ADR-0002: Copilot first; App Runner in v0.2; no Proton tooling

• Status: accepted
• Date: 2026-09-29
• Deciders: maintainer; council round 1 (Opus and Fable for Copilot first, gpt-6-astra for App Runner first; all three against Proton tooling)

Context

AWS retired three container front ends in 2026. Moving from App Runner to Express Mode is a single Terraform resource, and AWS documents it end to end. Leaving Copilot means tearing down CloudFormation stacks whose custom resources delete certificates, DNS records and bucket contents, and whose env-controller removes the shared ALB, NAT gateways and EFS. Nothing covers that. Proton reaches end of support on 2026-10-07, eight days after this decision.

Decision

v0.1 covers Copilot Load Balanced Web Services and Backend Services. App Runner image-based services come in v0.2. There is no Proton tooling, only one docs page pointing to generic CloudFormation adoption.

Consequences

The differentiator is safe Copilot teardown, which is also the riskiest part. It needs the retain patches (ADR-0004) and a real AWS run before release (ADR-0008).