Track example migrations from existing Rails + React apps

[justin808]

React on Rails Migration Examples: Meta Tracking Issue

This issue tracks open-source Rails applications that are strong candidates for incremental migration to react_on_rails, along with the public PRs, blockers, benchmark notes, and follow-up work.

Public docs should only carry durable example references. This issue is the better home for in-progress third-party PRs, maintainer-contact notes, and other working material that may change quickly.

The goal is not to rewrite large apps wholesale. The goal is to prove a repeatable migration path from existing Rails-plus-React stacks such as react-rails, webpacker, shakapacker, vite_rails, and custom Rails React bridges.

Why This Matters

Teams evaluating react_on_rails want proof from real applications, not only toy examples.

The most credible evidence is:

1. Real open-source Rails repos
2. Narrow migration PRs
3. Reproducible before-and-after notes
4. Performance or maintainability evidence for each migrated slice

Selection Policy

1. Prefer very popular or institutionally credible Rails applications.
2. Favor apps already using React with Rails in some form.
3. Keep the first PR small enough to review quickly.
4. Avoid obscure dependencies or novelty migrations that do not help the main adoption story.
5. Treat Inertia-first apps as stretch targets unless the point is to document architecture differences.

First-Wave Status

Repo	Stars	Current Integration	Status	PR	Evidence so far	Missing proof
EFForg/action-center-platform	517	react-rails	PR ready for review	#975	Contributor-local benchmark note captured: warm request time and total JS weight both decreased for the slice; local maintainability note is captured for the new explicit Rails prop boundary and the narrowed page-scoped React on Rails entrypoint; local webpack compilation passes, the repo Docker build now passes with the Node 20 + Yarn-aligned container fix, and compose-backed db:test:prepare plus the focused request/helper specs pass	Optional browser-level proof if a maintainer asks for stronger route evidence; otherwise the next step is maintainer review
thewca/worldcubeassociation.org	383	react-rails	PR ready for review and mergeable	#14010	Local maintainability note captured for the legacy disclaimer page; after rebasing onto upstream main, the compose-backed disclaimer request spec, Shakapacker build, Corepack Yarn lint, and focused RuboCop all pass with the legacy-helper coexistence override	Optional CI confirmation or one more low-risk legacy Rails slice if maintainers want broader proof; otherwise the next step is maintainer review
demarche-numerique/demarche.numerique.gouv.fr	259	vite_rails + custom React bridge	Closed after maintainer feedback	#12954	Focused component spec passed; local maintainability note captured for replacing a custom coldwired/react mount contract with a maintained helper contract	External blocker: maintainer said the repo depends on coldwired updating React components during DOM morphs, so this migration slice is not a fit for their architecture
GSA/search-gov	68	react-rails + Shakapacker	PR rebased and mergeable; CircleCI in progress	#2010	Branch rebased onto upstream main at fa0ea57fb; focused Jest passes locally for SearchResultsLayout, SearchResultsHeader, and SearchResultsFooter; GitHub now reports the PR as mergeable; CircleCI is in progress after the force-push with checkout code and jest green while rspec and cucumber are still pending; local maintainability note captured for splitting low-coupling SERP chrome into smaller mounts; PR rationale already explains the maintainability-first value of shrinking the shell boundary without rewriting the results body	Wait for the remaining CircleCI jobs; optional public-friendly benchmark note if stronger marketing proof is needed; otherwise the next step is maintainer review
hackclub/hcb	845	react-rails	PR ready for review and mergeable	#13489	After rebasing onto upstream main, the repo Dockerfile rebuilds successfully, compose-backed db:test:prepare plus the focused bookkeeping controller spec pass, yarn build, yarn build:css, focused RuboCop, and yarn lint all pass once the app uses an explicit React-on-Rails alias plus a legacy-helper coexistence override; local maintainability note is captured for that coexistence path; asset-level comparison shows bundle.js moved from 2,739,714 to 2,754,760 bytes while yarn build improved from 10,035 ms to 9,101 ms	Optional browser-level pass if stronger public performance proof is needed; otherwise the next step is maintainer review
broadinstitute/single_cell_portal_core	70	vite_rails + custom window.SCP.renderComponent bridge	Draft PR open	#2381	Local helper-test, focused Jest, and vite build --force --clear all pass for the studies#usage_stats slice; asset-level comparison shows application-*.js moved from 2,083,391 to 2,099,314 bytes while full rebuild time moved from 22,947 ms to 23,486 ms	Controller/request-level HTML proof once Mongo-backed test auth is available

Second-Wave Targets

These matter, but they are weaker first proof points than the current wave.

