fix(cache): preserve staged cache invalidation parity

[james-elicx]

Part 16 of the staged CDN adapter stack. Depends on #3155.

Summary

• preserves canonical invalidation tags through Vary-based cache-key expansion and clean-EOF admission
• tags Pages HTML and data responses consistently and purges regenerated response variants after revalidation
• keeps independently deployed stage caches partitioned by authority during invalidation
• extends App, Pages, Cloudflare adapter, and HTTP-stage regression coverage

Validation

• 413 focused cache, revalidation, request-pipeline, and Cloudflare adapter tests passed
• ppr-impact-demo cacheability admission E2E passed
• workers-cache example production build passed
• focused format, lint, and type checks passed

This remains a draft while the full stack is reviewed and CI completes.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@vinext/cloudflare@3156

npm i https://pkg.pr.new/create-vinext-app@3156

npm i https://pkg.pr.new/@vinext/types@3156

npm i https://pkg.pr.new/vinext@3156

commit: a6efbb2

[github-actions]

Performance benchmarks

Compared a6efbb2 against base d961900 using alternating same-runner rounds. Next.js was unchanged and skipped.

0 improved · 0 regressed · 6 within ±1.5%

Scenario	Framework	Baseline	Current	Change
Client bundle size (gzip)	vinext	142.3 KB	142.4 KB	⚫ +0.0%
Client entry size (gzip)	vinext	129.6 KB	129.6 KB	⚫ +0.0%
Dev server cold start	vinext	3.43 s	3.38 s	⚫ -1.5%
Production build time	vinext	3.73 s	3.68 s	⚫ -1.4%
RSC entry closure size (gzip)	vinext	125.7 KB	125.5 KB	⚫ -0.1%
Server bundle size (gzip)	vinext	216.4 KB	216.2 KB	⚫ -0.1%

View detailed results and traces

_{🟢 improvement · 🔴 regression · ⚫ change below 1.5% · paired base/head}

[github-actions]

Example	Preview	Production	Original
app-router-cloudflare	preview	production
pages-router-cloudflare	preview	production
app-router-playground	preview	production	original
realworld-api-rest	preview	production
nextra-docs-template	preview	production
benchmarks	preview	production
hackernews	preview	production	original
workers-cache	preview	production
static-export	preview	production
web	preview	production