feat!: per-part chain decoupling (chain_id required per trigger/node)

aggregator/rest/handlers_workflows.go

@@ -43,21 +43,9 @@ func (s *Server) CreateWorkflow(ctx echo.Context) error {
 		return badRequest("WORKFLOWS_BAD_PAYLOAD", "Invalid workflow payload", err.Error())
 	}
 
-	// Fall back to the JWT's audience chain when the body omits chainId.
-	// Studio 4.0.0-dev.1 builds the CreateWorkflowRequest body without a
-	// chainId field even though the surrounding deploy flow already knows
-	// the target chain — without this fallback the task lands with
-	// ChainId=0 and engine.ResolveSmartWalletConfig(0) returns chains[0]
-	// (Ethereum mainnet via the IsGateway fallback in config.go). The
-	// deployed-execution VM then dials the mainnet RPC, queries the
-	// Sepolia paymaster on mainnet, and the bundler returns
-	// "failed to get paymaster hash: no contract code at given address".
-	// Same pattern as WithdrawWallet / SimulateWorkflow / RunNode.
-	if req.ChainId == 0 {
-		if authed := restmw.UserFromContext(ctx); authed != nil && authed.ChainID != 0 {
-			req.ChainId = authed.ChainID
-		}
-	}
+	// A task no longer carries a workflow-level chain (G5) — each chain-aware
+	// trigger/node specifies its own chain_id. The JWT audience chain is API
+	// auth scope only; it is not stamped onto the task.
 
 	workflow, err := s.engine.CreateWorkflow(user, req)
 	if err != nil {