[duplicate-code] Duplicate Code Pattern: Raw MCP Text-Content Envelope Construction

[github-actions]

Part of duplicate code analysis: #4325

Summary

The raw MCP text response structure — {"content": [{"type": "text", "text": "..."}]} — is hand-built with map[string]interface{} in at least 4 locations across 3 files. There is no shared helper, so every call site must be updated independently if the envelope format ever changes.

Duplication Details

Pattern: Raw MCP text-content envelope construction

• Severity: Medium

• Occurrences: 4

• Locations:

  • internal/server/unified.go (lines ~349–354) — callCollaboratorPermission
  • internal/proxy/proxy.go (lines ~334–339) — restBackendCaller
  • internal/server/system_tools.go (lines ~93–99) — sysInit
  • internal/server/system_tools.go (lines ~109–116) — listServers

• Code Sample (repeated verbatim or near-verbatim in all 4 locations):

  mcpResp := map[string]interface{}{
      "content": []map[string]interface{}{
          {"type": "text", "text": string(body)},
      },
  }
  return mcpResp, nil

Impact Analysis

• Maintainability: Every location must be updated by hand if the MCP content envelope changes (e.g., adding a "role" field, switching to a typed struct). One missed site causes silent inconsistency.
• Bug Risk: Low today, but grows as new call sites are added following the same copy-paste pattern.
• Code Bloat: Minor — 5 lines × 4 sites = ~20 duplicated lines.

Refactoring Recommendations

1. Add a BuildMCPTextResponse(text string) interface{} helper

   • Suggested location: internal/mcp/tool_result.go (alongside existing ConvertToCallToolResult, NewErrorCallToolResult)
   • Alternatively internal/server/ if the raw-map form is intentionally kept internal to the server package
   • Estimated effort: < 1 hour
   • Benefits: single definition of the envelope, easier to evolve format, type-checked call sites

   // BuildMCPTextResponse returns a raw MCP response map with a single text content item.
   // Use this when a raw map[string]interface{} is required (e.g., for WASM guard parsing).
   func BuildMCPTextResponse(text string) map[string]interface{} {
       return map[string]interface{}{
           "content": []map[string]interface{}{
               {"type": "text", "text": text},
           },
       }
   }

2. Replace all 4 call sites with the new helper.

Implementation Checklist

• Add BuildMCPTextResponse (or equivalent) helper
• Replace usages in unified.go, proxy.go, system_tools.go
• Verify existing tests still pass (make test)
• Add a unit test for the helper

Parent Issue

See parent analysis report: #4325
Related to #4325

Generated by Duplicate Code Detector · ● 2.6M · ◷

• expires on Apr 29, 2026, 6:13 AM UTC

[github-actions]

🤖 This is an automated response from Repo Assist.

I verified all four call sites. The pattern is real and consistent — all four hand-build the identical map[string]interface{}{"content": []map[string]interface{}\{\{"type": "text", "text": ...}}} structure.

A few thoughts that may help the implementation:

Natural home: internal/mcp/tool_result.go already has ConvertToCallToolResult and NewErrorCallToolResult. A BuildMCPTextResponse(text string) map[string]interface{} helper there would sit alongside its siblings and be importable from all four call sites without creating a new dependency.

Two sub-populations: The four usages split into two groups:

• system_tools.go lines 93–99 and 109–116 — pass a formatted string directly; these are simple and unambiguous.
• unified.go line 349–354 and proxy.go lines 334–339 — both serve get_collaborator_permission, are nearly identical (see also [duplicate-code] Duplicate Code Pattern: Collaborator Permission Parse/Log/Wrap Block #4327), and already have a shared logging block worth cleaning up at the same time.

Addressing both #4326 and #4327 together would be more efficient than separate PRs: extract BuildMCPTextResponse for the envelope, and either extract a logAndWrapCollaboratorPermission helper or (better) consolidate the two get_collaborator_permission code paths so there's only one place making the REST call. The second option removes ~30 lines of duplication from #4327 without introducing an additional helper function.

Happy to put together a PR if this looks like the right direction.

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