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Code Quality · Version 1.0.0 · Reviewed 2026-08-02

Regex Correctness Reviewer

Make a defensible decision about backtracking risk and anchoring and escaping with evidence, explicit trade-offs, and a verification plan.

4 method steps 5 documented failure modes 4 diagnostic checks 7 quality gates

Reviews regular expressions for correctness, catastrophic backtracking, anchoring, and Unicode behavior.

₹149 one-time

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What this skill helps you do

  • Backtracking risk
  • Anchoring and escaping
  • Unicode handling

How Regex Correctness Reviewer works

You provide

The code, its invariants, and how failures currently surface

It inspects

Error paths and lifetime handling for backtracking risk

It decides

A anchoring and escaping change that makes invalid states unrepresentable

You verify

A deliberately invalid input fails clearly at the boundary

What it checks first

Regex Correctness Reviewer reviews regular expressions for correctness, catastrophic backtracking, anchoring, and Unicode behavior. Use it when the work involves Backtracking risk, Anchoring and escaping, Unicode handling.

  1. Whether errors are handled where they can be resolved or merely passed upward with less context.
  2. Whether types make invalid states unrepresentable or merely document intent.
  3. Ownership and lifetime of resources, and whether every path releases what it acquired.
  4. Whether abstractions hide complexity or relocate it somewhere harder to inspect.

Failure modes it recognizes

  • A caught exception logged and swallowed, allowing execution to continue with invalid state.
  • Error types collapsed into a single generic type, losing the ability to handle cases differently.
  • Nullable fields encoding several distinct meanings, forcing every caller to guess.
  • A helper abstraction with one caller, which adds indirection without removing duplication.
  • Silent coercion masking a type mismatch until it surfaces as corrupt data.

Answers it will reject

  • Rewriting for elegance without a behavioral test suite, which converts known code into unknown risk.
  • Adding a lint rule to enforce a pattern nobody has justified.
  • Treating warnings as noise, which trains the team to ignore the one that matters.

Decision rules it applies

  • Fail fast on invalid state rather than continuing with a defaulted value.
  • Encode invariants in types and constraints where the language allows it.
  • Prefer local clarity over global cleverness; the reader is the constraint.

Evidence it asks for

  • Confirm each error path is exercised by a test rather than assumed correct.
  • Check that a deliberately invalid input produces a clear failure at the boundary.
  • Compare behavior before and after refactoring with characterization tests.

The method inside

  1. Map the artifact, actors, boundaries, and invariants relevant to backtracking risk.
  2. Trace concrete failure or abuse paths for anchoring and escaping; do not report checklist items without a mechanism.
  3. Prioritize unicode handling findings by impact, likelihood, confidence, and cost of correction.
  4. Recommend the smallest defensible change, then define how an independent reviewer can verify it.

Deliverables

  • Backtracking risk assessment
  • Anchoring and escaping decision and action plan
  • Unicode handling verification checklist

Evidence requirements

  • Functional and quality requirements
  • Scale, latency, consistency, cost, and compliance constraints
  • Current topology and alternatives considered

Quality gates

  • Every material claim traces to supplied evidence or is labeled as a hypothesis.
  • The response follows the declared deliverable contract.
  • No execution, access, measurement, or verification is invented.
  • Secrets and personal data are redacted rather than repeated.
  • The user receives a concrete independent verification step.
  • The relevant failure modes in this domain were considered rather than only the reported symptom.
  • No listed anti-pattern was recommended as a solution.

Example task

Input

This validation regex works in tests but occasionally pins a CPU core to 100 percent in production for minutes.

Expected output

That is catastrophic backtracking: nested quantifiers over overlapping character classes create exponential paths on a near-match input. The fix is making the alternation mutually exclusive or using a possessive quantifier, not adding a timeout around it...

Boundaries and compatibility

Ideal for

  • Backtracking risk: produce a decision or artifact grounded in supplied evidence.
  • Anchoring and escaping: produce a decision or artifact grounded in supplied evidence.
  • Unicode handling: produce a decision or artifact grounded in supplied evidence.

Out of scope

  • Producing a generic reference architecture without requirements
  • Hiding material trade-offs behind best-practice language

Agent compatibility

  • GitHub Copilot custom agents
  • Claude Agent Skills / SKILL.md
  • Any instruction-following chat model

Tool policy: Advisory by default. No tools are assumed. If the host provides tools, use read-only evidence gathering unless the user explicitly approves a scoped write or execution action.