes from anomaly events; generate a proposal or PR only.

Schema recommendations

Review open schema recommendations.

For each recommendation, capture:

• Type: add index, remove redundant index, primary key exhaustion, unused table, legacy charset/collation, or other.
• Affected table and keyspace.
• Supporting query telemetry.
• DDL.
• Expected benefit.
• Risk.
• Test plan.

Recommend implementation path:

• Convert the recommendation into an application migration or PlanetScale branch schema change.
• Open a deploy request.
• Review generated DDL and shard impact.
• Benchmark or validate on a branch.
• Deploy with safe migrations.
• Monitor Insights and anomaly state after deployment.

Do not apply recommendations directly.

Backups and restore

Check backup posture and restore runbooks.

Recommend:

• Verify automated backups exist.
• Run a non-production restore drill periodically.
• Document restore target, RPO/RTO expectation, and application cutover plan.
• For sharded databases, document shard-aware restore expectations.

Sharding and keyspace safety

If the database is sharded, review:

• Keyspaces and shards.
• Vschema.
• Cross-shard query patterns.
• Whether schema deploy requests show per-shard impact.
• Whether queries use shard-friendly access paths.

Recommend an agent-safe sharding review only as a proposal. Never reshard, change vschema, or alter routing automatically.

Webhook recommendations for Vitess

Evaluate and recommend webhooks for:

• branch.anomaly
• branch.primary_promoted
• branch.ready
• branch.sleeping
• cluster.storage
• keyspace.storage
• deploy_request.opened
• deploy_request.queued
• deploy_request.in_progress
• deploy_request.pending_cutover
• deploy_request.schema_applied
• deploy_request.errored
• deploy_request.reverted
• deploy_request.closed
• branch.schema_recommendation if available in the webhook API for the customer’s database

Recommended destinations:

• Alerting for anomaly, primary promotion, storage, and deploy errors.
• Slack or internal notifications for deploy request lifecycle.
• Agent intake queue for schema recommendations and anomalies, with PR-only output by default.

Output

Return:

• Current Vitess safety posture.
• Missing safety features.
• Recommended workflow.
• Recommended webhook subscriptions.
• Schema recommendation triage table.
• Deploy safety gaps.
• Proposed changes requiring approval.

End with:

“No Vitess changes have been applied.”