Review Packet: Edge and Delivery

When to use

Use this packet for CDN rules, edge routing, NGINX/proxy behavior, static asset delivery, cache headers, compression, redirects, origin failover, asset deploy changes, and high-traffic launch readiness.

Intake questions

• Which routes and assets are affected?
• What is cached at browser, CDN, proxy, and origin?
• What varies by tenant, locale, auth, experiment, or device?
• How are immutable assets and HTML coordinated across deploys?
• What happens when origin is slow or unavailable?
• How are cache purges scoped, authenticated, logged, and reversible?
• Which logs prove delivery behavior?

Required artifacts

• Edge request flow.
• Cache header examples for HTML, assets, APIs, fonts, and images.
• Compression policy.
• Redirect and rewrite table.
• Purge and rollback runbook.
• Access/error log field list.

Decision matrix

Resource	Default policy
Hashed JS/CSS/assets	Long-lived immutable cache.
HTML shell	Short TTL or revalidation strategy aligned with deploy safety.
Personalized API	Private or no-store unless explicitly safe.
Public API/content	Cache by explicit freshness and variation keys.
Redirects	Versioned and monitored; avoid accidental chains.

Red flags

• HTML and assets can get out of sync during deploy.
• Cache keys ignore tenant, auth, locale, or experiment variation.
• Purges are broad and unaudited.
• Compression is assumed but not verified.
• Edge logs cannot correlate cache status, route, release, and upstream latency.

Approval criteria

• Cache behavior is explicit per resource class.
• Private and personalized data cannot leak through shared caches.
• Deploy ordering is safe.
• Purge and rollback paths exist.
• Edge observability can diagnose failures.

Example reviewer comments

• "This route varies by experiment assignment. Include the variation key or avoid shared caching."
• "HTML TTL must be coordinated with asset retention to prevent boot failures after deploy."
• "The purge runbook needs authentication, scope, and audit logging."

Example ADR prompt

Write an ADR covering edge routing, cache policy, compression, deploy coordination, private-data protection, observability, and rollback.

Release readiness checklist

• Cache headers reviewed.
• Variation keys tested.
• Compression verified.
• Purge runbook exists.
• Access logs include cache, upstream, route, release, and request id.