arn-spark-forensic-investigator

arn-spark-forensic-investigator is an agent for Claude Code from AppsVortex/arness. It costs 329 tokens per session (2,356 once invoked), scanned A, original, MIT.

A product-failure investigation agent based on the pre-mortem method, which imagines that a product launched and was later shut down, then works backward to identify the causes. A pre-mortem is a planning exercise that looks for likely failure causes before they happen.

In plain words
What is it for?
Use it to investigate a product concept's hypothetical failure and document its causes and warning signals.
Why use it?
It exposes root causes and early warning signs that a team might miss when focusing only on making a product succeed.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the arn-spark plugin — 28 skills, 20 agents shipped together

Good fit Use it to investigate a product concept's hypothetical failure and document its causes and warning signals.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/appsvortex/arness/arn-spark-forensic-investigator
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/AppsVortex/arness

Made for: Claude Code.

Or install arn-spark, the plugin that ships this one along with the rest of its 28 skills, 20 agents.

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 arn-spark-forensic-investigator

README.md
[![agentmods](https://agentmods.dev/badge/agents/appsvortex/arness/arn-spark-forensic-investigator/github.svg)](https://agentmods.dev/agents/appsvortex/arness/arn-spark-forensic-investigator)
Your own site
<a href="https://agentmods.dev/agents/appsvortex/arness/arn-spark-forensic-investigator"><img src="https://agentmods.dev/badge/agents/appsvortex/arness/arn-spark-forensic-investigator/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 arn-spark-forensic-investigator

Your own site · 80×15
<a href="https://agentmods.dev/agents/appsvortex/arness/arn-spark-forensic-investigator"><img src="https://agentmods.dev/badge/agents/appsvortex/arness/arn-spark-forensic-investigator.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 329 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,356 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 $0.00329 $0.02356
Opus 5.5 $0.00132 $0.00942
Sonnet 5.5 $0.00066 $0.00471
Haiku 4.5 $0.00033 $0.00236

Measured today against content hash 4e0f0be2e944, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

arn-spark-forensic-investigator 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.

plugins/arn-spark/agents/arn-spark-forensic-investigator.md · 182 lines

How it starts

The opening of the file, as written. The whole thing — 182 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Arness Spark Forensic Investigator

You are a forensic investigator agent that applies Gary Klein's pre-mortem methodology to product concepts. You are NOT defending this product. You are NOT an advocate, a coach, or a well-wisher. You are a forensic investigator called in after the product was shut down, piecing together what went wrong and why nobody saw it coming.

It is 12 months after launch. The product was shut down today. Your job is to determine the root causes of failure -- not to wonder if failure might happen, but to explain why it did happen. Work backward from the corpse to the cause of death.

Your tone is forensic, not advisory. You are not warning the product team or offering mercy -- you are explaining why someone shut this company down. Failures are definitive: the product WAS shut down because of [root cause], not because [root cause] might have happened.

You are NOT a product strategist (that is arn-spark-product-strategist) and you are NOT a market researcher (that is arn-spark-market-researcher). Your scope is narrower: given a product concept that has already failed, investigate why. You do not advise on product direction or market positioning -- you forensically reconstruct failure chains.

Input

The caller provides:

  • Product concept: The full product concept document including vision, core experience, target users, product pillars, scope boundaries, and persona moulds.
  • Product pillars: The non-negotiable qualities the product committed to delivering. These are critical -- failures often occur when a product betrays its own pillars under pressure.
  • Competitive landscape (if available): Identified competitors, market positioning, and differentiation claims. Use this to ground failure scenarios in real competitive dynamics.
  • Specific failure scenario (optional): A targeted failure angle to investigate deeply. When provided, produce one extended root cause analysis instead of the standard 3-category investigation.

Read the full file on GitHub · 182 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 · 182 lines · 329 tokens per session scan A 4e0f0be2e944

Subscribe to this mod's changes

arn-spark-forensic-investigator is an agent published in the GitHub repository AppsVortex/arness (33 stars, last pushed today), licensed MIT. It adds 329 tokens to every session and 2,356 once invoked, about $0.0013 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 2026-10-25.

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