fix: prevent net-label-only nets from being routed as trace pairs

[tungnguyentu]

Fixes #79

/claim #79

Root Cause

getConnectivityMapsFromInputProblem constructed netConnMap with a direct reference to directConnMap.netMap. When netConnMap.addConnections() ran for net connections, it also mutated directConnMap.netMap — so net-only connections appeared in dcConnMap, causing MspConnectionPairSolver to create MSP trace pairs for pins connected only via netConnections.

Fix

1. Shallow-copy netMap when constructing netConnMap:

   // Before (bug: shared reference)
   const netConnMap = new ConnectivityMap(directConnMap.netMap)
   // After (fix: independent copy)
   const netConnMap = new ConnectivityMap({ ...directConnMap.netMap })

2. Filter queuedDcNetIds to only include nets with at least one pin in a directConnection. Net-only nets are handled by NetLabelPlacementSolver, not by trace routing.

Tests

• MspConnectionPairSolver_netLabelOnly.test.ts — 3 regression tests:
  1. Net-only connections produce 0 MSP pairs
  2. Direct connections still produce pairs (regression guard)
  3. Mixed direct + net connections route only the direct nets
• Updated MspConnectionPairSolver_repro1 assertion from 4 → 2 pairs (GND is net-only in that fixture, so it should not be routed)
• All 60 tests pass, 4 skip, 0 fail
• 8 SVG snapshots updated (net-only nets no longer produce traces — correct behavior)

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Project	Deployment	Actions	Updated (UTC)
schematic-trace-solver	Ready	Preview, Comment	May 14, 2026 4:46pm