Validation errors

DocDraw tools should fail invalid structure loudly, with errors that are easy to fix.

Error design goals

• include line number (and column if available)
• include a stable error code
• include a short message and a “how to fix”
• never “guess” structure to make validation pass

Example: invalid DocDraw list level jump

Input:

-1: Top level
-3: Skips level 2

Suggested validator output:

{
  "line": 2,
  "code": "LIST_LEVEL_JUMP",
  "message": "List level jumped from 1 to 3; did you mean -2?"
}

Example: Markdown (DMP-1) ambiguous indent

Input:

- Item
  - Sub item

Suggested converter output:

{
  "line": 2,
  "code": "AMBIGUOUS_LIST_INDENT",
  "message": "List indentation must increase by exactly 4 spaces per level."
}

Next

• Define the full error code list (v1) and add “bad → fix → good” examples.
• Add a small conformance test suite of pass/fail fixtures.