Engineering Decisions v1.0

1. Architectural Decisions

The service is intentionally shipped as a monolithic backend for v1.0 to reduce operational overhead and keep delivery scope focused.
The codebase follows Clean Architecture-inspired layering (presentation, application, domain, infrastructure) with pragmatic coupling where it improves implementation speed and maintainability.
Packaging is feature-oriented (board, project, task, security, etc.) while preserving layer separation inside each feature.

Authorization uses a hybrid model:
- Global roles (for example admin-only operational actions).
- Membership and ownership checks at service level for board/project/task operations.
Ownership and collaborator checks are enforced in application/domain services rather than only via URL-level role checks.
HTTP semantics are explicit:
- 401 for missing/invalid authentication.
- 403 for authenticated users without permission.
- 404 when resources are not found (including membership-filtered access patterns in some flows).

Structural DTO validation was expanded to enforce request-shape constraints at boundary level.
@Valid is consistently applied on request DTO entry points.
IllegalArgumentException is mapped to 400 Bad Request through centralized exception handling.
Result: API contract behavior is stabilized for malformed payloads and invalid argument combinations.

Strict domain isolation from Spring Data abstractions is not fully enforced.
Key rotation is not automated.
Concealment normalization between 403 and 404 is not globally standardized.
Distributed architecture is intentionally deferred; no microservice split in v1.0.
CI/CD pipeline automation is not included as part of v1.0 scope.

Improve automated key rotation and operational key management.
Unify authorization response semantics where concealment vs explicit denial is needed.
Move closer to strict hexagonal boundaries where practical.
Expand observability (metrics, tracing, structured operational dashboards).