ThemeRegistry.GetThemesInFamily("catppuccin") returns no themes, though FindTheme("catppuccin mocha") ignores case

[matt-edmondson]

What's wrong

ThemeRegistry.ThemesByFamily is built with ToDictionary using the default, case-sensitive string comparer (ThemeProvider/ThemeRegistry.cs:106-109). GetThemesInFamily (:146-152) and CreateThemeInstancesInFamily look families up in that dictionary.

Meanwhile, FindTheme is documented and implemented as case-insensitive. So at 9454d42:

• GetThemesInFamily("Catppuccin").Count is 4.
• GetThemesInFamily("catppuccin").Count is 0.
• FindTheme("catppuccin mocha") finds the theme.
• GetThemesInFamily(null!) throws ArgumentNullException from the dictionary, while FindTheme(null!) returns null.

Why it matters

A theme picker or config file that stores family names in a different case, such as lower-cased keys from a settings file or a CLI argument, gets an empty family back. Nothing reports an error, and the behaviour contradicts the registry's name lookup.

Suggested fix

• Pass StringComparer.OrdinalIgnoreCase to the ToDictionary call.
• Handle a null family the same way FindTheme handles a null name.

Acceptance criteria

• GetThemesInFamily("catppuccin") and CreateThemeInstancesInFamily("CATPPUCCIN") return the four Catppuccin themes.
• Null handling matches FindTheme.
• A test covers the lower-case family lookup.

[matt-edmondson]

Triage

• Category: Bug
• Priority: Low. The two lookups are inconsistent, and a differently cased family name gets an empty result instead of an error. The workaround is trivial and nothing is corrupted.
• Area / suggested assignment: ThemeProvider/ThemeRegistry.cs (ThemesByFamily ~lines 106-109, GetThemesInFamily ~lines 146-152, CreateThemeInstancesInFamily).
• Duplicates: none.
• In progress: no matching open PR.

Notes: This is a small fix: StringComparer.OrdinalIgnoreCase on the ToDictionary call, plus null handling that matches FindTheme. If ThemesByFamily is public, the comparer change is visible to callers who read the dictionary directly. That is harmless, but mention it in the release notes.

---

Generated by Claude Code