Function compile_policy 

pub fn compile_policy(
    policy: &PolicyConfig,
    resources: Arc<PluginResources>,
) -> Result<CompiledGraph, String>

Compiles a PolicyConfig into a ready-to-execute CompiledGraph.

Instantiates each node’s plugin via plugins::create_plugin, records client nodes as terminals, and indexes edges per node by source port (out normalizes to success). The entry node is the target of the listener’s success/out edge. Fails if the policy has no listener node, a plugin cannot be constructed, an edge names a port its node type does not declare, two edges leave the same node.port (fan-out is not supported), or a node’s success/outcome port (PortKind::Success or PortKind::Outcome) has no outgoing edge — error ports are exempt (fallback chain: per-node error edge -> policy catch-all -> default 500).

Edge endpoints use the node_id.port form:

edges:
  - from: listener.out
    to: rewrite.in
  - from: rewrite.success
    to: client.in
  - from: rewrite.error
    to: error-handler.in