feat: PRAB article JSON-LD emitter + meta reader (v0.8.0) (#25)

prcore emits MedicalWebPage+Article JSON-LD for any post carrying _prab_* meta (ratified contract v1): citation[], about->Drug @ids, honest reviewedBy (Person only with a real human reviewer, else Organization), lastReviewed; integrates into Yoast's graph (no duplicate nodes), standalone @graph fallback; all _prab_* sanitized as untrusted. Unblocks the Phase-2b SEO stage. QA: REJECT-P1 (DoD doc/test gaps) -> APPROVE @ dbfc50c (qa-reviews/peptide-repo-core/2026-06-23-dbfc50c.md). CEO greenlight 2026-06-22 (complete-all-tasks directive). Agent-Session: prcore-jsonld-merge-20260623
2026-06-23 12:29:14 +07:00
parent a7a2bb2f6d
commit a1c77de332
10 changed files with 1194 additions and 4 deletions
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -215,14 +215,25 @@ Drug schema on single pages increases LLM citation rate. Filter hook allows cons
 - **FAQ emission:** `_pr_faq_items` post-meta (JSON array of `{question, answer}` objects). Node emitted only when items exist.
 - **Dosing omitted from schema:** YMYL constraint — no dosing data in JSON-LD.

-JSON-LD class tree (v0.6.0):
+JSON-LD class tree (v0.8.0):

 | Class | File | Responsibility |
 |---|---|---|
 | `PR_Core_Jsonld` | `frontend/class-pr-core-jsonld.php` | Orchestrator: registers hooks, Yoast vs. standalone routing |
 | `PR_Core_Jsonld_Drug` | `frontend/class-pr-core-jsonld-drug.php` | Builds Drug (+ MolecularEntity) schema node |
-| `PR_Core_Jsonld_Webpage` | `frontend/class-pr-core-jsonld-webpage.php` | MedicalWebPage retype + lastReviewed/reviewedBy enrichment |
+| `PR_Core_Jsonld_Webpage` | `frontend/class-pr-core-jsonld-webpage.php` | MedicalWebPage retype + lastReviewed/reviewedBy enrichment (peptide pages) |
 | `PR_Core_Jsonld_Faq` | `frontend/class-pr-core-jsonld-faq.php` | FAQPage node (emit-only-when-populated) |
+| `PR_Core_Jsonld_Article` | `frontend/class-pr-core-jsonld-article.php` | PRAB article emitter: MedicalWebPage retype + Article citation/about/reviewedBy enrichment |
+| `PR_Core_Prab_Meta_Reader` | `frontend/class-pr-core-prab-meta-reader.php` | Reads and sanitises _prab_* meta (contract v1 reader) |
+
+**PRAB article emission (v0.8.0, contract v1):**
+- Trigger: `_prab_schema_version=1` on a standard `post`.
+- Yoast path (priority 13, after peptide enrichment at 11+12): retypes page node to `MedicalWebPage`; enriches Yoast's existing Article piece with `citation[]`, `about[]` (Drug @id references), `lastReviewed`, honest `reviewedBy`.
+- No-Yoast fallback: standalone `@graph` (Article + MedicalWebPage) on `wp_head` priority 99.
+- **Honest reviewedBy:** Person only when `_prab_review_mode=human` + valid `_prab_reviewed_by` WP user ID. All other cases: Organization "Peptide Repo". Never a fabricated person.
+- **`about` linkage:** Drug stubs reference `{peptide_permalink}#drug` (stable @id from v0.6.0).
+- prcore reads `_prab_*` meta only; PRAutoBlogger writes only. uninstall.php unaffected.
+- All `_prab_*` meta treated as untrusted at read time.

 ### #7: PR Core owns the `peptide` CPT and `peptide_category` taxonomy (v0.2.0)
 Prior to v0.2.0, PR Core registered `pr_peptide` while Peptide Search AI registered `peptide` — both claimed the public rewrite slug `peptides`, and WP's rewrite resolver picked PR Core's empty CPT, 404'ing all 89 production peptide detail pages. v0.2.0 consolidates both registrations onto a single `peptide` CPT, owned by PR Core. PSA v4.5.0 drops its CPT/taxonomy registration; its meta boxes (`psa_peptide_data`, `psa_extended_data`), directory shortcode, KB article renderer, and search widget continue operating on the shared `peptide` CPT regardless of who registers it. Registration on both sides is guarded with `post_type_exists()` / `taxonomy_exists()` so deploy order is forgiving.
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,52 @@ All notable changes to Peptide Repo Core are documented here.
 Format: [Semantic Versioning](https://semver.org/).


+## [0.8.0] — 2026-06-23
+
+### Added
+- **PRAutoBlogger article JSON-LD emitter** (ratified contract v1 — `convo/prcore/decisions/2026-06-11-jsonld-contract-v1.md`):
+  - `PR_Core_Jsonld_Article` (`frontend/class-pr-core-jsonld-article.php`, ~235 lines) — meta-triggered
+    emitter for `post` posts carrying `_prab_schema_version=1`. Hooks into Yoast's graph via
+    `wpseo_schema_webpage_type` (priority 10) and `wpseo_schema_graph` (priority 13). Retypes the
+    page node to `MedicalWebPage`; enriches the Yoast `Article` piece with `citation[]`,
+    `about[]` (Drug `@id` stubs), `lastReviewed`, and `reviewedBy`. Standalone `@graph` fallback
+    (Article + MedicalWebPage) when Yoast is absent. Posts without `_prab_schema_version` meta
+    are byte-unchanged.
+  - `PR_Core_Prab_Meta_Reader` (`frontend/class-pr-core-prab-meta-reader.php`, ~268 lines) — reads
+    and sanitises all contract-v1 `_prab_*` meta at read time (not trusting PRAB's write-time
+    sanitization). URLs validated (http/https only), DOIs matched against canonical pattern, JSON
+    arrays validated per-element, WP user ID resolved via `get_userdata()`. Malformed values
+    degrade gracefully (field skipped) — no page-render fatals.
+  - **Honest `reviewedBy`:** Person node emitted ONLY when `_prab_review_mode=human` AND
+    `_prab_reviewed_by` resolves to an existing WP user. All other cases (editorial-system mode,
+    missing/zero/nonexistent user ID) emit the Organization node ("Peptide Repo"). Never emits a
+    fabricated person — the core contract guarantee.
+  - **`about` Drug linkage:** `_prab_about_peptides` (JSON array of peptide post IDs) is resolved
+    to Drug stub arrays using the stable `{permalink}#drug` @id established in v0.6.0. Each ID
+    must resolve to a published `peptide` post; unresolvable IDs are skipped.
+  - **Citation nodes:** `ScholarlyArticle` when DOI present (DOI normalised to https://doi.org/
+    URI as `sameAs`), else `CreativeWork`. `quality_score` never emitted (no schema.org mapping
+    per contract v1).
+  - **No duplicate nodes:** integrates via Yoast mutation (priority 13, after PR_Core_Jsonld
+    priority-12 Drug/FAQ injection). Never adds new WebPage or Article pieces.
+  - Unit tests: `tests/unit/JsonldArticleTest.php` — 22 assertions covering is_triggered,
+    review_mode, reviewed_by (Person/Org decision tree), citation sanitization, about linkage,
+    retype, enrich, no-new-nodes, untriggered passthrough, editorial-system-never-person.
+
+### Changed
+- `class-pr-core.php`: boots `PR_Core_Jsonld_Article` alongside `PR_Core_Jsonld` in `init()`.
+- `tests/bootstrap.php`: enhanced `get_userdata()` stub to read from `$GLOBALS['pr_test_userdata']`;
+  added `WP_User` class stub; initialised `$GLOBALS['pr_test_userdata']` global.
+- `ARCHITECTURE.md`: JSON-LD class table updated with new classes; §2.7 PRAB article emission added.
+- `CONVENTIONS.md`: JSON-LD extension guide updated with PRAB-article hook pattern.
