inspect-elements

name

inspect-elements

description

Resolve on-screen 5chan DOM elements to React source files, line numbers, component names, and ownership stacks using the app's dev-only element-source helpers and playwright-cli. Use when an agent needs to inspect a page element, map a snapshot ref to source code, confirm which component rendered a node, or follow up after $profile-browsing finds a rerender hotspot and needs file-level attribution.

Inspect Elements

Use this skill to jump from a concrete DOM node in the running 5chan app to the React file and component stack that produced it.

Prerequisites

• Dev server running at https://5chan.localhost
• playwright-cli installed
• Use the local dev app, not production. The element-source helpers are only exposed in dev mode.

Quick workflow

1. Open the target route with playwright-cli.
2. Run playwright-cli snapshot and choose the relevant element ref.
3. Resolve that ref through the app helper:

playwright-cli -s=inspect eval "async el => JSON.stringify(await window.__ELEMENT_SOURCE__.resolve(el))" e7

The result includes:

• source: the most useful file/line match for the element
• componentName: the nearest meaningful React component
• stack: ownership stack from the concrete node upward
• tagName: the underlying DOM tag

Session setup

playwright-cli -s=inspect open https://5chan.localhost
playwright-cli -s=inspect goto https://5chan.localhost/all
playwright-cli -s=inspect eval "window.__ELEMENT_SOURCE__?.ready ?? false"
playwright-cli -s=inspect snapshot

If ready is false, wait a moment and evaluate again. If window.__ELEMENT_SOURCE__?.error is set, report that error instead of continuing.

Resolve strategies

Prefer snapshot refs because they target the exact live DOM node you just inspected.

Snapshot ref

playwright-cli -s=inspect eval "async el => JSON.stringify(await window.__ELEMENT_SOURCE__.resolve(el))" e7

Selector

Use this only when the element is easy to target and a snapshot ref is not practical.

playwright-cli -s=inspect eval "JSON.stringify(await window.__ELEMENT_SOURCE__.resolveBySelector('[data-testid=\"composer\"]'))"

Screen coordinates

Useful when you have a screenshot or a visually obvious hotspot.

playwright-cli -s=inspect eval "JSON.stringify(await window.__ELEMENT_SOURCE__.resolveAtPoint(320, 420))"

Format the ownership stack

playwright-cli -s=inspect eval "async el => { const info = await window.__ELEMENT_SOURCE__.resolve(el); return JSON.stringify({ ...info, formattedStack: window.__ELEMENT_SOURCE__.formatStack(info.stack, 5) }); }" e7

Use formattedStack when you need a short, readable trace for the final report.

Profiling follow-up

When $profile-browsing reports a hot route or rerender-heavy area:

1. Reopen the route in a fresh playwright session.
2. Snapshot the concrete list item, card, modal, or toolbar node that looks relevant.
3. Resolve it with window.__ELEMENT_SOURCE__.resolve(...).
4. Use source.filePath as the direct edit target and stack to understand parent ownership.

This is a complement to react-scan, not a replacement. react-scan tells you which components rerender too often. inspect-elements tells you which exact source file produced the node you are looking at.

Rules

• Prefer snapshot refs over brittle selectors.
• Inspect the actual node the user cares about, not a distant wrapper, unless wrappers are the suspected problem.
• If source is null but stack exists, use the first useful stack frame rather than guessing.
• If both source and stack are empty, report that the node could not be resolved and pick a nearby parent element instead.