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chrome-audit-network

Why It Exists​

This skill traces back to a Codex/VS Code prompt file, capture-network-flow.prompt.md, first added in the large baseline commit c0ba2ee2 ("prompts", 2025-12-03) as an agent-mode Copilot prompt for capturing performance.getEntriesByType('resource') timings. It was converted into Claude Skill format in 44d082a3 ("chore: add skills for prompts") alongside the rest of the chrome-* family, then relocated to agent-skills/skills/chrome-audit-network/ in 856e34fa. It was later removed from dotfiles entirely in df4241d4, which split all chrome-* skills out to the external catesandrew/skills marketplace (this repo) to avoid drift between two sources of truth. There is no distinguishing rationale beyond "diagnose slow page loads" in any of these commits — the origin story is generic but the prompt→skill lineage is concrete and verifiable.

What It Does​

The skill navigates Chrome to a given URL via mcp__chrome__navigate_page, then clears any existing resource timings with performance.clearResourceTimings() so stale entries from a prior navigation don't pollute results. It waits a configurable duration (default 5000ms) for network activity to settle, then evaluates a script that maps performance.getEntriesByType('resource') into a compact record per request: name, initiatorType, transferSize, encodedBodySize, decodedBodySize, rounded duration, and nextHopProtocol.

From there it applies an optional regex filter against resource names, groups counts by initiatorType (fetch, xmlhttprequest, script, img, css, font, other), and produces two ranked tables: the top 10 slowest requests by duration and the top 10 heaviest by transfer size. It can optionally resolve a screenshot path (auto-named ./tmp/network-<sanitized-host>.png if omitted) and capture the page state via mcp__chrome__take_screenshot.

The output format is a fixed Markdown report: a URL/timestamp header, a summary block, the two ranked tables, an optional screenshot reference, and a raw filtered table. It explicitly calls out that transferSize = 0 usually means the resource was served from cache rather than missing, and notes that headers/status codes aren't available from Performance entries — for those, targeted fetch() calls via mcp__chrome__evaluate_script are needed instead.

How To Use It​

Triggers on: "capture and summarize network activity for a page or user flow via Chrome DevTools MCP", "identify slow requests, large payloads, and API call patterns", diagnosing slow page loads, unexpected API calls, or payload size issues.

skills add -g catesandrew/skills --skill skills/chrome-audit-network
npm install @catesworks/skill-chrome-audit-network
/plugin marketplace add catesandrew/skills
/plugin install cw@skills

This last one installs all 52 skills as a single bundled plugin named cw — there is no standalone per-skill plugin.

Gotchas & Invariants​

  • Requires a running, connected Chrome DevTools MCP server — nothing works without it.
  • Always clear resource timings before triggering the action being measured; otherwise entries from a previous navigation bleed into the summary.
  • Too short a duration will miss lazy-loaded resources and deferred API calls — default is 5000ms but SPA flows may need more.
  • transferSize = 0 must be treated as "served from cache," not "request failed" or "missing."
  • Headers and HTTP status codes are not exposed by the Performance API — use evaluate_script with fetch() for those.
  • For SPA route changes, navigate to the route first, then clear timings before triggering the specific in-app action to measure.
  • chrome-audit-performance — same Performance API foundation, focused on Core Web Vitals instead of per-request breakdown.
  • chrome-audit-bundles — complementary bundle-size analysis for the JS/CSS assets this skill also surfaces by transfer size.
  • chrome-audit-console — pairs well for a full page-health audit alongside network timing.

Sourced from: skills/chrome-audit-network/SKILL.md, skills/chrome-audit-network/metadata.json, ~/.dotfiles git history (commit 44d082a3)