Module validate 

runtime/validate.rs — Kernel graph validation engine

Purpose:

• Validates an ExpandedGraph against the registered primitive catalog before execution, ensuring all structural and semantic constraints are satisfied.

Behavior:

• Returns Result<ValidatedGraph, GraphValidationError>.
• Short-circuits on the first encountered error — callers receive a single GraphValidationError, not a collected list.

Owns (invariant → enforcing function → rule ID):

• V.1 No cycles in graph → topological_sort (CycleDetected)
• V.2 Wiring matrix / port legality→ enforce_wiring_matrix (InvalidEdgeKind / MissingInputMetadata / MissingOutputMetadata)
• V.3 Required inputs connected → enforce_required_inputs (MissingRequiredInput)
• V.4 Type constraints at edges → enforce_types (TypeMismatch)
• V.5 Action trigger gating → enforce_action_gating (ActionNotGated)
• V.7 Single edge per input port → enforce_single_edge_per_input(MultipleInboundEdges)
• V.8 Primitive catalog existence → validate main loop (MissingPrimitive)
• (boundary outputs — no doc V-number) → enforce_boundary_outputs (MissingOutputMetadata)
• E.3 ExternalInput rejection → validate main loop (ExternalInputNotAllowed)

Note: V.6 (“All nodes pass validation before any action executes”) is a meta-invariant satisfied by the fact that validate runs to completion before execute is called — it is not a single check function.

Does not own:

• Graph execution (see execute.rs)
• Primitive registration (see catalog.rs)
• Graph construction or expansion (see cluster.rs)
• E.3 expansion-time enforcement (see cluster.rs::expand)

Connects to:

• execute.rs — produces ValidatedGraph consumed by execution
• types.rs — uses GraphValidationError for reporting violations
• catalog.rs — queries primitive metadata for validation

Safety notes:

• Validation is pure and deterministic — no side effects
• E.3 is enforced twice: first during expansion (cluster.rs), then again here as a defense-in-depth check

Functions

validate