Reduces JS/TS bundle size via unused deps, tree-shaking, code splitting with keep/discard
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Type: L3 Worker Category: 8XX Optimization Parent: ln-830-code-modernization-coordinator
Reduces JavaScript/TypeScript bundle size. Metric: bundle size in bytes. Each optimization verified via build with keep/discard pattern. JS/TS projects only.
| Aspect | Details |
|---|---|
| Input | JS/TS project (auto-detect from package.json) |
| Output | Smaller bundle, optimization report |
| Scope | JS/TS only (skip for other stacks) |
Phases: Pre-flight → Baseline → Analyze → Optimize Loop → Report
| Check | Required | Action if Missing |
|---|---|---|
| package.json exists | Yes | Block (not a JS/TS project) |
| Build command available | Yes | Block (need build for size measurement) |
| dist/ or build/ output | Yes | Run build first to establish baseline |
| Git clean state | Yes | Block (need clean baseline for revert) |
MANDATORY READ: Load shared/references/ci_tool_detection.md — use Build section for build command detection.
MANDATORY READ: Load shared/references/git_worktree_fallback.md — use ln-832 row.
1. Run build: npm run build (or detected build command)
2. Measure: total size of dist/ or build/ directory
3. Record: baseline_bytes, baseline_files
| Metric | How |
|---|---|
| Total size | Sum of all files in output directory |
| Per-chunk sizes | Individual JS/CSS file sizes |
| Source map excluded | Do not count .map files |
| Check | Tool | What It Finds |
|---|---|---|
| Unused dependencies | npx depcheck | Packages in package.json not imported anywhere |
| Bundle composition | npx vite-bundle-visualizer or webpack-bundle-analyzer | Large dependencies, duplicates |
| Tree-shaking gaps | Manual scan | import * as instead of named imports |
| Code splitting | Route analysis | Large initial bundle, lazy-loadable routes |
| Category | Example | Typical Savings |
|---|---|---|
| Remove unused deps | lodash installed but not imported | 10-50KB per dep |
| Named imports | import { debounce } from 'lodash-es' vs import _ from 'lodash' | 50-200KB |
| Lighter alternatives | date-fns instead of moment | 50-300KB |
| Dynamic imports | React.lazy(() => import('./HeavyComponent')) | Reduce initial load |
| CSS optimization | Purge unused CSS, minify | 10-100KB |
FOR each optimization (O1..ON):
1. APPLY: Make change (remove dep, rewrite import, add lazy load)
2. BUILD: Run build command
IF build FAILS → DISCARD (revert) → next optimization
3. MEASURE: New bundle size
4. COMPARE:
IF new_bytes < baseline_bytes → KEEP (new baseline = new_bytes)
IF new_bytes >= baseline_bytes → DISCARD (revert, no improvement)
5. LOG: Record result
| Condition | Decision |
|---|---|
| Build fails | DISCARD |
| Bundle smaller | KEEP (update baseline) |
| Bundle same or larger | DISCARD |
| Order | Category | Reason |
|---|---|---|
| 1 | Remove unused deps | Safest, immediate savings |
| 2 | Named imports / tree-shaking | Medium risk, good savings |
| 3 | Lighter alternatives | Higher risk (API changes) |
| 4 | Dynamic imports / code splitting | Structural change, test carefully |
| 5 | CSS optimization | Lowest priority |
| Field | Description |
|---|---|
| project | Project path |
| baseline_bytes | Original bundle size |
| final_bytes | Final bundle size |
| reduction_bytes | Bytes saved |
| reduction_percent | Percentage reduction |
| optimizations_applied | Count of kept optimizations |
| optimizations_discarded | Count + reasons |
| details[] | Per-optimization: category, description, bytes saved |
| deps_removed[] | Unused dependencies removed |
Options:
# Build
build_command: "" # Auto-detect from ci_tool_detection.md
output_dir: "" # Auto-detect: dist/ or build/
# Analysis
run_depcheck: true
run_bundle_analyzer: false # Opens browser, skip in CI
# Optimization scope
remove_unused_deps: true
fix_tree_shaking: true
suggest_alternatives: true
add_code_splitting: false # Structural change, opt-in
# Verification
run_build: true
| Error | Cause | Solution |
|---|---|---|
| depcheck not available | Not installed | npx depcheck (runs without install) |
| Build fails after removal | Dep used in dynamic import / config | Revert, mark as false positive |
| No output directory | Non-standard build setup | Check package.json for output config |
| Not a JS/TS project | No package.json | Skip entirely with info message |
shared/references/ci_tool_detection.md (build detection)Version: 1.0.0 Last Updated: 2026-03-08
まだレビューはありません。使ってみた感想をお寄せください。
概要と使いどころ
Design, implement, and audit inclusive digital products using WCAG 2.2 Level AA standards. Use this skill to generate semantic ARIA for Web and accessibility traits for Web and Native platforms (iOS/Android).
