# Sync Conflicts - Quality Requirements {#sync-conflicts---quality-requirements}


**Version:** 1.0  
**Last Updated:** 2026-07-16

This document defines the quality standards and requirements for the Sync Conflicts feature.

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## Functional Requirements {#functional-requirements}



### FR-01: Conflict Detection {#fr-01-conflict-detection}


The system shall detect conflicts when:
- A push request receives HTTP 409 from the data-service
- Server data differs from client data after timestamp comparison


### FR-02: Conflict Preservation {#fr-02-conflict-preservation}


The system shall preserve both versions of conflicting data:
- Server version stored in `server_version` JSONB field
- Client version stored in `client_version` JSONB field
- Both versions retained until explicit resolution


### FR-03: Resolution Strategies {#fr-03-resolution-strategies}


The system shall support the following resolution strategies:
- `server_wins`: Accept server version, mark push record as failed
- `client_wins`: Overwrite server with client version via PUT


### FR-04: Tenant Isolation {#fr-04-tenant-isolation}


All conflict operations shall be scoped to the current tenant via `X-Tenant-ID` header.


### FR-05: Pagination {#fr-05-pagination}


Conflict listing endpoints shall support pagination with `skip` and `limit` parameters.

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## Non-Functional Requirements {#non-functional-requirements}



### NFR-01: Performance {#nfr-01-performance}


- Conflict list retrieval shall complete within 2 seconds for datasets under 1000 records
- Conflict resolution shall complete within 5 seconds for typical response sizes
- Database indexes shall exist on `tenant_id`, `response_id`, and `resolution`


### NFR-02: Availability {#nfr-02-availability}


- Conflict endpoints shall be available whenever sync-service is operational
- Conflict resolution shall be idempotent (re-running same strategy has no additional effect)


### NFR-03: Security {#nfr-03-security}


- All endpoints require `response:read` permission
- JWT tokens must be validated before processing
- Tenant ID must be extracted from request state and cannot be overridden by client


### NFR-04: Auditability {#nfr-04-auditability}


- All conflicts shall be timestamped with `created_at`
- All resolutions shall record `resolved_at` and `resolved_by` user
- Conflict records shall not be deleted, only marked resolved

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## Validation Rules {#validation-rules}



### V-01: Conflict Resolution {#v-01-conflict-resolution}


- Cannot resolve an already-resolved conflict
- Unknown strategies shall return HTTP 400
- Missing conflict ID shall return HTTP 404


### V-02: Data Integrity {#v-02-data-integrity}


- `response_id` in conflict record must reference a valid response or push record
- Both `server_version` and `client_version` must be valid JSON
- Resolution field must be one of the defined strategies

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## Test Requirements {#test-requirements}



### T-01: Unit Tests {#t-01-unit-tests}


The following scenarios shall have unit test coverage:
- Conflict detection with timestamp comparison
- Conflict detection with data comparison
- Server wins resolution flow
- Client wins resolution flow
- Per-tenant conflict isolation


### T-02: Integration Tests {#t-02-integration-tests}


- End-to-end conflict creation during push
- Conflict resolution via API
- Permission enforcement verification
- Multi-tenant isolation verification


### T-03: Test Files {#t-03-test-files}


| File | Purpose |
|------|---------|
| `mobile/test/unit/conflict_resolution_test.dart` | Mobile conflict logic tests |
| `sync-service/tests/` | Backend conflict detection tests (to be created) |

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## Operational Requirements {#operational-requirements}



### O-01: Monitoring {#o-01-monitoring}


- Conflict count metric should be available for dashboard display
- Resolution attempts should be logged
- Failed resolutions should emit warning-level logs


### O-02: Backup {#o-02-backup}


- Conflict records are part of sync_db and follow standard backup procedures
- Both versions in JSONB format are preserved in backups


### O-03: Maintenance {#o-03-maintenance}


- Conflict records should be retained indefinitely for audit purposes
- Push records with conflict status may be cleaned after resolution

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## Compliance Requirements {#compliance-requirements}



### C-01: Data Protection {#c-01-data-protection}


- Conflicts contain response data subject to retention policies
- Access to conflicts requires same permissions as response data
- Deleted respondent data should cascade appropriately


### C-02: GDPR Considerations {#c-02-gdpr-considerations}


- Conflict records contain personal data from responses
- Resolution does not create additional personal data exposure
- Right to erasure applies to unresolved conflicts via respondent deletion