[samkeen]

Port fuzzymatch to Rust in rust/, keeping the Python package as is.

Branches are declared as variants of the caller's own enum (via the
branches! macro or a hand-written Branches impl), and a Matcher
returns a Verdict<B> to dispatch on with a native match. That moves
the Python runtime machinery into the type system:

• @otherwise / Unmatched become the non-Matched arms, which the
  compiler requires (E0004), and a new variant breaks every match until
  it is routed.
• Verdict::{Matched, LowConfidence, GuardFailed}(B) and NoMatch
  replace Outcome plus a nullable branch, so misses can be handled
  per branch and per reason.
• Model labels are parsed back into B; unknown ones are errors.
• Configuration is validated once in build().
• The Jev adapter speaks the HTTP API directly, with tagged serde
  enums for questions and answers (unknown answer types ignored).

Includes ports of both examples (the shell guard's Permission enum
has no Deny variant), the matcher test suite, an HTTP round-trip test
against a local server, and a CI job for fmt, clippy and tests.

Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com
Claude-Session: https://claude.ai/code/session_01XvSGXaFnctMyew8CowkNRS

Summary by CodeRabbit

• New Features
  • Added a Rust port for classifying input into defined categories, with confidence thresholds, guard checks, ranked results, and explicit outcomes for unmatched or uncertain cases.
  • Added an optional TypeSafe Jev adapter and examples for routing support messages and evaluating shell commands.
  • Added scripted decision-making tools for testing classifications without network access.
• Documentation
  • Added Rust setup and usage guidance, including examples and current limitations. The Rust port is described as a proof of concept and has not been verified against the live API.

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⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 3fd3d4df-7087-476d-b1c5-e4ec429feda5

📥 Commits

Reviewing files that changed from the base of the PR and between 2bacd50 and b711ccb.

📒 Files selected for processing (2)

• rust/src/matcher.rs
• rust/tests/matcher.rs

📝 Walkthrough

Walkthrough

The pull request adds a Rust crate for enum-based branch matching, including a matcher, a Jev adapter, scripted testing support, and two examples. It also adds crate documentation, a root README link, and a Rust CI job.

Changes

Rust Port

Layer / File(s)	Summary
Branch and decision contracts rust/Cargo.toml, rust/src/branch.rs, rust/src/decider.rs, rust/src/lib.rs	The crate defines branch criteria and enum declarations, decider requests and decisions, and public exports. The manifest sets package compatibility, features, dependencies, and examples.
Matcher classification rust/src/matcher.rs, rust/src/testing.rs, rust/tests/matcher.rs, rust/src/lib.rs, rust/README.md	The matcher validates configuration and classifies state into verdicts with confidence and guard results. Scripted deciders, tests, and crate documentation cover its API and outcomes.
Jev adapter and HTTP tests rust/src/jev.rs, rust/tests/jev.rs, rust/README.md	The adapter sends dispatch and guard questions to the Jev API and parses its answers. Tests use a local HTTP stand-in to check requests, responses, configuration, and errors.
Examples and project support rust/examples/*, rust/README.md, README.md, .github/workflows/ci.yml, .gitignore, rust/rustfmt.toml	The examples demonstrate support routing and a shell hook. Documentation describes the Rust port and its limits. CI checks formatting, Clippy, and tests; project settings cover Rust build output and formatting.

Estimated code review effort: 4 (Complex) | ~60 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant Matcher
  participant JevDecider
  participant TypeSafeJevAPI as TypeSafe Jev API
  Matcher->>JevDecider: decide with state, Choice options, and Noul guards
  JevDecider->>TypeSafeJevAPI: send request
  TypeSafeJevAPI-->>JevDecider: return Choice and Noul answers
  JevDecider-->>Matcher: return Decision
  Matcher-->>Matcher: resolve Decision into Verdict

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🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 68.70% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 115 functions across 10 files. (6 skipped…	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the primary change: adding a Rust port that represents branches as enum variants.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 68.70% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 115 functions across 10 files. (6 skipped: 6 unsupported.)

✨ Finishing Touches 💡 1

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• Commit to this branch
• Create a new PR

🧪 Generate unit tests (beta)

• Commit to this branch
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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

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Inline comments:
In @rust/src/matcher.rs:
- Around line 236-250: In `resolve`, validate `decision.confidence` and any
retrieved guard probability as finite values within 0 to 1 before comparing
them, returning an error for invalid values. Add and use an `InvalidProbability`
variant in `Error`; leave valid verdict selection unchanged.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: bc982b02-45cd-48c4-b70f-2ac89e8081f3

📥 Commits

Reviewing files that changed from the base of the PR and between 6ed277c and 2bacd50.

⛔ Files ignored due to path filters (1)

• rust/Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (16)

• .github/workflows/ci.yml
• .gitignore
• README.md
• rust/Cargo.toml
• rust/README.md
• rust/examples/shell_guard.rs
• rust/examples/support_router.rs
• rust/rustfmt.toml
• rust/src/branch.rs
• rust/src/decider.rs
• rust/src/jev.rs
• rust/src/lib.rs
• rust/src/matcher.rs
• rust/src/testing.rs
• rust/tests/jev.rs
• rust/tests/matcher.rs

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