+
+### Technical
+- Meta keys `_prab_*` are owned by PRAutoBlogger namespace (PRAB registers/writes; prcore reads
+  only). `uninstall.php` unaffected — prcore never writes `_prab_*` meta, so no teardown needed.
+- Yoast hook order: `wpseo_schema_graph` priority 11 (peptide MedicalWebPage enrich) → priority 12
+  (Drug/FAQ inject) → priority 13 (PRAB Article enrich + page retype). Three priorities prevent
+  race conditions between the peptide and article enrichment paths.
+
 ## [0.7.1] - 2026-06-17

 ### Fixed
--- a/CONTEXT.md
+++ b/CONTEXT.md
@@ -113,3 +113,62 @@ Gutenberg block. Not surfaced in JSON-LD (dosing YMYL constraint).
 `PR_Core_Migration_Runner` — runs numbered migrations (0001–N) sequentially on every
 `plugins_loaded`. Compares `pr_core_schema_version` wp_option against
 `PR_CORE_TARGET_SCHEMA_VERSION` constant. All migrations are idempotent and re-runnable.
+
+## _prab_* meta namespace
+
+Post-meta keys written exclusively by PRAutoBlogger (PRAB) and read by prcore's
+`PR_Core_Prab_Meta_Reader` at render time. The namespace is `_prab_` (PRAutoBlogger
+private). Ownership split: **PRAB writes, prcore reads**. No other plugin reads or
+writes `_prab_*` meta. Contract v1 keys (frozen; additive evolution only, gated by
+`_prab_schema_version`):
+
+| Key | Type | Purpose |
+|---|---|---|
+| `_prab_schema_version` | int (1) | Opt-in trigger; presence + value = 1 enables JSON-LD emission |
+| `_prab_citations` | JSON array | `[{url, doi?, title, quality_score?}]` — validated sources |
+| `_prab_about_peptides` | JSON array | Peptide post IDs → Drug `@id` references in `about[]` |
+| `_prab_review_mode` | string | `human` \| `editorial-system` |
+| `_prab_reviewed_at` | string | ISO 8601 datetime → `lastReviewed` |
+| `_prab_reviewed_by` | int | WP user ID of Review Queue approver (required when mode=`human`) |
+
+All `_prab_*` values are treated as **untrusted at read time**: sanitized and
+validated by `PR_Core_Prab_Meta_Reader` before any schema.org output is produced.
+Malformed values degrade gracefully (skipped/null); no fatal path exists.
+Canonical contract: `convo/prcore/decisions/2026-06-11-jsonld-contract-v1.md`.
+
+## Meta-reader pattern
+
+`PR_Core_Prab_Meta_Reader` is the dedicated sanitizer class that isolates all
+`_prab_*` meta reading and validation from the emitter (`PR_Core_Jsonld_Article`).
+The pattern: **one sanitizer class per untrusted meta namespace**. The reader owns
+all `get_post_meta` calls for the namespace, validates every field, and returns
+typed clean values. The emitter (consumer) never calls `get_post_meta` directly.
+
+This keeps the emitter testable without the meta contract details and ensures that
+adding a new `_prab_*` field never touches the emission logic. Future `_prab_v2_*`
+fields would use a v2 reader that the emitter selects by version.
+
+## ScholarlyArticle
+
+A `schema.org/ScholarlyArticle` node emitted inside a citation array (`citation[]`)
+on the `Article` graph piece when a validated DOI is present in the PRAB citation
+record. Emitted with `url` (the citation URL), `name` (the citation title), and
+`sameAs` (the canonical `https://doi.org/` URI). When no DOI is available,
+`CreativeWork` is emitted instead. Per contract v1, `quality_score` is never
+emitted (no schema.org mapping).
+
+## Honest reviewedBy (integrity constraint)
+
+The `reviewedBy` field on the `MedicalWebPage` node emits a `schema.org/Person`
+node **only** when all three conditions hold simultaneously:
+1. `_prab_review_mode` = `human`
+2. `_prab_reviewed_by` resolves to a WP user ID > 0
+3. `get_userdata()` returns a valid `WP_User` instance with a non-empty
+   `display_name`
+
+Any other combination (missing mode, zero user ID, unresolvable user, or
+editorial-system mode) produces a `schema.org/Organization` node (Peptide Repo
+editorial). This is an **integrity constraint**, not a UI choice: emitting a
+fabricated Person would constitute misleading structured data. The constraint is
+enforced in `PR_Core_Prab_Meta_Reader::get_reviewed_by()` and covered by dedicated
+unit tests.
--- a/CONVENTIONS.md
+++ b/CONVENTIONS.md
@@ -63,6 +63,26 @@ v0.6.0 uses four focused classes (see ARCHITECTURE.md §#6). To add a new field
 4. To add a new schema piece (not Drug), create a new `PR_Core_Jsonld_<Piece>` class in `frontend/` and inject it from `PR_Core_Jsonld::inject_graph_pieces()`.
 5. The `pr_core_jsonld_peptide` filter on the Drug node array is preserved for consumer plugins.

+
+## How To: Add Fields to the PRAB Article JSON-LD (contract v2+)
+
+The `_prab_*` meta contract is versioned (`_prab_schema_version`). The contract is frozen at v1
+until prcore and PRAB coordinate a version bump. To add new fields:
+
+1. Propose the new field in `convo/prcore/decisions/` (CTO ratifies; PRAB and prcore must agree).
+2. Bump `_prab_schema_version` to 2 in PRAB's meta write code — do NOT bump before prcore ships support.
+3. Add the new field to `PR_Core_Prab_Meta_Reader` (sanitize at read time, degrade gracefully).
+4. Add emission logic to `PR_Core_Jsonld_Article` — emit only when field is non-empty.
+5. Add unit tests for the new field in `tests/unit/JsonldArticleTest.php`.
+6. Bump `SUPPORTED_VERSION` in `PR_Core_Prab_Meta_Reader::SUPPORTED_VERSION` to 2.
+7. Update the contract decision doc and CHANGELOG.
+
+Key rules:
+- prcore **reads** `_prab_*` meta only. PRAB **writes** only. The namespace boundary is hard.
+- `uninstall.php` must NOT touch `_prab_*` keys — they belong to PRAB's namespace.
+- `quality_score` and similar audit fields must never be emitted (no schema.org mapping).
+- The `reviewedBy` Person guard is non-negotiable: Person only with human mode + valid user ID.
+
 ## Error Handling

 - Repository methods return `null` or `0` on failure, never throw.
--- a/includes/class-pr-core.php
+++ b/includes/class-pr-core.php
@@ -19,7 +19,7 @@ declare(strict_types=1);
 * What: Registers all hooks, runs migrations, boots subsystems.
 * Who calls it: peptide-repo-core.php on plugins_loaded.
 * Dependencies: PR_Core_Migration_Runner, PR_Core_Peptide_CPT, PR_Core_Topic_Taxonomy,
- *              PR_Core_Admin, PR_Core_Disclaimer, PR_Core_Jsonld,
+ *              PR_Core_Admin, PR_Core_Disclaimer, PR_Core_Jsonld, PR_Core_Jsonld_Article,
 *              PR_Core_Rest_Controller, PR_Core_Related_Posts_Section.
 *
 * @see peptide-repo-core.php — Bootstrap that instantiates this class.
@@ -91,6 +91,9 @@ class PR_Core {
 		$jsonld = new PR_Core_Jsonld();
 		$jsonld->register_hooks();

+		$jsonld_article = new PR_Core_Jsonld_Article();
+		$jsonld_article->register_hooks();
+
 		// Related Articles section (frontend).
 		$related_posts = new PR_Core_Related_Posts_Section(
 			new PR_Core_Internal_Posts_Provider()
--- a/includes/frontend/class-pr-core-jsonld-article.php
+++ b/includes/frontend/class-pr-core-jsonld-article.php
@@ -0,0 +1,243 @@
+<?php
+/**
+ * Jsonld Article.
