peptide-repo-core v0.6.0: peptide schema backfill + Yoast-integrated Drug/MedicalWebPage/FAQ (#19)

Backfill psa_*->_pr_* meta (migration 0004 + PubChem fallback); enrich Drug node with {permalink}#drug @id + molecularFormula/Weight/alternateName; rewrite emitter into Yoast schema graph (MedicalWebPage retype + FAQPage, no duplicate nodes).

QA: APPROVE (independent) — qa-reviews/peptide-repo-core/2026-06-13-817690c1b6ec2118ddcf3b8cfe8bc5ea7f3933b3.md

Agent-Session: peptide-schema-backfill v0.6.0 merge

CONTEXT.md

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+# Peptide Repo Core — Domain Glossary (CONTEXT.md)
+
+This file defines domain terms introduced or used in the peptide-repo-core codebase.
+Per AGENT-OPERATING-STANDARD v1.2.0, update this file in the same PR as any change
+that introduces, renames, or redefines a domain term.
+
+---
+
+## Peptide
+
+A short chain of amino acids studied for biological activity. In this codebase, a
+"peptide" refers to one of the 93 canonical monograph posts (`post_type = 'peptide'`)
+on peptiderepo.com. Each monograph covers identity, mechanism, evidence, and regulatory
+status. **No dosing data appears in schema output** (YMYL constraint).
+
+## Monograph
+
+A single-peptide page (`/peptides/{slug}/`) containing the canonical research profile
+for that compound. Populated from the `peptide` CPT plus its associated meta fields,
+dosing rows (`pr_dosing_rows` table), and legal cells (`pr_legal_cells` table).
+
+## Drug node
+
+The `schema.org/Drug` structured-data entity emitted on each monograph page. Stable
+`@id` is `{permalink}#drug` — this URI is the cross-plugin linking target used by
+PRAutoBlogger article `about` references (per `jsonld-contract-v1`, ratified 2026-06-11).
+
+## MedicalWebPage
+
+A `schema.org/MedicalWebPage` subtype of `WebPage`. Applied to peptide monograph pages
+via the `wpseo_schema_webpage_type` Yoast filter. Signals to search engines and LLMs
+that the page carries medical/scientific content reviewed by an organization.
+
+## FAQPage
+
+A `schema.org/FAQPage` node emitted when `_pr_faq_items` post-meta is populated.
+Contains `Question`/`Answer` pairs curated by the CMO content sprint (v0.6.0 ships
+the meta key and emitter; population is a separate sprint). Emitted only when items
+exist — never an empty node.
+
+## _pr_molecular_formula
+
+Post-meta key (string). Stores the molecular formula of a peptide compound
+(e.g., `C62H98N16O22`). Written by migration 0004 from PSA's `psa_molecular_formula`
+key. Sanitized: only `[A-Za-z0-9().\[\]{}]` characters allowed.
+
+## _pr_molecular_weight
+
+Post-meta key (string). Stores the molecular weight of a peptide compound as a
+float string (e.g., `"1419.5"`). Unit: g/mol (equivalent to Da, but g/mol is the
+standard SI label used in schema.org `QuantitativeValue`). Written by migration 0004
+from PSA's `psa_molecular_weight` — "Da" suffix stripped, `floatval()` applied.
+
+## _pr_aliases
+
+Post-meta key (string, JSON array). Stores alternate names / synonyms for a peptide
+(e.g., `'["Body Protection Compound-157","PL 14736","Bepecin"]'`). Written by
+migration 0004 from PSA's comma-separated `psa_aliases`. Each alias sanitized via
+`sanitize_text_field`. Maps to `schema.org/alternateName` array on the Drug node.
+
+## _pr_faq_items
+
+Post-meta key (string, JSON array of objects). Stores curated FAQ entries for a
+peptide monograph, each as `{question: string, answer: string}`. Registered in v0.6.0;
+population is a CMO content sprint. Maps to `schema.org/FAQPage` when non-empty.
+Sanitized by `PR_Core_Schema_Sanitizers::sanitize_faq_items()` on save.
+Purged on uninstall.
+
+## Schema-input meta
+
+The collective term for the four `_pr_*` meta keys (`_pr_molecular_formula`,
+`_pr_molecular_weight`, `_pr_aliases`, `_pr_faq_items`) introduced in v0.6.0. These
+are the data-layer inputs to the JSON-LD emitter. The emitter reads only these keys
+at render time — it never reads PSA's `psa_*` keys directly (no cross-plugin read
+coupling). Sourced from PSA via migration 0004 (one-time backfill).
+
+## psa_* meta
+
+Post-meta keys written by Peptide Search AI (PSA) plugin using its PubChem integration.
+Includes `psa_molecular_formula`, `psa_molecular_weight`, `psa_aliases`,
+`psa_pubchem_cid`, `psa_cas_number`, `psa_drugbank_id`. Migration 0004 treats all
+`psa_*` values as UNTRUSTED and sanitizes them before writing to PR Core's `_pr_*` keys.
+PR Core never reads `psa_*` keys at render time.
+
+## PubChem CID
+
+A numeric compound identifier in the NCBI PubChem database (e.g., `9941957` for
+BPC-157). Used by migration 0004 as a fallback lookup for the 4 peptide posts that
+lack `psa_molecular_formula`. Fetched via `PR_Core_Pubchem_Client`.
+
+## Yoast integration contract
+
+The agreed schema architecture ratified 2026-06-11 (`convo/prcore/decisions/2026-06-11-jsonld-contract-v1.md`):
+PR Core integrates into Yoast's schema graph via `wpseo_schema_*` filters; never
+emits duplicate `WebPage` or `BreadcrumbList` nodes; maintains a standalone `@graph`
+fallback for when Yoast is inactive. The Drug `@id` convention (`{permalink}#drug`)
+is part of this contract.
+
+## Evidence strength
+
+Ordered enum: `preclinical`, `case-series`, `observational`, `rct-small`, `rct-large`,
+`meta-analysis`. Stored in the `evidence_strength` post-meta key. Does **not** appear
+in schema.org output (dosing/evidence YMYL constraint).
+
+## Verdict
+
+One of five editorial states assigned to a monograph: `effective`, `promising`,
+`mixed`, `insufficient_evidence`, `avoid`. Stored in post content via a verdict card
+Gutenberg block. Not surfaced in JSON-LD (dosing YMYL constraint).
+
+## Migration runner
+
+`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.