HomeAssistantVS/opencode/printer-stats-z-chart-fix.md

Printer Stats Dashboard — Z Position Chart Fix

Date: 2026-08-07

Problem

On the /printer-stats dashboard, the Z Position (24h) history chart showed large gaps.

Root cause: sensor.octoprint_current_z only publishes when the printer moves (Z position changes). During idle periods there are no new state records, so the native history-graph card renders those stretches as a gap. An overnight OctoPrint outage (~19:50–21:33) also produced a long unavailable break in the line.

The native history-graph card does not support connect_spans (it is silently ignored), so an initial attempt to bridge the gaps that way was a no-op.

Fix

Replaced the "Z Position (24h)" card with custom:apexcharts-card (v2.2.3, already installed and in use on the dashboard — "Print Outcomes (30 days)").

• fill_raw: "last" bridges null/unavailable values, so idle freezes and the outage render as a continuous flat line instead of a gap
• ApexCharts connects consecutive history points directly, so periods with no new records draw as a straight line
• Stroke width set to 1 (apex_config.stroke) so the line matches the dashboard's other charts
• Card moved to directly below the "Print Activity" section header

Final Card Config

Located at /printer-stats → History view → Print Activity section, views[1].sections[1].cards[1].

type: custom:apexcharts-card
header:
  show: true
  title: Z Position (24h)
  show_states: true
  colorize_states: true
graph_span: 24h
series:
  - entity: sensor.octoprint_current_z
    name: Current Z
    color: "#ab47bc"
    type: line
    curve: straight
    fill_raw: "last"
grid_options:
  columns: full
apex_config:
  chart:
    height: 300
  stroke:
    width: 1

Config Hash History

Action	Config hash
Replaced card with apexcharts-card	4c1f4ac4de6971e9
Thinned stroke to 1px	deda8faff03c7b8b
Moved card below header	df9fb734b0cb1562

Related Decisions

See decisions.yaml:

• 2026-08-07-octoprint-frozen-sensors-shown-via-idle-2 — why the sensor freezes during idle
• 2026-08-07-octoprint-controls-are-mqtt-via — print controls go through MQTT/input_boolean, not the old MQTT automation