Gameable Engine

ADR 0011: Packages are implemented by opus subagents; Fable orchestrates ​

  • Status: Accepted — followed through M0-M6
  • Date: 2026-09-13
  • Plan decision: architecture decision 11

Context ​

The work decomposes cleanly into packages with narrow interfaces, and the plan already contains a self-contained brief for each. The cost profile of running everything on the largest model for the whole build is unattractive.

Decision ​

Implement each package with an opus subagent given a self-contained brief — its section of the plan plus the relevant POC file list. Fable orchestrates, reviews and integrates. Work proceeds milestone by milestone; a package is not integrated until its own tests and npm run check pass.

Consequences ​

  • Packages can be built in parallel where their interfaces are already fixed.
  • Briefs must be genuinely self-contained, which forces the interfaces to be written down before the implementation starts.
  • Integration review is a named step, not an afterthought; this ADR set and the concept pages are the shared context those briefs cite.