# Pipeline Personalities — what each rendering layer does to your HTML The newsletter passes through multiple rendering layers between source file and subscriber inbox. Each layer has its own quirks. This file documents every known one so the stylist agent and the auditor can pre-flight check for them. **This file is universal — do NOT customize it.** These are email client facts, not brand preferences. Add your own failures to MISTAKES-LOG.md as you discover them. --- ## The pipeline (top to bottom) ``` issues/NNN.md (source markdown + frontmatter + raw HTML for TIP_BODY) | build.py applies template + replaces placeholders v issues/NNN-rendered.html (rendered HTML) | paste into Beehiiv/Substack/etc. v Platform post (platform strips/transforms before send) | platform sends to subscriber v Email rendering (varies per client) | v The actual subscriber experience ``` --- ## Layer 1: Beehiiv ### What Beehiiv strips - `