# Fix validation issues

The builder validates the pipeline continuously. When a blocking rule fires, the
toolbar issue badge shows the count and global preview/save are gated until the
state is runnable.

In the fixed linear builder, the most common blocking issue is a required side
value that has not been filled yet.

## Step 1 - Introduce an issue

Click `GaussianBlur`, then `FilamentousFungiDetector`. The main spine is
linear, but `FilamentousFungiDetector.inoculum_detector` is required and still
empty:

![FilamentousFungiDetector selected with an empty required inoculum_detector side value and active issue badge.](../../_static/gui_images/fix-validation-issues/01_issue_introduced.png)

The issue badge appears because the whole pipeline cannot run until every
required side value has a compatible source.

## Step 2 - Read the issue

Click the issue badge to open the issue list:

![Issue badge popover listing the missing required side value.](../../_static/gui_images/fix-validation-issues/02_issue_focused.png)

Use the badge as a triage surface when a loaded pipeline has more than one
problem. Issues remain non-destructive: reading them does not change the
pipeline.

## Step 3 - Resolve the issue

Select the `inoculum_detector` side port, then click `OtsuDetector` in the
palette:

![inoculum_detector filled with OtsuDetector and the issue cleared.](../../_static/gui_images/fix-validation-issues/03_issue_resolved.png)

The issue clears because the consumer now has a compatible side value. You can
replace or clear that value from the side loader later.

## Unsupported development DAGs

The linear map is the default production authoring surface. The builder still
keeps DAG state internally, but arbitrary non-linear development states are not
edited as movable graphs. If a loaded state cannot be represented as one linear
spine with side values, the map shows an unsupported-state panel instead of
silently dropping blocks or inventing a repair.

## Reference

- **Blocking issues** - disable global preview/save until fixed.
- **Prefix preview** - `Preview here` on an output/continuation port can preview
  a valid prefix, but it does not override whole-pipeline validation.
- **Required side values** - select the gold side port and choose a compatible
  palette item.
- **Defensive unsupported panel** - protects non-linear development states that
  do not match the fixed map.

## Where to next

- [Fill a scalar aux target](12_aux_wire_in_dag.md) - side target selection.
- [Open an embedded Pipeline aux](13_wire_pipeline_as_aux.md) - nested pipeline
  side values and breadcrumbs.
- [GUI hub guide](../../how_to/pages/gui_hub.md) - full reference for the hub.