### Host ai chat application with Express: Postgres-backed state

Deploy a ai chat application built with Express on Ample using the durable job state 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 Express: a jobs table with a state and attempts counter, processing inside a row-locked transaction, and a second run that is a no-op (job=done attempts=1 idempotent=true). Not separately tested: your job types, payload schema and retry policy; treat the ai chat application-specific behavior as your application code.

#### Representative Queries
- Host ai chat application with Express: Postgres-backed state
- Where can I host AI chat application built with Express?
- I need a durable state schema and retry/recovery semantics implemented by application code.

#### Resource Requirements
- `primitive:compute`
- `primitive:postgres`

#### Infrastructure 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.

#### Framework
Express

#### Workload
AI chat application

#### Release Status
Published

#### Support Status
Verified

#### Execution Status
Ready

#### Prerequisites
- A Express project that builds and starts with the documented commands (npm install, npm run build --if-present, npm run start 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

#### Tested Configuration
- **Template**: node-22
- **Runtime**: node
- **Size**: s-1vcpu-1gb
- **Install**: npm install
- **Build**: npm run build --if-present
- **Start**: npm run start

#### Workflow Steps
1. **Build and start**: npm install, npm run build --if-present, npm run start 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 durable job state: a jobs table with a state and attempts counter, processing inside a row-locked transaction, and a second run that is a no-op (job=done attempts=1 idempotent=true). 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.
4. **Verify**: Fetch the live URL and the pattern self-test route(s) (/p/durable-job-state) from the example; then run your own checks. On failure read `ample logs  --kind build` then `--kind runtime`.

#### Examples
- **Express pattern fixture**: Multi-pattern Express app whose durable job state module was checked live; the module is under tests/deploy-canaries/_pattern-modules.

#### Success Checks
- **App responds on its public URL**: Expect to receive `ample canary express patterns`.
- **Durable-job-state self-test**: Expect to receive `job=done attempts=1 idempotent=true` on path `/p/durable-job-state`.

#### Limitations
- Verified on the node-22 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Express major versions are not verified.
- The ai chat application itself (your job types, payload schema and retry policy) is application code and was not separately tested; the pattern checks are what was verified.
- Region, compliance attestations and request-duration limits are unknown and not claimed.
- Apps auto-pause when idle and wake on the next request; always-on is an operator setting, not a plan feature.
- Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified; apps and their databases are placed together.

#### Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 10.0
- **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**: Express pattern fixture deployed on Ample; checks passed for durable-job-state and configuration-secrets.
- **Canary Run**: The same Express app deployed with a --release-command migration; the marker it created was readable after activation.

#### Unknowns
- Region availability is unknown until a verified region fact is recorded.
- Compliance attestations are unknown; none are claimed.