# Database Schema (Version 4)

This document defines the relational schema for the document transcription system.

## Entity Relationship Diagram

```mermaid
erDiagram
DOCUMENT_TYPE {
UUID id PK
TEXT code
TEXT label
BOOLEAN is_active
INTEGER sort_order
TIMESTAMPTZ created_at
TIMESTAMPTZ updated_at
}

PERSON_ROLE {
UUID id PK
TEXT code
TEXT label
BOOLEAN is_active
TIMESTAMPTZ created_at
TIMESTAMPTZ updated_at
}

PERSON {
UUID id PK
TEXT full_name
TEXT display_name
TEXT maiden_name
DATE birth_date
TEXT birth_date_raw
TEXT birth_place
DATE death_date
TEXT death_date_raw
TEXT death_place
TEXT biography
TEXT portrait_path
JSONB metadata
TIMESTAMPTZ created_at
TIMESTAMPTZ updated_at
}

DOCUMENT {
UUID id PK
UUID document_type_id FK
TEXT name
DATE document_date
TEXT document_date_raw
TEXT location_created
TEXT notes
TEXT archive_identifier
TIMESTAMPTZ created_at
TIMESTAMPTZ updated_at
}

DOCUMENT_PERSON {
UUID id PK
UUID document_id FK
UUID person_id FK
UUID role_id FK
TIMESTAMPTZ created_at
TIMESTAMPTZ updated_at
}

JOB {
UUID id PK
UUID document_id FK
VARCHAR status
INTEGER retry_count
TEXT provider
TEXT model
TEXT prompt_name
TEXT prompt_hash
TEXT system_prompt
TEXT user_prompt
FLOAT temperature
FLOAT top_p
TIMESTAMPTZ date_created
TIMESTAMPTZ date_updated
}

SOURCE {
UUID id PK
UUID document_id FK
INTEGER page_number
TEXT upload_name
TEXT filename
TEXT file_path
TEXT file_hash
BIGINT file_size_bytes
TEXT raw_transcription
TEXT revised_text
TIMESTAMPTZ date_uploaded
TIMESTAMPTZ date_revised
}

JOB_SOURCE {
UUID id PK
UUID job_id FK
UUID source_id FK
VARCHAR status
TEXT raw_transcription
JSONB ai_metadata
JSONB raw_api_response
TEXT error_detail
TIMESTAMPTZ executed_at
}

DOCUMENT_TYPE ||--o{ DOCUMENT : classifies
DOCUMENT ||--o{ DOCUMENT_PERSON : has_people
PERSON ||--o{ DOCUMENT_PERSON : appears_in
PERSON_ROLE ||--o{ DOCUMENT_PERSON : labels
DOCUMENT ||--o{ JOB : has_jobs
DOCUMENT ||--o{ SOURCE : contains_pages
JOB ||--o{ JOB_SOURCE : executes
SOURCE ||--o{ JOB_SOURCE : processed_in
```

## Domain Invariants and Provenance Rules

### Page-Level Execution and AI Outputs

- Every single page execution by an AI model produces a dedicated `JOB_SOURCE` record.
- Every `JOB` stores the frozen prompt identifier, prompt text, and hyperparameters used at submission time.
- Every `JOB_SOURCE` stores the complete provider response envelope and page-level operational metadata.
- `SOURCE.raw_transcription` caches the latest successful machine output for that page.

### Image Storage and Integrity

- Binary images are stored on disk; `SOURCE.file_path` stores the persisted path.
- `SOURCE.file_hash` stores a SHA-256 digest.
- `SOURCE.file_size_bytes` stores the original file size.

### Page Ordering and Revisions

- `SOURCE.page_number` dictates page ordering within a document.
- `SOURCE.raw_transcription` remains immutable machine output.
- `SOURCE.revised_text` stores human edits and is the preferred display value when present.

### Document-Person Role Governance

- Documents support zero, one, or many people per relationship role.
- Relationship roles are defined by `PERSON_ROLE` rather than hardcoded columns.
- `DOCUMENT_PERSON` must be unique for `(document_id, person_id, role_id)`.
- Relationship writes must be deterministic and use explicit add/remove link intent.

### Document Type Governance

- Every document type is defined by `DOCUMENT_TYPE`.
- `DOCUMENT_TYPE.code` is a stable machine identifier.
- `DOCUMENT_TYPE.label` is mutable display text.
- Inactive types remain valid for historical rows but should be excluded from default selection UIs.

## Constraint Summary

- `DOCUMENT_TYPE.code` is unique.
- `PERSON_ROLE.code` is unique.
- `DOCUMENT_PERSON(document_id, person_id, role_id)` is unique.

## Indexing Guidance

- `document(document_type_id)`
- `document_person(document_id)`
- `document_person(person_id)`
- `document_person(role_id)`
- `source(document_id, page_number)`
- `job(document_id, status)`
- `job_source(job_id)`
- `job_source(source_id)`

## Related Local References

- [System Overview](index_v4.md)
- [System Architecture](architecture_v4.md)
- [System Requirements](requirements_v4.md)
- [Error Handling Policy](error_handling_v4.md)