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.
npx skills add caiaffa/claude-code-ultimate-engineering-system --skill deep-root-cause-investigatorgit clone --depth 1 https://github.com/caiaffa/claude-code-ultimate-engineering-systemWrote 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.
[](https://agentmods.dev/skills/caiaffa/claude-code-ultimate-engineering-system/deep-root-cause-investigator)<a href="https://agentmods.dev/skills/caiaffa/claude-code-ultimate-engineering-system/deep-root-cause-investigator"><img src="https://agentmods.dev/badge/skills/caiaffa/claude-code-ultimate-engineering-system/deep-root-cause-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.
<a href="https://agentmods.dev/skills/caiaffa/claude-code-ultimate-engineering-system/deep-root-cause-investigator"><img src="https://agentmods.dev/badge/skills/caiaffa/claude-code-ultimate-engineering-system/deep-root-cause-investigator.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00029 | $0.00572 |
| Opus 5 | $0.00015 | $0.00286 |
| Sonnet 5 | $0.00006 | $0.00114 |
| Haiku 4.5 | $0.00003 | $0.00057 |
Grade A, and why
deep-root-cause-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 8d 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.
How it starts
The opening of the file, as written. The whole thing — 53 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Mission
Eliminate classes of failure, not just the latest instance.
When to use
- Incidents recur.
- A fix addressed symptoms but not causes.
- A failure passed existing safeguards.
- The team needs deeper learning from an outage or bug.
Handoff
- Receives from: staff-sre or incident-response (after incident contained).
- Hands off to: postmortem-reviewer (for postmortem), incident-learning-loop (for systemic changes).
The cause chain method
Every incident has layers. Peel all of them:
1. SYMPTOM → What did users/systems experience?
2. TRIGGER → What specific event started the failure?
3. LOCAL CAUSE → Why did the trigger cause harm? (the bug, the misconfiguration)
4. ENABLING CONDITION → Why was the local cause possible? (missing validation, weak contract)
5. FAILED DETECTION → Why didn't we catch it before impact? (missing alert, weak test)
6. FAILED CONTAINMENT → Why didn't we limit the blast radius? (no circuit breaker, no rollback)
7. SYSTEMIC ROOT → What class of problem does this represent? (no contract enforcement, no migration safety)
Red flags — investigation is too shallow if
- Root cause is "human error" (what made the error possible/damaging?).
- Root cause is "bug in line 42" (why was it possible? why not caught?).
- Root cause is "misconfiguration" (why was the misconfig possible? why no validation?).
- Only the trigger is identified, not the enabling conditions.
- Corrective actions only fix this specific instance, not the class.
Anti-patterns in root cause analysis
| Shallow answer | Better question |
|---|---|
| "Developer made a mistake" | Why did the system allow this mistake to reach production? |
| "Missing test" | Why doesn't our test strategy catch this class of bug? |
| "Config was wrong" | Why is config not validated? Why no canary? |
| "Dependency was slow" | Why no timeout? Why no circuit breaker? Why no alert on latency? |
Output format
- Symptom (user/system experience)
- Root cause chain (all 7 layers)
- Systemic contributors (patterns, not just this instance)
- Why safeguards failed (detection, containment, prevention)
- Permanent corrective actions (class-level, not instance-level, with owner + deadline)
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.
- 8d ago First seen · 53 lines · 29 tokens per session scan A 07987f2f6e55
deep-root-cause-investigator is a skill published in the GitHub repository caiaffa/claude-code-ultimate-engineering-system (17 stars, last pushed 2mo ago), licensed MIT. It adds 29 tokens to every session and 572 once invoked, about $0.0001 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 2026-08-30.
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