feat: add require-cd-guard rule

[nzakas]

Adds shell/require-cd-guard, which mirrors ShellCheck SC2164: if cd fails, the script keeps running in the wrong directory.

Behavior

• Reports cd unless its exit status is used:
  • on the left of && or || (cd dir || exit, cd dir && make);
  • as an if, while, or until condition;
  • negated with !.
• cd on the right of && is still reported.
• Suggestion (not an autofix): append || exit. It's a suggestion because return may be the right choice inside functions. It isn't offered when the cd has redirects or runs in the background.
• Recommended config: "error".

Known limitations

• set -e isn't taken into account, so scripts that rely on errexit still get reports.
• cd inside a subshell ((cd dir; make)) is reported too.

Documentation

Adds docs/rules/require-cd-guard.md, following the format of the @eslint/json, @eslint/css, and @eslint/markdown rule docs: description, background, rule details with incorrect and correct examples, options, when not to use it, and the ShellCheck reference. The rule's meta.docs.url points at that file, and its README table entry links to it.

Testing

10 RuleTester cases, including suggestion output, and 5 documentation checks (312 total); build, lint, and format checks pass.

🤖 Generated with Claude Code

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Summary by CodeRabbit

• New Features

  • Added a rule that flags unguarded cd commands, based on ShellCheck SC2164.
  • Provides suggestions to append || exit where appropriate.
  • Enabled the rule as an error in the recommended configuration.

• Documentation

  • Added usage guidance, examples, supported conditions, and configuration details for the new rule.

• Tests

  • Added coverage for valid and invalid command patterns, diagnostics, and automated suggestions.

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📥 Commits

Reviewing files that changed from the base of the PR and between 8437b3a and fa0e219.

📒 Files selected for processing (6)

• README.md
• docs/rules/require-cd-guard.md
• src/index.spec.ts
• src/index.ts
• src/rules/require-cd-guard.spec.ts
• src/rules/require-cd-guard.ts

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📥 Commits

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📒 Files selected for processing (6)

• README.md
• docs/rules/require-cd-guard.md
• src/index.spec.ts
• src/index.ts
• src/rules/require-cd-guard.spec.ts
• src/rules/require-cd-guard.ts

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📝 Walkthrough

Walkthrough

The PR adds the require-cd-guard rule, exports it, enables it in the recommended configuration, adds tests, and documents its behavior and suggestions.

Changes

Require CD Guard

Layer / File(s)	Summary
Rule behavior and validation src/rules/require-cd-guard.ts, src/rules/require-cd-guard.spec.ts	The rule reports unchecked cd commands and suggests `
Plugin registration and recommended configuration src/index.ts, src/index.spec.ts	The plugin exports require-cd-guard, enables it as an error in the recommended configuration, and verifies the exported rule list.
Rule documentation docs/rules/require-cd-guard.md, README.md	The documentation describes the checks, suggestions, examples, options, disabling guidance, ShellCheck SC2164, and the documented rule list.

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

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[Copilot]

Copilot review overview

🟡 Changes recommended

Status-use detection has false positives and negatives, and the suggested guard can incorrectly terminate scripts.

Review effort: Balanced
Findings: 1

Open (1)

• Account for logical-expression ancestors in status handling · New

What changed in this PR

Adds the bash/require-cd-guard rule based on ShellCheck SC2164.

Changes:

• Detects unguarded cd commands and offers an || exit suggestion.
• Enables the rule in the recommended configuration.
• Adds tests and documentation.

File	Description
src/​rules/​require-cd-guard.ts	Implements detection and suggestions.
src/​rules/​require-cd-guard.spec.ts	Tests rule behavior.
src/​index.ts	Registers and enables the rule.
src/​index.spec.ts	Verifies rule registration.
README.md	Adds the rule to the catalog.
docs/​rules/​require-cd-guard.md	Documents usage and behavior.

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[nzakas]

@copilot address review comments. Be sure to add tests.

[Copilot]

@copilot address review comments. Be sure to add tests.

Updated the rule to walk enclosing logical-expression ancestors and added &&/|| chain regression tests. Committed as df636d5.