15. Execution Model (Phases 1–5)

Hypervisor execution order is strict:

1. Resolution
2. Type checking
3. Reactive compute (R-DAG)
4. Layout (Token Box Model)
5. Render (Canonical JSON)

Phase 1: Resolution

• UTF-8 + NFC + LF normalization
• parse to AST
• import resolution
• deterministic merge

Phase 2: Type checking

• validate facets and schemas
• pipeline typing
• interface schema mappability
• @input placement/type constraints
• policy schema and condition typing

AST is immutable after successful Phase 2.

Phase 3: R-DAG

• build dependency graph from $var references
• detect unknown refs (F401) and cycles (F505)
• evaluate topologically
• tie-break independent nodes by merged ordered-map insertion order
• materialize runtime @input values
• enforce gas/mode/cache/policy/guard rules

Phase 4: Layout

• compute section sizes in FACET Units
• enforce critical load
• apply deterministic compression/truncation/drop for flexible sections
• preserve canonical message order

Phase 5: Render

• emit canonical JSON
• emit provider payload preserving canonical semantics
• optionally emit execution artifact (Hypervisor run/test)

Modes

• pure: no volatile/external behavior; strict cache-only for Level-1 lenses
• exec: runtime effects possible if allowed by policy + guard