# Sampling gaps and unavailable sensors

Chart history describes observations, not continuous knowledge of the Mac. Use the horizontal time axis and availability labels before comparing values or drawing a conclusion about an interval.

## Reading states

| What you see | What it supports | What it does not establish |
| --- | --- | --- |
| A plotted sample | A reading at its observation time | That the same value held until the next sample |
| A gap between observations | Missing measurements in that interval | Zero CPU, no traffic or a healthy service |
| An unavailable sensor | This reading was not supplied | An idle component or a broken component |
| No battery information | Battery information is not present for this hardware | A battery at zero charge |
| A current process row | The process was observed in the current table | Application-level health |

## Time ranges

CPU and Memory focus offer 15 seconds, 30 seconds, 1 minute and 2 minutes. These are viewing ranges, not promises of complete samples at every instant. Compare actual observation times across ranges. Do not infer a sampling cadence from a screenshot, and do not interpolate across a missing interval when reporting an incident.

## Hardware-dependent readings

Battery information appears only when a battery exists. Temperature and fan readings depend on hardware support. A missing sensor should stay unavailable in notes and support reports; replacing it with zero changes the meaning of the evidence.

## Resource and service evidence differ

Machine-resource histories answer a monitoring question. A controller service record answers attribution and supervision questions. A configured health check that actually ran answers a narrower service-health question. If one of those observations is stale or absent, another does not fill the gap.

When a reading surprises you, return to [Quick View and timed charts](/docs/fleet-console/read-quick-view-and-timed-charts), confirm the destination and time range, then record the label you actually saw. The [maintained application documentation](https://github.com/janestreetshiller/fleet-console#architecture-and-system-design) is the primary reference for available chart ranges and hardware limitations.