fix(rendering): refuse unsupported markup as an error and keep large documents linear #50

New Issue

2026-11-10T23:19:06Z

james.maes commented

2026-11-10 23:19:06 +00:00

Problem

Three robustness defects in the Markdown renderer, found by the engine and security reviews on main (8763ff3) and reproduced by running:

A small document can end the whole process instead of being reported as unsupported. Details are in the private audit ledger until the fix is released.
Some malformed HTML blocks make a document impossible to open (ArgumentOutOfRangeException while formatting raw text).
Render time grows faster than document size in two places: repeated heading titles, and raw HTML blocks with many short text runs. The parse cannot be cancelled.

Expected

Unsupported markup is refused as an ordinary error before any work that cannot be interrupted or recovered from.
Malformed blocks render (sanitized) instead of failing the open.
The renderer's own work is linear, and the outline build honours cancellation between its phases.
The threat model states what is and is not bounded.

## Problem Three robustness defects in the Markdown renderer, found by the engine and security reviews on `main` (8763ff3) and reproduced by running: - A small document can end the whole process instead of being reported as unsupported. Details are in the private audit ledger until the fix is released. - Some malformed HTML blocks make a document impossible to open (`ArgumentOutOfRangeException` while formatting raw text). - Render time grows faster than document size in two places: repeated heading titles, and raw HTML blocks with many short text runs. The parse cannot be cancelled. ## Expected - Unsupported markup is refused as an ordinary error before any work that cannot be interrupted or recovered from. - Malformed blocks render (sanitized) instead of failing the open. - The renderer's own work is linear, and the outline build honours cancellation between its phases. - The threat model states what is and is not bounded.

james.maes added the bug label 2026-11-10 23:19:06 +00:00

james.maes referenced this issue from a commit

2026-11-10 23:19:32 +00:00

fix(rendering): refuse unsupported markup as an error and keep large documents linear

james.maes referenced a pull request that will close this issue

2026-11-10 23:19:33 +00:00

fix(rendering): refuse unsupported markup as an error and keep large documents linear #51

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Reference: KofTwentyTwo/MarkdownViewr.Windows#50