diagram-design 2026 SVG/PNG Exports Look Wrong: How to QA AI Architecture Diagrams?

The HTML preview looks right, but the exported SVG or PNG is clipped, restyled, or hard to read.

Fastest fix: compare the source HTML, browser preview, and exported file to find where the mismatch first appears; then check the SVG structure or PNG rendering separately. Verify every architecture relationship against code, an interface contract, or a clearly labeled assumption. A clean export does not prove the diagram is correct.

Who should use this guide: Engineers exporting agent-generated diagrams into documentation, presentations, or repositories. Also for: Documentation owners checking visual output and platform teams adding artifact validation to a pipeline.

Start at the first point of failure

Treat the HTML, SVG, and PNG as separate artifacts, not interchangeable previews. A browser can render the source successfully while an export command produces a different file. Equally, an exported image can look polished while the source diagram contains a false connection.

Record the exact input file, export command, output path, and tool version before changing anything. Check the current diagram-design repository and README and its export command documentation for the documented invocation and formats. Confirm that your installed revision matches the documentation you are following; don’t infer support for a renderer, Agent client, or format from another setup.

Why does a diagram-design PNG differ from its HTML preview? The PNG is a rendered output, not proof that the browser and export path used identical fonts, viewport dimensions, scale, or styling. Reproduce the export from the same input, then compare the saved image with the preview. If the mismatch only appears in the delivery pipeline, inspect that pipeline’s rendering environment before editing the source layout.

A practical example: if a service label is visible in the browser but missing from the PNG, first establish whether the label exists in the HTML. If it does, check whether the output is clipped or whether the rendering environment handles its font or style differently. Moving the node immediately may hide the symptom without identifying the stage that introduced it.

SVG structure and styling

An SVG is structured markup, so a successful file extension check is not enough. Open the exported file as text and inspect the root element, drawing bounds, visible text, styles, and references. The SVG structure specification describes the document structure; the MDN reference for the SVG <style> element explains how styles can be included in an SVG document.

How can you check that an SVG export is complete? Open it in a text editor and in a separate SVG-capable viewer. Search for important labels and compare the bounds and referenced definitions with the original. If the image relies on styles from the HTML page, test whether those rules were carried into the exported file. Don’t assume diagram-design supports a particular CSS feature or repairs duplicate IDs unless its current export documentation says so and your file confirms it.

A useful isolation test is to save an unchanged copy of the source and make one controlled change at a time. For example, compare the exported SVG before and after embedding a style rule that is already present in the source page. If that resolves the appearance difference, the evidence points to style handling; it does not prove that all SVG exports require embedded styles.

Keep the original. Before applying cleanup or post-processing, retain the generated HTML and untouched export. Otherwise, you may lose the evidence needed to distinguish a source problem from an exporter or viewer problem.

PNG rendering differences

PNG is a raster image. It does not preserve editable diagram elements in the way SVG markup does. That makes font substitution, viewport size, scale, clipping, and color handling important to inspect when the pixels differ from the HTML preview.

Compare the same source in your local browser and in the target pipeline. Keep the viewport and export options consistent where you can, and save both output files rather than relying on a visual memory of the preview. The Playwright page screenshot API documents screenshot options such as fullPage and scale. These are useful parameters to check when a pipeline uses Playwright; they are not evidence that diagram-design itself uses Playwright.

What should you check when the PNG is cropped or labels are hard to read? Compare the image dimensions and visible boundaries first. Then check whether the rendering path captures the full page or only the current viewport, whether the scale is appropriate for the destination, and whether the target environment has the expected fonts. If text wraps or changes width, compare the font actually available in each environment before rearranging nodes.

Do not “fix” a pipeline-only rendering difference by changing the architecture layout until you have reproduced the same behavior locally. A different font can alter spacing across the whole diagram, while an incorrect viewport can crop a correct layout. Identify the cause first, then decide whether the source or the rendering settings should change.

Architecture meaning and evidence

A diagram can be visually correct and factually wrong. Check each important node and connection against code, an API or interface contract, or an approved design document. A line that looks plausible is not evidence that two components communicate directly, share a dependency, or run in the same process.

What if the export looks fine but the connections mean the wrong thing? Return to the evidence, not the renderer. Mark any relationship you cannot confirm as an unverified assumption, and ask the responsible engineer or document owner to resolve it before publication. Do not let an Agent invent a missing service or connection simply to complete a tidy-looking diagram.

Use a short evidence record as you review:

• Node: Is the component present in code or in an approved design source?
• Edge: What code path, contract, or design statement supports the relationship?
• Direction: Does the arrow match the documented request, event, or dependency direction?
• Boundary: Does the diagram distinguish a direct call from an indirect or assumed relationship?
• Uncertainty: Is any unverified relationship visibly marked for review?

This check is especially important when an Agent has inferred structure from partial context. A generated diagram may omit a component because the input did not mention it, or add a plausible connection that the repository does not support. Treat such details as claims to verify, not as trustworthy defaults.

For a deeper review of diagram content, keep the check close to the evidence used to generate it: a code reference, an interface contract, or an explicit design decision. If you maintain a remote Agent workflow, preserve the prompt or task input alongside the output so reviewers can tell what the Agent was actually asked to represent.

A CI handoff that preserves evidence

Add validation in layers. Automation can catch missing files, unreadable output, or a failed export command. It cannot establish that an arrow accurately describes runtime behavior unless the relevant evidence has been encoded and checked separately. Human review remains necessary for diagram meaning and visual suitability.

For a repeatable pipeline, make the following sequence part of the job:

1. Pin the input. Preserve the source HTML or other generated diagram input used for the run.
2. Record the invocation. Store the export command and the relevant tool revision in the job log.
3. Generate each required format. Keep SVG and PNG outputs separate and label their destinations clearly.
4. Run file checks. Fail the job if an expected file is absent, unreadable, or missing required structural content.
5. Save visual evidence. Retain the exported images so a reviewer can compare them with the source preview.
6. Review relationships. Route unverified nodes, edges, or directions to an owner rather than treating a successful export as approval.
7. Publish the artifacts and logs. Use the workflow’s artifact mechanism; GitHub Actions documentation on workflow artifacts explains how workflow outputs can be retained and shared.

This split gives you useful failure signals without promising more than the pipeline can verify. A parser can catch malformed SVG structure; a screenshot can reveal clipping; neither can determine whether a service call exists in the product unless you compare it with evidence.

Choosing the right validation path

Use a source-first review when the diagram is wrong in the browser preview. Use an export-focused review when the source looks right but SVG or PNG differs. Use an evidence review when the file opens and renders correctly but the architecture may be inaccurate.

If you are also choosing a working environment for remote Agents, separate that decision from export debugging. A remote Mac can provide an isolated macOS workspace when your workflow needs one, but it will not repair missing SVG styles, incorrect bounds, or unsupported architecture claims. Start with the files and logs you already have. If you need help assessing a separate remote workflow, use the kvmboot help center or contact kvmboot to discuss whether temporary access fits the task.

For a short export investigation, local tooling may be sufficient. A temporary remote environment can make sense when you need an isolated workspace to run an Agent and package its outputs, but it adds access and handoff considerations. For a workflow that needs continuous, stable, heavy use or a physical interface, evaluate a dedicated local machine instead. Choose the environment for the work you need to run; keep export validation grounded in the source, the generated files, and the evidence behind the diagram.