What triggers it. Comments between statements in a structurally-modeled body: the typed tree does not model them, so serializeMermaid writes the body back without them. The warning carries the count and line numbers.

How to fix it. Move essential comment content into a label or title before mutating, keep a source-level edit instead of a typed mutation when comments must survive, or accept the loss knowingly.

Minimal reproducer

This source triggers COMMENT_DROPPED — checked at build time against the same engine the editor runs.

flowchart LR
  %% review note that structured serialization drops
  A[Start] --> B[Done]

Open this reproducer in the editor

Run am verify diagram.mmd --json, inspect this code, and apply the smallest source or typed mutation that clears it. If it persists after two mechanical attempts, return the warning and ask for human review.

In the cloned repo, am is bun run bin/am.ts.

Machine-readable: this page as Markdown.

Back to all warning codes, or open a blank editor to try a fix.