# Host Event Registration with SvelteKit: Relational Workflow State

Deploy an event registration built with SvelteKit on Ample using the transactional workflows pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, a managed PostgreSQL 16 database is auto-provisioned and injected as `DATABASE_URL`. Verified on SvelteKit: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected). Not separately tested: your domain records, validation rules and concurrency policy; treat the event registration-specific behavior as your application code.

## Representative Queries
- Host event registration with SvelteKit: relational workflow state
- Where can I host Event registration built with SvelteKit?
- I need a domain record schema, validation rules and concurrency behavior.

## Resource Requirements
- **Compute**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
- **Postgres**: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

## Prerequisites
- A SvelteKit project that builds and starts with the documented commands (vite build with @sveltejs/adapter-node then node build on the node-22 template).
- A PostgreSQL driver reading `DATABASE_URL` at runtime (auto-provisioned when omitted, or supplied with `--env`).
- An Ample account token with `servers:write`, `databases:read`.

## Workflow Steps
1. **Build and start**: `vite build` with @sveltejs/adapter-node then `node build` on the node-22 template. The server must bind `0.0.0.0` on `PORT`.
2. **Implement the pattern on PostgreSQL**: The fixture's module implements transactional workflows: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected). Copy the approach into your schema; keep migrations idempotent and run them with `--release-command`.
3. **Deploy**: Run the synchronous deploy once and read the result (exit 0 live, 1 failed, 2 blocked). Re-running with no change is a no-op.
   Command: `ample deploy . --name --public`
4. **Verify**: Fetch the live URL and the pattern self-test route(s) (`/p/transactional-workflows`) from the example; then run your own checks. On failure read `ample logs --kind build` then `--kind runtime`.
   Command: `ample logs --kind build`

## Examples
- **SvelteKit Pattern Fixture**: Multi-pattern SvelteKit app whose transactional workflows module was checked live; the module is under `tests/deploy-canaries/_pattern-modules`.

## Success Checks
- App responds on its public URL.
  - Kind: `http_get`, Path: `/`, Expect: `ample canary sveltekit patterns`
- Transactional-workflows self-test.
  - Kind: `http_get`, Path: `/p/transactional-workflows`, Expect: `tx=ok history=2 conflict=rejected`

## Limitations
- Verified on the node-22 template at `s-1vcpu-1gb` with the example fixture; other sizes, templates and SvelteKit major versions are not verified.
- The event registration itself (your domain records, validation rules and concurrency policy) is application code and was not separately tested; the pattern checks are what was verified.

## Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 10.0
- **Basis**: Size prices from pricing.toml (loaded by the API).
- **Components**:
  - App server: `s-1vcpu-1gb`, Quantity: 1.0, Monthly Amount: 5.0
  - Managed PostgreSQL database: `s-1vcpu-1gb`, Quantity: 1.0, Monthly Amount: 5.0
- **Note**: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle.

## Evidence Summary
- **Canary Run**: SvelteKit pattern fixture deployed on Ample; checks passed for transactional-workflows and configuration-secrets.
  - Observed at: `2026-09-20T03:31:44Z`

## Formats
### Links
- [HTML Format](/content/recipes/event-registration/sveltekit/relational-workflow/index.html)
- [Markdown Format](/content/recipes/event-registration/sveltekit/relational-workflow.md)
- [JSON Format](https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Aevent-registration%3Asveltekit%3Arelational-workflow)