034 graph classifier

[akollegger]

This pull request introduces a new, extensible graph classification system for pattern graphs, refactoring the core graph logic to use a pluggable GraphClassifier and updating related APIs and tests. The changes enable more flexible and canonical graph element categorization, improve compatibility, and simplify classification logic across the codebase.

Graph classification refactor

• Introduced the new Pattern.Graph.GraphClassifier module, which defines the GraphClass type and pluggable GraphClassifier record, as well as canonical and shape-based classification logic. (libs/pattern/src/Pattern/Graph/GraphClassifier.hs)
• Refactored PatternGraph and related functions to use the new GraphClassifier, updating the data structure to store "other" elements and removing legacy classification logic. (libs/pattern/src/Pattern/PatternGraph.hs) [1] [2] [3] [4]
• Updated Pattern.Graph to use the new classifier, including adding the mkGraphLens constructor for backward compatibility and rewiring node, relationship, and walk detection to use classification results. (libs/pattern/src/Pattern/Graph.hs) [1] [2] [3] [4] [5] [6]

Test and build system updates

• Updated tests to use the canonical classifier when constructing pattern graphs, ensuring round-trip correctness and canonical structure. (libs/gram/tests/Spec/Gram/RoundtripSpec.hs) [1] [2] [3]
• Registered new modules and test suites in the package build configuration. (libs/pattern/pattern.cabal) [1] [2]

Documentation and rule specification

• Added rule and documentation entries for the new graph classifier feature, including its ecosystem and usage. (.cursor/rules/specify-rules.mdc) [1] [2]

[Copilot]

Pull request overview

Introduces a new, pluggable GraphClassifier vocabulary (GraphClass + GraphClassifier) and refactors PatternGraph / GraphLens to use classifier-driven categorization, updating tests and build metadata to support canonical + custom classification and improved walk validation.

Changes:

• Added Pattern.Graph.GraphClassifier with canonical shape-based classification (including walk chain validation).
• Refactored Pattern.PatternGraph to be parameterized by extra, store non-canonical elements in pgOther, and require a GraphClassifier for construction/merge.
• Reworked Pattern.Graph (GraphLens) to be backed by a classifier and added mkGraphLens; updated affected tests and cabal module lists.

Reviewed changes

Copilot reviewed 24 out of 26 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
specs/034-graph-classifier/tasks.md	Task breakdown for implementing/refactoring graph classification.
specs/034-graph-classifier/spec.md	Feature spec describing goals, scenarios, and requirements for graph classification.
specs/034-graph-classifier/research.md	Design decisions for pgOther, GraphLens re-derivation, and walk validation.
specs/034-graph-classifier/quickstart.md	Usage examples for canonical and custom classifiers + legacy lens usage.
specs/034-graph-classifier/plan.md	Implementation plan artifact (currently template-like).
specs/034-graph-classifier/data-model.md	Data model definitions for GraphClass, GraphClassifier, and updated PatternGraph.
specs/034-graph-classifier/contracts/GraphClassifier.hs	Contract stub for the classifier API.
specs/034-graph-classifier/checklists/requirements.md	Spec-quality checklist for the feature.
proposals/pipeline-scenarios.md	Adds motivating scenarios for graph pipelines using GraphClassifier/GraphView concepts.
proposals/graph-transform.md	Design-only proposal building on GraphClassifier (introduces GraphView, transforms).
proposals/graph-query.md	Design-only proposal updated to reference follow-on proposals and context helpers.
proposals/graph-mutation.md	Design-only proposal updated to depend on GraphTransform and use GraphView.
proposals/graph-classifier.md	Design-only proposal updated with implementation ordering notes.
proposals/files.zip	Adds a zip archive containing proposal markdown files.
libs/pattern/tests/Test.hs	Registers new GraphClassifierSpec in the pattern test suite.
libs/pattern/tests/Spec/Pattern/PatternGraphSpec.hs	Updates PatternGraph tests to use canonicalClassifier and validates pgOther + custom classifier behavior.
libs/pattern/tests/Spec/Pattern/PatternGraphProperties.hs	Updates property tests to pass canonicalClassifier into merges/builds.
libs/pattern/tests/Spec/Pattern/GraphSpec.hs	Updates GraphLens tests to construct lenses via mkGraphLens.
libs/pattern/tests/Spec/Pattern/Graph/GraphClassifierSpec.hs	New unit tests for classifyByShape walk validation and canonical behavior.
libs/pattern/src/Pattern/PatternGraph.hs	Refactors PatternGraph to use GraphClassifier, adds pgOther, and updates merge/build APIs.
libs/pattern/src/Pattern/Graph/GraphClassifier.hs	New classifier module with GraphClass, GraphClassifier, shape classification, and walk validation.
libs/pattern/src/Pattern/Graph.hs	Re-derives GraphLens around a classifier, adds mkGraphLens, rewires node/rel/walk detection.
libs/pattern/pattern.cabal	Exposes the new classifier module and adds the new spec module to test suite modules.
libs/gram/tests/Spec/Gram/RoundtripSpec.hs	Updates roundtrip tests to build graphs using canonicalClassifier.
.gitignore	Adds ignores for Thumbs.db and *.tmp.
.cursor/rules/specify-rules.mdc	Documents the new feature in the Cursor/specify rules index.