[plan] Add fuzzy matching for common user input errors

[github-actions]

Objective

Implement "Did you mean?" fuzzy matching for engine names, MCP server names, and event types to help users quickly fix typos and misspellings.

Context

From discussion #33307: Users currently see unhelpful errors like "invalid engine: copiliot" when they make typos. The codebase already has excellent fuzzy matching in pkg/cli/run_workflow_validation.go that can be reused for other common error scenarios.

Approach

1. Extract the fuzzy matching logic from pkg/cli/run_workflow_validation.go into a reusable utility function in pkg/stringutil/
2. Apply fuzzy matching to these high-impact error scenarios:
   • Engine names (copilot, claude, codex, custom)
   • MCP server names (from registry or user-configured)
   • GitHub event types (push, pull_request, issues, etc.)
   • Permission scopes (contents, issues, pull_requests, etc.)

Files to Modify

• Create: pkg/stringutil/fuzzy_match.go (extract from run_workflow_validation.go)
• Create: pkg/stringutil/fuzzy_match_test.go (test coverage)
• Update: pkg/workflow/engine_validation.go (add fuzzy matching for engine names)
• Update: pkg/workflow/mcp_property_validation.go (add fuzzy matching for MCP servers)
• Update: pkg/workflow/event_validation.go (add fuzzy matching for event types)
• Update: pkg/workflow/permissions_validation.go (add fuzzy matching for permission scopes)

Example Implementation

Extracted utility function:

// pkg/stringutil/fuzzy_match.go
package stringutil

// FindClosestMatches returns suggestions for misspelled input
func FindClosestMatches(input string, validOptions []string, maxDistance int) []string {
    // Use Levenshtein distance or similar algorithm
    // Return top 3 closest matches if distance <= maxDistance
}

Usage in validation:

// Before
return fmt.Errorf("invalid engine: %s", engineName)

// After
validEngines := []string{"copilot", "claude", "codex", "custom"}
matches := stringutil.FindClosestMatches(engineName, validEngines, 2)
if len(matches) > 0 {
    return NewValidationError(
        "engine",
        engineName,
        fmt.Sprintf("engine '%s' is not valid", engineName),
        fmt.Sprintf("Did you mean '%s'?\n\nValid engines: %s", 
            strings.Join(matches, "', '"), 
            strings.Join(validEngines, ", "))
    )
}

Acceptance Criteria

• Fuzzy matching utility function extracted to pkg/stringutil/fuzzy_match.go
• Engine name validation suggests closest match when typo detected
• MCP server validation suggests closest match when typo detected
• Event type validation suggests closest match when typo detected
• Permission scope validation suggests closest match when typo detected
• All fuzzy matching logic has test coverage with common typo scenarios
• Suggestions include valid options list for reference
• Run make agent-finish successfully before committing

Testing Strategy

1. Test common typos: "copiliot" → suggests "copilot"
2. Test case sensitivity: "Copilot" → suggests "copilot"
3. Test partial matches: "cop" → suggests "copilot"
4. Test distance threshold: "xyz" → no suggestions (too different)
5. Verify existing tests still pass

Reference

• Source: Discussion [repository-quality] Repository Quality Improvement Report - Error Message UX & Actionability #33307 (Repository Quality Improvement Report - Error Message UX)
• Pattern: pkg/cli/run_workflow_validation.go (existing fuzzy matching implementation)
• Similar feature: Command-line tools like git that suggest "Did you mean 'commit'?"

Generated by 📋 Plan Command · ● 12.7M · ◷

• expires on May 21, 2026, 2:12 PM UTC

[github-actions]

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