The plugin is intentionally lightweight. It integrates with Kedro's CLI, converts a pipeline into a simplified dependency graph, and renders Mermaid markup. Understanding the moving parts makes customisation and contributions easier.

Entry Points

• kedro_mermaid.plugin.commands defines the root kedro mermaid command group. Kedro discovers it via the kedro.hooks entry point and provides ProjectMetadata for logging and context.
• kedro_mermaid.cli.generate.generate implements the kedro mermaid generate command. It parses CLI flags, looks up the requested pipeline, and applies Kedro's filtering API (Pipeline.filter).

Graph Construction

kedro_mermaid.lib.graph.DiagramGraph performs the heavy lifting:

1. Collect edges – Every Kedro node becomes an edge between each input dataset and output dataset (DiagramEdge). Self-loops are discarded (input != output).
2. Parse names – Nodes are wrapped in DiagramNode, which consults ParsedName to apply regex patterns from --set-node-attr pattern=....
3. Simplify – After filters remove nodes, DiagramGraph.simplify reconnects surviving nodes so the diagram remains readable. It traverses from each included node to the next reachable included node, skipping hidden intermediates.
4. Group categories – When ParsedName emits a category, the renderer surrounds the grouped nodes with a subgraph and auto-generates colour accents.
5. Render – DiagramGraph.render emits Markdown-friendly Mermaid blocks. Optional Mermaid config is written as YAML front matter, which Mermaid Live Editor understands out of the box.

Name Parsing

kedro_mermaid.lib.parsed_name.ParsedName centralises regex handling.

• Named capture groups labelled category create subgraphs.
• Named (or numbered) groups labelled node form the rendered node label.
• If the regex does not match, the node remains in the graph with its original name but is flagged as is_match=False so simplification can skip it when requested.

The implementation relies on the third-party regex module so advanced features like repeated named groups ((?P<node>...)) are available.

Utilities

• kedro_mermaid.lib.utils.parse_list converts comma-separated CLI options into Python lists (click uses it as a callback on list-like options).
• Tests in tests/kedro_mermaid/lib/test_parsed_name.py cover the name parsing behaviour to guarantee backwards compatibility when upgrading the regex logic.

Understanding the structure above should give you enough confidence to extend the CLI, add new filters, or alter the rendering step.