Add maui errors list command for error code introspection

[rmarinho]

Summary

Adds the \maui errors list [--json]\ command that emits the registered error code catalogue, enabling AI agents and IDE consumers to statically verify they handle every \MauiToolException\ error code.

Changes

• \ErrorCodeDescriptor.cs\ — model record with snake_case JSON properties
• \ErrorCodeCatalogue.cs\ — static catalogue covering all 23 registered error codes
• \ErrorsCommands.cs\ — \maui errors list [--category] [--prefix] [--json]\ command
• \MauiCliJsonContext.cs\ — added 3 [JsonSerializable]\ entries
• \Program.cs\ — registered \ErrorsCommands.Create()\
• \ErrorsCatalogueTests.cs\ — 17 unit tests including reflection-based drift detection

Usage

\
maui errors list
maui errors list --category platform
maui errors list --prefix E21
maui errors list --json
\\

The \Catalogue_CoversEveryConstantInErrorCodes\ test uses reflection on \ErrorCodes\ to catch future drift when new codes are added.

[github-actions]

Expert Code Review — PR #202

Methodology: 3 independent reviewers with adversarial consensus (2-reviewer fallback — 1 reviewer's detailed output was unavailable)

Result: 1 finding posted as inline comment (1 minor)

CI Status

✅ Build passes on both macOS and Windows

Test Coverage

✅ PR includes 17 unit tests with reflection-based drift detection covering the catalogue, filters, serialization, and command registration

Discarded Findings (single-reviewer only, no consensus)

Reviewer	Severity	File	Finding
2	🟡	ErrorsCommands.cs:52	SpectreOutputFormatter downcast silently produces no output for non-Spectre formatters
3	🟡	ErrorCodeCatalogue.cs:36	Public API exposes mutable shared array instance via IReadOnlyList over ErrorCodeDescriptor[]
2	🟢	MauiCliJsonContext.cs	List<ErrorCodeDescriptor> registered but not ErrorCodeDescriptor[] — potential AOT issue if array serialized directly
3	🟢	ErrorsCatalogueTests.cs:55	Drift test is one-directional (catches missing entries but not stale/removed ones)
2	🟢	ErrorsCatalogueTests.cs:90	Case-insensitivity tests compare counts not actual item sets

Generated by Expert Code Review · 3 independent reviewers with adversarial consensus

Generated by Expert Code Review (auto) for issue #202 · ● 7.5M · ◷

[github-actions]

Expert Review — maui errors list Command

Good addition overall. The reflection-based drift test (Catalogue_CoversEveryConstantInErrorCodes) is an excellent pattern. Two moderate issues worth addressing before merge:

Findings

#	Severity	File	Line	Issue	Recommendation
1	🟡 MODERATE	ErrorsCommands.cs	50	Non-Spectre formatter in non-JSON mode silently produces zero output and returns success.	Add fallback else branch (plain-text output or error).
2	🟡 MODERATE	ErrorsCommands.cs	33–37	--category and --prefix supplied together silently ignores --prefix with no warning.	Either enforce mutual exclusivity with an error, or compose both filters (AND semantics).
3	🟡 MODERATE	ErrorsCommands.cs	39–41	JSON mode emits {"codes":[],"count":0} for empty results with no warning, while non-JSON mode prints a warning. Asymmetric UX for consumers.	Document or harmonize behavior across output modes.
4	🟢 MINOR	ErrorCodeCatalogue.cs	38–42	ByCategory/ByPrefix allocate a new list per call.	Fine for CLI use; consider lazy IEnumerable if reused in hot paths.
5	🟢 MINOR	MauiCliJsonContext.cs	50	List<ErrorCodeDescriptor> registration appears unused (property is IReadOnlyList).	Remove or retain intentionally — no runtime impact.

Generated by Expert Code Review (auto) for issue #202 · ● 7.5M

[github-actions]

🟢 MINOR · Consensus: 2/2 reviewers

--prefix is silently discarded when --category is also supplied.

maui errors list --category platform --prefix E21 silently ignores --prefix and returns all platform errors instead of only Android codes. The user receives no indication that one filter was dropped.

Suggestion: Either make the options mutually exclusive with a validation error, or AND the filters together:

IReadOnlyList<ErrorCodeDescriptor> codes = ErrorCodeCatalogue.All
    .Where(d => category is null || d.Category.Equals(category, StringComparison.OrdinalIgnoreCase))
    .Where(d => prefix is null || d.Code.StartsWith(prefix, StringComparison.OrdinalIgnoreCase))
    .ToList();