refactor: host function wrappers to use structured request and response types

- Updated the host function signatures in `nd_host_artwork.go`, `nd_host_scheduler.go`, `nd_host_subsonicapi.go`, and `nd_host_websocket.go` to accept a single parameter for JSON requests.
- Introduced structured request and response types for various cache operations in `nd_host_cache.go`.
- Modified cache functions to marshal requests to JSON and unmarshal responses, improving error handling and code clarity.
- Removed redundant memory allocation for string parameters in favor of JSON marshaling.
- Enhanced error handling in WebSocket and cache operations to return structured error responses.

plugins/cmd/hostgen/internal/generator.go

@@ -14,45 +14,23 @@ var templatesFS embed.FS
 // hostFuncMap returns the template functions for host code generation.
 func hostFuncMap(svc Service) template.FuncMap {
 	return template.FuncMap{
-		"lower":            strings.ToLower,
+		"lower":        strings.ToLower,
-		"title":            strings.Title,
+		"title":        strings.Title,
-		"exportName":       func(m Method) string { return m.FunctionName(svc.ExportPrefix()) },
+		"exportName":   func(m Method) string { return m.FunctionName(svc.ExportPrefix()) },
-		"requestType":      func(m Method) string { return m.RequestTypeName(svc.Name) },
+		"requestType":  func(m Method) string { return m.RequestTypeName(svc.Name) },
-		"responseType":     func(m Method) string { return m.ResponseTypeName(svc.Name) },
+		"responseType": func(m Method) string { return m.ResponseTypeName(svc.Name) },
-		"valueType":        GoTypeToValueType,
-		"isSimple":         IsSimpleType,
-		"isString":         IsStringType,
-		"isBytes":          IsBytesType,
-		"needsJSON":        NeedsJSON,
-		"needsRequestType": func(m Method) bool { return m.NeedsRequestType() },
-		"needsRespType":    func(m Method) bool { return m.NeedsResponseType() },
-		"isErrorOnly":      func(m Method) bool { return m.IsErrorOnly() },
-		"hasErrFromRead":   hasErrorFromRead,
-		"readParam":        generateReadParam,
-		"writeReturn":      generateWriteReturn,
-		"encodeReturn":     generateEncodeReturn,
 	}
 }
 
 // clientFuncMap returns the template functions for client code generation.
 func clientFuncMap(svc Service) template.FuncMap {
 	return template.FuncMap{
-		"lower":             strings.ToLower,
+		"lower":        strings.ToLower,
-		"title":             strings.Title,
+		"title":        strings.Title,
-		"exportName":        func(m Method) string { return m.FunctionName(svc.ExportPrefix()) },
+		"exportName":   func(m Method) string { return m.FunctionName(svc.ExportPrefix()) },
-		"responseType":      func(m Method) string { return m.ResponseTypeName(svc.Name) },
+		"requestType":  func(m Method) string { return m.RequestTypeName(svc.Name) },
-		"isSimple":          IsSimpleType,
+		"responseType": func(m Method) string { return m.ResponseTypeName(svc.Name) },
-		"isString":          IsStringType,
+		"formatDoc":    formatDoc,
-		"isBytes":           IsBytesType,
-		"needsJSON":         NeedsJSON,
-		"needsRespType":     func(m Method) bool { return m.NeedsResponseType() },
-		"isErrorOnly":       func(m Method) bool { return m.IsErrorOnly() },
-		"wasmParamType":     wasmParamType,
-		"wasmReturnType":    wasmReturnType,
-		"wrapperReturnType": func(m Method, svcName string) string { return wrapperReturnType(m, svcName) },
-		"clientCallArg":     clientCallArg,
-		"decodeResult":      decodeResult,
-		"formatDoc":         formatDoc,
 	}
 }
 
@@ -69,11 +47,8 @@ func GenerateHost(svc Service, pkgName string) ([]byte, error) {
 	}
 
 	data := templateData{
-		Package:          pkgName,
+		Package: pkgName,
-		Service:          svc,
+		Service: svc,
-		NeedsJSON:        serviceNeedsJSON(svc),
-		NeedsWriteHelper: serviceNeedsWriteHelper(svc),
-		NeedsErrorHelper: serviceNeedsErrorHelper(svc),
 	}
 
 	var buf bytes.Buffer
@@ -97,9 +72,7 @@ func GenerateClientGo(svc Service) ([]byte, error) {
 	}
 
