sequenceDiagram
    autonumber
    participant P as Platform / agent
    participant G as PALO Gateway
    participant R as Registry + OPA
    participant H as Human reviewer
    participant X as Governed executor
    participant V as Authoritative verifier
    participant L as Ledger / incidents

    P->>G: Submit canonical Action Claim 1.2
    G->>G: Validate schema, expiry and replay material
    G->>R: Resolve active profiles and evaluate policy
    alt malformed, missing profile, policy unavailable or denied
        R-->>G: denied (fail closed)
        G->>L: Persist decision evidence
        G-->>P: denied, tool does not execute
    else approval required
        R-->>G: pending_approval
        G->>L: Persist digest-bound approval request
        G-->>P: review_required + approvalId
        H->>G: Resolve exact approval
        Note over H,G: Current preview uses a caller-supplied reviewer label
        P->>G: Re-submit identical claim + approvalId
        G->>R: Revalidate profile, policy, digest and approval
    else allowed
        R-->>G: allowed
    end

    G->>V: Read authoritative pre-state
    alt pre-state unavailable or preconditions fail
        V-->>G: unavailable / mismatch
        G-->>P: review_required or denied, no execution
    else preconditions satisfied
        G->>G: Issue and atomically consume one-time capability
        G->>L: Persist execution intent
        G->>X: Execute immutable arguments + idempotency key
        X-->>G: Result or failure
        G->>L: Sign and persist Execution Receipt
        G->>V: Read authoritative post-state
        V-->>G: Effect Contract checks
        alt verified
            G->>L: Persist signed verified attestation
            G-->>P: verified
        else mismatch or inconclusive
            G->>L: Persist attestation, open incident and hold resource
            G-->>P: review_required
        end
    end