Repo	Stars	Current Integration	Current status
thecartercenter/nemo	65	react-rails + shakapacker	PR ready for review: #1110. Fresh local db:setup, compile, react_on_rails:doctor, request spec, system spec, RuboCop, and focused JS lint all pass; shared global components chunk dropped from 305,252 to 293,091 bytes; request harness measured 35.01 ms / 32,009 HTML bytes / 11 script tags baseline versus 44.20 ms / 33,068 HTML bytes / 16 script tags migrated, so the honest claim is maintainability plus shared-bundle reduction, not route-level speedup
Codeminer42/cm42-central	324	vite_rails + React	Draft PR open: #1029. Local Docker/Linux validation passes: db:setup, focused controller spec, focused JS specs, ESLint, and vite build all succeed; the built application-*.js bundle moved from 2,193,537 to 2,209,328 bytes; request harness measured /projects at 39.74 ms / 8,081 HTML bytes / 6 scripts baseline versus 45.62 ms / 7,746 HTML bytes / 8 scripts migrated, so this remains a maintainability-first slice
broadinstitute/single_cell_portal_core	70	vite_rails + custom window.SCP.renderComponent bridge	Draft PR open: #2381. Local helper-test, focused Jest, and vite build --force --clear pass; the built application-*.js bundle moved from 2,083,391 to 2,099,314 bytes
indentlabs/notebook	398	react-rails + Webpacker (ReactRailsUJS auto-mount)	Compile still passes locally, but a real landing-page request now fails because the migrated helper expects config/shakapacker.yml; the branch is therefore blocked on whether to add real Shakapacker config or stage a broader migration first
saeloun/miru-web	256	vite_rails + SPA root	Local Ruby and package installs pass, but the router still falls through home#index into one global Vite entrypoint that mounts a single #react-root, so this is an app-shell case study rather than an incremental island migration
codeforpdx/dwellingly-app	49	react-rails with SPA routing	Local work is blocked by the pinned Ruby 3.0.1 not building on this macOS arm64 host
rubyforgood/demand-progress	56	Webpacker + ad hoc React mount	Local work is blocked by the locked Ruby 2.5.1 not building on this macOS arm64 host

Stretch and Blocked Targets

Repo	Status	Reason
antiwork/gumroad	Stretch target	Important repo, but it is Inertia-first and is not the cleanest first proof point
exercism/website	Process-blocked	Useful technically, but the repo documents that outside PRs are not accepted

Whale Targets

These are the high-value proof points that should come after the first wave is clearly credible.

Repo	Stars	Current Integration	Notes
mastodon/mastodon	49,825	vite_rails + React	Probably the most visible Rails + React migration story if a narrow slice can be found
gitlabhq/gitlabhq	24,295	vite_rails + React	Worth documenting, but too broad for the first implementation wave

Institutional Middle Tier

These are not whales, but they are still strong proof points once the first wave is done.

Repo	Stars	Current Integration	Why it matters	Recommendation
thecartercenter/nemo	65	react-rails + shakapacker	Institutionally credible and still close to the classic migration story	Keep using ready PR #1110 as the second-wave institutional proof point; the first slice is maintainability-first, shows an honest shared-bundle reduction and clean coexistence path, and now explicitly documents that the admin route itself is not faster in the local request harness
Codeminer42/cm42-central	324	vite_rails + React	Strong star count and real page-scoped mounts instead of a catch-all SPA shell	Move this up with nemo; draft PR #1029 is now open for the validated projects.index slice with asset and request-harness notes
broadinstitute/single_cell_portal_core	70	vite_rails + custom window.SCP.renderComponent bridge	Broad Institute credibility plus a repo-owned Rails-to-React mount contract makes it a meaningful non-demo proof point	Promote alongside cm42-central; draft PR #2381 is open for the validated studies#usage_stats slice, and the remaining gap is Mongo-backed controller/request proof
digitalepidemiologylab/crowdbreaks	12	Webpacker + webpacker-react	Research-institution ownership gives it some signal, but it is the weakest of this tier	De-prioritize behind the other institutional targets

Reference Repos Already On React on Rails

These are useful references. Some are also legitimate upgrade-PR candidates.