 	data := templateData{
-		Service:     svc,
+		Service: svc,
-		NeedsJSON:   serviceClientNeedsJSON(svc),
-		NeedsErrors: serviceClientNeedsErrors(svc),
 	}
 
 	var buf bytes.Buffer
@@ -111,269 +84,8 @@ func GenerateClientGo(svc Service) ([]byte, error) {
 }
 
 type templateData struct {
-	Package          string
+	Package string
-	Service          Service
+	Service Service
-	NeedsJSON        bool
-	NeedsErrors      bool // Client: needs "errors" import
-	NeedsWriteHelper bool
-	NeedsErrorHelper bool
-}
-
-// serviceNeedsJSON returns true if any method needs JSON encoding.
-func serviceNeedsJSON(svc Service) bool {
-	for _, m := range svc.Methods {
-		for _, p := range m.Params {
-			if NeedsJSON(p.Type) {
-				return true
-			}
-		}
-		for _, r := range m.Returns {
-			if NeedsJSON(r.Type) {
-				return true
-			}
-		}
-		// Error responses are also JSON
-		if m.HasError && m.NeedsResponseType() {
-			return true
-		}
-	}
-	return false
-}
-
-// serviceNeedsWriteHelper returns true if any method needs the write helper.
-func serviceNeedsWriteHelper(svc Service) bool {
-	for _, m := range svc.Methods {
-		if m.NeedsResponseType() {
-			return true
-		}
-	}
-	return false
-}
-
-// serviceClientNeedsJSON returns true if any method needs JSON encoding in client code.
-// This is true if any method has a response type (complex returns) or if any param/return needs JSON.
-func serviceClientNeedsJSON(svc Service) bool {
-	for _, m := range svc.Methods {
-		// Response types use JSON for serialization
-		if m.NeedsResponseType() {
-			return true
-		}
-		// Parameters that need JSON marshaling
-		for _, p := range m.Params {
-			if NeedsJSON(p.Type) {
-				return true
-			}
-		}
-	}
-	return false
-}
-
-// serviceClientNeedsErrors returns true if any method needs the errors package in client code.
-// This is only true for error-only methods (methods that return just error).
-func serviceClientNeedsErrors(svc Service) bool {
-	for _, m := range svc.Methods {
-		if m.IsErrorOnly() {
-			return true
-		}
-	}
-	return false
-}
-
-// serviceNeedsErrorHelper returns true if any method needs error handling with JSON.
-func serviceNeedsErrorHelper(svc Service) bool {
-	for _, m := range svc.Methods {
-		if m.HasError && m.NeedsResponseType() {
-			return true
-		}
-	}
-	return false
-}
-
-// hasErrorFromRead returns true if reading params declares an err variable.
-// This happens when using needsRequestType (JSON) or when any param is a PTR type.
-func hasErrorFromRead(m Method) bool {
-	if m.NeedsRequestType() {
-		return true
-	}
-	for _, p := range m.Params {
-		if IsStringType(p.Type) || IsBytesType(p.Type) {
-			return true
-		}
-	}
-	return false
-}
-
-// generateReadParam generates code to read a parameter from the stack.
-func generateReadParam(p Param, stackIndex int) string {
-	switch {
-	case IsSimpleType(p.Type):
-		return generateReadSimple(p, stackIndex)
-	case IsStringType(p.Type):
-		return fmt.Sprintf(`%s, err := p.ReadString(stack[%d])
-			if err != nil {
-				return
-			}`, p.Name, stackIndex)
-	case IsBytesType(p.Type):
-		return fmt.Sprintf(`%s, err := p.ReadBytes(stack[%d])
-			if err != nil {
-				return
-			}`, p.Name, stackIndex)
-	default:
-		// Complex type - JSON
-		return fmt.Sprintf(`%sBytes, err := p.ReadBytes(stack[%d])
-			if err != nil {
-				return
-			}
-			var %s %s
-			if err := json.Unmarshal(%sBytes, &%s); err != nil {
-				return
-			}`, p.Name, stackIndex, p.Name, p.Type, p.Name, p.Name)
-	}
-}
-
-// generateReadSimple generates code to read a simple type from the stack.
-func generateReadSimple(p Param, stackIndex int) string {
-	switch p.Type {
-	case "int32":
-		return fmt.Sprintf(`%s := extism.DecodeI32(stack[%d])`, p.Name, stackIndex)
-	case "uint32":
-		return fmt.Sprintf(`%s := extism.DecodeU32(stack[%d])`, p.Name, stackIndex)
-	case "int64":
-		return fmt.Sprintf(`%s := int64(stack[%d])`, p.Name, stackIndex)
-	case "uint64":
-		return fmt.Sprintf(`%s := stack[%d]`, p.Name, stackIndex)
-	case "float32":
-		return fmt.Sprintf(`%s := extism.DecodeF32(stack[%d])`, p.Name, stackIndex)
