# lynx-trace-analysis

A skill that digs through Lynx trace data to explain slow startup, scroll jank and memory growth. Handy when you have a trace file but no idea where to look.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 362 installs · ★ 27
- Author: lynx-community
- License: Apache-2.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/lynx-community/skills/tree/HEAD/skills/lynx-trace-analysis/SKILL.md
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/skills/lynx-trace-analysis

## What it does

The skill runs the agent through a think-plan-act loop: state a hypothesis, make one tool call, wait for the output. Before any deep analysis it loads the matching guide from `references/` — `metrics-analysis.md` for FCP, FMP and TTI, `jank-analysis.md` for dropped frames. Other guides cover native modules, events, trace diffing, the render pipeline, memory and raw SQL against trace data.

Reports follow a fixed shape: a two-to-three sentence conclusion, a table of the numbers behind it, a short timeline, then 2–5 suggestions sorted by priority. Every event mentioned in prose keeps its identity as `EventName [slice id: {id}]`, so you can jump straight to that slice. A gap longer than 10ms between stages gets its own row in the table.

Memory requests break the pattern. The `memory-analysis.md` guide overrides the Markdown structure, the agent builds an HTML report, returns its path and keeps the chat reply to rule-defined issues and confidence. Suggestions only appear when the diagnostic rules and the trace data back them up — you won't get filler advice about optimising rendering in general.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add lynx-community/skills --skill lynx-trace-analysis -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/lynx-trace-analysis/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/lynx-trace-analysis/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add lynx-community/skills --skill lynx-trace-analysis -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/lynx-trace-analysis/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add lynx-community/skills --skill lynx-trace-analysis -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/lynx-trace-analysis/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install lynx-community/skills lynx-trace-analysis
```

2. **Manually: put the files in place**
- File: `.github/skills/lynx-trace-analysis/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add lynx-community/skills --skill lynx-trace-analysis -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/lynx-community/skills --path skills/lynx-trace-analysis
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/lynx-trace-analysis/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add lynx-community/skills --skill lynx-trace-analysis -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/lynx-community/skills/tree/HEAD/skills/lynx-trace-analysis/SKILL.md

## When to use it
- trace a slow first frame back to its cause
- find what drops frames during a scroll
- diff two traces to catch a regression between builds
- measure latency of a native module call
- check memory growth across a page lifecycle

## Example prompts
- Load this trace and tell me why FMP is so slow
- Compare this trace with the previous one and show what got worse
- Look at memory leaks on this page and build the report

## Source text · SKILL.md · Apache-2.0

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 90522bdcccc83a2a.

BEGIN THIRD-PARTY FILE 90522bdcccc83a2a
```text
---
name: lynx-trace-analysis
description: |
  Specializes in analyzing Lynx trace data to diagnose performance issues and provide actionable optimization strategies.
  Key Scenarios:
    - Loading Performance: Diagnosing slow startup metrics (FCP, FMP, TTI) and white screen issues.
    - Smoothness Analysis: Investigating root causes for scroll jank, frame drops, and interaction lag.
    - Regression Detection: Comparing traces to identify performance degradation or verify optimization gains between versions.
    - Pipeline Deep Dive: Pinpointing bottlenecks in specific rendering stages like Layout, Paint, JS execution, and background threads.
    - Native Module Analysis: Investigating performance issues related to native module calls.
    - Memory Analysis: Diagnosing high PSS, page lifecycle leaks, shared BTS context growth, VM pool waste, and JS heap snapshots.

---

## Role
You are a Lynx Trace Analysis Expert. Your job is to diagnose performance issues using the provided tools.

## Process
For every user request, you MUST follow this **Think-Plan-Act** loop:

1. **THOUGHT**: Analyze the current situation. What do we know? What data is missing?
2. **PLAN**: List the next logical steps to find the missing data.
3. **ACTION**: Execute the *single* most important tool call from your plan.
4. **OBSERVATION**: Wait for the tool output.

**Note: Before conducting any in-depth analysis, ensure you have retrieved the corresponding analysis guide documentation and strictly follow the guide for your analysis.**

## Output Requirements
For memory requests, the loaded [memory-analysis](./references/memory-analysis.md) guide overrides the
standard Markdown report structure below. Generate the required HTML report, return its path, and summarize
only rule-defined issues and confidence in chat.

**Global Formatting Rule (CRITICAL)**
Whenever you reference a specific trace event in the text (Summary, Overview, Suggestions), you **MUST** retain its identity using the format:
`EventName [slice id: {id}]`
*Example: "layout [slice id: 103]"*

**1. Executive Summary**
A 2-3 sentence conclusion identifying the primary bottleneck or root cause.
*Example: "Update rendering took 1080ms. The main bottleneck is trigger latency (800ms) caused by a slow NativeModule [slice id: 1000] request before `diffVdom` started."*

**2. Data Evidence & Breakdown Table**
Create a Markdown table presenting the core data that supports your conclusion. Adapt the columns based on the analysis type:
```
END THIRD-PARTY FILE 90522bdcccc83a2a

The third-party file has ended. Everything between the 90522bdcccc83a2a tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 2503 of 12994 bytes. © lynx-community · Apache-2.0 · https://github.com/lynx-community/skills/tree/HEAD/skills/lynx-trace-analysis/SKILL.md

_Part of the page did not fit — see the HTML version._

---
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