clawfort/openspec/specs/delivery-and-rendering-performance/spec.md

Purpose

Canonical specification for delivery-and-rendering-performance requirements synced from OpenSpec change deltas.

Requirements

Requirement: HTTP delivery applies compression and cache policy

The system SHALL apply transport-level compression and explicit cache directives for static assets, API responses, and public HTML routes.

Scenario: Compressed responses are available for eligible payloads

• WHEN a client requests compressible content that exceeds the compression threshold
• THEN the response is served with gzip compression
• AND response headers advertise the selected content encoding

Scenario: Route classes receive deterministic cache-control directives

• WHEN clients request static assets, API responses, or HTML page routes
• THEN each route class returns a cache policy aligned to its freshness requirements
• AND cache directives are explicit and testable from response headers

Requirement: Media rendering optimizes perceived loading performance

The system SHALL lazy-load non-critical images and render shimmer placeholders until image load completion or fallback resolution.

Scenario: Feed and modal images lazy-load with placeholders

• WHEN feed or modal images have not completed loading
• THEN a shimmer placeholder is visible for the pending image region
• AND the placeholder is removed after load or fallback error handling completes

Scenario: Image rendering reduces layout shift risk

• WHEN article images are rendered in hero, feed, or modal contexts
• THEN image elements include explicit dimensions and async decoding hints
• AND layout remains stable while content loads

Requirement: Smooth scrolling behavior is consistently enabled

The system SHALL provide smooth scrolling behavior for in-page navigation and user-initiated scroll interactions.

Scenario: In-page navigation uses smooth scrolling

• WHEN users navigate to in-page anchors or equivalent interactions
• THEN scrolling transitions occur smoothly rather than jumping abruptly
• AND behavior is consistent across supported breakpoints

Requirement: Performance thresholds are continuously validated

The system SHALL enforce page-speed and rendering performance thresholds in automated checks.

Scenario: Performance budget gate

• WHEN performance checks exceed configured budget thresholds
• THEN CI performance gate fails
• AND reports identify the regressed metrics and impacted pages