Module runtime 

2026-09-30: Runtime routes. A runtime route is a condition the engine checks at run time, not a policy setting. When it holds, a step leaves the arm its plan names and runs another. A FUSIONS.toml declares each route ([[runtime]]) with the settings its arm plans as. A plan is rendered, estimated and executed with the arm of every route that applies beside it.

Owner: metrale-circuit. Invariants:

• A route applies to a run when its modes and rows contain the run and the policy states every when setting at that value. Its arm is fused under the policy with plans_as substituted, and is kept only when its digest differs from the primary plan’s.
• plans_as changes only settings that when fixes, each to another value. A route re-plans an arm the policy selected; it never adds a setting.
• Route ids are unique and never a rule’s id.

Structs

RuleSet

2026-09-30: A FUSIONS.toml’s rules and routes.

RuntimeRoute

2026-09-30: One [[runtime]] entry.

Functions

check_ids

2026-09-30: No route shares an id with a rule.

overlay

2026-09-30: own over base: a route of the same id replaces the base’s, others are added.

parse_rule_set

2026-09-30: Parse FUSIONS.toml text into its rules and routes.

route_arms

2026-09-30: The arm of each route in runtime that applies to mode at rows and plans differently from primary, fused with rules and available as the primary was.