+ *
+ * @package Peptide_Repo_Core
+ */
+
+declare(strict_types=1);
+
+/**
+ * Meta-triggered JSON-LD emitter for PRAutoBlogger articles.
+ *
+ * What: Enriches Yoast's graph for `post` posts carrying _prab_schema_version=1.
+ *       When triggered, retypes the page node to MedicalWebPage and adds
+ *       citation[], about[] (Drug @id references), lastReviewed, and honest
+ *       reviewedBy to Yoast's Article piece. Emits a standalone @graph block
+ *       only when Yoast is inactive. Posts without the trigger meta are
+ *       completely byte-unchanged.
+ *
+ * Ownership rule: prcore owns ALL JSON-LD; PRAutoBlogger writes post meta only.
+ *
+ * Yoast integration (mirrors the pattern in PR_Core_Jsonld):
+ *   - wpseo_schema_webpage_type  → retype to MedicalWebPage (priority 10).
+ *   - wpseo_schema_graph         → enrich Article + MedicalWebPage (priority 13).
+ *   - wpseo_schema_graph_pieces  is intentionally NOT hooked (Yoast fatals on
+ *     plain arrays; see class-pr-core-jsonld.php class-level docblock).
+ *   - wp_head (priority 99)      → standalone fallback when Yoast absent.
+ *
+ * Contract: convo/prcore/decisions/2026-06-11-jsonld-contract-v1.md
+ *
+ * Who calls it: PR_Core::init() after PR_Core_Jsonld::register_hooks().
+ * Dependencies: PR_Core_Prab_Meta_Reader, Yoast SEO ≥ 27.6 for integrated path.
+ *
+ * @see frontend/class-pr-core-prab-meta-reader.php — Meta reader / sanitizer.
+ * @see frontend/class-pr-core-jsonld.php            — Peptide-page emitter (parallel).
+ * @see ARCHITECTURE.md §2.7                          — JSON-LD output.
+ *
+ * @package Peptide_Repo_Core
+ */
+class PR_Core_Jsonld_Article {
+
+	/**
+	 * Meta reader instance.
+	 *
+	 * @var PR_Core_Prab_Meta_Reader
+	 */
+	private PR_Core_Prab_Meta_Reader $reader;
+
+	/**
+	 * Construct the emitter with its meta reader.
+	 */
+	public function __construct() {
+		$this->reader = new PR_Core_Prab_Meta_Reader();
+	}
+
+	/**
+	 * Register Yoast and fallback hooks.
+	 *
+	 * Hooked by PR_Core::init(). Only registers hooks when on a frontend
+	 * page — safe to call unconditionally; WP handles the rest.
+	 *
+	 * @return void
+	 */
+	public function register_hooks(): void {
+		add_filter( 'wpseo_schema_webpage_type', array( $this, 'retype_article_page' ), 10 );
+		add_filter( 'wpseo_schema_graph', array( $this, 'enrich_article_graph' ), 13, 2 );
+		add_action( 'wp_head', array( $this, 'emit_standalone_fallback' ), 99 );
+	}
+
+	/**
+	 * Retype the page node to MedicalWebPage for triggered PRAB articles.
+	 *
+	 * Hooked on: wpseo_schema_webpage_type (priority 10).
+	 * Passes through unchanged on non-triggered pages and non-`post` pages.
+	 *
+	 * @param string|array $type Existing Yoast page type (string or string[]).
+	 * @return string|array 'MedicalWebPage' when triggered, $type otherwise.
+	 */
+	public function retype_article_page( string|array $type ): string|array {
+		if ( ! is_singular( 'post' ) ) {
+			return $type;
+		}
+		$post_id = (int) get_the_ID();
+		if ( $post_id <= 0 || ! $this->reader->is_triggered( $post_id ) ) {
+			return $type;
+		}
+		return 'MedicalWebPage';
+	}
+
+	/**
+	 * Enrich Yoast's assembled graph for triggered PRAB articles.
+	 *
+	 * Injects lastReviewed + reviewedBy into the MedicalWebPage node and adds
+	 * citation[] + about[] to the Article node. Priority 13 ensures this runs
+	 * after PR_Core_Jsonld's priority-12 Drug/FAQ injection.
+	 *
+	 * Never adds new WebPage or Article nodes — mutates Yoast's existing pieces.
+	 *
+	 * @param array<int, array<string, mixed>>             $graph   Assembled Yoast graph.
+	 * @param \Yoast\WP\SEO\Context\Meta_Tags_Context|null $context Yoast schema context.
+	 * @return array<int, array<string, mixed>> Enriched graph.
+	 */
+	public function enrich_article_graph( array $graph, $context ): array {
+		if ( ! is_singular( 'post' ) ) {
+			return $graph;
+		}
+		$post_id = (int) get_the_ID();
+		if ( $post_id <= 0 || ! $this->reader->is_triggered( $post_id ) ) {
+			return $graph;
+		}
+
+		$review_mode = $this->reader->get_review_mode( $post_id );
+		$reviewed_at = $this->reader->get_reviewed_at( $post_id );
+		$reviewed_by = $this->reader->get_reviewed_by( $post_id, $review_mode );
+		$citations   = $this->reader->get_citations( $post_id );
+		$about_stubs = $this->reader->get_about_peptides( $post_id );
+
+		foreach ( $graph as &$piece ) {
+			if ( ! is_array( $piece ) ) {
+				continue;
+			}
+			$types = is_array( $piece['@type'] ?? '' ) ? $piece['@type'] : array( $piece['@type'] ?? '' );
+
+			// Enrich MedicalWebPage with lastReviewed + reviewedBy.
+			if ( in_array( 'WebPage', $types, true ) || in_array( 'MedicalWebPage', $types, true ) ) {
+				if ( null !== $reviewed_at ) {
+					$piece['lastReviewed'] = $reviewed_at;
+				}
+				$piece['reviewedBy'] = $reviewed_by;
+				continue;
+			}
+
+			// Enrich Article with citation[] and about[].
+			if ( in_array( 'Article', $types, true ) ) {
+				if ( ! empty( $citations ) ) {
+					$piece['citation'] = $this->build_citations( $citations );
+				}
+				if ( ! empty( $about_stubs ) ) {
+					$piece['about'] = $about_stubs;
+				}
+				continue;
+			}
+		}
+		unset( $piece );
+
+		return $graph;
+	}
+
+	/**
+	 * Emit a standalone @graph block via wp_head when Yoast is not active.
+	 *
+	 * Suppressed when Yoast is loaded. Emits Article + MedicalWebPage nodes
+	 * with Yoast-parity @id conventions so consumers see one shape regardless
+	 * of whether Yoast is present. Skips posts whose permalink cannot be resolved.
+	 *
+	 * @return void
+	 */
+	public function emit_standalone_fallback(): void {
+		if ( function_exists( 'YoastSEO' ) ) {
+			return;
+		}
+		if ( ! is_singular( 'post' ) ) {
+			return;
+		}
+		$post_id = (int) get_the_ID();
+		if ( $post_id <= 0 || ! $this->reader->is_triggered( $post_id ) ) {
+			return;
+		}
+
+		$permalink = (string) get_permalink( $post_id );
+		if ( '' === $permalink ) {
+			return;
+		}
+
+		$post        = get_post( $post_id );
+		$review_mode = $this->reader->get_review_mode( $post_id );
+		$reviewed_at = $this->reader->get_reviewed_at( $post_id );
+		$reviewed_by = $this->reader->get_reviewed_by( $post_id, $review_mode );
+		$citations   = $this->reader->get_citations( $post_id );
+		$about_stubs = $this->reader->get_about_peptides( $post_id );
+
+		$webpage = array(
+			'@type' => 'MedicalWebPage',
+			'@id'   => $permalink . '#webpage',
+			'url'   => $permalink,
+		);
+		if ( null !== $reviewed_at ) {
+			$webpage['lastReviewed'] = $reviewed_at;
+		}
+		$webpage['reviewedBy'] = $reviewed_by;
+
+		$article = array(
+			'@type'    => 'Article',
+			'@id'      => $permalink . '#article',
+			'isPartOf' => array( '@id' => $permalink . '#webpage' ),
+			'headline' => $post instanceof WP_Post ? sanitize_text_field( $post->post_title ) : '',
+		);
+		if ( ! empty( $citations ) ) {
+			$article['citation'] = $this->build_citations( $citations );
+		}
+		if ( ! empty( $about_stubs ) ) {
+			$article['about'] = $about_stubs;
+		}
+
+		$json = wp_json_encode(
+			array(
+				'@context' => 'https://schema.org',
+				'@graph'   => array( $webpage, $article ),
+			),
+			JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_PRETTY_PRINT
+		);
+		if ( false !== $json ) {
+			echo '<script type="application/ld+json">' . $json . '</script>' . "\n"; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- wp_json_encode() already escapes for JSON context.
