fix(docs): preserve negotiated response cache headers

[waleedlatif1]

Summary

• Preserve application Vary fields when Next's Node response pipeline adds router dimensions, so HTML and Markdown at one docs URL remain distinct cache variants.
• Pin the small CommonJS/ESM framework patch, preserve native validation and cookie behavior, and retain production HTTP and native edge-case checks in path-scoped CI.

Type of Change

• Bug fix

Testing

Root lint, all 26 workspace type checks, all 60 audits, the block-registry check, and actionlint pass. Production build and 12 HTTP checks pass. The production regression fails on unpatched HTML and passes with the fix. The retained native suite passes 16 checks across both entry points; removing merging causes eight expected failures, and removing validation causes four. CI runs the full existing suites and uploads both docs HTTP reports.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing (new tests pass the test-audit authoring gate)
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

[vercel]

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Project	Deployment	Actions	Updated
docs	Ready	Preview	Oct 14, 2026 10:21pm UTC

[cubic-dev-ai]

No issues found across 7 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Turn on auto-fix | Re-trigger cubic}

[greptile-apps]

Confidence Score: 5/5

[High impact] The PR appears safe to merge; no actionable new issue was found.

Summary

Preserves application Vary fields when Next adds its router fields.

• Docs responses keep Accept alongside Next.js router cache fields.

The review used the full PR diff because the previous-review history checks did not pass. Tests were not run during this review.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  A["Application sets Vary: Accept"] --> B["Next adds router Vary fields"]
  B --> C["Check incoming header value"]
  C --> D["Combine existing and incoming fields"]
  D --> E["Remove case-insensitive duplicates"]
  E --> F["Send combined Vary header"]

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_{Reviews (2) · Last reviewed commit: "fix(docs): retain native header regressi..." · Reviewed by Greptile}

[waleedlatif1]

@greptile

[waleedlatif1]

@cubic-dev-ai review this PR

[cubic-dev-ai]

@cubic-dev-ai review this PR

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[cubic-dev-ai]

No issues found across 8 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Turn on auto-fix | Re-trigger cubic}