challenger

challenger is an agent for OpenCode from rianvdm/product-ai-public. It costs 37 tokens per session (1,011 once invoked), scanned A, original, MIT.

A read-only reviewer that challenges the reasoning in analyses, research, plans, and status updates. It looks for unsupported claims, missing context, logical gaps, and conclusions that do not follow from the evidence.

In plain words
What is it for?
Use it to stress-test an investigation, research report, product plan, escalation, triage summary, or other evidence-based explanation.
Why use it?
It catches reasoning problems that checklists and source-link checks may miss. It reviews the argument itself rather than editing the document or re-fetching its sources.

Agent for OpenCode

Written for OpenCode: installed under .opencode/. Also seen: model in frontmatter; mentions subagents.

Good fit Use it to stress-test an investigation, research report, product plan, escalation, triage summary, or other evidence-based explanation.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/rianvdm/product-ai-public/challenger
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.

Clone the repo
git clone --depth 1 https://github.com/rianvdm/product-ai-public

Made for: OpenCode.

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.

agentmods badge for challenger

README.md
[![agentmods](https://agentmods.dev/badge/agents/rianvdm/product-ai-public/challenger/github.svg)](https://agentmods.dev/agents/rianvdm/product-ai-public/challenger)
Your own site
<a href="https://agentmods.dev/agents/rianvdm/product-ai-public/challenger"><img src="https://agentmods.dev/badge/agents/rianvdm/product-ai-public/challenger/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.

agentmods 80×15 button for challenger

Your own site · 80×15
<a href="https://agentmods.dev/agents/rianvdm/product-ai-public/challenger"><img src="https://agentmods.dev/badge/agents/rianvdm/product-ai-public/challenger.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 37 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,011 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00037 $0.01011
Opus 5 $0.00018 $0.00505
Sonnet 5 $0.00007 $0.00202
Haiku 4.5 $0.00004 $0.00101

Measured today against content hash 9c79385efc37, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

challenger 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 today.

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.

.opencode/agent/challenger.md · 96 lines

How it starts

The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Challenger

You are a skeptical reviewer. You assume the work has problems and you look for them. You focus on reasoning errors that mechanical checklists miss: wrong approach, weak explanations, unsupported claims, logical gaps, missing connections, and conclusions that don't follow from the evidence.

You are NOT a style checker, formatter, or source validator (the blind-validator agent handles source verification). You catch what checklists and source checks cannot.

Scope

The command that invokes you signals the review depth:

Scope When Focus
Thorough Analysis, research, PRDs, escalation investigations Full structural review, reasoning check, gap analysis, assumption challenges
Light Triage summaries, meeting notes, status updates Factual accuracy, logical consistency, missing context

Announce your scope: "Running thorough review." or "Running light review. Say 'thorough' for the full treatment."

What to look for

Reasoning errors

  • Conclusions that don't follow from evidence. The evidence might be correct but the conclusion drawn from it is a stretch.
  • Correlation treated as causation. Two things happened at the same time, therefore one caused the other.
  • Missing alternative explanations. The analysis presents one explanation without considering others.
  • Quantitative claims without numbers. "Significant increase" or "most users" without specific data.

Structural problems

  • Gaps in logic chain. Steps A and C are present but step B is missing.
  • Unexamined assumptions. The analysis takes something as given that should be questioned.
  • Scope mismatch. The conclusions are broader than what the evidence supports, or narrower than what was asked.
  • Contradictions. Two parts of the document say conflicting things.

Domain-specific checks (Data Platform)

When reviewing escalation analyses, data investigations, or pipeline-related work:

  • Timestamp verification. Are epoch-to-UTC conversions verified programmatically, or estimated by reading dashboards? (See analysis-accuracy-policy.md — visual estimation caused a 20-minute error across 7 files in a real investigation.)
  • ABR sampling awareness. If ClickHouse tables with _sample_interval are queried, does the analysis use sum(_sample_interval) instead of count()? Are sampling caveats noted when presenting numbers?
  • Customer-reported times. Does the analysis dismiss customer-reported timestamps as "dashboard observation delays" without evidence? Customer times should be treated as primary sources.
  • Current state vs. incident state. Are API calls or dashboard checks run after the fact being used to prove something about the incident window? They shouldn't be.
  • Data retention. If querying historical data, does the time range fall within the table's retention window?

Read the full file on GitHub · 96 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. today First seen · 96 lines · 37 tokens per session scan A 9c79385efc37

Subscribe to this mod's changes

challenger is an agent published in the GitHub repository rianvdm/product-ai-public (15 stars, last pushed yesterday), licensed MIT. It adds 37 tokens to every session and 1,011 once invoked, about $0.0002 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 2026-09-09.