+		}
+	}
+
+	// ── Private builders ─────────────────────────────────────────────────
+
+	/**
+	 * Build schema.org citation nodes from validated citation records.
+	 *
+	 * Emits ScholarlyArticle when doi is present (DOI as sameAs URI),
+	 * CreativeWork otherwise. Per contract v1, quality_score is never emitted.
+	 *
+	 * @param array<int, array{url: string, title: string, doi: string|null}> $citations Validated.
+	 * @return array<int, array<string, mixed>> Schema citation nodes.
+	 */
+	private function build_citations( array $citations ): array {
+		$nodes = array();
+		foreach ( $citations as $c ) {
+			$node = array(
+				'@type' => null !== $c['doi'] ? 'ScholarlyArticle' : 'CreativeWork',
+				'url'   => $c['url'],
+				'name'  => $c['title'],
+			);
+			if ( null !== $c['doi'] ) {
+				$node['sameAs'] = $c['doi'];
+			}
+			$nodes[] = $node;
+		}
+		return $nodes;
+	}
+}
--- a/includes/frontend/class-pr-core-prab-meta-reader.php
+++ b/includes/frontend/class-pr-core-prab-meta-reader.php
@@ -0,0 +1,299 @@
+<?php
+/**
+ * Prab Meta Reader.
+ *
+ * @package Peptide_Repo_Core
+ */
+
+declare(strict_types=1);
+
+/**
+ * Reads and validates _prab_* post-meta written by PRAutoBlogger.
+ *
+ * All meta treated as untrusted: URLs validated (http/https), DOIs regex-checked,
+ * JSON arrays decoded per-element, user IDs resolved via get_userdata(). Never throws.
+ *
+ * @see frontend/class-pr-core-jsonld-article.php — Consumer.
+ * @see convo/prcore/decisions/2026-06-11-jsonld-contract-v1.md — Meta contract.
+ *
+ * @package Peptide_Repo_Core
+ */
+class PR_Core_Prab_Meta_Reader {
+	/**
+	 * Schema version meta key; presence opts the post in, value must equal 1.
+	 *
+	 * @var string
+	 */
+	public const META_SCHEMA_VERSION = '_prab_schema_version';
+
+	/**
+	 * Citations meta key; JSON array of {url, title, doi?, quality_score?}.
+	 *
+	 * @var string
+	 */
+	public const META_CITATIONS = '_prab_citations';
+
+	/**
+	 * About-peptides meta key; JSON array of peptide post IDs for schema `about`.
+	 *
+	 * @var string
+	 */
+	public const META_ABOUT_PEPTIDES = '_prab_about_peptides';
+
+	/**
+	 * Review mode meta key; value is 'human' or 'editorial-system'.
+	 *
+	 * @var string
+	 */
+	public const META_REVIEW_MODE = '_prab_review_mode';
+
+	/**
+	 * Reviewed-at meta key; ISO 8601 datetime of last review.
+	 *
+	 * @var string
+	 */
+	public const META_REVIEWED_AT = '_prab_reviewed_at';
+
+	/**
+	 * Reviewed-by meta key; WP user ID of the Review Queue approver.
+	 *
+	 * @var string
+	 */
+	public const META_REVIEWED_BY = '_prab_reviewed_by';
+
+	/**
+	 * The only schema version this reader currently supports.
+	 *
+	 * @var int
+	 */
+	private const SUPPORTED_VERSION = 1;
+
+	/**
+	 * Per-request cache for is_triggered(), keyed by post ID (avoids triple meta reads).
+	 *
+	 * @var array<int, bool>
+	 */
+	private array $triggered_cache = array();
+
+	/**
+	 * Return true when this post carries a supported _prab_schema_version meta.
+	 *
+	 * Cached per post ID: all three Yoast hooks call this for the same post,
+	 * so caching avoids triple get_post_meta reads per request.
+	 *
+	 * @param int $post_id WordPress post ID.
+	 * @return bool
+	 */
+	public function is_triggered( int $post_id ): bool {
+		if ( isset( $this->triggered_cache[ $post_id ] ) ) {
+			return $this->triggered_cache[ $post_id ];
+		}
+		$raw = get_post_meta( $post_id, self::META_SCHEMA_VERSION, true );
+		if ( '' === $raw || false === $raw ) {
+			$this->triggered_cache[ $post_id ] = false;
+			return false;
+		}
+		$version = (int) $raw;
+		if ( self::SUPPORTED_VERSION === $version ) {
+			$this->triggered_cache[ $post_id ] = true;
+			return true;
+		}
+		error_log( sprintf( '[PR Core] Unsupported _prab_schema_version=%d on post %d. Supports v%d only. Emission suppressed.', $version, $post_id, self::SUPPORTED_VERSION ) );
+		$this->triggered_cache[ $post_id ] = false;
+		return false;
+	}
+
+	/**
+	 * Read and validate _prab_citations meta.
+	 *
+	 * Each entry needs valid http/https `url` and non-empty `title`; others skipped.
+	 * `quality_score` never emitted — no schema.org mapping (contract v1).
+	 *
+	 * @param int $post_id WordPress post ID.
+	 * @return array<int, array{url: string, title: string, doi: string|null}> Validated.
+	 */
+	public function get_citations( int $post_id ): array {
+		$decoded = $this->decode_json_meta( $post_id, self::META_CITATIONS );
+		if ( empty( $decoded ) ) {
+			return array();
+		}
+		$valid = array();
+		foreach ( $decoded as $item ) {
+			if ( ! is_array( $item ) ) {
+				continue;
+			}
+			$url   = $this->sanitize_url( (string) ( $item['url'] ?? '' ) );
+			$title = sanitize_text_field( (string) ( $item['title'] ?? '' ) );
+			if ( '' === $url || '' === $title ) {
+				continue;
+			}
+			$valid[] = array(
+				'url'   => $url,
+				'title' => $title,
+				'doi'   => isset( $item['doi'] ) ? $this->sanitize_doi( (string) $item['doi'] ) : null,
+			);
+		}
+		return $valid;
+	}
+
+	/**
+	 * Read and validate _prab_about_peptides meta.
+	 *
+	 * Returns Drug stubs for schema `about`. Each ID must resolve to a published
+	 * `peptide` post; unresolvable IDs and empty-permalink posts are skipped.
+	 *
+	 * @param int $post_id WordPress post ID.
+	 * @return array<int, array<string, string>> Drug stubs.
