dart-intellij-third-party: Skill for Claude Code

.agents/skills/root-cause-regression/SKILL.md

root-cause-regression is a skill for Claude Code, Codex from flutter/dart-intellij-third-party. It costs 47 tokens per session (478 once invoked), scanned A, original, BSD-3-Clause.

A guided investigation for finding which recent code change likely caused a bug reported in a GitHub issue.

In plain words
What is it for?
Use it to inspect an issue, identify when the problem began, review commits and changed files, and suggest possible causes.
Why use it?
It narrows a regression to a likely commit by connecting the reported symptoms and timing with recent changes.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is flutter/dart-intellij-third-party's own configuration. It tells Claude Code and Codex how to work on dart-intellij-third-party itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything dart-intellij-third-party configures →

Reuse

Borrowing it

Nothing to install: this file belongs to flutter/dart-intellij-third-party. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/flutter/dart-intellij-third-party/main/.agents/skills/root-cause-regression/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/flutter/dart-intellij-third-party

Made for: Claude Code, Codex.

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 root-cause-regression

README.md
[![agentmods](https://agentmods.dev/badge/skills/flutter/dart-intellij-third-party/root-cause-regression/github.svg)](https://agentmods.dev/skills/flutter/dart-intellij-third-party/root-cause-regression)
Your own site
<a href="https://agentmods.dev/skills/flutter/dart-intellij-third-party/root-cause-regression"><img src="https://agentmods.dev/badge/skills/flutter/dart-intellij-third-party/root-cause-regression/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 root-cause-regression

Your own site · 80×15
<a href="https://agentmods.dev/skills/flutter/dart-intellij-third-party/root-cause-regression"><img src="https://agentmods.dev/badge/skills/flutter/dart-intellij-third-party/root-cause-regression.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 478 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00047 $0.00478
Opus 5 $0.00023 $0.00239
Sonnet 5 $0.00009 $0.00096
Haiku 4.5 $0.00005 $0.00048

Measured 9d ago against content hash ac11c81c6147, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

root-cause-regression 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 9d 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.

.agents/skills/root-cause-regression/SKILL.md · 24 lines

What it actually says

Root Cause Regression Analysis

This skill guides you through investigating a GitHub issue to find the likely commit that caused a regression.

Steps

  1. Read the Issue:
    • Primary: Use the github MCP server (issue_read or equivalent) to fetch the details of the issue.
    • Fallback: If the github MCP server is not available, try using the gh CLI (e.g., gh issue view <number>) or ask the user to paste the issue description into the chat.
    • Understand the symptoms of the regression and when it started happening.
  2. Identify the Timeframe: Determine the approximate timeframe when the regression was introduced based on the issue description, comments, and reported version. If the timeframe isn't clear, ask the user or look at the repository's recent releases.
  3. Fetch Recent Commits: Use search_commits or list_commits from the github MCP server. If unavailable, fall back to local git commands (e.g., git log --since="<date>" --until="<date>") to fetch commits within the suspected timeframe.
  4. Analyze Commits: Review the commit messages, changed files, and diffs for the suspected commits.
    • Look for changes related to the systems, files, or components mentioned in the regression issue.
    • Use get_commit (MCP) or git show (local) to view the details of specific commits.
  5. Synthesize Findings: Compile a list of the top suspect commits. For each suspect, explain why it is a potential culprit based on the code changes and how they relate to the regression symptoms.
  6. Report Findings: Generate a clean, well-formatted markdown Artifact containing your analysis. Present the findings clearly so the user can easily review the information and paste it into the GitHub issue UI if they choose to. Do not post the comment directly to GitHub.
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. 9d ago First seen · 24 lines · 47 tokens per session scan A ac11c81c6147

Subscribe to this mod's changes

root-cause-regression is a skill published in the GitHub repository flutter/dart-intellij-third-party (25 stars, last pushed today), licensed BSD-3-Clause. It adds 47 tokens to every session and 478 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 2026-08-30.

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