# PDR 006: Keep graph discovery available without WebGL

- HTML version: https://robbiepalmer.me/projects/personal-knowledge-graph/pdrs/006-non-webgl-graph-discovery
- Project: Personal Knowledge Graph
- Status: Accepted
- Opened: 2026-08-29
- Decided: 2026-08-29

## Context

The first graph explorer rendered through WebGL. It worked for pointer users
with a compatible browser, but its nodes and links were not available to screen
readers. Touch users also lost hover details, and a graphics failure could
remove the discovery path entirely.

Those limits came from the renderer rather than the content model. The site
already had canonical pages and labels for every graph node.

## Decision

Keep an HTML index of the filtered graph available alongside the visual
explorer on every viewport. The index must expose the same node labels and
canonical destinations, support keyboard navigation, and remain usable when
WebGL is unavailable.

The visual graph may add pan, zoom, drag, animation, and neighbourhood
highlighting. Those interactions cannot become the only way to find or open a
node. Reduced-motion and mobile modes may simplify the graphics without
removing the HTML discovery path.

## Consequences

Screen-reader, keyboard, touch, and non-WebGL users can still browse the graph.
The HTML list also gives automated checks a direct way to compare rendered
nodes with repository data.

The feature now has two coordinated presentations. Filtering, search, labels,
and destination links must stay consistent between them. The HTML index does
not reproduce spatial relationships, so it provides equivalent discovery, not
an equivalent visual layout.

## Evaluation

Every visible graph node must appear in the current HTML index with the same
label and destination. A reader must be able to search, filter, and open a node
with a keyboard while animations are disabled and WebGL is unavailable.

## Migration note

This record preserves the accessibility policy added with the graph explorer
revision on 2026-08-29. It is a later product change prompted by the limitations
documented in ADR 038, not part of the original 2026-02-07 decision now stored
as PDR 003.

## Related records

- Project: [Personal Knowledge Graph](https://robbiepalmer.me/projects/personal-knowledge-graph.md)
- Informed by ADR: [ADR 038: Content Graph Explorer Rendering](https://robbiepalmer.me/projects/personal-knowledge-graph/adrs/038-content-graph.md)

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