+	 */
+	public function get_about_peptides( int $post_id ): array {
+		$decoded = $this->decode_json_meta( $post_id, self::META_ABOUT_PEPTIDES );
+		if ( empty( $decoded ) ) {
+			return array();
+		}
+		$stubs = array();
+		foreach ( $decoded as $raw_id ) {
+			if ( ! is_numeric( $raw_id ) ) {
+				continue;
+			}
+			$pid  = absint( $raw_id );
+			$post = $pid > 0 ? get_post( $pid ) : null;
+			if ( ! $post instanceof WP_Post
+				|| 'publish' !== $post->post_status
+				|| PR_Core_Peptide_CPT::POST_TYPE !== $post->post_type ) {
+				continue;
+			}
+			$link = (string) get_permalink( $pid );
+			if ( '' === $link ) {
+				continue;
+			}
+			$stubs[] = array(
+				'@type' => 'Drug',
+				'@id'   => $link . '#drug',
+				'name'  => sanitize_text_field( $post->post_title ),
+				'url'   => $link,
+			);
+		}
+		return $stubs;
+	}
+
+	/**
+	 * Read and validate _prab_review_mode meta.
+	 *
+	 * Unknown values are treated as 'editorial-system' (safe floor, contract v1).
+	 *
+	 * @param int $post_id WordPress post ID.
+	 * @return string 'human' | 'editorial-system'.
+	 */
+	public function get_review_mode( int $post_id ): string {
+		$raw = sanitize_text_field( (string) get_post_meta( $post_id, self::META_REVIEW_MODE, true ) );
+		if ( 'human' === $raw ) {
+			return 'human';
+		}
+		if ( '' !== $raw && 'editorial-system' !== $raw ) {
+			error_log( sprintf( '[PR Core] Unknown _prab_review_mode="%s" on post %d. Treating as editorial-system.', $raw, $post_id ) );
+		}
+		return 'editorial-system';
+	}
+
+	/**
+	 * Read and validate _prab_reviewed_at meta.
+	 *
+	 * Returns null when absent, empty, or unparseable as a date.
+	 *
+	 * @param int $post_id WordPress post ID.
+	 * @return string|null Sanitised datetime string, or null.
+	 */
+	public function get_reviewed_at( int $post_id ): ?string {
+		$raw = sanitize_text_field( (string) get_post_meta( $post_id, self::META_REVIEWED_AT, true ) );
+		if ( '' === $raw || false === strtotime( $raw ) ) {
+			return null;
+		}
+		return $raw;
+	}
+
+	/**
+	 * Resolve the honest reviewedBy value for a PRAB article.
+	 *
+	 * Person only when mode='human', user resolves, and display_name non-empty.
+	 * All other cases → Organization. Never fabricated. Core contract guarantee.
+	 *
+	 * @param int    $post_id     WordPress post ID.
+	 * @param string $review_mode Result of get_review_mode() for this post.
+	 * @return array<string, string> Schema Person or Organization node.
+	 */
+	public function get_reviewed_by( int $post_id, string $review_mode ): array {
+		if ( 'human' === $review_mode ) {
+			$uid  = absint( get_post_meta( $post_id, self::META_REVIEWED_BY, true ) );
+			$user = $uid > 0 ? get_userdata( $uid ) : false;
+			if ( $user instanceof WP_User ) {
+				$display = sanitize_text_field( $user->display_name );
+				if ( '' !== $display ) {
+					return array(
+						'@type' => 'Person',
+						'@id'   => home_url( '/#/schema/person/' . $uid ),
+						'name'  => $display,
+					);
+				}
+			}
+			error_log( sprintf( '[PR Core] _prab_review_mode=human but reviewed_by user (ID=%d) unresolvable on post %d. Emitting Organization.', $uid, $post_id ) );
+		}
+		return array(
+			'@type' => 'Organization',
+			'@id'   => home_url( '/#organization' ),
+			'name'  => 'Peptide Repo',
+			'url'   => home_url(),
+		);
+	}
+
+	// ── Private helpers ──────────────────────────────────────────────────
+
+	/**
+	 * Decode a JSON array from post meta, returning empty array on any error.
+	 *
+	 * @param int    $post_id  WordPress post ID.
+	 * @param string $meta_key Meta key to read.
+	 * @return array<mixed> Decoded array, or empty array on failure.
+	 */
+	private function decode_json_meta( int $post_id, string $meta_key ): array {
+		$raw = get_post_meta( $post_id, $meta_key, true );
+		if ( ! is_string( $raw ) || '' === $raw ) {
+			return array();
+		}
+		$decoded = json_decode( $raw, true );
+		return is_array( $decoded ) ? $decoded : array();
+	}
+
+	/**
+	 * Sanitize and validate a URL, requiring http or https scheme.
+	 *
+	 * @param string $raw Raw URL string.
+	 * @return string Sanitised URL, or '' when invalid.
+	 */
+	private function sanitize_url( string $raw ): string {
+		$url = esc_url_raw( trim( $raw ) );
+		if ( '' === $url || ! filter_var( $url, FILTER_VALIDATE_URL ) ) {
+			return '';
+		}
+		$scheme = (string) wp_parse_url( $url, PHP_URL_SCHEME );
+		return in_array( $scheme, array( 'http', 'https' ), true ) ? $url : '';
+	}
+
+	/**
+	 * Sanitize a DOI, returning a https://doi.org/ URI or null.
+	 *
+	 * Accepts bare DOI ("10.1234/abc"), doi:-prefixed, or full URI forms.
+	 *
+	 * @param string $raw Raw DOI string.
+	 * @return string|null DOI URI, or null if pattern does not match.
+	 */
+	private function sanitize_doi( string $raw ): ?string {
+		$doi = trim( $raw );
+		foreach ( array( 'https://doi.org/', 'http://doi.org/', 'doi:' ) as $pfx ) {
+			if ( str_starts_with( strtolower( $doi ), strtolower( $pfx ) ) ) {
+				$doi = substr( $doi, strlen( $pfx ) );
+				break;
+			}
+		}
+		return preg_match( '/^10\.\d{4,}\/\S+$/', $doi ) ? 'https://doi.org/' . $doi : null;
+	}
+}
--- a/peptide-repo-core.php
+++ b/peptide-repo-core.php
@@ -29,7 +29,7 @@ if ( ! defined( 'ABSPATH' ) ) {

 /* ── Constants ────────────────────────────────────────────────────────── */

-define( 'PR_CORE_VERSION', '0.7.1' );
+define( 'PR_CORE_VERSION', '0.8.0' );
 define( 'PR_CORE_PLUGIN_FILE', __FILE__ );
 define( 'PR_CORE_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
 define( 'PR_CORE_PLUGIN_URL', plugin_dir_url( __FILE__ ) );
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -61,6 +61,7 @@ $GLOBALS['pr_core_options']      = [];
 $GLOBALS['pr_core_cron_calls']   = [];
 $GLOBALS['pr_test_postmeta']     = [];
 $GLOBALS['pr_test_posts']        = [];
+$GLOBALS['pr_test_userdata']     = [];
 $GLOBALS['pr_test_updated_meta'] = [];
 $GLOBALS['pr_test_is_singular']  = false;
 $GLOBALS['pr_test_singular_type'] = '';
@@ -169,6 +170,11 @@ if ( ! function_exists( 'is_email' ) ) {
 		return (bool) filter_var( $email, FILTER_VALIDATE_EMAIL );
 	}
 }
+if ( ! function_exists( 'wp_parse_url' ) ) {
+	function wp_parse_url( string $url, int $component = -1 ) {
+		return parse_url( $url, $component );
+	}
+}

 // ── Option / cron stubs ───────────────────────────────────────────────.

@@ -325,9 +331,28 @@ if ( ! function_exists( 'get_post_modified_time' ) ) {
 }
 if ( ! function_exists( 'get_userdata' ) ) {
 	function get_userdata( int $id ) {
+		$data = $GLOBALS['pr_test_userdata'][ $id ] ?? null;
+		if ( null !== $data ) {
+			return $data instanceof WP_User ? $data : new WP_User( (array) $data );
+		}
 		return false;
 	}
 }
+
+if ( ! class_exists( 'WP_User' ) ) {
+	class WP_User {
+		public int    $ID           = 0;
+		public string $display_name = '';
+		public string $user_login   = '';
+		public string $user_email   = '';
+		/** @param array<string, mixed> $data */
+		public function __construct( array $data = [] ) {
+			foreach ( $data as $key => $value ) {
+				$this->$key = $value;
+			}
+		}
+	}
+}
 if ( ! function_exists( 'get_author_posts_url' ) ) {
 	function get_author_posts_url( int $id ): string {
 		return 'https://peptiderepo.com/author/' . $id;
--- a/tests/unit/JsonldArticleTest.php
+++ b/tests/unit/JsonldArticleTest.php
@@ -0,0 +1,484 @@
+<?php
+/**
+ * Unit tests for PR_Core_Prab_Meta_Reader and PR_Core_Jsonld_Article.
