ci-forensics

ci-forensics is a skill for Claude Code from rpraharaj/forward-deployed-engineer. It costs 111 tokens per session (2,214 once invoked), scanned A, original, MIT.

A method for investigating failing, unreliable, or slow automated build pipelines. It separates real code failures from flaky tests, changed environments, ordering problems, and limited resources.

In plain words
What is it for?
Use it when tests pass locally but fail in the pipeline, builds fail intermittently, or the pipeline takes too long.
Why use it?
It prevents repeated retries from hiding genuine failures and helps restore the pipeline as a trustworthy signal.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the fde-operate plugin — 3 skills shipped together

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/rpraharaj/forward-deployed-engineer/ci-forensics
Any agent
npx skills add rpraharaj/forward-deployed-engineer --skill ci-forensics
Clone the repo
git clone --depth 1 https://github.com/rpraharaj/forward-deployed-engineer

Made for: Claude Code.

Or install fde-operate, the plugin that ships this one along with the rest of its 3 skills.

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 ci-forensics

README.md
[![agentmods](https://agentmods.dev/badge/skills/rpraharaj/forward-deployed-engineer/ci-forensics.svg)](https://agentmods.dev/skills/rpraharaj/forward-deployed-engineer/ci-forensics)
Your own site
<a href="https://agentmods.dev/skills/rpraharaj/forward-deployed-engineer/ci-forensics"><img src="https://agentmods.dev/badge/skills/rpraharaj/forward-deployed-engineer/ci-forensics.svg" alt="Measured on agentmods" height="20"></a>
Per session 111 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,214 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 5.1 $0.00111 $0.02214
Opus 5 $0.00056 $0.01107
Sonnet 5 $0.00022 $0.00443
Haiku 4.5 $0.00011 $0.00221

Measured 6d ago against content hash da282420fd89, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

ci-forensics 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 6d 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.

fde-operate/skills/ci-forensics/SKILL.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.

CI forensics

Getting the pipeline back to meaning something.

Why this exists

A flaky pipeline is worse than no pipeline. Once "just re-run it" becomes the standard response to a red build, the suite has stopped being a signal — and the genuine failure it eventually catches gets re-run away like all the others.

Teams reach this state gradually and rarely climb out, because each individual re-run is cheaper than each individual investigation. The economics only look right locally.

An FDE lands in this often, and has a specific advantage: no accumulated tolerance for it. You haven't learned which failures to ignore, which means you notice that the team has learned to ignore them.

The main discipline is diagnosing the class of failure before fixing anything. The classes look identical from the outside — a red build — and have completely different causes and fixes.

When this applies

  • The build is failing and the cause isn't obvious
  • Tests pass locally, fail in CI
  • Intermittent red builds
  • The pipeline is too slow to be useful
  • "Just re-run it" has become normal

When it doesn't

  • A single obvious failure with a clear cause — just fix it
  • Production is broken — that's incident-triage
  • You need to build a pipeline that doesn't exist yet

Prerequisites

  • Locate the workspace: FDE_WORKSPACE, else the charter Location, else .fde/, else ../<repo>-fde/
  • .fde/01-environment.md — a working local build, so you can compare against CI
  • Access to CI logs and history. Build history is the primary evidence here.

Procedure

1. Classify the failure before fixing anything

Five classes. They present identically and have nothing else in common.

Class Signature Fix direction
Genuine break Fails consistently, same point, correlates with a change Fix the code
Flake Same commit passes and fails Find the nondeterminism
Environment drift Passes locally, fails in CI; or worked last week Align the environments
Ordering dependency Fails only in some run orders or in parallel Isolate the shared state
Resource contention Fails under load; timeouts; more common on busy days Resource limits

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. 6d ago First seen · 182 lines · 111 tokens per session scan A da282420fd89

Subscribe to this mod's changes

ci-forensics is a skill published in the GitHub repository rpraharaj/forward-deployed-engineer (6 stars, last pushed 19d ago), licensed MIT. It adds 111 tokens to every session and 2,214 once invoked, about $0.0006 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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