schema

Designing database schemas, planning migrations, and authoring ER diagrams. Handles normalization, index strategies, and relation definitions. Use when DB schema design is needed.

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Repository: simota/agent-skills
Last source activity: August 1, 2026 at 17:25
Detected SKILL.md language: English
Stars: 71
Forks: 14

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Schema

Database schema specialist for data modeling, migration planning, and ER diagrams.

Trigger Guidance

Use Schema when the task needs one or more of the following:

New table or relationship design

Primary key, foreign key, constraint, or naming decisions

Migration planning, rollback design, or zero-downtime change strategy

Index selection from query patterns

Database-specific SQL patterns for PostgreSQL, MySQL, or SQLite

ORM schema output for Prisma, TypeORM, or Drizzle

Mermaid erDiagram output for documentation

Multi-tenant schema design (shared-schema with RLS, schema-per-tenant, or database-per-tenant)

Vector/embedding column design with pgvector (HNSW/IVFFlat index selection, float16 quantization)

Temporal constraint design using PostgreSQL 18 WITHOUT OVERLAPS for scheduling/time-series

Expand-contract migration planning for zero-downtime DDL

Route elsewhere when the task is primarily:

Query execution tuning or EXPLAIN ANALYZE optimization → Tuner

API endpoint or resource lifecycle design → Gateway

Architecture decomposition or service boundary decisions → Atlas

Application-level ORM query implementation → Builder

Core Contract

Follow Model -> Migrate -> Validate.

Default to 3NF; denormalize only with explicit read/performance rationale.

Design from access patterns, data integrity, and expected growth.

Schema

Database schema specialist for data modeling, migration planning, and ER diagrams.

Trigger Guidance

Use Schema when the task needs one or more of the following:

New table or relationship design

Primary key, foreign key, constraint, or naming decisions

Migration planning, rollback design, or zero-downtime change strategy

Index selection from query patterns

Database-specific SQL patterns for PostgreSQL, MySQL, or SQLite

ORM schema output for Prisma, TypeORM, or Drizzle

Mermaid erDiagram output for documentation

Multi-tenant schema design (shared-schema with RLS, schema-per-tenant, or database-per-tenant)

Vector/embedding column design with pgvector (HNSW/IVFFlat index selection, float16 quantization)

Temporal constraint design using PostgreSQL 18 WITHOUT OVERLAPS for scheduling/time-series

Expand-contract migration planning for zero-downtime DDL

Route elsewhere when the task is primarily:

Query execution tuning or EXPLAIN ANALYZE optimization → Tuner

API endpoint or resource lifecycle design → Gateway

Architecture decomposition or service boundary decisions → Atlas

Application-level ORM query implementation → Builder

Core Contract

Follow Model -> Migrate -> Validate.

Default to 3NF; denormalize only with explicit read/performance rationale.

Design from access patterns, data integrity, and expected growth.

File

Read this when...

reference/normalization-guide.md

You need the 1NF/2NF/3NF checklist or denormalization decision rules.

reference/index-strategies.md

You are choosing index type, column order, partial indexes, or monitoring queries.

reference/migration-patterns.md

You need safe migration sequencing, expand-contract, or framework migration commands.

reference/schema-examples.md

You need concrete schema, migration, ORM, or ER diagram examples.

reference/schema-design-anti-patterns.md

You are reviewing table structure, constraints, naming, or data-type choices.

reference/data-modeling-anti-patterns.md

You are evaluating EAV, polymorphic relations, denormalization, or temporal design.

reference/migration-deployment-anti-patterns.md

You are planning a risky migration, zero-downtime rollout, or rollback strategy.

reference/index-performance-anti-patterns.md

You are reviewing composite indexes, bloat, FK indexes, or index health.

reference/postgresql18-features.md

You are on PostgreSQL 18 (GA 2025-09-25) and need UUIDv7, virtual generated columns (default), temporal WITHOUT OVERLAPS / PERIOD, RETURNING OLD.*/NEW.*, B-tree skip scan, async I/O, OAuth, or DDL replication.

reference/postgresql17-features.md

You are on PostgreSQL 17 and need SQL/JSON (JSON_TABLE, JSON_VALUE, JSON_QUERY, JSON_EXISTS), SPLIT/MERGE PARTITION, logical-replication failover, or pg_createsubscriber. Legacy reference — see postgresql18-features.md for current release.

reference/multi-tenant-patterns.md

You are designing a multi-tenant schema (database/schema/shared-schema with RLS).

reference/advanced-patterns.md

You need event sourcing schema, CQRS projections, pgvector/AI schema, or bitemporal design.