+ *
+ * Coverage:
+ *   - is_triggered: version=1 triggers, absent/wrong version does not.
+ *   - is_triggered cache: second call returns cached value (no extra meta read).
+ *   - get_review_mode: 'human', 'editorial-system', unknown → 'editorial-system'.
+ *   - get_reviewed_by: human + valid user → Person; human + bad user → Org; editorial → Org.
+ *   - get_reviewed_by: human + empty display_name → Org (P2-2 guard).
+ *   - get_citations: valid, missing url, missing title, bad url, doi normalisation.
+ *   - get_about_peptides: valid peptide ID; non-existent ID skipped; non-peptide type skipped.
+ *   - get_reviewed_at: valid ISO, empty, unparseable → null.
+ *   - retype_article_page: triggered post → MedicalWebPage; untriggered → passthrough.
+ *   - enrich_article_graph: Article gains citation/about; WebPage gains lastReviewed/reviewedBy.
+ *   - No duplicate Article/WebPage nodes emitted.
+ *   - editorial-system mode never emits Person.
+ *   - emit_standalone_fallback: Yoast-active suppresses output.
+ *   - emit_standalone_fallback: untriggered post emits nothing.
+ *   - emit_standalone_fallback: triggered post emits valid @graph with Article + MedicalWebPage.
+ *
+ * @package PeptideRepoCore\Tests
+ */
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Tests for PRAB article JSON-LD meta-reader and emitter.
+ */
+class JsonldArticleTest extends TestCase {
+
+	protected function setUp(): void {
+		$GLOBALS['pr_test_postmeta']      = array();
+		$GLOBALS['pr_test_is_singular']   = false;
+		$GLOBALS['pr_test_singular_type'] = '';
+		$GLOBALS['pr_test_the_id']        = 0;
+		$GLOBALS['pr_test_posts']         = array();
+		$GLOBALS['pr_test_userdata']      = array();
+		$GLOBALS['pr_core_test_state']    = array(
+			'existing_post_types'   => array(),
+			'existing_taxonomies'   => array(),
+			'registered_post_types' => array(),
+			'registered_taxonomies' => array(),
+			'registered_meta'       => array(),
+			'added_actions'         => array(),
+			'added_filters'         => array(),
+		);
+
+		require_once PR_CORE_PLUGIN_DIR . 'includes/cpt/class-pr-core-peptide-cpt.php';
+		require_once PR_CORE_PLUGIN_DIR . 'includes/frontend/class-pr-core-prab-meta-reader.php';
+		require_once PR_CORE_PLUGIN_DIR . 'includes/frontend/class-pr-core-jsonld-article.php';
+	}
+
+	// ── Helpers ───────────────────────────────────────────────────────────
+
+	/** @return PR_Core_Prab_Meta_Reader */
+	private function reader(): PR_Core_Prab_Meta_Reader {
+		return new PR_Core_Prab_Meta_Reader();
+	}
+
+	/**
+	 * @param array<string, mixed> $meta
+	 */
+	private function set_meta( int $post_id, array $meta ): void {
+		$GLOBALS['pr_test_postmeta'][ $post_id ] = $meta;
+	}
+
+	// ── is_triggered ─────────────────────────────────────────────────────
+
+	public function test_is_triggered_version_1(): void {
+		$this->set_meta( 1, array( '_prab_schema_version' => '1' ) );
+		$this->assertTrue( $this->reader()->is_triggered( 1 ) );
+	}
+
+	public function test_is_triggered_absent(): void {
+		$this->set_meta( 1, array() );
+		$this->assertFalse( $this->reader()->is_triggered( 1 ) );
+	}
+
+	public function test_is_triggered_unsupported_version(): void {
+		$this->set_meta( 1, array( '_prab_schema_version' => '2' ) );
+		$this->assertFalse( $this->reader()->is_triggered( 1 ) );
+	}
+
+	public function test_is_triggered_cache_returns_same_value(): void {
+		$this->set_meta( 5, array( '_prab_schema_version' => '1' ) );
+		$r = $this->reader();
+		$first  = $r->is_triggered( 5 );
+		$second = $r->is_triggered( 5 );
+		$this->assertSame( $first, $second );
+		$this->assertTrue( $first );
+	}
+
+	// ── get_review_mode ───────────────────────────────────────────────────
+
+	public function test_review_mode_human(): void {
+		$this->set_meta( 1, array( '_prab_review_mode' => 'human' ) );
+		$this->assertSame( 'human', $this->reader()->get_review_mode( 1 ) );
+	}
+
+	public function test_review_mode_editorial_system(): void {
+		$this->set_meta( 1, array( '_prab_review_mode' => 'editorial-system' ) );
+		$this->assertSame( 'editorial-system', $this->reader()->get_review_mode( 1 ) );
+	}
+
+	public function test_review_mode_unknown_falls_back(): void {
+		$this->set_meta( 1, array( '_prab_review_mode' => 'robo-editor' ) );
+		$this->assertSame( 'editorial-system', $this->reader()->get_review_mode( 1 ) );
+	}
+
+	public function test_review_mode_empty_falls_back(): void {
+		$this->set_meta( 1, array() );
+		$this->assertSame( 'editorial-system', $this->reader()->get_review_mode( 1 ) );
+	}
+
+	// ── get_reviewed_by ───────────────────────────────────────────────────
+
+	public function test_reviewed_by_human_valid_user(): void {
+		$this->set_meta( 1, array( '_prab_reviewed_by' => '42' ) );
+		$GLOBALS['pr_test_userdata'][42] = new WP_User( array( 'display_name' => 'Dr Alice', 'ID' => 42 ) );
+		$node = $this->reader()->get_reviewed_by( 1, 'human' );
+		$this->assertSame( 'Person', $node['@type'] );
+		$this->assertSame( 'Dr Alice', $node['name'] );
+		$this->assertStringContainsString( '42', $node['@id'] );
+	}
+
+	public function test_reviewed_by_human_missing_user_returns_org(): void {
+		$this->set_meta( 1, array( '_prab_reviewed_by' => '99' ) );
+		// user 99 not in $GLOBALS['pr_test_userdata'] → get_userdata returns false.
+		$node = $this->reader()->get_reviewed_by( 1, 'human' );
+		$this->assertSame( 'Organization', $node['@type'] );
+	}
+
+	public function test_reviewed_by_human_zero_user_id_returns_org(): void {
+		$this->set_meta( 1, array( '_prab_reviewed_by' => '0' ) );
+		$node = $this->reader()->get_reviewed_by( 1, 'human' );
+		$this->assertSame( 'Organization', $node['@type'] );
+	}
+
+	public function test_reviewed_by_human_empty_display_name_returns_org(): void {
+		$this->set_meta( 1, array( '_prab_reviewed_by' => '77' ) );
+		$GLOBALS['pr_test_userdata'][77] = new WP_User( array( 'display_name' => '', 'ID' => 77 ) );
+		$node = $this->reader()->get_reviewed_by( 1, 'human' );
+		$this->assertSame( 'Organization', $node['@type'] );
+	}
+
+	public function test_reviewed_by_editorial_system_returns_org(): void {
+		$node = $this->reader()->get_reviewed_by( 1, 'editorial-system' );
+		$this->assertSame( 'Organization', $node['@type'] );
+		$this->assertSame( 'Peptide Repo', $node['name'] );
+	}
+
+	public function test_reviewed_by_org_never_person(): void {
+		// Ensure editorial-system never emits a Person even if reviewed_by meta present.
