# ! Rushabh | Linux Shill - ### Proposal: Treat i...

Channel: #contributor
Source: https://discord.com/channels/1233487248129921135/1552332430193467486
Started: 2026-09-23T14:54:52.973000+00:00
Last activity: 2026-09-23T15:13:13.248000+00:00

## ! Rushabh | Linux Shill — 2026-09-23T14:54:52.300000+00:00

### Proposal: Treat inferred trace-length limits as warnings

tscircuit automatically assigns a `1 mm` maximum length to traces connected to detected decoupling capacitors. When placement exceeds this value, preflight currently stops autorouting for the entire board.

This default should be advisory because:

- The [Renesas FS3000 datasheet](https://www.renesas.com/en/document/dst/fs3000-datasheet) specifies the required capacitor values and connections but does not specify a 1 mm trace limit.
- SparkFun’s [official FS3000 board design](https://github.com/sparkfun/SparkFun_Air_Velocity_Sensor_FS3000_Qwiic) uses approximately 2.03 mm between `U1.VREG` and the associated capacitor—already longer than tscircuit’s inferred limit.

Proposed behavior:

- Automatically inferred limits should emit a warning and allow autorouting to continue.
- Explicit `maxLength` or `maxDecouplingTraceLength` values should emit an error and stop autorouting when violated.
- Store the constraint origin, for example:

```json
{
  "max_length": 1,
  "max_length_source": "automatic_decoupling"
}
```

This preserves useful layout guidance without allowing an undocumented heuristic to block otherwise valid reference-board designs.

## ! Rushabh | Linux Shill — 2026-09-23T14:55:00.063000+00:00

<@757706909351411845>

## ! Rushabh | Linux Shill — 2026-09-23T15:13:13.248000+00:00

<@809856037376491570>