Analyze Bundle Agent Skill

by vercel-labs

Convert Next.js bundle analyzer data to NDJSON and explore it

616 tokens

context cost

the whole folder, loaded on every use

files

instructions only

copies elsewhere

how many repositories repackaged it

1561

stars on the repo

on the repository, not the skill itself

Install

one command, takes just this skill from the repository

npx skills add https://github.com/vercel-labs/dev3000 --skill analyze-bundle

What it tells the agent to use

found in the instruction text

Bash runs shell commands — read the instruction before connecting

The instruction itself

10 sections, as written by the author

analyze-to-ndjson

Converts Next.js bundle analyzer binary .data files into grep/jq-friendly NDJSON.

Analyze artifacts

This workflow pre-generates analyzer artifacts in:

.next/diagnostics/analyze/ndjson/routes.ndjson
.next/diagnostics/analyze/ndjson/sources.ndjson
.next/diagnostics/analyze/ndjson/output_files.ndjson
.next/diagnostics/analyze/ndjson/module_edges.ndjson
.next/diagnostics/analyze/ndjson/modules.ndjson

Focus on reading these files and using their evidence to prioritize changes.

Output files

| File | What's in it |

|---|---|

| modules.ndjson | Global module registry (id, ident, path) |

| module_edges.ndjson | Module dependency graph (from, to, kind: sync/async) |

| sources.ndjson | Per-route source tree with sizes and environment flags |

| chunk_parts.ndjson | Granular size data: one line per (source, output_file) pair |

| output_files.ndjson | Per-route output files with aggregated sizes |

| routes.ndjson | Route-level summaries |

Browsing the output

Route overview

jq -s 'sort_by(-.total_compressed_size)' .next/diagnostics/analyze/ndjson/routes.ndjson

Find large sources

jq -s '
  group_by(.full_path)
  | map(max_by(.compressed_size))
  | sort_by(-.compressed_size)
  | .[0:10]
  | .[] | {full_path, compressed_size, size, route}
' .next/diagnostics/analyze/ndjson/sources.ndjson

Client-side JS

grep '"client":true' .next/diagnostics/analyze/ndjson/sources.ndjson \
  | grep '"js":true' \
  | jq -s 'sort_by(-.compressed_size) | .[0:10] | .[] | {full_path, compressed_size}'

Module dependencies

grep '"from":42,' .next/diagnostics/analyze/ndjson/module_edges.ndjson | jq .to
grep '"to":42,' .next/diagnostics/analyze/ndjson/module_edges.ndjson | jq .from
grep 'react-dom' .next/diagnostics/analyze/ndjson/modules.ndjson | jq '{id, path}'

Output files for a route

grep '"route":"/"' .next/diagnostics/analyze/ndjson/output_files.ndjson \
  | jq -s 'sort_by(-.total_compressed_size) | .[0:10] | .[] | {filename, total_compressed_size, num_parts}'

Directory tree for a route

grep '"route":"/"' .next/diagnostics/analyze/ndjson/sources.ndjson \
  | jq 'select(.parent_id == null)'

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How to use it

Copy the folder

Take vercel-labs/analyze-bundle from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.