# ADR-0054: OSHUN Nisaba as a First-Class Customer Domain

**Status**: Accepted  
**Date**: 2026-03-24  
**Authors**: OSHUN Product, OSHUN Design, OSHUN Web Engineering  
**Reviewers**: Tara, Nisaba, Arete, Veritas, Nyx leads  
**Supersedes**: N/A  
**Superseded by**: N/A

## Context and Problem Statement

ADR-0053 established Tara as the customer product center and intentionally
deferred Nisaba. Since then, the shell route contracts, search taxonomy, and
domain metadata have all gained Nisaba-aware primitives, but the customer IA
still behaved as though Nisaba were secondary:

- the shared IA contract only modeled three Tara companion domains
- the shared domain registry still classified Nisaba as planned
- launch-oriented shell surfaces omitted Nisaba from their canonical domain set
- customer-facing metadata and documentation still described a four-domain shell

That split creates a product contradiction. Nisaba already exists as a real
customer domain in search, route, and adapter contracts, but the shell still
communicates that it is not a peer domain.

## Decision Drivers

- **IA consistency**: the shell cannot claim a unified multi-domain model while
  excluding a domain that already has route, search, and adapter contracts.
- **Study continuity**: users need a deliberate way to move from practice,
  claims, and sky context into primary texts and comparative study.
- **Navigation coherence**: domain launch surfaces, sidebars, and command flows
  should agree on the available domain set.
- **Contract clarity**: shared metadata should not describe Nisaba as planned if
  customer launch paths are expected to route into it.

## Decision Outcome

**Chosen decision**: Nisaba is now a first-class customer domain inside the
Tara-centered shell.

### Normative Rule

Nisaba does not replace Tara as the customer center. It becomes a first-class
companion domain that participates in the same launch, routing, discovery, and
home-entry systems as Arete, Veritas, and Nyx.

### Tara Companion-Layer Update

The Tara-centered shell now has four first-class companion layers:

- Arete for embodiment and execution
- Veritas for clarity and discernment
- Nyx for awe and temporal perspective
- Nisaba for source-grounded study, commentary, and comparative reading

### Availability Rule

For shell IA purposes, Nisaba must no longer be hidden behind `planned`
availability. It is launchable as a customer-facing shell domain and may be
classified as `beta` while its implementation breadth continues to expand.

### Surface Rule

Any shared shell surface that enumerates customer domains must treat Nisaba as a
peer domain. This includes at minimum:

- domain switchers
- domain hub or launcher surfaces
- in-shell domain navigation
- command or shortcut launch surfaces
- customer-facing product metadata and manifest copy

## Scope Boundaries

- This ADR does **not** yet define the full IA relationship among home, explore,
  activity, library, assistant, and profile. That remains `V1-UX-003` and
  `V1-UX-004`.
- This ADR does **not** require Nisaba to match every maturity level of Tara,
  Veritas, Nyx, or Arete. First-class means present in the shell IA, not feature
  parity with every existing domain.

## Architecture Implications

- `libs/oshun/navigation/src/customer-ia.ts` must publish Nisaba as a Tara
  companion with explicit role semantics.
- `@oshun/domain-registry` must expose Nisaba through the launchable domain set.
- Shared shell UI must stop hard-coding four-domain assumptions for customer
  launch surfaces.
- Customer shell docs must describe a five-domain shell with Tara-centered
  orchestration.

## Acceptance Criteria

`V1-UX-002` is complete only when all criteria below are true:

1. The shared customer IA contract models Nisaba as a first-class Tara
   companion.
2. The shared domain registry exposes Nisaba as launchable customer-shell domain
   metadata.
3. Shared shell launch surfaces and navigation enumerate Nisaba alongside Tara,
   Veritas, Nyx, and Arete.
4. Customer-facing docs and metadata no longer describe Oshun as a four-domain
   shell.

## Related Decisions

- `docs/adr/ADR-0059-oshun-customer-information-architecture-and-tara-centered-spine.md`
- `docs/adr/ADR-0013-oshun-shell-architecture-and-domain-adapters.md`
- `docs/adr/ADR-0015-deep-linking-and-cross-domain-routing.md`

## References

- `docs/releases/v1/reports/unified-product-gap-analysis-and-nisaba-integration-report-2026-03-22.md`
- `libs/oshun/navigation/src/customer-ia.ts`
- `libs/oshun/domain-registry/src/index.ts`