# Relationship and Document Type Governance Requirements (Version 4)

This document defines Version 4 baseline requirements for expanding relationships between `Document` and `Person` and introducing governed document type classification.

V4 preserves all applicable V3 capabilities and adds role extensibility, assisted suggestion workflows, explicit relationship policy enforcement, and registry-driven `Document` type governance.

## Requirements Model

| ID | Category | Requirement | Verify Method |
| --- | --- | --- | --- |
| REQ-0 | System | Provide end-to-end, reviewable, policy-enforced document-person relationship management supporting asserted and suggested links. | demonstration |
| REQ-1 | Functional | Preserve many-to-many `Document` ↔ `Person` linking, and allow multiple people per role on a single document. | test |
| REQ-2 | Functional | Support an extensible role taxonomy for document-person relationships beyond fixed `author`/`recipient`. | inspection |
| REQ-3 | Functional | Represent relationship assertion state explicitly (`asserted` and `suggested`) and keep machine suggestions non-canonical until human acceptance. | test |
| REQ-4 | Functional | Provide assisted suggestion lifecycle operations: create/list/filter suggestions, accept suggestion, reject suggestion, and promote accepted suggestions to asserted links. | test |
| REQ-5 | Policy Constraint | Enforce a role exclusivity matrix for a single `(document_id, person_id)` pair on asserted links; initial rule set must block `author` + `recipient` coexistence while allowing `mentioned` to coexist with other roles. | test |
| REQ-6 | Data Constraint | Store canonical asserted links in `document_person` and lifecycle-managed suggestions in a separate `document_person_suggestion` table. | test |
| REQ-7 | Functional | Provide set-based synchronization behavior for relationship mutations (add/remove delta), replacing single-value replacement patterns that can drop unrelated links. | test |
| REQ-8 | Interface | Render grouped relationship metadata by role and assertion state on document detail and person detail views. | demonstration |
| REQ-9 | Interface | Document create/edit UI must support selecting multiple people per role and reviewing pending suggestions with explicit accept/reject controls. | demonstration |
| REQ-10 | API Constraint | Expose additive, role-aware and state-aware retrieval/filtering in API contracts for documents, people, and relationship records. | test |
| REQ-11 | Data Provenance | Capture suggestion provenance metadata sufficient for operator review (for example source mechanism, confidence, and evidence reference) without mutating canonical asserted links implicitly. | inspection |
| REQ-12 | Operations | Provide migration/backfill validation that identifies and resolves historical records violating newly enforced exclusivity policies before hard enforcement. | test |
| REQ-13 | Revision Upgrade | Support deterministic in-place revision upgrade behavior by mapping existing author/recipient links into V4 asserted semantics without requiring long-lived runtime legacy compatibility layers. | test |
| REQ-14 | Reliability | Ensure document/person deletion and cleanup workflows remain safe and deterministic with expanded relationship semantics, including suggestion records. | test |
| REQ-15 | Quality | Add automated test coverage for role extensibility, exclusivity enforcement, suggestion lifecycle transitions, and regression scenarios across service/API/UI flows. | test |
| REQ-16 | Functional | Support a registry-driven document type taxonomy (`document_type`) with stable machine-readable codes, mutable display labels, and active/inactive lifecycle control. | test |
| REQ-17 | Data Constraint | Replace unconstrained free-text document type assignment with controlled type references or deterministic code mapping governed by the document type registry. | test |
| REQ-18 | Interface | Document create/edit UI must present type selection from active registry entries and prevent invalid type assignment. | demonstration |
| REQ-19 | API Constraint | Provide additive API contracts for document type catalog retrieval, including active-only filtering and stable code-based selection for document writes. | test |
| REQ-20 | Operations | Provide deterministic one-time manual normalization/backfill for existing document type strings in the current small corpus, assigning each document to a canonical registry type before strict write enforcement. | test |

## Clarifying Constraints

1. Suggestions are advisory only until accepted by a human operator.
2. Relationship acceptance/rejection must be explicit and auditable.
3. Role-policy enforcement must occur consistently across service and API boundaries.
4. Many-per-role behavior is required for both asserted and suggested states where applicable.
5. Suggestions that would violate asserted exclusivity may exist as `pending`, but acceptance must fail until the exclusivity conflict is resolved.
6. Document type codes are stable identifiers; display labels may evolve without changing canonical type identity.

## Assumptions

1. V4 scope is limited to document-person relationship expansion and does not redesign the core transcription job execution model.
2. Existing V3 data remains the starting corpus and is transformed via deterministic backfill/validation rules.
3. V4 uses a role registry model and separate suggestion storage; enum-first role expansion is out of scope for this revision.
4. V4 introduces document type registry governance and deprecates unconstrained free-text typing as an authoring-time default.

## Element Satisfaction Mapping

- **UI (NiceGUI):** Satisfies REQ-0, REQ-1, REQ-3, REQ-4, REQ-8, REQ-9, REQ-18.
- **API (FastAPI):** Satisfies REQ-0, REQ-3, REQ-4, REQ-5, REQ-7, REQ-10, REQ-19.
- **PERSISTENCE (SQLModel/SQLAlchemy):** Satisfies REQ-1, REQ-2, REQ-5, REQ-6, REQ-11, REQ-12, REQ-13, REQ-14, REQ-16, REQ-17, REQ-20.
- **SERVICES (Domain Layer):** Satisfies REQ-4, REQ-5, REQ-7, REQ-10, REQ-14, REQ-17, REQ-20.
- **TEST SUITE:** Satisfies REQ-15 and verifies all test-marked requirements.

## Change Classification vs V3

- **Semantic expansion:** role model and assertion state model.
- **Policy expansion:** exclusivity matrix enforcement.
- **Workflow expansion:** suggestion review and promotion lifecycle.
- **Contract expansion:** role/state-aware read and write behavior.
- **Governance expansion:** registry-managed document type taxonomy and normalization workflow.

## Related Local References

- [V4 Scope Boundary](scope_boundary_v4.md)
- [System Overview V3](../index_v3.md)
- [System Requirements V3](../requirements_v3.md)
- [Data Model V3](../schema_v3.md)