Preserve explicit ground connections instead of redundant GND branches

[imrishabh18]

Stack

• Reproduction: Reproduce PGA300 redundant ground traces at COMP #930 (main → codex/repro-pga300-redundant-ground-traces)
• This fix targets the reproduction branch. Merge Reproduce PGA300 redundant ground traces at COMP #930 first, then retarget this PR to main.

Fix

The global ground spanning tree replaced the explicit PGA300 COMP–R1 wire with nearby COMP–U1.GND and COMP–C3 ground branches.

• Honor the isGround metadata already supplied by core.
• Preserve physically connected groups defined by explicit pin-to-pin traces on marked ground nets; use ground labels for connectivity between those groups and label-only pins.
• Apply the same restriction to long-distance recovery so it cannot recreate the removed branches.
• Leave unannotated nets and ground buses without explicit traces unchanged. No PGA300 pin IDs or coordinates are hard-coded in production code.
• Update the full-circuit regression to require COMP–R1, reject both redundant branches, preserve all GND connectivity, and retain the vertical Q1–R1 connection.
• Add focused coverage for shared net names, non-ground/unannotated nets, automatic ground buses, fallback recovery, labels, and distance/section boundaries.

Before / after

Before (#930)

After

Validation

• Confirmed the corrected regression assertions fail on the reproduction branch before applying the fix.
• bun test: 225 passed, 4 existing skips, 0 failures.
• bunx tsc --noEmit, bun run build, focused formatting, and git diff --check: passed.
• Tested the locally built solver with the actual circuit from tscircuit/ti#117: both highlighted branches disappear and COMP routes to R1. Restored the published dependency afterward; this PR does not modify the TI source.

Integration limitation

The full core render also shows an extra automatically generated GND label beside the manually placed upper GND label. Handling that manual/automatic-label duplication is outside this solver routing fix; this is not a claim of pixel-perfect reference matching.

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Project	Deployment	Actions	Updated (UTC)
schematic-trace-solver	Ready	Preview	Aug 26, 2026 11:25am