Batch Preview — Stub Demotions 2026 04 19

Previewing frontmatter changes for §2f source density demotion. 68 publishable pages are below threshold and need `stub: true` + `stub_reason`.

Sample 1: Microbe entity (betaproteobacteria.md)

Before: ```yaml source_count: 2 platform: wikibiome ```

After: ```yaml source_count: 2 platform: wikibiome stub: true stub_reason: "below §2f source density threshold — 2 sources, minimum 3 required" ```

Sample 2: Disease entity (celiac-disease.md)

Before: ```yaml source_count: 1 platform: wikibiome ```

After: ```yaml source_count: 1 platform: wikibiome stub: true stub_reason: "below §2f source density threshold — 1 sources, minimum 5 required" ```

Sample 3: Metal entity (bismuth.md)

Before: ```yaml source_count: 1 platform: wikibiome ```

After: ```yaml source_count: 1 platform: wikibiome stub: true stub_reason: "below §2f source density threshold — 1 sources, minimum 5 required" ```

Assessment

Pattern is consistent across all 3 subtypes. The transform adds two YAML lines after `platform:`. No existing content is modified. Proceeding to full batch.