[refactor] Semantic Function Clustering Analysis - Code Organization Improvements

[github-actions]

Analysis of 50 non-test Go files in the MCP Gateway repository identified 351 total symbols (184 functions, 167 methods) across 27 significant semantic clusters.

Key Findings

• 62 exact function name matches across different files
• 30 similar function names indicating potential consolidation opportunities
• 2 outlier functions in validation files
• 1 high-priority duplicate function for removal

Most significant findings:

1. Duplicate authentication header extraction (ExtractAgentIDFromAuthHeader wrapper)
2. Confusing SetVersion() naming (should be SetGatewayVersion())
3. Acceptable duplicates (Go idioms like Error(), Clone(), Get())

Priority 1: High Impact, Low Effort ⚡

1.1 Remove Duplicate Authentication Header Extraction

Issue: guard/context.go:68 has ExtractAgentIDFromAuthHeader() that simply wraps auth.ExtractAgentID().

Current code:

// internal/guard/context.go
func ExtractAgentIDFromAuthHeader(authHeader string) string {
    return auth.ExtractAgentID(authHeader)
}

Recommendation:

• ❌ Remove: guard.ExtractAgentIDFromAuthHeader()
• ✅ Use directly: auth.ExtractAgentID() at all call sites
• Benefit: Eliminates unnecessary wrapper, single source of truth
• Estimated effort: 1 hour

---

Priority 2: Medium Impact, Medium Effort 🔧

2.1 Clarify Version Management Function Names

Issue: Two SetVersion() functions with different purposes.

Current:

// internal/cmd/root.go
func SetVersion(v string) {
    version = v
    rootCmd.Version = v
    config.SetVersion(v)  // Calls the config version
}

// internal/config/validation_schema.go
func SetVersion(version string) {
    if version != "" {
        gatewayVersion = version
    }
}

Recommendation:

• Rename config.SetVersion() → config.SetGatewayVersion()
• Update call site in cmd/root.go
• Benefit: Clearer intent, reduces confusion
• Estimated effort: 30 minutes

2.2 Add Error Type Documentation

Issue: Multiple Error() implementations (idiomatic Go) but could use better documentation.

Affected types:

• ValidationError (config/rules)
• EnvValidationResult (config/validation_env)
• ViolationError (difc/labels)

Recommendation:

• Add godoc comments explaining each error type's purpose
• Benefit: Better developer experience when handling errors
• Estimated effort: 30 minutes

---

What's Working Well ✅

The analysis identified several well-organized areas:

• ✅ Sanitization Package (internal/logger/sanitize/) - Single-purpose, well-documented
• ✅ Logger Package - Clear separation of concerns (file, JSONL, markdown loggers)
• ✅ DIFC Package - Clean separation with strong type safety
• ✅ MCP Package - Focused protocol types with clear boundaries

---

Acceptable "Duplicates" (No Action Needed)

These patterns are idiomatic Go and should NOT be changed:

Multiple Error() Methods

• Why: Standard Go error interface implementation
• Types: ValidationError, EnvValidationResult, ViolationError
• ✅ Verdict: Keep as-is (proper Go design)

Multiple init() Functions

• Files: cmd/root.go, middleware/jqschema.go
• Why: Standard Go package initialization
• ✅ Verdict: No action needed

Multiple Clone() Methods

• Types: AgentLabels, Label
• Why: Type-specific deep copy for DIFC security
• ✅ Verdict: Good design, keep as-is

Multiple Get() Methods

• Types: AgentRegistry, Registry, SessionConnectionPool
• Why: Registry pattern with different key/value types
• ✅ Verdict: Keep as-is (generics would add complexity)

---

Implementation Checklist

Immediate Actions (Priority 1)

• Review ExtractAgentIDFromAuthHeader usage in guard/context.go
• Update call sites to use auth.ExtractAgentID() directly
• Remove wrapper function
• Run tests to verify no functionality broken

Short-term Actions (Priority 2)

• Rename config.SetVersion() to config.SetGatewayVersion()
• Update call site in cmd/root.go
• Add godoc comments to error types

---

Analysis Details

Files Analyzed (50 total)

By Package

• cmd (2 files): CLI initialization
• config (6 files): Configuration loading and validation
• difc (5 files): Security labels and enforcement
• guard (4 files): Security guard registry
• launcher (2 files): Backend process management
• logger (9 files): Logging infrastructure
• mcp (2 files): Protocol types and connections
• server (10 files): HTTP server and routing
• middleware (1 file): Request middleware
• auth (1 file): Authentication
• sys (1 file): System utilities
• timeutil (1 file): Time formatting
• tty (2 files): TTY handling
• testutil (4 files): Test utilities

Top Files by Symbol Count

File	Package	Total Symbols	Functions	Methods
connection.go	mcp	29	14	15
unified.go	server	26	5	21
labels.go	difc	20	5	15
agent.go	difc	18	4	14
validation_env.go	config	15	13	2
connection_pool.go	launcher	13	2	11

Function Clusters (27 patterns found)

By Prefix

• Get (31 functions): Registry lookups, accessor methods
• New (31 functions): Constructors and factory methods
• Close (11 functions): Resource cleanup
• Set (8 functions): Setter methods
• Create (5 functions): Factory methods
• Extract (4 functions): Data extraction
• Register (4 functions): Registry operations
• Validate (3 functions): Input validation
• Start (3 functions): Initialization
• Stop (3 functions): Cleanup
• Handle (3 functions): Request handlers

By Suffix

• Logger (15 functions): Logging infrastructure
• Error (9 functions): Error interface implementations
• Request (7 functions): Request handling
• Server (7 functions): Server management
• Config (5 functions): Configuration
• Response (4 functions): Response handling
• Handler (4 functions): HTTP handlers

---

Summary

The MCP Gateway codebase is generally well-organized with clear package boundaries and consistent naming conventions. The identified refactoring opportunities are incremental improvements rather than critical issues.

Total estimated effort for Priority 1 + 2: ~2 hours
Expected benefit: Improved maintainability, clearer code organization, eliminated unnecessary wrapper

Recommended approach:

1. Start with Priority 1 (auth header consolidation)
2. Address naming clarity (Priority 2)
3. Document why certain "duplicates" are intentional and correct

---

Analysis Metadata

• Total Files: 50
• Total Symbols: 351 (184 functions + 167 methods)
• Semantic Clusters: 27
• Exact Duplicates Found: 62
• High-Priority Issues: 1
• Medium-Priority Issues: 2
• Analysis Date: 2026-01-21

AI generated by Semantic Function Refactoring