Repo	Current stack snapshot	Upgrade fit	Recommendation
ifmeorg/ifme	react_on_rails 12.0.1, webpacker 5.4.4, React 17	Strong	Fork branch justin808/ifme:codex/upgrade-react-on-rails-16 is pushed and locally revalidated; upstream PR is blocked only by the project's Slack-first contribution process
houdiniproject/houdini	gem react_on_rails 12.6.0, JS package 12.2.0, webpacker 5.4.4, React 17	Strong	Still worth an upgrade PR, but current local work is blocked before app code because Ruby 3.0.7 is brittle on this macOS arm64 host and the patched local install was not healthy enough to run Bundler
avalonmediasystem/avalon	react_on_rails 14.2.1, shakapacker 8.3.0, React 19	Good	Queue after ifme and houdini, but first fix the missing pinned active-fedora git revision in the baseline app
sharetribe/sharetribe	react_on_rails 13.0.2, React 16	Weak	Do not prioritize; the repo says it is no longer actively maintained
hostolab/covidliste	react_on_rails 12.2.0, webpacker 5.3.0, React 17, Node 12	Weak	Do not prioritize; activity looks too stale for unsolicited upgrade work

Known Cross-Cutting Blockers

1. Existing Rails apps use materially different integration stacks, so this is not a single codemod problem.
2. Some repos have heavy local setup or native dependency chains that block fast validation, so benchmark and request-proof notes need a pinned Docker or service-backed environment instead of a half-working host install.
3. Large repos often require very narrow PR scope to be reviewable upstream.
4. Performance or maintainability evidence needs a shared method or the results will not be credible.

Related Issues and PRs

• Docs PR: #3126 merged
• Proof-artifacts issue: #3127
• Legacy Webpacker compatibility follow-up: #3136
• React 16/17 react-dom/client warning follow-up: #3137
• Docs follow-up for legacy migration guidance: #3138
• Helper-name collision follow-up: #3143
• Vite package-manager check follow-up: #3145
• Nested client/ package layout follow-up: #3205
• Related but different scope: #1985 for RSC migration success stories
• Framework-level benchmarking issue: #2169
• Benchmark workflow issue: #2546

What Is Still Missing

1. A public-friendly publication path for the local proof notes now that the example-migrations docs page has landed
2. A public browser benchmark note for at least one more repo beyond ACP. nemo now has both asset and request-harness notes, but the request result is maintainability-first rather than a speedup story and it still needs a browser waterfall pass before it becomes a stronger public benchmark
3. A decision on whether Gumroad stays in the migration queue or becomes an Inertia case study
4. A later whale-target scouting pass once the first wave lands
5. A decision on which institutional middle-tier repo should become the next serious target after the current wave once nemo maintainer feedback lands
6. A reusable benchmark environment for side-by-side demos and videos that includes the service dependencies some apps need for request-level proof
7. A product/docs answer for supported upgrades where JS dependencies intentionally live under client/ rather than the Rails root

[justin808]

I pushed codex/example-migrations-docs and am opening the companion docs PR now so this issue can serve as the broader tracking thread for public migration examples and benchmark notes.

[justin808]

Companion docs PR is open: #3126

[justin808]

Companion issue for the missing proof work is now open: #3127. I am using #3125 for the target queue and public migration pipeline, and #3127 for the concrete performance/maintainability evidence that each example still needs.

[justin808]

Follow-up issues opened from the indentlabs/notebook migration findings:

• Legacy Webpacker/Webpack 4 apps need package-specific compatibility shims on react_on_rails 16.6.0 #3136 Legacy Webpacker/Webpack 4 apps need package-specific compatibility shims on react_on_rails 16.6.0
• React 16/17 apps still see a react-dom/client resolution warning on react_on_rails 16.6.0 #3137 React 16/17 apps still see a react-dom/client resolution warning on react_on_rails 16.6.0
• Docs: add explicit legacy Webpacker and migration-fit guidance #3138 Docs: add explicit legacy Webpacker and migration-fit guidance

This keeps the meta issue focused on repo tracking while the framework-level compatibility and docs gaps get their own work items.