GitLab backend produces unrenderable lazy-loaded <img> tags

[nickhaddady]

Note: This bug was discovered by me, but claude wrote this bug report and helped create a simple example to reproduce the issue.

When using the gitlab backend images render blank in the MATLAB Help Browser (and in any plain browser opening the generated HTML).

When DOCMAKER_CONVERTER=GitLab, docconvert emits tags with data-src and class="lazy" plus a 1×1 GIF placeholder in src. The real image path lives in data-src and is only swapped into src by GitLab's web-UI lazy-load JavaScript, which DocMaker does not ship.

Environment

• DocMaker 0.7
• MATLAB R2026a
• DOCMAKER_CONVERTER=GitLab against an internal GitLab instance (/api/v4/markdown)

Reproduction
Minimal repro attached (docmakerimagebug.zip): a single markdown file with one image, a buildfile, and the PNG.

docmakerimagebug/
├── buildfile.m
└── doc/
├── image_test.md
├── helptoc.md
└── images/test_image.png
.

1. Ensure the GitLab backend is selected:

   setpref("docmaker", "converter", "GitLab")
   OR
   setenv("DOCMAKER_CONVERTER", "GitLab")),

and configure DOCMAKER_GITLAB_HOSTNAME / DOCMAKER_GITLAB_TOKEN.

2. From the repro folder, run buildtool doc.
3. Open doc/image_test.html in a browser, or via doc in MATLAB after the build.

Expected

<img alt="Cluster State" src="images/test_image.png"/>

(matches what the GitHub backend backend produces)

Actual

<img alt="Cluster State" class="lazy" data-src="images/test_image.png"
decoding="async" src="data:image/gif;base64,R0lGODlh...placeholder..."/>

The image area is blank — src resolves to the placeholder GIF and no JS runs to swap in data-src.

Root cause
The GitLab Markdown API (/api/v4/markdown) returns HTML pre-decorated for GitLab's web UI, which ships a lazysizes-style bundle that performs the data-src → src swap on page load. DocMaker embeds the API response verbatim, but the rendering context (Help Browser / standalone HTML) has no such JS. The GitHub backend is unaffected because api.github.com/markdown/raw returns plain .

Suggested fix (from Claude, and completely not validated or thought through)

In +docmaker/GitLab.m, post-process the API response to undo the lazy-load decoration before returning the DOM:

• replace data-src= with src=
• remove class="lazy" and decoding="async"
• strip the placeholder src="data:image/gif;base64,..." that precedes data-src

Workaround

Use the GitHub backend and produces clean output.