find-duplication

A Go code-analysis guide that finds identical or nearly identical blocks of code.

In plain words
What is it for?
Use it before a pull request or during a full codebase scan to group duplicate code by severity and assess whether shared code should be extracted. It does not perform the refactoring.
Why use it?
It shows where copy-and-paste code may make maintenance harder or where repeated code is acceptable.

Skill for Claude CodeCodexCursor

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/openshift/lightspeed-agentic-operator/find-duplication
Any agent
npx skills add openshift/lightspeed-agentic-operator --skill find-duplication
Clone the repo
git clone --depth 1 https://github.com/openshift/lightspeed-agentic-operator

Made for: Claude Code, Codex, Cursor.

Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 937 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00055 $0.00937
Opus 5 $0.00028 $0.00468
Sonnet 5 $0.00011 $0.00187
Haiku 4.5 $0.00006 $0.00094

Measured 2d ago against content hash 4b455e4c5838, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

find-duplication scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/skills/find-duplication/SKILL.md · 111 lines

How it starts

The opening of the file, as written. The whole thing — 111 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Find Code Duplication

Detect duplicated or near-duplicate Go code and suggest consolidation candidates.

Rules

  • Report findings, do not refactor. Refactoring is a separate task.
  • Focus on production code (controller/, api/, cmd/, cli/). Skip test duplication unless explicitly asked.
  • Group findings by severity: exact duplicates first, then near-duplicates.
  • For each finding, state whether extraction is worth it or acceptable duplication.

Step 1: Determine Scope

Ask the user:

  • Branch mode: only files changed in the current branch vs main.
  • Full mode: scan the entire codebase.

For branch mode:

git diff --name-only upstream/main -- 'controller/' 'api/' 'cmd/' 'cli/' | grep '\.go$' | grep -v '_test\.go$'

For full mode, the target is controller/ api/ cmd/ cli/.

Step 2: Run dupl

Install and run dupl to find duplicate code blocks:

go install github.com/mibk/dupl@latest
dupl -threshold 15 <target>

-threshold 15 means at least 15 tokens of duplication. Lower values = more noise.

Review output and filter false positives:

  • Import blocks (common imports are not duplication)
  • Error constant declarations (repeated pattern is intentional)
  • Single-line patterns (logging, error wrapping)
  • Kubebuilder boilerplate (RBAC markers, webhook setup)

dupl only catches textual similarity. Also look for:

  1. Similar function signatures — functions with near-identical parameter lists doing similar work across different packages.
  2. Repeated error handling — same if err != nil { return fmt.Errorf(...) } pattern with slight variations.
  3. Copy-pasted reconciler logic — similar reconciliation patterns across different controllers.
  4. Duplicated struct definitions — similar structs in different packages (candidate for shared types).

Search for patterns:

# Find similar error wrapping
rg "fmt\.Errorf.*%w.*err\)" controller/ api/ cmd/ cli/ -A 1 -B 1

# Find similar reconciler patterns
rg "func.*Reconcile" controller/ -l

# Find similar generation helpers
rg "func Generate" controller/ -l

Read the full file on GitHub · 111 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 111 lines · 55 tokens per session scan A 4b455e4c5838

Subscribe to this mod's changes

find-duplication is a skill published in the GitHub repository openshift/lightspeed-agentic-operator (10 stars, last pushed 3d ago), licensed Apache-2.0. It adds 55 tokens to every session and 937 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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