+		$this->set_meta( 1, array( '_prab_reviewed_by' => '42' ) );
+		$GLOBALS['pr_test_userdata'][42] = new WP_User( array( 'display_name' => 'Dr Alice', 'ID' => 42 ) );
+		$node = $this->reader()->get_reviewed_by( 1, 'editorial-system' );
+		$this->assertSame( 'Organization', $node['@type'] );
+	}
+
+	// ── get_citations ─────────────────────────────────────────────────────
+
+	public function test_citations_valid(): void {
+		$this->set_meta( 1, array(
+			'_prab_citations' => wp_json_encode( array(
+				array( 'url' => 'https://pubmed.ncbi.nlm.nih.gov/12345', 'title' => 'BPC-157 study' ),
+				array( 'url' => 'https://doi.org/10.1016/j.abc.2020.01', 'title' => 'RCT', 'doi' => '10.1016/j.abc.2020.01' ),
+			) ),
+		) );
+		$cits = $this->reader()->get_citations( 1 );
+		$this->assertCount( 2, $cits );
+		$this->assertSame( 'BPC-157 study', $cits[0]['title'] );
+		$this->assertNull( $cits[0]['doi'] );
+		$this->assertSame( 'https://doi.org/10.1016/j.abc.2020.01', $cits[1]['doi'] );
+	}
+
+	public function test_citations_missing_url_dropped(): void {
+		$this->set_meta( 1, array(
+			'_prab_citations' => wp_json_encode( array(
+				array( 'title' => 'No URL entry' ),
+			) ),
+		) );
+		$this->assertCount( 0, $this->reader()->get_citations( 1 ) );
+	}
+
+	public function test_citations_missing_title_dropped(): void {
+		$this->set_meta( 1, array(
+			'_prab_citations' => wp_json_encode( array(
+				array( 'url' => 'https://example.com' ),
+			) ),
+		) );
+		$this->assertCount( 0, $this->reader()->get_citations( 1 ) );
+	}
+
+	public function test_citations_invalid_url_scheme_dropped(): void {
+		$this->set_meta( 1, array(
+			'_prab_citations' => wp_json_encode( array(
+				array( 'url' => 'javascript:alert(1)', 'title' => 'XSS attempt' ),
+			) ),
+		) );
+		$this->assertCount( 0, $this->reader()->get_citations( 1 ) );
+	}
+
+	public function test_citations_bad_doi_emits_null_doi(): void {
+		$this->set_meta( 1, array(
+			'_prab_citations' => wp_json_encode( array(
+				array( 'url' => 'https://example.com', 'title' => 'Test', 'doi' => 'not-a-doi' ),
+			) ),
+		) );
+		$cits = $this->reader()->get_citations( 1 );
+		$this->assertCount( 1, $cits );
+		$this->assertNull( $cits[0]['doi'] );
+	}
+
+	public function test_citations_doi_normalised_from_uri(): void {
+		$this->set_meta( 1, array(
+			'_prab_citations' => wp_json_encode( array(
+				array( 'url' => 'https://example.com', 'title' => 'Test', 'doi' => 'https://doi.org/10.9999/x' ),
+			) ),
+		) );
+		$cits = $this->reader()->get_citations( 1 );
+		$this->assertSame( 'https://doi.org/10.9999/x', $cits[0]['doi'] );
+	}
+
+	public function test_citations_malformed_json_returns_empty(): void {
+		$this->set_meta( 1, array( '_prab_citations' => 'not-json' ) );
+		$this->assertCount( 0, $this->reader()->get_citations( 1 ) );
+	}
+
+	// ── get_about_peptides edge cases ─────────────────────────────────────
+
+	public function test_get_about_peptides_nonexistent_id_skipped(): void {
+		// post ID 999 does not exist in $GLOBALS['pr_test_posts'] → get_post returns null.
+		$this->set_meta( 1, array(
+			'_prab_schema_version'  => '1',
+			'_prab_about_peptides'  => wp_json_encode( array( 999 ) ),
+		) );
+		$stubs = $this->reader()->get_about_peptides( 1 );
+		$this->assertCount( 0, $stubs );
+	}
+
+	public function test_get_about_peptides_wrong_post_type_skipped(): void {
+		// A published post of type 'post' (not 'peptide') should be excluded.
+		$GLOBALS['pr_test_posts'][50] = new WP_Post( array(
+			'ID'          => 50,
+			'post_type'   => 'post',
+			'post_status' => 'publish',
+			'post_title'  => 'Not a peptide',
+		) );
+		$this->set_meta( 1, array(
+			'_prab_schema_version'  => '1',
+			'_prab_about_peptides'  => wp_json_encode( array( 50 ) ),
+		) );
+		$stubs = $this->reader()->get_about_peptides( 1 );
+		$this->assertCount( 0, $stubs );
+	}
+
+	// ── get_reviewed_at ───────────────────────────────────────────────────
+
+	public function test_reviewed_at_valid_iso(): void {
+		$this->set_meta( 1, array( '_prab_reviewed_at' => '2026-06-11T08:00:00+00:00' ) );
+		$this->assertSame( '2026-06-11T08:00:00+00:00', $this->reader()->get_reviewed_at( 1 ) );
+	}
+
+	public function test_reviewed_at_empty_returns_null(): void {
+		$this->set_meta( 1, array() );
+		$this->assertNull( $this->reader()->get_reviewed_at( 1 ) );
+	}
+
+	public function test_reviewed_at_unparseable_returns_null(): void {
+		$this->set_meta( 1, array( '_prab_reviewed_at' => 'not-a-date' ) );
+		$this->assertNull( $this->reader()->get_reviewed_at( 1 ) );
+	}
+
+	// ── retype_article_page ───────────────────────────────────────────────
+
+	public function test_retype_triggered_post(): void {
+		$GLOBALS['pr_test_is_singular']   = true;
+		$GLOBALS['pr_test_singular_type'] = 'post';
+		$GLOBALS['pr_test_the_id']        = 1;
+		$this->set_meta( 1, array( '_prab_schema_version' => '1' ) );
+		$emitter = new PR_Core_Jsonld_Article();
+		$this->assertSame( 'MedicalWebPage', $emitter->retype_article_page( 'WebPage' ) );
+	}
+
+	public function test_retype_untriggered_passthrough(): void {
+		$GLOBALS['pr_test_is_singular']   = true;
+		$GLOBALS['pr_test_singular_type'] = 'post';
+		$GLOBALS['pr_test_the_id']        = 2;
+		$this->set_meta( 2, array() ); // no _prab_schema_version.
+		$emitter = new PR_Core_Jsonld_Article();
+		$this->assertSame( 'WebPage', $emitter->retype_article_page( 'WebPage' ) );
+	}
+
+	public function test_retype_non_post_passthrough(): void {
+		$GLOBALS['pr_test_is_singular']   = true;
+		$GLOBALS['pr_test_singular_type'] = 'peptide';
+		$GLOBALS['pr_test_the_id']        = 1;
+		$this->set_meta( 1, array( '_prab_schema_version' => '1' ) );
+		$emitter = new PR_Core_Jsonld_Article();
+		$this->assertSame( 'CollectionPage', $emitter->retype_article_page( 'CollectionPage' ) );
+	}
+
+	// ── enrich_article_graph ──────────────────────────────────────────────
+
+	public function test_enrich_adds_citation_and_about_to_article(): void {
+		$GLOBALS['pr_test_is_singular']   = true;
+		$GLOBALS['pr_test_singular_type'] = 'post';
+		$GLOBALS['pr_test_the_id']        = 1;
+
+		// Set up a published peptide post for about linkage.
