Supervision-topology conformance: diff the intended tree against the one the code actually produces, and report the drift.

Firebreak already projects each supervisor into a model bundle (Firebreak.Model). The same projection doubles as a committable spec of the intended topology: a team snapshots it on a known-good commit, commits the file, and a later run compares the current topology to it. What changed — a strategy flipped to :one_for_all, a child dropped out of a supervisor, the restart intensity loosened — surfaces as topology_drift findings that gate in CI just like any other finding.

This is the structural sibling of the finding baseline (Firebreak.Baseline): the baseline pins the findings you've accepted; conformance pins the shape of the tree you designed. The diff is the same idea Uppsala's process-structure work framed as "compare the specification to the abstraction of the implementation" — here the specification is just a prior projection of the implementation.

Spec format

The committed file is a plain Elixir term (read with Code.eval_string, like .firebreak.exs) — a list of per-supervisor maps:

[
  %{
    supervisor: MyApp.Sup,
    strategy: :one_for_one,
    max_restarts: 3,
    max_seconds: 5,
    children: [
      %{module: MyApp.Cache, restart: :permanent, type: :worker},
      %{module: MyApp.Pool, restart: :permanent, type: :supervisor}
    ]
  }
]

Generate it with mix firebreak --write-expected FILE; check against it with mix firebreak --expect FILE.