fix(cache): compare tag revalidation timestamps

[JamesbbBriz]

Summary

• record request-local tag revalidations with timestamps instead of membership only
• use the same high-resolution epoch clock for cache writes, invalidations, request starts, and fill starts
• discard use cache, unstable_cache, and tagged fetch entries only when they predate the latest matching revalidation
• suppress cache writes when a fill starts before a matching invalidation and completes afterward
• securely forward revalidated-tag state across internal Server Action redirect dispatches without exposing protocol headers to application code
• preserve comma-containing tags losslessly in a separate authenticated vinext JSON header while retaining the Next.js comma-delimited header for ordinary-tag rolling compatibility
• import the timestamp helper directly from the lightweight cache-handler module on the common App Router path
• preserve strict timestamp semantics across Memory, custom, and Cloudflare KV cache handlers

This follows the behavior introduced by vercel/next.js#96726 and commit 5da1c1ae03d2ee39c27a2d6d8807c573c46b37f9.

The separate JSON tag header is a deliberate vinext protocol extension: Next.js''s comma-delimited wire format cannot represent a legal tag containing a comma. New vinext peers prefer the authenticated JSON header; the standard header remains available to older peers for ordinary tags. Older peers cannot preserve comma-containing tags.

Closes #2819

Tests

• Nine-file cache/ISR/action matrix passed: tests/shims.test.ts, tests/fetch-cache.test.ts, tests/unified-request-context.test.ts, tests/revalidated-tags.test.ts, tests/app-server-action-execution.test.ts, tests/app-rsc-handler.test.ts, tests/features.test.ts, tests/isr-cache.test.ts, and tests/kv-cache-handler.test.ts
• vp check scoped to all changed product/test files (format, lint, and types clean)
• git diff --check

Adversarial coverage includes repeated same-tag invalidation, fills straddling invalidation for all three public cache APIs, two-read Server Action dedupe before and after updateTag, custom-handler old/new timestamps, authenticated redirect forwarding, comma-containing and JSON-looking legacy tags, protocol-header filtering, soft/hard tag handler behavior, and Memory/KV strict timestamp boundaries.

[JamesbbBriz]

/bigbonk

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@vinext/cloudflare@2916

npm i https://pkg.pr.new/create-vinext-app@2916

npm i https://pkg.pr.new/@vinext/types@2916

npm i https://pkg.pr.new/vinext@2916

commit: 36bbfdc

[github-actions]

Performance benchmarks

Compared 36bbfdc against base a3d1d1d 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	135.4 KB	135.5 KB	⚫ +0.0%
Client entry size (gzip)	vinext	122.8 KB	122.9 KB	⚫ +0.0%
Dev server cold start	vinext	2.29 s	2.28 s	⚫ -0.3%
Production build time	vinext	2.41 s	2.42 s	⚫ +0.1%
RSC entry closure size (gzip)	vinext	114.6 KB	115.4 KB	⚫ +0.7%
Server bundle size (gzip)	vinext	194.8 KB	195.9 KB	⚫ +0.5%

View detailed results and traces

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

[chatgpt-codex-connector]

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Reviewed commit: dab5b34173

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[JamesbbBriz]

/bigbonk

[JamesbbBriz]

CI follow-up: fixed the integration failure by separating high-resolution mutation ordering (lastModified) from wall-clock TTL policy (writtenAt) in both Memory and KV handlers. Existing KV entries remain compatible via the lastModified fallback. Local verification: exact failed sequence 2/2, full features file 355/355, related 8-file matrix 1,903/1,903, scoped checks/diff-check, and independent Standards + blast-radius reviews pass. Waiting for CI; not requesting re-review yet.

[JamesbbBriz]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: dbd28c1de2

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[JamesbbBriz]

@james-elicx I think this is ready for another look now. I fixed the latest ISR review comments, and CI is green. Thanks!

[NathanDrake2406]

I think we should generate the timestamp and pass it through the adapter, then have it persist and return that instead