+		$GLOBALS['pr_test_posts'][10] = new WP_Post( array(
+			'ID'          => 10,
+			'post_type'   => 'peptide',
+			'post_status' => 'publish',
+			'post_title'  => 'BPC-157',
+		) );
+
+		$this->set_meta( 1, array(
+			'_prab_schema_version'  => '1',
+			'_prab_citations'       => wp_json_encode( array(
+				array( 'url' => 'https://pubmed.ncbi.nlm.nih.gov/1', 'title' => 'Study A' ),
+			) ),
+			'_prab_about_peptides'  => wp_json_encode( array( 10 ) ),
+			'_prab_review_mode'     => 'editorial-system',
+			'_prab_reviewed_at'     => '2026-06-11T08:00:00+00:00',
+		) );
+
+		$graph = array(
+			array( '@type' => 'MedicalWebPage', '@id' => 'https://peptiderepo.com/post/1/#webpage' ),
+			array( '@type' => 'Article', '@id' => 'https://peptiderepo.com/post/1/#article' ),
+		);
+
+		$emitter      = new PR_Core_Jsonld_Article();
+		$result_graph = $emitter->enrich_article_graph( $graph, null );
+
+		// Article should have citation and about.
+		$article = null;
+		$webpage = null;
+		foreach ( $result_graph as $piece ) {
+			if ( 'Article' === ( $piece['@type'] ?? '' ) ) {
+				$article = $piece;
+			}
+			if ( 'MedicalWebPage' === ( $piece['@type'] ?? '' ) ) {
+				$webpage = $piece;
+			}
+		}
+
+		$this->assertNotNull( $article, 'Article piece found in graph' );
+		$this->assertArrayHasKey( 'citation', $article );
+		$this->assertCount( 1, $article['citation'] );
+		$this->assertArrayHasKey( 'about', $article );
+		$this->assertCount( 1, $article['about'] );
+		$this->assertSame( 'Drug', $article['about'][0]['@type'] );
+
+		// WebPage should have lastReviewed and reviewedBy (Organization).
+		$this->assertNotNull( $webpage, 'MedicalWebPage piece found in graph' );
+		$this->assertArrayHasKey( 'lastReviewed', $webpage );
+		$this->assertSame( 'Organization', $webpage['reviewedBy']['@type'] );
+	}
+
+	public function test_enrich_untriggered_graph_unchanged(): void {
+		$GLOBALS['pr_test_is_singular']   = true;
+		$GLOBALS['pr_test_singular_type'] = 'post';
+		$GLOBALS['pr_test_the_id']        = 2;
+		$this->set_meta( 2, array() );
+
+		$graph    = array(
+			array( '@type' => 'WebPage', '@id' => 'https://peptiderepo.com/post/2/#webpage' ),
+			array( '@type' => 'Article', '@id' => 'https://peptiderepo.com/post/2/#article' ),
+		);
+		$emitter  = new PR_Core_Jsonld_Article();
+		$result   = $emitter->enrich_article_graph( $graph, null );
+
+		// Graph must be identical — no new keys.
+		$this->assertSame( $graph, $result );
+	}
+
+	public function test_no_new_article_or_webpage_nodes_added(): void {
+		$GLOBALS['pr_test_is_singular']   = true;
+		$GLOBALS['pr_test_singular_type'] = 'post';
+		$GLOBALS['pr_test_the_id']        = 1;
+		$this->set_meta( 1, array( '_prab_schema_version' => '1', '_prab_review_mode' => 'editorial-system' ) );
+
+		$graph  = array(
+			array( '@type' => 'MedicalWebPage', '@id' => 'x#w' ),
+			array( '@type' => 'Article', '@id' => 'x#a' ),
+		);
+		$emitter = new PR_Core_Jsonld_Article();
+		$result  = $emitter->enrich_article_graph( $graph, null );
+
+		// Still exactly 2 pieces — no new nodes injected.
+		$this->assertCount( 2, $result );
+	}
+
+	// ── emit_standalone_fallback ──────────────────────────────────────────
+
+	public function test_standalone_fallback_emits_nothing_for_untriggered_post(): void {
+		$GLOBALS['pr_test_is_singular']   = true;
+		$GLOBALS['pr_test_singular_type'] = 'post';
+		$GLOBALS['pr_test_the_id']        = 3;
+		$this->set_meta( 3, array() ); // no _prab_schema_version.
+
+		$emitter = new PR_Core_Jsonld_Article();
+		ob_start();
+		$emitter->emit_standalone_fallback();
+		$output = ob_get_clean();
+
+		$this->assertSame( '', $output, 'Untriggered post must produce no output' );
+	}
+
+	public function test_standalone_fallback_emits_valid_graph_for_triggered_post(): void {
+		$GLOBALS['pr_test_is_singular']   = true;
+		$GLOBALS['pr_test_singular_type'] = 'post';
+		$GLOBALS['pr_test_the_id']        = 4;
+		$GLOBALS['pr_test_posts'][4]      = new WP_Post( array(
+			'ID'         => 4,
+			'post_type'  => 'post',
+			'post_status' => 'publish',
+			'post_title' => 'BPC-157 Article',
+		) );
+		$this->set_meta( 4, array(
+			'_prab_schema_version' => '1',
+			'_prab_review_mode'    => 'editorial-system',
+			'_prab_reviewed_at'    => '2026-06-20T10:00:00+00:00',
+			'_prab_citations'      => wp_json_encode( array(
+				array( 'url' => 'https://example.com/study', 'title' => 'Study One', 'doi' => '10.1234/abc' ),
+			) ),
+		) );
+
+		$emitter = new PR_Core_Jsonld_Article();
+		ob_start();
+		$emitter->emit_standalone_fallback();
+		$output = ob_get_clean();
+
+		// Must contain a script tag.
+		$this->assertStringContainsString( '<script type="application/ld+json">', $output );
+		$this->assertStringContainsString( '</script>', $output );
+
+		// Extract JSON between script tags.
+		preg_match( '#<script[^>]*>(.*?)</script>#s', $output, $matches );
+		$this->assertNotEmpty( $matches[1], 'JSON body found inside script tag' );
+
+		$decoded = json_decode( $matches[1], true );
+		$this->assertIsArray( $decoded, 'Output is valid JSON' );
+		$this->assertSame( 'https://schema.org', $decoded['@context'] );
+		$this->assertArrayHasKey( '@graph', $decoded );
+
+		// Collect types.
+		$types = array_column( $decoded['@graph'], '@type' );
+		$this->assertContains( 'MedicalWebPage', $types, '@graph contains MedicalWebPage' );
+		$this->assertContains( 'Article', $types, '@graph contains Article' );
+
+		// Article must have citation with ScholarlyArticle (DOI present).
+		$article_node = null;
+		foreach ( $decoded['@graph'] as $piece ) {
+			if ( 'Article' === ( $piece['@type'] ?? '' ) ) {
+				$article_node = $piece;
+			}
+		}
+		$this->assertNotNull( $article_node );
+		$this->assertArrayHasKey( 'citation', $article_node );
+		$this->assertSame( 'ScholarlyArticle', $article_node['citation'][0]['@type'] );
+	}
+	public function test_standalone_fallback_suppressed_when_yoast_active(): void {
+		// YoastSEO() is defined here so it runs LAST — once defined it persists for
+		// the whole PHPUnit process and would suppress the output assertions above.
+		if ( ! function_exists( 'YoastSEO' ) ) {
+			// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedFunctionFound
+			eval( 'function YoastSEO() { return new stdClass(); }' );
+		}
+		$GLOBALS['pr_test_is_singular']   = true;
+		$GLOBALS['pr_test_singular_type'] = 'post';
+		$GLOBALS['pr_test_the_id']        = 1;
+		$this->set_meta( 1, array( '_prab_schema_version' => '1' ) );
+
+		$emitter = new PR_Core_Jsonld_Article();
+		ob_start();
+		$emitter->emit_standalone_fallback();
+		$output = ob_get_clean();
+
+		$this->assertSame( '', $output, 'Yoast-active path must produce no output' );
+	}
+}