What is check-duplicates?

A check of one GitHub issue against other issues and pull requests, which are proposed code changes, to find duplicates or existing fixes.

Use it before working on an issue to search related titles, errors, and component names; it can add a comment when a duplicate is found.

It helps avoid starting work that someone else has already reported or fixed.

check-duplicates — Skill for Claude Code by tomzx/agents

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.

Any agent

npx skills add tomzx/agents --skill check-duplicates

Clone the repo

git clone --depth 1 https://github.com/tomzx/agents

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/tomzx/agents/check-duplicates/github.svg)](https://agentmods.dev/skills/tomzx/agents/check-duplicates)

Your own site

<a href="https://agentmods.dev/skills/tomzx/agents/check-duplicates"><img src="https://agentmods.dev/badge/skills/tomzx/agents/check-duplicates/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/tomzx/agents/check-duplicates"><img src="https://agentmods.dev/badge/skills/tomzx/agents/check-duplicates.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 21 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 938 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00021	$0.00938
Opus 5.5	$0.00008	$0.00375
Sonnet 5.5	$0.00004	$0.00188
Haiku 4.5	$0.00002	$0.00094

Measured 22d ago against content hash 08f4fc73c912, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

check-duplicates 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 22d 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.

skills/check-duplicates/SKILL.md · 132 lines

How it starts

The opening of the file, as written. The whole thing — 132 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Check Duplicates

Checks a GitHub issue for duplicate issues and existing fix PRs. Use before starting work on any issue to avoid wasted effort.

This skill performs read-only checks and posts a comment only if a duplicate is found. It does not modify the issue or create any branches.

Prerequisites

Apply the shared SDLC conventions in skills/sdlc/references/shared.md.
If no argument is provided, target the issue from $ISSUE_NUMBER (and $REPO).
ghx CLI authenticated with read access to the target repository
A GitHub issue number to check

Skill attribution (GitHub)

If posting a comment about a duplicate, read ../github-post-attribution/SKILL.md and append the footer for SKILL_DIR = check-duplicates.

Communication guidelines (outbound text)

Before composing any text posted or drafted on the user's behalf, apply communication-guidelines/SKILL.md.

Steps

1. Fetch the issue

Fetch the issue details to extract search keywords:

ghx issue view $ISSUE_NUMBER --repo $REPO

Extract keywords from:

Title
Error messages or stack traces
Key nouns describing the affected component or behavior

2. Search for duplicate issues

Using 2-3 different keyword combinations, search for similar open and closed issues:

ghx issue list --repo $REPO --search "<keywords>" --state all --limit 10

Exclude the current issue from results. For each candidate, compare:

Whether it describes the same root cause or behavior
Whether it is still open (closed may indicate a previous fix)
Whether it covers the same scope or a subset

If a duplicate is found, comment on the current issue and stop:

ghx issue comment $ISSUE_NUMBER --repo $REPO --body "$(cat <<'EOF'
Duplicate of #<existing-issue-number>.

---

Posted with [check-duplicates](SKILL_FILE_URL) (`SKILL_SHORT_SHA`)
EOF
)"

3. Check for existing fix PRs

Search for open PRs that reference this issue:

ghx pr list --repo $REPO --search "$ISSUE_NUMBER" --state open --limit 10

Read the full file on GitHub · 132 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.

22d ago Changed · +4 lines 08f4fc73c912
27d ago Changed 9156ef478d62
28d ago Changed · +4 lines aeb6ecab04c4
2mo ago First seen · 124 lines · 21 tokens per session scan A 7adcc65b8229

Subscribe to this mod's changes

check-duplicates is a skill published in the GitHub repository tomzx/agents (13 stars, last pushed yesterday), licensed MIT. It adds 21 tokens to every session and 938 once invoked, about $0.0001 per session on Opus 5.5. 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.

Project management

story-readiness

Checks whether a story is ready to implement: clear acceptance criteria, no open questions, valid ADR and dependencies. Use when the user asks if a story, or the sprint's stories, are ready to start or build.

Donchitos/Claude-Code-Game-Studios · 48 tokens

recipe-create-meet-space

Create a Google Meet meeting space and share the join link.

googleworkspace/cli · 18 tokens

workthreads

SpecStory Workthreads - a weekly work-thread rollup across a team's repos from SpecStory coding histories (any agent - Claude Code, Codex, Cursor, Gemini, and more). It groups the window's sessions into threads of work per project and labels each new / open / recently closed, so a lead sees what shipped, what is still…

specstoryai/getspecstory · 126 tokens

atmos-config

Atmos root configuration: atmos.yaml discovery, precedence, deep merging, basepath, imports, minimal bootstrap, and routing to narrower Atmos skills.

cloudposse/atmos · 31 tokens

qa-project-bootstrap

Onboard a new QA engineer to an existing codebase, or audit an existing test architecture. Produces a 30-day ramp plan: codebase orientation, framework walkthrough, test architecture audit, mentorship pairing, and first-test guidance. Use when: "QA onboarding," "new tester," "ramp up," "test architecture audit,"…

petrkindlmann/qa-skills · 124 tokens

remove

Remove a deployed framework or addon from the current workspace.

jmagly/aiwg · 12 tokens