Duplicate Code: Repeated field-removal codemod scaffolding in pkg/cli

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Overview

Recent commit analysis found a repeated codemod implementation pattern in pkg/cli where multiple get*Codemod() constructors duplicate the same frontmatter guard/check/transform scaffold with only field names changed.

This exceeds the duplication threshold via 3+ similar occurrences and increases maintenance risk when codemod behavior or validation flow changes.

Critical Information

• Pattern type: Structural duplication (copy-adapted logic)
• Severity: Medium
• Occurrences: 3 confirmed instances in production code
• Commit analyzed: 04e391b8945b082ee18a5a54da81646ac9a09f7f

Duplication Details

Repeated pattern

The following functions repeat the same sequence:

1. Read top-level frontmatter key
2. Type-assert map[string]any
3. Check child field presence
4. Invoke applyFrontmatterLineTransform(...)
5. Log and return

Locations

• pkg/cli/codemod_grep_tool.go:14
• pkg/cli/codemod_mcp_scripts.go:16
• pkg/cli/codemod_network_firewall.go:18

View representative duplicated block (semantic shape)

Apply: func(content string, frontmatter map[string]any) (string, bool, error) {
    parentValue, hasParent := frontmatter["(parent)"]
    if !hasParent {
        return content, false, nil
    }

    parentMap, ok := parentValue.(map[string]any)
    if !ok {
        return content, false, nil
    }

    _, hasField := parentMap["(field)"]
    if !hasField {
        return content, false, nil
    }

    newContent, applied, err := applyFrontmatterLineTransform(content, func(lines []string) ([]string, bool) {
        return removeFieldFromBlock(lines, "(field)", "(parent)")
    })
    if applied {
        // log
    }
    return newContent, applied, err
}

View evidence from two near-identical implementations

• getGrepToolRemovalCodemod: pkg/cli/codemod_grep_tool.go:14
• getMCPScriptsModeCodemod: pkg/cli/codemod_mcp_scripts.go:16

These differ primarily by string literals (tools/grep vs mcp-scripts/mode) while control flow and transform wiring are equivalent.

Impact Analysis

• Maintainability: Any behavior change to guard/transform flow must be replicated across many codemods.
• Bug risk: Divergence risk is high when one codemod receives a safety fix and others do not.
• Code bloat: Repeated scaffolding obscures codemod-specific intent.

Refactoring Recommendations

1. Introduce a generic field-removal codemod builder

• Suggested location: pkg/cli/codemod_factory.go
• Shape: newFieldRemovalCodemod(meta..., parentKey, fieldKey, logMsg) returning Codemod
• Benefit: Centralized guard logic and consistent behavior across codemods

2. Allow optional post-transform hook for special cases

• Needed for extended behavior in codemod_network_firewall.go
• Benefit: Reuse common preconditions while preserving custom migration logic

3. Add table-driven tests for the shared builder

• Validate parent missing / wrong type / field missing / successful removal
• Benefit: One test surface for common behavior

Implementation Checklist

• Add shared codemod builder for field-removal migrations
• Migrate grep and mcp-scripts.mode codemods to builder
• Evaluate partial migration of network.firewall codemod via hook-based extension
• Add/adjust unit tests for shared path and migrated codemods
• Verify no behavior regressions in codemod output

Analysis Metadata

• Analyzed files: 562 changed non-test pkg/**/*.go files in available commit snapshot
• Detection method: Serena symbol analysis + structural comparison
• Workflow run: §23035479736
• Analysis date: 2026-03-13 UTC

References:

• §23035479736

Generated by Duplicate Code Detector · ◷

Warning

⚠️ Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

• ab.chatgpt.com

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "ab.chatgpt.com"

See Network Configuration for more information.