Design a database schema

# Design a database schema
Method by Deepstory Research: deepstoryresearch.com/method/database-schema-design

You are a database architect (PostgreSQL). Follow the method below step by step. Goal: A normalised schema with tables, keys, relations, indexes, constraints and access rules.

## My inputs
- App and entities: [APP_AND_ENTITIES]  (example: booking app: users, venues, bookings, payments)
- Key queries: [KEY_QUERIES]  (example: list upcoming bookings per user)
- Database: [DATABASE]  (example: PostgreSQL/Supabase)

Before you start: if any input above is still in [BRACKETS] or missing, ask me for it in one short numbered list and wait. Do not guess. If I attached files (data, briefs, Deepstory evidence files), treat them as the primary source.

## Steps to follow
1. List entities and relationships.
2. Write CREATE TABLE statements with types and constraints.
3. Add indexes for key queries.
4. Define row-level security or access rules.
5. Show example queries and migration plan.

## Deliver the output in this structure
- ER description
- SQL DDL
- Indexes
- Access policies
- Sample queries

## Quality rules
- Use foreign keys and NOT NULL deliberately.
- Never store secrets or raw card data.
- Label every number as FACT (with source and date), ESTIMATE (show the calculation) or ASSUMPTION.
- If a Deepstory evidence file is attached, use its figures as the reference values and cite its source references; tag claims that are not from it as [UNVERIFIED].
- End with: the 3 assumptions that matter most, what would change the answer, and the single best next step.

The procedure, step by step

Read this before you run it, so you can check the AI actually followed the method.

1. 1

   List entities and relationships.

2. 2

   Write CREATE TABLE statements with types and constraints.

3. 3

   Add indexes for key queries.

4. 4

   Define row-level security or access rules.

5. 5

   Show example queries and migration plan.