-	case "float64":
-		return fmt.Sprintf(`%s := extism.DecodeF64(stack[%d])`, p.Name, stackIndex)
-	case "bool":
-		return fmt.Sprintf(`%s := extism.DecodeI32(stack[%d]) != 0`, p.Name, stackIndex)
-	default:
-		return fmt.Sprintf(`// FIXME: unsupported type: %s`, p.Type)
-	}
-}
-
-// generateWriteReturn generates code to write a return value to the stack.
-func generateWriteReturn(p Param, stackIndex int, varName string) string {
-	switch {
-	case IsSimpleType(p.Type):
-		return fmt.Sprintf(`stack[%d] = %s`, stackIndex, generateEncodeReturn(p, varName))
-	case IsStringType(p.Type):
-		return fmt.Sprintf(`if ptr, err := p.WriteString(%s); err == nil {
-				stack[%d] = ptr
-			}`, varName, stackIndex)
-	case IsBytesType(p.Type):
-		return fmt.Sprintf(`if ptr, err := p.WriteBytes(%s); err == nil {
-				stack[%d] = ptr
-			}`, varName, stackIndex)
-	default:
-		// Complex type - JSON
-		return fmt.Sprintf(`if bytes, err := json.Marshal(%s); err == nil {
-				if ptr, err := p.WriteBytes(bytes); err == nil {
-					stack[%d] = ptr
-				}
-			}`, varName, stackIndex)
-	}
-}
-
-// generateEncodeReturn generates the encoding expression for a simple return.
-func generateEncodeReturn(p Param, varName string) string {
-	switch p.Type {
-	case "int32":
-		return fmt.Sprintf("extism.EncodeI32(%s)", varName)
-	case "uint32":
-		return fmt.Sprintf("extism.EncodeU32(%s)", varName)
-	case "int64":
-		return fmt.Sprintf("uint64(%s)", varName)
-	case "uint64":
-		return varName
-	case "float32":
-		return fmt.Sprintf("extism.EncodeF32(%s)", varName)
-	case "float64":
-		return fmt.Sprintf("extism.EncodeF64(%s)", varName)
-	case "bool":
-		return fmt.Sprintf("func() uint64 { if %s { return 1 }; return 0 }()", varName)
-	default:
-		return "0"
-	}
-}
-
-// Client-side helper functions for template
-
-// wasmParamType returns the WASM parameter type for a Go parameter.
-func wasmParamType(p Param) string {
-	if IsSimpleType(p.Type) {
-		return p.Type
-	}
-	// All pointer types (string, []byte, complex) use uint64 offset
-	return "uint64"
-}
-
-// wasmReturnType returns the WASM return type declaration for a method.
-func wasmReturnType(m Method) string {
-	// Methods with JSON responses or error-only return uint64 (pointer)
-	if m.NeedsResponseType() || m.IsErrorOnly() {
-		return "uint64"
-	}
-	// Simple return types
-	if len(m.Returns) == 1 && IsSimpleType(m.Returns[0].Type) {
-		return m.Returns[0].Type
-	}
-	// No returns or multiple returns - use uint64 for pointer
-	if len(m.Returns) == 0 {
-		return ""
-	}
-	return "uint64"
-}
-
-// wrapperReturnType returns the Go return type for the wrapper function.
-func wrapperReturnType(m Method, svcName string) string {
-	if m.NeedsResponseType() {
-		return fmt.Sprintf("(*%s%sResponse, error)", svcName, m.Name)
-	}
-	if m.IsErrorOnly() {
-		return "error"
-	}
-	if len(m.Returns) == 1 {
-		return m.Returns[0].Type
-	}
-	return ""
-}
-
-// clientCallArg returns the argument expression for calling the host function.
-func clientCallArg(p Param) string {
-	if IsSimpleType(p.Type) {
-		return p.Name
-	}
-	// Pointer types use .Offset()
-	return p.Name + "Mem.Offset()"
-}
-
-// decodeResult generates code to decode a simple return value.
-func decodeResult(p Param, varName string) string {
-	switch p.Type {
-	case "int32":
-		return fmt.Sprintf("int32(%s)", varName)
-	case "uint32":
-		return fmt.Sprintf("uint32(%s)", varName)
-	case "int64":
-		return fmt.Sprintf("int64(%s)", varName)
-	case "uint64":
-		return varName
-	case "float32":
-		return fmt.Sprintf("math.Float32frombits(uint32(%s))", varName)
-	case "float64":
-		return fmt.Sprintf("math.Float64frombits(%s)", varName)
-	case "bool":
-		return fmt.Sprintf("%s != 0", varName)
-	case "string":
-		// pdk.FindMemory returns a value type, ReadBytes has pointer receiver
-		return fmt.Sprintf("func() string { m := pdk.FindMemory(%s); return string(m.ReadBytes()) }()", varName)
-	case "[]byte":
-		return fmt.Sprintf("func() []byte { m := pdk.FindMemory(%s); return m.ReadBytes() }()", varName)
-	default:
-		return varName
-	}
 }
 