日本語の概要は準備中です。原文の説明を表示しています。
Whole site or product — a full web accessibility (a11y) audit against WCAG 2.2, following the WCAG-EM methodology. Defines scope, samples representative pages and flows, runs the automated tier (`accessibility-scan`) and the hands-on manual tier (`accessibility-inspect`), and produces one conformance report. Grades each finding by severity and evidence basis, and states per-criterion conformance as pass, fail, or undetermined (needs a human). Use it for 'audit my site for accessibility', 'is this product accessible', 'a11y audit', 'WCAG or Section 508 conformance report', or any multi-page assessment. Assesses; does not fix (use `accessibility-fix`) or diff (use `accessibility-diff`). For a single page use `accessibility-scan`; for hands-on keyboard and screen-reader checks use `accessibility-inspect`.
日本語の概要は準備中です。原文の説明を表示しています。
Regression check — diff a live page's web accessibility (a11y) violations against a baseline. By default it compares your uncommitted changes (stash-based); pass `--branch [<name>]` to compare against a branch. Reports the new WCAG violations introduced, the ones fixed, and the count of pre-existing ones. Use it for 'did my change break accessibility', 'what a11y issues did this PR add', or as a CI gate. For a full scan of one page use `accessibility-scan`; for a whole site use `accessibility-audit`.
日本語の概要は準備中です。原文の説明を表示しています。
Remediation only — repair web accessibility (a11y) violations against WCAG 2.2 with a baseline, edit, and verify loop. Takes a target (URL, files, directory) or a findings worklist from `accessibility-scan`/`accessibility-inspect`/`accessibility-audit`, applies mechanical fixes as given, leaves TODOs for visual or contextual judgment, and verifies by re-running the baseline check. It only fixes. To find issues use `accessibility-scan` (one page, automated), `accessibility-inspect` (one page, manual), or `accessibility-audit` (whole site, WCAG-EM); to check for regressions use `accessibility-diff`. Use it for 'fix the a11y issues in X', 'make this accessible', 'add missing alt text and labels', 'apply these accessibility fixes', 'remediate these violations'.
日本語の概要は準備中です。原文の説明を表示しています。
One page, hands-on manual tier — drive a live page through the web accessibility (a11y) checks a rule engine can't decide: keyboard operation and focus order, screen-reader names, roles and states from the accessibility tree, reflow and zoom, reduced motion, form errors, and target size. Grades each finding by evidence basis (verified / confirm-with-a-human / human-required) and severity, and closes every criterion in a ledger: verified, flagged, not exercised, or N/A. Locates and assesses; does not fix (use `accessibility-fix`). Use it for keyboard testing, focus-order checks, screen-reader or a11y-tree review, reflow and zoom at 200%, or 'is this operable, not just lint-clean'. The automated tier is `accessibility-scan`; `accessibility-audit` runs both across a sampled site.
日本語の概要は準備中です。原文の説明を表示しています。
One page, automated tier — run the web accessibility (a11y) rule engine against a live page and locate every violation it can detect mechanically. Pass a URL, a config target name (e.g. `accesslint:accessibility-scan dev`), or nothing to use the default target from `accesslint.config.json`. Ensures a debuggable Chrome, runs the @accesslint/core engine over CDP, and returns a worklist of live-DOM WCAG 2.2 violations, each grounded to its DOM selector and source `file:line`. Locates; doesn't edit. Use it for 'is this page accessible', 'check a11y on this URL', 'find contrast and alt-text issues', or to verify a UI change. For hands-on keyboard and screen-reader checks use `accessibility-inspect`; for a whole site or product use `accessibility-audit`; to diff against uncommitted changes or a branch use `accessibility-diff`.
日本語の概要は準備中です。原文の説明を表示しています。