reference/migration-rollback.md

You are designing reverse-operation DDL, dual-write windows, backfill scripts, or destructive-change alternatives (rollback recipe).

reference/partition-strategies.md

You are designing range/list/hash/time-based partitioning, pruning, maintenance, or staged migration from existing tables (partition recipe).

reference/audit-log-schema.md

You are designing append-only audit-log tables — actor/action/before-after image, retention, WORM, HMAC chain (audit-log recipe).

reference/event-sourcing-schema.md

You are designing event store, projections, snapshots, outbox pattern, or aggregate boundaries (event-sourcing recipe).

reference/soft-delete-patterns.md

You are designing logical deletion (deleted_at / status / tombstone), partial unique indexes, FK cascade, or GDPR right-to-erasure pathway (soft-delete recipe).

_common/OPUS_5_AUTHORING.md

You are sizing the schema/migration spec, deciding adaptive thinking depth at PLAN, or front-loading DB version/multi-tenant flag at AUDIT. Critical for Schema: P3, P5.

reference/autorun-schema.md

You are emitting the AUTORUN _STEP_COMPLETE block — Schema-specific Output/Next schema.

_common/CODE_QUALITY.md

You are about to write or modify code — the 7-axis quality bar (SLD/SEC/RDB/MNT/TST/PRF/SCL), its sourced anti-patterns, and the CODE_QUALITY_GATE emitted before done.

Phase	Focus	Required checks	Read
`Model`	Entities, relationships, data types, constraints	Tables, PK/FK, normalization rationale, common-pattern choice	`reference/normalization-guide.md`
`Migrate`	Safe schema change plan	Ordered migration steps, rollback note, lock-risk notes	`reference/migration-patterns.md`
`Validate`	Query patterns, indexes, framework fit, growth	Index plan, risks, DB/framework notes, ER diagram when useful	`reference/index-strategies.md`

Mode	Use when	Output focus
Standard	Default schema work	Tables, constraints, indexes, migration steps
Framework-specific	Repo or request needs ORM output	Prisma / TypeORM / Drizzle snippet plus SQL rationale
Visualization	Relationships are complex or documentation is requested	Mermaid `erDiagram` plus table/relationship summary
Nexus AUTORUN	Input explicitly invokes AUTORUN	Normal deliverable plus `_STEP_COMPLETE:` footer
Nexus Hub	Input contains `## NEXUS_ROUTING`	Return only `## NEXUS_HANDOFF` packet

Query pattern	Default index	Notes
Exact match / range	`B-tree`	PG18 skip scan allows efficient queries on non-leading columns
JSON / array membership	`GIN`
Full-text	`GIN` or engine-native full-text
Geospatial	`GiST` / engine-native spatial index
Vector similarity (KNN)	`HNSW` (pgvector)	Use `halfvec` for memory savings; prefilter by tenant/category

Situation	Route	What to send
API payload or resource lifecycle drives the model	`Gateway`	Entities, relations, constraints, business keys
ORM implementation or repository code is next	`Builder`	Table definitions, migration order, framework mapping
Query performance or index validation is primary	`Tuner`	Query patterns, index plan, table sizes, lock notes
ER diagram or architecture visualization is needed	`Canvas` via `SCHEMA_TO_CANVAS_HANDOFF`	Entities, relationships, cardinality, PK/FK labels
Migration or schema regression testing is needed	`Radar`	Migration steps, rollback path, high-risk cases
Task originates from orchestration	`Nexus`	Schema package only; do not delegate further inside hub mode

Signal	Approach	Primary output	Read next
new table / relationship design	Model → Migrate → Validate	DDL, ER diagram, migration plan	`reference/normalization-guide.md`
migration for existing schema	Expand-contract safety analysis	ordered migration steps, rollback path, lock-risk notes	`reference/migration-patterns.md`
index design / slow query schema	Access-pattern-driven index selection	index plan with type rationale	`reference/index-strategies.md`
multi-tenant schema	Isolation strategy evaluation	RLS policies, partitioning plan, tenant_id design	`reference/multi-tenant-patterns.md`
vector / AI embedding schema	pgvector column + index design	vector column DDL, HNSW/IVF config, halfvec, hybrid prefilter guidance	`reference/advanced-patterns.md`
temporal / scheduling schema	Temporal constraint design	WITHOUT OVERLAPS PK/FK, period columns, bitemporal pattern	`reference/advanced-patterns.md`
anti-pattern review	Schema audit against known anti-patterns	findings with severity and fix recommendations	`reference/schema-design-anti-patterns.md`
complex multi-agent task	Nexus-routed execution	structured handoff	`_common/BOUNDARIES.md`
unclear request	Clarify scope and route	scoped analysis	`reference/`

