Fill in four stub landing pages and restore the missing preview banner

[anegg0]

Action 2 from the codebase review, plus the backlog file for everything deferred.

Four landing pages were byte-identical stubs

launch-arbitrum-chain/configuration/{core,costs,data-availability,sequencer}/index.mdx had the same body SHA1 under four different titles, all rendering the same three cards — Layer Leap, Sequencer timing adjustments, DA API integration — none of which belongs to the section. So "Fees and costs" advertised Layer Leap. Unfilled codemod stubs.

$ for f in core costs data-availability sequencer; do
    awk 'n>=2{print} /^---$/{n++}' .../$f/index.mdx | tr -s ' \n' ' ' | shasum | cut -c1-12
  done
3d00149b3644   # core   — "Customize your chain"
3d00149b3644   # costs  — "Fees and costs"
3d00149b3644   # data-availability
3d00149b3644   # sequencer

Each now lists its own children, ordered by the section's meta.json and described from each child's own frontmatter — derived from the content, not invented: core 5 cards, costs 11, data-availability 4 (three pages plus the DAC subsection), sequencer 7. Frontmatter is untouched.

The public-preview banner was missing

overview/public-preview-expectations.mdx read "…disclaimers that look like this:" and then, with nothing in between, "This banner's purpose is…". The partial existed but was included nowhere, so the page pointed at an element that was not there. partials:check has no unused-partial rule, so nothing caught it.

.claude/docs/code-review-backlog.md

Records the review findings left for later, with the verifying command for each. Three need a product decision rather than a cleanup:

• the 440-call-site VanillaAdmonition / Callout overlap (Callout is registered and used zero times)
• the 9 partials orphaned by the FloatingHoverModal deletion in Remove dead code left by the Docusaurus migration #48
• the 5 of 6 FAQStructuredData call sites that console.warn and render nothing

On that middle item: FloatingHoverModal ESM-imported 18 partials. Nine (*-pc.mdx) are also <include>d by a live choose-*.mdx page and stay reachable; the other nine had no second consumer. An earlier revision of this file said seven — that count wrongly treated prose mentions inside .claude/ planning docs as references. The backlog records both traps: exclude .claude/ when judging reachability, and match the basename literally, since a regex like include[^>]*<basename> matches nothing (<include cwd> itself contains a >).

Verification

All seven blocking gates pass. check-links holds at 15 — unchanged — which is what proves all 27 new hrefs resolve; a single bad card link would have pushed it to 16.

Banner render confirmed in a browser: frontmatter stripped, no literal <include> leaked, no stray ::: or undefined. The costs page now links only into its own section (Layer Leap and DA API gone).

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Project	Deployment	Actions	Updated (UTC)
fumadocs-test	Ready	Preview	Aug 21, 2026 11:47pm