[SE-3-02] Add cross-page duplicate content detector

docs-guide/indexes/scripts-index.mdx

@@ -55,6 +55,7 @@ Run command: node tests/unit/script-docs.test.js --write --rebuild-indexes
 | `tests/run-all 2.js` | Utility script for tests/run-all.js. | `*   node tests/run-all.js` | docs |
 | `tests/run-all.js` | Test orchestrator — dispatches all unit test suites. Called by pre-commit hook and npm test. | `node tests/run-all.js [flags]` | docs |
 | `tests/run-pr-checks.js` | PR orchestrator — runs changed-file scoped validation checks for pull request CI. Dispatches per-file validators based on PR diff. | `node tests/run-pr-checks.js [flags]` | docs |
+| `tests/unit/check-duplicate-content.test.js` | Unit tests for check-duplicate-content.js — validates exact-duplicate, near-duplicate, and duplicate-block detection logic. | `node tests/unit/check-duplicate-content.test.js` | docs |
 | `tests/unit/codex-commit.test.js` | Tests codex-commit.js — validates commit message generation and contract compliance | `node tests/unit/codex-commit.test.js [flags]` | docs |
 | `tests/unit/codex-safe-merge-with-stash.test.js` | Tests codex-safe-merge-with-stash.js — validates safe merge logic with stash handling | `node tests/unit/codex-safe-merge-with-stash.test.js [flags]` | docs |
 | `tests/unit/codex-skill-sync.test.js` | Tests sync-codex-skills.js — validates skill file synchronisation between sources | `node tests/unit/codex-skill-sync.test.js [flags]` | docs |
@@ -210,6 +211,7 @@ Run command: node tests/unit/script-docs.test.js --write --rebuild-indexes
 | `tools/scripts/validators/content/check-alt-text-quality.js` | Flags weak alt text in English v2 docs by detecting generic placeholders and single-word descriptions. | `node tools/scripts/validators/content/check-alt-text-quality.js [--path <repo-path>] [--strict]` | docs |
 | `tools/scripts/validators/content/check-description-quality.js` | Validates English v2 frontmatter descriptions for SEO length, boilerplate openings, and duplicate reuse | `node tools/scripts/validators/content/check-description-quality.js [--path <repo-path>] [--strict]` | docs |
 | `tools/scripts/validators/content/check-double-headers.js` | Detects duplicate body H1 headings and opening paragraphs that repeat frontmatter title or description content. | `node tools/scripts/validators/content/check-double-headers.js [--file <path>] [--files <a,b>] [--fix]` | docs |
+| `tools/scripts/validators/content/check-duplicate-content.js` | Detects duplicate content across v2 MDX pages: exact-duplicate pages, near-duplicate pages, and shared duplicate paragraph blocks. | `node tools/scripts/validators/content/check-duplicate-content.js [--path <repo-path>] [--strict] [--min-block-pages <n>] [--json]` | docs |
 | `tools/scripts/validators/content/check-grammar-en-gb.js` | Deterministic UK English grammar checker for prose content with optional conservative autofix for safe rules. | `node tools/scripts/validators/content/check-grammar-en-gb.js [--scope full\|changed] [--file <path[,path...]>] [--fix] [--strict]` | docs |
 | `tools/scripts/validators/content/check-page-endings.js` | Checks English route-backed v2 docs for canonical resources or next-step endings in the visible last 20 lines. | `node tools/scripts/validators/content/check-page-endings.js [--path <repo-path>] [--strict]` | docs |
 | `tools/scripts/validators/content/check-proper-nouns.js` | Detects and fixes incorrect proper noun capitalisation in prose while skipping code, frontmatter, URLs, and path-like tokens. | `node tools/scripts/validators/content/check-proper-nouns.js [--file <path[,path...]>] [--fix]` | docs |

tests/script-index.md

@@ -15,6 +15,7 @@
 | `tests/run-all 2.js` | Utility script for tests/run-all.js. | `*   node tests/run-all.js` | docs |
 | `tests/run-all.js` | Test orchestrator — dispatches all unit test suites. Called by pre-commit hook and npm test. | `node tests/run-all.js [flags]` | docs |
 | `tests/run-pr-checks.js` | PR orchestrator — runs changed-file scoped validation checks for pull request CI. Dispatches per-file validators based on PR diff. | `node tests/run-pr-checks.js [flags]` | docs |
+| `tests/unit/check-duplicate-content.test.js` | Unit tests for check-duplicate-content.js — validates exact-duplicate, near-duplicate, and duplicate-block detection logic. | `node tests/unit/check-duplicate-content.test.js` | docs |
 | `tests/unit/codex-commit.test.js` | Tests codex-commit.js — validates commit message generation and contract compliance | `node tests/unit/codex-commit.test.js [flags]` | docs |
 | `tests/unit/codex-safe-merge-with-stash.test.js` | Tests codex-safe-merge-with-stash.js — validates safe merge logic with stash handling | `node tests/unit/codex-safe-merge-with-stash.test.js [flags]` | docs |
 | `tests/unit/codex-skill-sync.test.js` | Tests sync-codex-skills.js — validates skill file synchronisation between sources | `node tests/unit/codex-skill-sync.test.js [flags]` | docs |