schema

Install options

Review the source files

Schema

Trigger Guidance

Core Contract

Schema

Trigger Guidance

Core Contract

Boundaries

Always

Ask First

Never

Workflow

Execution Modes

Critical Decision Rules

Routing And Handoffs

Output Routing

Recipes

Subcommand Dispatch

Output Requirements

Operational

Collaboration

Overlap Boundaries

Reference Map

AUTORUN Support

Nexus Hub Mode

`## NEXUS_HANDOFF`

name	schema
description	Designing database schemas, planning migrations, and authoring ER diagrams. Handles normalization, index strategies, and relation definitions. Use when DB schema design is needed.

Recipe	Subcommand	Default?	When to Use	Read First
Schema Design	`design`	✓	New table or entity design	`reference/schema-examples.md`
Migration Plan	`migration`		Schema change and migration design	`reference/migration-patterns.md`
ER Diagram	`er`		ER diagram generation and review	`reference/schema-examples.md`
Normalization	`normalize`		Normalization vs denormalization decisions	`reference/normalization-guide.md`
Index Strategy	`index`		Index design and optimization	`reference/index-strategies.md`
Migration Rollback	`rollback`		Reverse-operation design for destructive migrations (reverse DDL / dual-write / backfill / alternatives to destructive changes)	`reference/migration-rollback.md`
Multi-Tenant Design	`tenant`		Tenant isolation strategy (shared-DB / schema-per-tenant / DB-per-tenant / shard) with RLS and routing design	`reference/multi-tenant-patterns.md`
Partitioning	`partition`		range / list / hash / time-based partition design (pruning / maintenance / migration)	`reference/partition-strategies.md`
Audit Log	`audit-log`		Append-only audit-log schema — temporal tables, logical replication, before/after image, retention	`reference/audit-log-schema.md`
Event Sourcing	`event-sourcing`		Event store schema — events / projections / snapshots / outbox, aggregate boundaries	`reference/event-sourcing-schema.md`
Soft Delete	`soft-delete`		Logical deletion patterns (deleted_at / status / tombstone) with GDPR right-to-erasure interaction	`reference/soft-delete-patterns.md`

Direction	Handoff	Purpose
Builder → Schema	`BUILDER_TO_SCHEMA`	Data requirements and domain model for schema design
Atlas → Schema	`ATLAS_TO_SCHEMA`	Architecture context and service boundaries
Gateway → Schema	`GATEWAY_TO_SCHEMA`	API data needs and resource lifecycle
Lens → Schema	`LENS_TO_SCHEMA`	Codebase query pattern analysis
Sentinel → Schema	`SENTINEL_TO_SCHEMA`	Security audit findings for RLS policies, tenant isolation gaps
Schema → Builder	`SCHEMA_TO_BUILDER`	Table definitions, migration order, framework mapping
Schema → Tuner	`SCHEMA_TO_TUNER`	Query patterns, index plan, table sizes, lock notes
Schema → Canvas	`SCHEMA_TO_CANVAS_HANDOFF`	Entities, relationships, cardinality, PK/FK labels
Schema → Judge	`SCHEMA_TO_JUDGE`	Schema review request
Schema → Radar	`SCHEMA_TO_RADAR`	Migration steps, rollback path, high-risk test cases

Agent	Schema owns	They own
Builder	Database schema DDL, migrations, index strategies, ER design	Domain model code (Entity, VO, Repository), ORM query implementation
Tuner	Index design recommendations from access patterns	Query execution optimization, slow query rewriting, EXPLAIN ANALYZE
Gateway	Table structure that backs API resources	API specification, request/response shape, endpoint design
Atlas	Logical data model, table-level service ownership	Service decomposition, ADR/RFC for architecture decisions
Scribe	Schema documentation (data dictionary, ER diagram docs)	Implementation specification, API docs, code comments
Sentinel	RLS policy design, tenant isolation schema patterns	Application-level security audit, secret detection, CVE scanning

schema

Source facts

Install options

Review the source files

More from this repository

Schema

Trigger Guidance

Core Contract

More from this repository

Schema

Trigger Guidance

Core Contract

Boundaries

Always

Ask First

Never

Workflow

Execution Modes

Critical Decision Rules

Routing And Handoffs

Output Routing

Recipes

Subcommand Dispatch

Output Requirements

Operational

Collaboration

Overlap Boundaries

Reference Map

AUTORUN Support

Nexus Hub Mode

## NEXUS_HANDOFF

`## NEXUS_HANDOFF`