feat: add pred CLI tool for problem reductions

[GiggleLiu]

Summary

Complete CLI tool (pred) for exploring NP-hard problem reductions, creating problem instances, and solving them.

Commands

Command	Description
pred list	List all registered problem types with aliases
pred show <problem>	Show variants and reductions for a problem
pred path <src> <dst>	Find cheapest reduction path (supports --all, -o)
pred export-graph	Export the reduction graph as JSON
pred create	Create a problem instance from CLI args
pred evaluate	Evaluate a configuration against a problem
pred reduce	Reduce a problem to a target type (outputs bundle)
pred solve	Solve a problem with ILP (default) or brute-force

Key Features

• ILP auto-reduction: pred solve problem.json automatically reduces any problem to ILP, solves, and maps the solution back — works for both plain problem files and reduction bundles
• Reduction bundles: pred reduce outputs a bundle with source, target, and path; pred solve can solve bundles and extract source solutions
• Configurable ILP backends: cargo install --features coin-cbc to switch backend (highs, coin-cbc, clarabel, scip, lpsolve, microlp)
• Problem aliases: MIS, MVC, SAT, 3SAT, TSP etc.
• Variant support: MIS/UnitDiskGraph, SpinGlass/SimpleGraph
• Type-erased dispatch: Single dispatch table with monomorphized solver function pointers — no duplicated match tables
• Single-source help: Each command's help is defined once in cli.rs and shown both on --help and on parse errors (via Cli::command().find_subcommand())

Architecture

• dispatch.rs — LoadedProblem with DynProblem trait + Deref for type-erased problem operations; solve_with_ilp() handles auto-reduction
• problem_name.rs — Alias resolution and variant parsing
• commands/ — One module per command (graph, create, evaluate, reduce, solve)
• Feature flags: ilp-solver marker feature + per-backend features forwarded through CLI crate

CI Changes

• Replaced --all-features with --features ilp-highs in CI and Makefile (scip/cbc/lpsolve require system libraries not available in CI runners)

Typical Workflow

pred create MIS --edges 0-1,1-2,2-3 -o problem.json
pred solve problem.json                    # auto-reduces to ILP
pred evaluate problem.json --config 1,0,1,0
pred reduce problem.json --to QUBO -o reduced.json
pred solve reduced.json                    # solves QUBO, maps back to MIS

Test plan

• 25 CLI integration tests pass (cargo test -p problemreductions-cli)
• All library tests pass
• Clippy clean
• Manual smoke tests for all commands
• Help messages shown on error (single source in cli.rs)
• CI passes (fixed --all-features → --features ilp-highs)

🤖 Generated with Claude Code

[GiggleLiu]

@isPANN
This is a CLI tool for problem reductions. I hope you could review the design document.

[codecov]

Codecov Report

❌ Patch coverage is 95.90164% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.35%. Comparing base (e8d1804) to head (458208a).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/rules/graph.rs	93.67%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #82      +/-   ##
==========================================
+ Coverage   96.33%   96.35%   +0.01%     
==========================================
  Files         193      193              
  Lines       26682    26722      +40     
==========================================
+ Hits        25704    25747      +43     
+ Misses        978      975       -3     

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[Copilot]

Pull request overview

This PR introduces a comprehensive CLI tool (pred) for exploring NP-hard problem reductions, creating problem instances, and solving them without writing Rust code. The implementation follows a clean architecture with a separate workspace crate and includes significant library refactoring to support type-erased operations.

Changes:

• New problemreductions-cli workspace crate with 8 commands for graph exploration, problem creation, solving, and reduction
• Library refactoring: replaced typed ExecutablePath<S,T> + ChainedReduction<S,T> with untyped ReductionChain + reduce_along_path() API
• Feature flag restructuring: ilp → ilp-solver marker feature with backend-specific features (highs, coin-cbc, clarabel, scip, lpsolve, microlp)

Reviewed changes

Copilot reviewed 34 out of 34 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Cargo.toml	Added CLI workspace member; restructured ILP features with marker feature and per-backend options
Makefile	Updated all targets from --all-features to --features ilp-highs; added cli target
.github/workflows/ci.yml	Updated CI to use --features ilp-highs instead of --all-features
src/rules/graph.rs	Replaced ExecutablePath/ChainedReduction with ReductionChain; added reduce_along_path(), variants_for(), outgoing_reductions(), incoming_reductions(), size_field_names()
src/rules/mod.rs	Updated exports from ExecutablePath/ChainedReduction to ReductionChain/ReductionEdgeInfo
src/rules/traits.rs	Updated doc comment reference from ExecutablePath to ReductionChain
src/solvers/mod.rs	Changed feature gates from ilp to ilp-solver
tests/suites/reductions.rs	Updated feature gates from ilp to ilp-solver
src/unit_tests/rules/graph.rs	Migrated 3 tests to use reduce_along_path() API
src/unit_tests/rules/reduction_path_parity.rs	Migrated 3 parity tests to new reduce_along_path() API
examples/chained_reduction_ksat_to_mis.rs	Updated example to use reduce_along_path()
problemreductions-cli/Cargo.toml	New CLI crate with feature forwarding to library backends
problemreductions-cli/src/main.rs	CLI entry point with subcommand dispatch
problemreductions-cli/src/cli.rs	Clap-based CLI structure with comprehensive help text
problemreductions-cli/src/dispatch.rs	Type-erased dispatch with DynProblem trait and match-based type resolution
problemreductions-cli/src/output.rs	Output handling for human-readable vs JSON modes
problemreductions-cli/src/problem_name.rs	Problem name/alias resolution with variant parsing
problemreductions-cli/src/commands/*.rs	Individual command implementations (graph, create, evaluate, reduce, solve)
problemreductions-cli/tests/cli_tests.rs	25 integration tests covering all commands
docs/src/cli.md	Comprehensive CLI documentation with examples
docs/src/*.md	Updates to introduction, getting-started, and SUMMARY
README.md	Added CLI installation and usage section

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