perf: form-bundle rollup pipeline — collapse serial ES module hops (FORMS-24968)

[dmaurya929]

Summary

Ports the FORMS-24968 performance enhancement from the HDFC forms-engine project to aem-boilerplate-forms so all downstream EDS Forms projects inherit the gains.

What this does: bundles form.js + rules/index.js and their static deps into a single form-bundle.min.js via Rollup, eliminating 5+ serial ES module fetches that currently block form startup. Adds <link rel="modulepreload"> hints in head.html so the browser fetches all critical modules in parallel during HTML parse.

Performance impact (measured on HDFC staging)

Metric	Before	After	Delta
JS request count	12 fetches	1 bundle + 2 shims	−11 requests
Serial import hop depth	~5 levels	2 hops	−3 levels
Bundled payload	29,709 B raw	25,788 B minified	−13%
Worker startup size	39,178 B	26,850 B	−31%
modulepreload hints in head	0	5	+5

Changes

• rollup/form.rollup.config.js — new Rollup config; dual output (unminified dev + terser prod); redirectRulesIndex plugin handles boilerplate's repeat.js importing subscribe from rules/index.js
• blocks/form/form.source.js — full form logic as Rollup input (never served at runtime)
• blocks/form/rules/index.source.js — full rules logic as Rollup input
• blocks/form/form.js — replaced with 1-line shim re-exporting from form-bundle.min.js
• blocks/form/rules/index.js — replaced with 1-line shim re-exporting subscribe from form-bundle.min.js (preserves singleton formSubscriptions Map for custom components)
• blocks/form/rules/RuleEngineWorker.js + functionRegistration.js — switched to afb-runtime.min.js (−31% worker startup)
• scripts/swap-shims.js — dev↔prod toggle; npm run build (prod) / npm run build:dev (dev + sourcemaps)
• package.json — adds build, build:dev, build:form-bundle scripts
• head.html — 5 <link rel="modulepreload"> hints for form.js, form-bundle.min.js, constant.js, afb-runtime.min.js, afb-formatters.min.js
• .husky/pre-commit.mjs — shim guard blocks commits that reference unminified bundles (dev-mode left on)
• blocks/form/form-bundle.js + form-bundle.min.js — generated bundles committed to repo

Test plan

• npm run build completes without errors; form-bundle.js (110 KB) and form-bundle.min.js (56 KB) are generated
• npm run build:dev flips all shims to .js; npm run build flips them back to .min.js
• Pre-commit guard: stage blocks/form/form.js after build:dev → commit should fail with ERROR: ... points at an unminified bundle
• Load a form page locally; verify form renders, rules fire, and custom component subscriptions work
• Network tab: only form.js (shim) + form-bundle.min.js fetched for form logic — no separate rules/index.js, util.js, etc.
• DevTools Network: all 5 modulepreload resources show (preload) initiator

Related

JIRA: https://jira.corp.adobe.com/browse/FORMS-24968

🤖 Generated with Claude Code

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Commits

• c0aa014 ✅ (latest)