build(msrv)!: require Rust 1.97.0

[acgetchell]

• Align Cargo, the pinned toolchain, Clippy, dependency-audit triggers, and maintainer guidance with the new baseline.
• Audit Rust 1.97 integer bit helpers against exact-arithmetic hot paths and retain existing operations where alternatives do not preserve performance.
• Correct v0.4.3 citation metadata and document exact decomposition and solve scaling accurately.

BREAKING CHANGE: Rust versions earlier than 1.97.0 are no longer supported.

Closes #174

Summary by CodeRabbit

• Compatibility

  • Updated the minimum supported and pinned Rust toolchain to 1.97.0 across builds, development environments, linting, and benchmarks.
  • Audit checks now also run when the Rust toolchain configuration changes.

• Documentation

  • Updated contributor, release, roadmap, and reference guidance for Rust 1.97.0.
  • Clarified exact decomposition workflows and refreshed citation release information.

• Tests

  • Added coverage for floating-point decomposition edge cases and determinant error-bound overflow handling.
  • Expanded stability checks for exact determinant-sign filtering.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: f3966f5f-d7f1-440b-ad92-4dfede2a8e9a

📥 Commits

Reviewing files that changed from the base of the PR and between 4303207 and 4033f1f.

📒 Files selected for processing (15)

• .github/workflows/audit.yml
• AGENTS.md
• CITATION.cff
• CONTRIBUTING.md
• Cargo.toml
• README.md
• REFERENCES.md
• clippy.toml
• docs/RELEASING.md
• docs/roadmap.md
• rust-toolchain.toml
• scripts/tests/test_archive_performance.py
• src/exact.rs
• src/matrix.rs
• tests/exact_bench_config.rs

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📝 Walkthrough

Walkthrough

The PR raises the Rust MSRV and pinned toolchain to 1.97.0 across configuration, documentation, CI, and benchmark fixtures. It also adds regression tests for exact f64 decomposition, determinant overflow classification, and exact-sign filter paths.

Changes

Rust 1.97 baseline and exactness validation

Layer / File(s)	Summary
Rust 1.97 baseline and repository guidance .github/workflows/audit.yml, Cargo.toml, rust-toolchain.toml, clippy.toml, AGENTS.md, CONTRIBUTING.md, README.md, docs/RELEASING.md, docs/roadmap.md, REFERENCES.md, CITATION.cff	The MSRV and pinned toolchain are updated to Rust 1.97.0, CI watches toolchain changes, contributor and release guidance is synchronized, and reference metadata is revised.
Benchmark toolchain expectations scripts/tests/test_archive_performance.py	Benchmark fixtures and environment assertions now expect Rust 1.97.0.
Exact f64 decomposition invariants src/exact.rs	Tests cover subnormal mantissa normalization, odd mantissas, and bit-preserving round trips.
Determinant and filter-path regression coverage src/matrix.rs, tests/exact_bench_config.rs	Tests cover determinant error-bound overflow classification and exact-sign filter-path stability for dimensions 2 through 5.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related issues

• acgetchell/delaunay issue 496 — similarly updates the Rust MSRV and toolchain from 1.96 to 1.97.0 across project configuration and documentation.

Possibly related PRs

• acgetchell/la-stack#178 — related exact decomposition and determinant error classification tests.
• acgetchell/la-stack#130 — related decompose_f64 mantissa representation and behavior.
• acgetchell/la-stack#45 — introduced the determinant error-bound API exercised by the new tests.

Suggested labels: rust, breaking change

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 52.17% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Linked Issues check	❓ Inconclusive	The MSRV bump and test/docs updates are in scope, but the summary does not verify the benchmark-evidence requirement or any concrete bit-helper audit results.	Add benchmark results or artifact references and briefly note which 1.97 bit-helper opportunities were adopted or rejected.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: bumping the repository MSRV/toolchain to Rust 1.97.0, and the breaking-change marker fits.
Out of Scope Changes check	✅ Passed	The changes stay focused on the Rust 1.97.0 baseline, exact-arithmetic coverage, and related docs/tests; no clear unrelated edits stand out.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch build/174-rust-1-97-msrv

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_{Comment @coderabbitai help to get the list of available commands.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.79%. Comparing base (4303207) to head (4033f1f).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #183      +/-   ##
==========================================
+ Coverage   97.77%   97.79%   +0.01%     
==========================================
  Files           8        8              
  Lines        4768     4809      +41     
==========================================
+ Hits         4662     4703      +41     
  Misses        106      106              

Flag	Coverage Δ
unittests	97.79% <100.00%> (+0.01%)	⬆️

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