# asset-readiness-and-fallback-retirement Specification

## Purpose
TBD - created by archiving change full-modernization-architecture-blueprint. Update Purpose after archive.
## Requirements
### Requirement: In-scope frontend assets SHALL be release-ready before deployment
In-scope routes SHALL rely on build/deploy readiness guarantees instead of runtime fallback behavior as the primary resilience mechanism.

#### Scenario: Build-readiness enforcement
- **WHEN** release artifacts are prepared for deployment
- **THEN** in-scope route assets SHALL be validated for presence and loadability
- **THEN** missing required in-scope assets SHALL fail the release gate

### Requirement: Runtime fallback retirement SHALL follow a governed phase policy
Runtime fallback behavior for in-scope modernization routes SHALL be retired under explicit governance milestones.

#### Scenario: Fallback retirement in phase scope
- **WHEN** a route is marked in-scope for fallback retirement
- **THEN** runtime fallback behavior for that route SHALL be removed or disabled by policy
- **THEN** reliability for that route SHALL be guaranteed by release-time readiness gates

### Requirement: Deferred-route assets SHALL be release-ready before promotion
Deferred follow-up routes SHALL adopt release-time asset-readiness checks and SHALL fail promotion when required assets are missing.

#### Scenario: Deferred-route readiness validation
- **WHEN** release artifacts are prepared for deferred-route promotion
- **THEN** required assets for `/tables`, `/excel-query`, `/query-tool`, and `/mid-section-defect` SHALL be validated
- **THEN** missing required assets SHALL fail release gating

### Requirement: Deferred-route runtime fallback SHALL be retired by governed policy
Deferred follow-up routes SHALL not remain on runtime fallback posture after readiness, parity, and manual acceptance gates pass.

#### Scenario: Deferred-route fallback retirement
- **WHEN** a deferred route passes readiness, parity, and manual acceptance gates
- **THEN** runtime fallback posture for that route SHALL be retired according to milestone policy
- **THEN** rollback control SHALL remain available via explicit route-level governance switch

### Requirement: Fallback-retirement failure response SHALL be consistent across route hosts
When in-scope runtime fallback retirement is enabled and route assets are unavailable, app-level and blueprint-level route handlers SHALL return a consistent retired-fallback response surface.

#### Scenario: App-level in-scope route enters retired fallback state
- **WHEN** an in-scope app-level route cannot serve required dist assets and fallback retirement is enabled
- **THEN** the route SHALL return the standardized retired-fallback response contract

#### Scenario: Blueprint-level in-scope route enters retired fallback state
- **WHEN** an in-scope blueprint-level route cannot serve required dist assets and fallback retirement is enabled
- **THEN** the route SHALL return the same standardized retired-fallback response contract used by app-level routes
