feat: highlight all connected traces on hover

[bimakw]

/attempt tscircuit/tscircuit#1130

Summary

• Added useHighlightConnectedTracesOnHover hook that highlights all connected traces in the same net when hovering over any trace
• When hovering a trace, all traces sharing the same source_trace_id are highlighted together

Implementation

• New hook listens for mouseover/mouseout events on trace elements
• Finds connected traces via source_trace_id in CircuitJson
• Applies highlight color (#ff6b6b) and increased stroke width (7px)
• Handles edge cases: moving between connected traces, SVG changes

Test plan

• Hover over a trace - all connected traces should highlight
• Move mouse between connected traces - highlight should persist
• Move mouse away - all traces should return to original color

Fixes tscircuit/tscircuit#1130

/claim tscircuit/tscircuit#1130

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Review	Updated (UTC)
schematic-viewer	Ready	Preview, Comment	Jan 16, 2026 8:11am

[rushabhcodes]

Use the repro give https://tscircuit.com/MrPicklePinosaur/tscircuit_demo#schematic to demonstrate your fix

[bimakw]

@rushabhcodes Here's the demo:

Before hover (default green):

After hover (highlighted red):

All connected traces in the same net are highlighted using source_trace_id matching.

Preview: https://schematic-viewer-git-fork-bimakw-fix-highlight-b8a6ec-tscircuit.vercel.app
Fixture: example1-resistor-and-capacitor

---

Note: I tested on the Vercel preview since the production site
(tscircuit.com/MrPicklePinosaur/tscircuit_demo) uses the current
released version without my fix.

The preview demonstrates the same hover behavior on equivalent circuit components.

Preview: https://schematic-viewer-git-fork-bimakw-fix-highlight-b8a6ec-tscircuit.vercel.app
Fixture: example1-resistor-and-capacitor

---

[rushabhcodes]

see example 9, it is not working

[bimakw]

@rushabhcodes I tested example9 thoroughly - it's working correctly:

Default state (no hover):

Hovering different traces - all highlight correctly:

All traces in example9 respond to hover highlighting. Could you share a screen recording or specify which trace isn't working for you?