Scenario 01 — Vite SPA, realistic

What this is

A plausible small application, not an isolating fixture. "Readwell" is a reading app built the way a person would build one today: Vite, React, TypeScript and Tailwind, with the libraries Lovable's older documented stack used.

• Routes with React Router DOM: /, /posts, /posts/:postId (the dynamic segment), /contact, /about, and a catch-all not-found page.
• A shared layout with navigation (src/components/Layout.tsx).
• A form with client-side validation: the contact form, validated with zod, including a date that may not be in the past (src/lib/contactSchema.ts).
• A data layer fetching from JSONPlaceholder, a public read-only API that needs no key, through TanStack Query, with loading and error states (src/lib/api.ts, src/hooks/usePosts.ts, src/components/StatusMessage.tsx).
• Ordinary dependencies: date-fns and lucide-react.
• Nineteen files, fifteen of them under src/ in components/, hooks/, lib/ and pages/ — small enough to read, large enough that a wholesale rewrite would be visible in the diff.

No secrets, no .env, nothing private. No lockfile, for the same reason the fixtures have none: how a platform resolves dependencies is part of what is being tested.

What it probes

The headline claim. stackfit's most important sentence will be that a Vite project imports into Lovable cleanly. So far that rests on 01-vite-react-spa, a single component. A false "works" costs a trust tool far more than a false "breaks", so the happy path needs checking at realistic scale before it is published.

React Router DOM against Lovable's TanStack scaffold. Lovable's own template (5081cd0, see fixtures/evidence/lovable-template-5081cd0.txt) is TanStack Start with file routes. React Router DOM matches Lovable's older documented stack. Whether an app built that way still imports cleanly is untested.

The dev server it lands on. Lovable's dev server runs whatever scripts.dev said when it started and is not restarted when an import arrives. For fixture 02 that meant a Vite server that could not serve a Next.js project. This project is Vite, and Vite restarts itself when its config file changes, so the already-running server may well pick it up. That is a prediction, not an observation.

It did not. On 2026-09-12 the running server still held the scaffold's config and returned HTTP 500 — by the agent's curl output — until Lovable's agent restarted it. The prediction stands here as the record of what was expected.

Fix build, on a codebase big enough to show what it touches. The scripts are what npm create vite produces: dev, build, preview. There is deliberately no build:dev, as in most projects not made by Lovable, so expect the "Build unsuccessful" card that 01-vite-react-spa saw. Pressing Fix build here answers the open question of what it changes. On nineteen files, anything beyond adding a script will be visible.

Fix build was not pressed on 2026-09-12: no card appeared. Lovable's agent, asked why the preview had not been built, added build:dev and src/vite-env.d.ts unasked and changed nothing else. What Fix build does here is still open.

Deep links. /posts/3 loaded directly, not by navigating, needs the server's single-page fallback. vite preview provides it locally; Lovable's preview and its published site are untested.

What to look for

Each page renders text that neither Lovable's scaffold nor another page does, so a glance tells you whether the preview is serving this project:

Page	Look for
/	"Short reads, worth your time." and three post cards
/posts	"All posts", twelve cards, and "Updated … ago"
/posts/3	the post's title, "By …" with an author name, and a list of comments
/contact	"Contact us"; submitting it empty should show four field errors (the date defaults to today, which is valid)
/about	"About Readwell"
/no-such-page	"Readwell could not find that page" — not Lovable's scaffold's own "Page not found"

Record the wall-clock time of everything you see, with its time zone, so it can be placed against Lovable's commits: see "The attribution window" in fixtures/OBSERVATION-LOG.md. Then export Lovable's commits on top of the scenario into fixtures/evidence/, as for the fixtures.

Verified locally

On 2026-09-12: npm install, then npm run build (tsc --noEmit && vite build) passed, and vite preview served /, /posts/3, /contact and /no-such-page with the single-page fallback. It has not been clicked through in a browser.

What our rules predict

Platform	Prediction	Findings
Lovable	risky	Warning: lovable-expects-scaffold-scripts, for the missing build:dev
Bolt	works	Nothing it cannot run
Replit	works	Nothing it cannot run
v0	works	Nothing it cannot run
Base44	works	Nothing it cannot run

Observed

Platform	Date and time	Preview served this app?	Every route renders?	Build error?	Notes
Lovable	2026-09-12, mid-afternoon UTC+3, approximate	embedded: yes, after a dev server restart; standalone: no, "Preview has not been built yet"	yes, in the embedded preview, with real data	no card; by the agent's account TS2882 under tsgo	The agent restarted the dev server unprompted, and added build:dev and src/vite-env.d.ts unasked. Standalone preview still to re-check. See the log.
Bolt
Replit
v0
Base44