 // formatDoc formats a documentation string for Go comments.

plugins/cmd/hostgen/internal/generator_test.go

@@ -11,7 +11,7 @@ import (
 var _ = Describe("Generator", func() {
 	Describe("GenerateHost", func() {
 		It("should generate valid Go code for a simple service with strings", func() {
-			// String params/returns don't need JSON - they use direct memory read/write
+			// All methods use JSON request/response types
 			svc := Service{
 				Name:       "SubsonicAPI",
 				Permission: "subsonicapi",
@@ -41,10 +41,11 @@ var _ = Describe("Generator", func() {
 			// Check for package declaration
 			Expect(codeStr).To(ContainSubstring("package host"))
 
-			// String params don't need request type - read directly from memory
+			// All methods now use request type for JSON protocol
-			Expect(codeStr).NotTo(ContainSubstring("type SubsonicAPICallRequest struct"))
+			Expect(codeStr).To(ContainSubstring("type SubsonicAPICallRequest struct"))
+			Expect(codeStr).To(ContainSubstring(`Uri string `))
 
-			// String return with error needs response type for error handling
+			// Response type with error handling
 			Expect(codeStr).To(ContainSubstring("type SubsonicAPICallResponse struct"))
 			Expect(codeStr).To(ContainSubstring(`Response string `))
 			Expect(codeStr).To(ContainSubstring(`Error string `))
@@ -55,8 +56,8 @@ var _ = Describe("Generator", func() {
 			// Check for host function name
 			Expect(codeStr).To(ContainSubstring(`"subsonicapi_call"`))
 
-			// Check for direct string read (not JSON unmarshal)
+			// Check for JSON unmarshal (all methods use JSON now)
-			Expect(codeStr).To(ContainSubstring("p.ReadString(stack[0])"))
+			Expect(codeStr).To(ContainSubstring("json.Unmarshal"))
 		})
 
 		It("should generate code for methods without parameters", func() {
@@ -80,8 +81,10 @@ var _ = Describe("Generator", func() {
 			Expect(err).NotTo(HaveOccurred())
 
 			codeStr := string(code)
-			// Should not have request type for methods without params
+			// Methods without params don't need a request type - no params to serialize
 			Expect(codeStr).NotTo(ContainSubstring("type TestNoParamsRequest struct"))
+			// But still uses PTR input/output for consistency
+			Expect(codeStr).To(MatchRegexp(`\[\]extism\.ValueType\{extism\.ValueTypePTR\},\s*\[\]extism\.ValueType\{extism\.ValueTypePTR\}`))
 		})
 
 		It("should generate code for methods without return values", func() {
@@ -144,8 +147,8 @@ var _ = Describe("Generator", func() {
 			Expect(codeStr).To(ContainSubstring("scheduler_cancelschedule"))
 		})
 
-		It("should handle multiple simple parameters without JSON", func() {
+		It("should handle multiple simple parameters with JSON", func() {
-			// All simple params (string, int32, bool) can be passed on stack directly
+			// All params use JSON - single PTR input
 			svc := Service{
 				Name:       "Test",
 				Permission: "test",
@@ -171,14 +174,12 @@ var _ = Describe("Generator", func() {
 			Expect(err).NotTo(HaveOccurred())
 
