# BAR_RANGE_EXCLUDES_ZERO

> BAR_RANGE_EXCLUDES_ZERO is a lint warning: an XY chart with bar series has an authored y-axis range that excludes zero, so bar lengths are not proportional to their values.

- **Tier:** lint
- **Severity:** warning
- **Origins:** source

## What triggers it

A `y-axis min --> max` range entirely above or below zero. Bars grow from zero clamped into the range, so every bar starts at the reported `baseline` and small differences look large.

## How to fix it

Include zero in the range with `set_y_axis`, or draw the series as a `line`, whose position (not length) carries the value.

## Example

```mermaid
xychart-beta
  x-axis [Q1, Q2, Q3]
  y-axis 90 --> 100
  bar [92, 95, 97]
```

Run `am verify diagram.mmd --json`, inspect this code, and apply the smallest source or typed mutation that clears it. If it persists after two mechanical attempts, return the warning and ask for human review.

Full page: https://agentic-mermaid.dev/warnings/BAR_RANGE_EXCLUDES_ZERO/