Schematic wires disconnected from component pins due to floating-point precision issues

[tommyhzx]

Problem Description

When converting Circuit JSON to KiCad schematic, wires may appear disconnected from component pins (particularly inductors and other components using predefined symbols) due to floating-point precision issues in coordinate calculations.

Specific Symptoms
Wires connect correctly to chip pins
Wires fail to connect to inductor/predefined symbol pins (coordinates appear misaligned)
Generated .kicad_sch file contains long floating-point numbers (e.g., 10.1599999 instead of 10.16)

Root Cause Analysis

Schematic relies on coordinate matching for connectivity
Unlike PCB, schematic conversion does not use a net system and relies on exact coordinate matching to determine electrical connections:

// lib/schematic/stages/AddSchematicTracesStage.ts:78-81
const x1 = from.x // Direct use of floating point, no precision control
const y1= from.y
const x2 = to.x
const y2 = to.y

Coordinate source differences
Chips: Pin positions dynamically calculated, continuous coordinates
Inductors/passive components: Use predefined symbols from schematic-symbols, fixed coordinates
After c2kMatSch matrix transformation, minute differences can accumulate

Suggested Solution

Add coordinate precision control in lib/schematic/stages/AddSchematicTracesStage.ts:

Option 1: Fixed decimal precision
const PRECISION = 6 // 6 decimal places (micron-level precision)
const x1 = Number(from.x.toFixed(PRECISION))
const y1 = Number(from.y.toFixed(PRECISION))
const x2 = Number(to.x.toFixed(PRECISION))
const y2 = Number(to.y.toFixed(PRECISION))
Option 2: Grid snapping (KiCad default grid is 1.27mm)

const snapToGrid = (coord: number) =>
Math.round(coord / 1.27) * 1.27
const x1 = snapToGrid(from.x)
// ...