[Copilot]

Description

The github-pages / deploy (pull_request) job failed during mdbook build specs because specs/book.toml used a removed mdBook config field (multilingual). This PR removes the incompatible field so the docs build can proceed on the current mdbook version used in CI.

Changes

• Root cause in CI

  • mdbook v0.5.x rejects [book].multilingual with: unknown field multilingual.

• Minimal fix

  • Removed multilingual = false from specs/book.toml.

• Scope

  • Single-file docs config change; no workflow logic or application code changes.

Patch excerpt

[book]
authors = ["Celestia Labs"]
language = "en"
src = "src"
title = "Celestia Node Specification"

[greptile-apps]

Greptile Summary

The specification-site configuration is compatible with mdBook 0.5.0. The build now completes and generates HTML when mdbook-toc is unavailable, while the deprecated multilingual setting no longer prevents startup.

Confidence Score: 5/5

Safe to merge: the specification-site build completes with the current mdBook configuration.

No blocking failure remains.

T-Rex Logs

What T-Rex did

• Ran the focused before-and-after mdBook build using mdBook 0.5.0 to validate the contract.
• Observed that the before state exited with 101 due to an unknown mdBook configuration field and that the after state exited with 0, skipping the unavailable mdbook-toc preprocessor with a warning and producing HTML output.
• Collected artifacts documenting the validation script and the build results to support review.

_{Ran code and verified through T-Rex}

_{Reviews (2): Last reviewed commit: "Merge branch 'main' into copilot/fix-git..." | Re-trigger Greptile}

[github-actions]

PR Preview Action v1.8.1
🚀 View preview at https://celestiaorg.github.io/celestia-node/pr-preview/pr-5201/
Built to branch gh-pages at 2026-08-25 17:43 UTC. Preview will be ready when the GitHub Pages deployment is complete.

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