portfolio-hub/docs/db-schema-spec.md

# PortfolioHub DB Schema Specification

## 1. Purpose

This document defines the database schema in an AI-agent-friendly format.

- Source of truth: Alembic revisions in `migrations/versions`
- Current baseline revision: `20260403_0004`
- Baseline files:
	- `migrations/versions/20260403_0001_initial_portfolio_schema.py`
	- `migrations/versions/20260403_0002_strategy_set_columns.py`
	- `migrations/versions/20260403_0003_portfolio_strategy_refs.py`
	- `migrations/versions/20260403_0004_users_table.py`

## 2. Scope

Schema objects covered by baseline revision:

- `strategy_sets`
- `users`
- `portfolios`
- `portfolio_ledger`
- secondary indexes
- Timescale hypertable conversion rule for `portfolio_ledger`

## 3. Conventions

- Data type names follow SQLAlchemy/Alembic declaration.
- `NULL` means nullable.
- Default means DB-level `server_default` where defined.
- Relationship columns are documented even when no FK constraint exists.

## 4. Tables

### 4.1 users

Purpose:

- Stores admin-managed user records for operational ownership and future identity mapping.

Columns:

| Column | Type | Null | Default | Constraints / Notes |
|---|---|---|---|---|
| id | Text | NO | - | Primary Key |
| username | Text | NO | - | Unique username |
| email | Text | YES | - | Unique when present |
| created_at | DateTime(timezone=True) | NO | NOW() | Creation timestamp |
| updated_at | DateTime(timezone=True) | NO | NOW() | Last update timestamp |

Constraints:

- Primary key: `id`
- Unique: `uq_users_username` on (`username`)
- Unique: `uq_users_email` on (`email`)

### 4.2 strategy_sets

Purpose:

- Stores normalized strategy configuration snapshots.

Columns:

| Column | Type | Null | Default | Constraints / Notes |
|---|---|---|---|---|
| id | Text | NO | - | Primary Key |
| name | Text | NO | - | Strategy name, part of unique pair |
| config | Text | NO | "" | Strategy config payload, part of unique pair |
| nick | Text | NO | - | Unique strategy set nickname |
| created_at | DateTime(timezone=True) | NO | NOW() | Creation timestamp |

Constraints:

- Primary key: `id`
- Unique: `uq_strategy_sets_name_config` on (`name`, `config`)
- Unique: `uq_strategy_sets_nick` on (`nick`)

### 4.3 portfolios

Purpose:

- Stores current portfolio state and strategy linkage.

Current baseline note:

- The columns below describe the currently migrated schema through revision `20260403_0004`.

Columns:

| Column | Type | Null | Default | Constraints / Notes |
|---|---|---|---|---|
| portfolio_id | Text | NO | - | Primary Key |
| broker | Text | NO | "kis" | Broker code |
| status | Text | NO | "enabled" | Portfolio status |
| symbol | Text | NO | - | Trading symbol |
| cash_balance | Float | NO | - | Current cash balance |
| asset_quantity | Float | NO | - | Current asset quantity |
| asset_price | Float | NO | 0 | Current price snapshot |
| profit_buffer | Float | NO | 0 | Profit buffer amount |
| active_strategy_id | Text | YES | - | Logical reference to `strategy_sets.id` |
| avabile_strategies | Text[] | YES | - | Nullable array of `strategy_sets.id` values |
| created_at | DateTime(timezone=True) | NO | NOW() | Creation timestamp |
| updated_at | DateTime(timezone=True) | NO | NOW() | Last update timestamp |
| last_trade_at | DateTime(timezone=True) | YES | - | Last trade time |

Constraints:

- Primary key: `portfolio_id`
- Foreign key constraints: none in baseline

Constraint notes:

- `active_strategy_id` is a nullable logical reference to `strategy_sets.id`
- `avabile_strategies` stores zero or more selectable strategy set IDs when present

### 4.4 portfolio_ledger

Purpose:

- Stores append-like ledger snapshots per portfolio action.

Columns:

| Column | Type | Null | Default | Constraints / Notes |
|---|---|---|---|---|
| portfolio_id | Text | NO | - | Logical reference to `portfolios.portfolio_id` (no FK) |
| recorded_at | DateTime(timezone=True) | NO | - | Event timestamp |
| action | Text | NO | - | Action type |
| price | Float | NO | - | Trade/valuation unit price |
| quantity | Float | NO | - | Quantity delta |
| fee_amount | Float | NO | 0 | Fees |
| tax_amount | Float | NO | 0 | Taxes |
| cash_balance_after | Float | NO | - | Post-action cash |
| asset_quantity_after | Float | NO | - | Post-action asset quantity |
| total_value_after | Float | NO | - | Post-action total value |
| profit_buffer_after | Float | NO | 0 | Post-action profit buffer |
| strategy_set_id | Text | NO | "legacy" | Logical strategy set reference |
| note | Text | NO | "" | Operator/system note |

Constraints:

- Primary key: none in baseline
- Foreign key constraints: none in baseline

## 5. Indexes

### 5.1 ix_users_created_at

- Table: `users`
- Columns/expressions: (`created_at`)
- Unique: no
- Intent: speed operational listing by recency.

### 5.2 idx_portfolio_ledger_portfolio_time

- Table: `portfolio_ledger`
- Columns/expressions: (`portfolio_id`, `recorded_at DESC`)
- Unique: no
- Intent: fetch recent ledger entries per portfolio efficiently.

### 5.3 idx_portfolios_broker_status_updated

- Table: `portfolios`
- Columns/expressions: (`broker`, `status`, `updated_at DESC`)
- Unique: no
- Intent: speed list/filter queries by broker/status and recency.

## 6. TimescaleDB Behavior

Conditional behavior in migration upgrade:

- Checks whether extension `timescaledb` exists.
- If present, executes:

`create_hypertable('portfolio_ledger', 'recorded_at', if_not_exists => TRUE)`

Implication:

- `portfolio_ledger` acts as a hypertable in environments with TimescaleDB extension enabled.

## 7. Integrity Notes

Current baseline intentionally has no DB-level FK constraints.

- Logical relations are managed by application/repository logic.
- When adding FK constraints in future migrations, update this document and include migration IDs.

## 8. Change Management Rule

When schema changes:

1. Add/modify Alembic revision under `migrations/versions`.
2. Update this document in the same commit.
3. Keep revision mapping table below in sync.

## 9. Revision Mapping

| Revision ID | File | Summary |
|---|---|---|
| 20260403_0001 | migrations/versions/20260403_0001_initial_portfolio_schema.py | Initial schema for strategy sets, portfolios, ledger, indexes, optional hypertable |
| 20260403_0002 | migrations/versions/20260403_0002_strategy_set_columns.py | Rename `strategy_name`->`name`, `strategy_config`->`config`, add unique `nick`, handle legacy unnamed unique constraint |
| 20260403_0003 | migrations/versions/20260403_0003_portfolio_strategy_refs.py | Remove embedded portfolio strategy fields, add `active_strategy_id` and `avabile_strategies` |
| 20260403_0004 | migrations/versions/20260403_0004_users_table.py | Add `users` table with unique username/email and created_at index |