spec: add circos-basic specification (#3007)

## New Specification: `circos-basic`

Related to #3005

---

### specification.md

# circos-basic: Circos Plot

## Description

A Circos plot is a circular visualization that displays data on
concentric tracks arranged around a circle, with ribbons or arcs
connecting related segments across the circular layout. Originally
designed for genomic data visualization, it excels at showing
relationships between segments while simultaneously displaying multiple
data attributes on different tracks. The circular arrangement makes
efficient use of space and reveals patterns in complex relational data.

## Applications

- Visualizing chromosomal rearrangements and genomic structural
variations in bioinformatics
- Displaying trade flows or migration patterns between countries or
regions
- Showing dependencies and relationships between software modules or
system components
- Analyzing co-occurrence or correlation patterns between categorical
variables

## Data

- `source` (categorical) - Origin segment or category identifier
- `target` (categorical) - Destination segment or category identifier
- `value` (numeric) - Connection strength or flow magnitude between
segments
- `segment_size` (numeric, optional) - Size of each segment on the outer
ring
- `track_data` (numeric, optional) - Values for additional concentric
data tracks
- Size: 5-30 segments with 10-100 connections
- Example: Genomic data showing 10 chromosomes with inter-chromosomal
connections and expression values on inner tracks

## Notes

- Segments should be arranged around the circle with gaps for visual
separation
- Ribbon width should be proportional to the connection value
- Use distinct colors for each segment to aid identification
- Consider adding 1-3 concentric tracks inside the outer ring for
additional data layers
- For genomic applications, segments typically represent chromosomes
with consistent color coding

---

**Next:** Add `approved` label to the issue to merge this PR.

---
:robot: *[spec-create
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20617371370)*

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

plots/circos-basic/specification.md

@@ -0,0 +1,30 @@
+# circos-basic: Circos Plot
+
+## Description
+
+A Circos plot is a circular visualization that displays data on concentric tracks arranged around a circle, with ribbons or arcs connecting related segments across the circular layout. Originally designed for genomic data visualization, it excels at showing relationships between segments while simultaneously displaying multiple data attributes on different tracks. The circular arrangement makes efficient use of space and reveals patterns in complex relational data.
+
+## Applications
+
+- Visualizing chromosomal rearrangements and genomic structural variations in bioinformatics
+- Displaying trade flows or migration patterns between countries or regions
+- Showing dependencies and relationships between software modules or system components
+- Analyzing co-occurrence or correlation patterns between categorical variables
+
+## Data
+
+- `source` (categorical) - Origin segment or category identifier
+- `target` (categorical) - Destination segment or category identifier
+- `value` (numeric) - Connection strength or flow magnitude between segments
+- `segment_size` (numeric, optional) - Size of each segment on the outer ring
+- `track_data` (numeric, optional) - Values for additional concentric data tracks
+- Size: 5-30 segments with 10-100 connections
+- Example: Genomic data showing 10 chromosomes with inter-chromosomal connections and expression values on inner tracks
+
+## Notes
+
+- Segments should be arranged around the circle with gaps for visual separation
+- Ribbon width should be proportional to the connection value
+- Use distinct colors for each segment to aid identification
+- Consider adding 1-3 concentric tracks inside the outer ring for additional data layers
+- For genomic applications, segments typically represent chromosomes with consistent color coding

plots/circos-basic/specification.yaml

@@ -0,0 +1,32 @@
+# Specification-level metadata for circos-basic
+# Auto-synced to PostgreSQL on push to main
+
+spec_id: circos-basic
+title: Circos Plot
+
+# Specification tracking
+created: 2025-12-31T10:44:45Z
+updated: null
+issue: 3005
+suggested: MarkusNeusinger
+
+# Classification tags (applies to all library implementations)
+# See docs/concepts/tagging-system.md for detailed guidelines
+tags:
+  plot_type:
+    - circos
+    - circular
+    - chord
+  data_type:
+    - categorical
+    - numeric
+    - relational
+  domain:
+    - general
+    - science
+    - bioinformatics
+  features:
+    - basic
+    - multi-track
+    - flow-visualization
+    - proportional