Add explicit DIFC labeling for list_issue_fields in GitHub guard

[Copilot]

The guard had a coverage gap for list_issue_fields: it lacked an explicit apply_tool_labels arm and fell through to default label inheritance. This left org/project issue field metadata without the intended project:github integrity constraints.

• DIFC rule coverage

  • Added a dedicated list_issue_fields match arm in tool_rules.rs.
  • Aligned integrity behavior with list_issue_types by applying project_github_label(ctx).

• Regression protection

  • Added a focused unit test in labels/mod.rs to assert list_issue_fields resolves to the same integrity labels as list_issue_types.

"list_issue_types" => {
    integrity = project_github_label(ctx);
}
"list_issue_fields" => {
    integrity = project_github_label(ctx);
}

[Copilot]

Pull request overview

This PR closes a DIFC labeling gap by giving list_issue_fields an explicit GitHub guard rule aligned with list_issue_types.

Changes:

• Adds a list_issue_fields arm in apply_tool_labels.
• Applies GitHub-global project integrity labels to issue field metadata.
• Adds a regression test comparing list_issue_fields and list_issue_types integrity behavior.

Show a summary per file

File	Description
guards/github-guard/rust-guard/src/labels/tool_rules.rs	Adds the explicit labeling rule for list_issue_fields.
guards/github-guard/rust-guard/src/labels/mod.rs	Adds a focused unit test for the new rule.

Copilot's findings

Tip

Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

• Files reviewed: 2/2 changed files
• Comments generated: 2