Set up a custom domain

llms.txt lists every page for a coding agent.

Optional: hand this page to your coding agentThe steps work by hand too.

Show the prompt

Read https://intentius.io/loomster/guides/set-up-a-custom-domain/ and work out which of its three paths fits the person's DNS: list their Route53 hosted zones and ACM certificates with read-only calls.
Report the variables to set for that path. Run `npm run dns-setup` only if the person asked for it in this session.
Never run `chant approve` or `just grant`, never deploy to or delete from a real AWS account unless the person asked for that in this session, never register an identity provider in Loom, and never push or edit the `chant/lifecycle` branch.

Result

The ALB serving HTTPS on LOOM_DOMAIN_NAME, with an alias record in a hosted zone and a certificate on the listener. Light serves on the ALB’s own DNS name and needs none of this; the production tiers require LOOM_DOMAIN_NAME.

Prerequisites

A domain, and either a Route53 hosted zone for it plus a DNS-validated ACM certificate in the deploy region, or access to the parent domain’s DNS provider.

Steps

Pick one path; each is a mode of the route53 and acm seams.

Reference an existing zone and certificate

The common case: you own the parent domain in Route53 and want records added to it, not a new zone.

export LOOM_DOMAIN_NAME=loom.example.com
export LOOM_HOSTED_ZONE_ID=<hosted zone id>
export LOOM_CERTIFICATE_ARN=<ACM certificate ARN, already validated>

loomster creates no zone and no certificate. It adds the alias record to your zone, attaches your certificate to the HTTPS listener, and passes both ids through as oHostedZoneId and oCertificateArn.

Let loomster create them

Set only LOOM_DOMAIN_NAME. The stack creates a hosted zone and a certificate validated through it. The certificate validates only once the parent delegates to the new zone, so run the DNS Op first:

LOOM_DOMAIN_NAME=loom.example.com npm run dns-setup

It creates the zone (adopting one that exists), prints LOOM_HOSTED_ZONE_ID and four NS records, and polls public DNS. At the parent’s provider add one record:

Field	Value
Name	`loom.example.com` (or `loom`, depending on the provider)
Type	`NS`
Value	the four `ns-.awsdns-` servers it printed, one per line

The Op finishes when dig +short NS loom.example.com returns them. It polls instead of asking for an approval because the delegation is something it can check. Export the printed LOOM_HOSTED_ZONE_ID before deploying.

Drop the custom domain

export LOOM_ROUTE53=omit
export LOOM_ACM=omit

The ALB serves HTTP on its own DNS name, as on light. Useful for an internal or throwaway production-tier deploy.

How the modes resolve, in src/shared-foundation/params.ts: a zone id or certificate ARN wins; otherwise LOOM_ROUTE53 and LOOM_ACM of omit or provision apply; unset leaves the tier’s default, provision on the production tiers.

Deploy to production on AWS.