## Host mcp server with Express: streamed responses

### Summary
Deploy a mcp server built with Express on Ample using the streaming response service 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 Server-Sent Events endpoint read incrementally through the public HTTPS gateway: five one-second chunks arrived spread over time with the first within seconds (not buffered), a 70-second stream of 36 chunks completed past common 60-second idle timeouts, and a client that disconnected after two chunks was observed and recorded by the server (disconnected=true). Not separately tested: your event schema, reconnection strategy and any per-request duration ceiling beyond the 70 seconds measured; treat the mcp server-specific behavior as your application code.

### Framework
- **Framework**: Express  
- **Workload**: MCP server  
- **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

### Infrastructure Requirements
1. **Compute**  
   - **Status**: verified  
   - **Summary**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.

2. **Postgres**  
   - **Status**: verified  
   - **Summary**: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

### 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 mcp server itself (your event schema, reconnection strategy and any per-request duration ceiling beyond the 70 seconds measured) is application code and was not separately tested; the pattern checks are what was verified.

### Cost Estimate
- **Monthly Amount**: 10.0 USD  
- **Components**:  
   - **app server**: s-1vcpu-1gb - $5.0  
   - **managed PostgreSQL database**: s-1vcpu-1gb - $5.0

### Workflow Steps
- **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.  
- **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.  
- **Verify**: Fetch the live URL and the pattern self-test route(s) (/p/streaming-response-service) from the example; then run your own checks. On failure read `ample logs  --kind build` then `--kind runtime`.

### Success Checks
- **App responds on its public URL**  
   - **Kind**: http_get  
   - **Path**: /  
   - **Expect**: ample canary express patterns

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