 			codeStr := string(code)
-			// No request type for simple params - they're read directly from stack
+			// All methods use request type with JSON protocol
-			Expect(codeStr).NotTo(ContainSubstring("type TestMultiParamRequest struct"))
+			Expect(codeStr).To(ContainSubstring("type TestMultiParamRequest struct"))
-			// Check for direct stack reads
+			// Check for JSON unmarshal (all methods use JSON now)
-			Expect(codeStr).To(ContainSubstring("p.ReadString(stack[0])"))
+			Expect(codeStr).To(ContainSubstring("json.Unmarshal"))
-			Expect(codeStr).To(ContainSubstring("extism.DecodeI32(stack[1])"))
+			// Check that input/output ValueType both use PTR (JSON)
-			Expect(codeStr).To(ContainSubstring("extism.DecodeI32(stack[2])"))
+			Expect(codeStr).To(MatchRegexp(`\[\]extism\.ValueType\{extism\.ValueTypePTR\},\s*\[\]extism\.ValueType\{extism\.ValueTypePTR\}`))
-			// Check that input ValueType slice has correct entries (3 params: PTR for string, I32 for int32, I32 for bool)
-			Expect(codeStr).To(ContainSubstring("extism.ValueTypePTR, extism.ValueTypeI32, extism.ValueTypeI32"))
 		})
 
 		It("should use single PTR for mixed simple and complex params", func() {
@@ -263,8 +264,8 @@ var _ = Describe("Generator", func() {
 			Expect(codeStr).To(ContainSubstring(`extism "github.com/extism/go-sdk"`))
 		})
 
-		It("should not include json import when not needed", func() {
+		It("should always include json import for JSON protocol", func() {
-			// Service with only simple types doesn't need JSON import
+			// All services use JSON protocol, so json import is always needed
 			svc := Service{
 				Name:       "Test",
 				Permission: "test",
@@ -283,7 +284,7 @@ var _ = Describe("Generator", func() {
 
 			codeStr := string(code)
 			Expect(codeStr).To(ContainSubstring(`"context"`))
-			Expect(codeStr).NotTo(ContainSubstring(`"encoding/json"`))
+			Expect(codeStr).To(ContainSubstring(`"encoding/json"`))
 			Expect(codeStr).To(ContainSubstring(`extism "github.com/extism/go-sdk"`))
 		})
 	})

plugins/cmd/hostgen/internal/templates/client_go.go.tmpl

@@ -8,12 +8,7 @@
 package main
 
 import (
-{{- if .NeedsJSON}}
 	"encoding/json"
-{{- end}}
-{{- if .NeedsErrors}}
-	"errors"
-{{- end}}
 
 	"github.com/extism/go-pdk"
 )
@@ -24,12 +19,20 @@ import (
 // {{exportName .}} is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user {{exportName .}}
-func {{exportName .}}({{range $i, $p := .Params}}{{if $i}}, {{end}}{{wasmParamType $p}}{{end}}) {{wasmReturnType .}}
+func {{exportName .}}(uint64) uint64
 {{- end}}
 
-{{- /* Generate response types for methods that need them */ -}}
+{{- /* Generate request/response types for all methods */ -}}
 {{range .Service.Methods}}
-{{- if needsRespType .}}
+{{- if .HasParams}}
+
+// {{requestType .}} is the request type for {{$.Service.Name}}.{{.Name}}.
+type {{requestType .}} struct {
+{{- range .Params}}
+	{{title .Name}} {{.Type}} `json:"{{.JSONName}}"`
+{{- end}}
+}
+{{- end}}
 
 // {{responseType .}} is the response type for {{$.Service.Name}}.{{.Name}}.
 type {{responseType .}} struct {
@@ -39,7 +42,6 @@ type {{responseType .}} struct {
 	Error string `json:"error,omitempty"`
 }
 {{- end}}
-{{- end}}
 
 {{- /* Generate wrapper functions */ -}}
 {{range .Service.Methods}}
@@ -48,28 +50,28 @@ type {{responseType .}} struct {
 {{- if .Doc}}
 {{formatDoc .Doc}}
 {{- end}}
-func {{$.Service.Name}}{{.Name}}({{range $i, $p := .Params}}{{if $i}}, {{end}}{{$p.Name}} {{$p.Type}}{{end}}) {{wrapperReturnType . $.Service.Name}} {
+func {{$.Service.Name}}{{.Name}}({{range $i, $p := .Params}}{{if $i}}, {{end}}{{$p.Name}} {{$p.Type}}{{end}}) (*{{responseType .}}, error) {
-{{- if needsRespType .}}
+{{- if .HasParams}}
-{{- /* Complex response - use JSON */}}
+	// Marshal request to JSON
+	req := {{requestType .}}{
 {{- range .Params}}
-{{- if isString .Type}}
+		{{title .Name}}: {{.Name}},
-	{{.Name}}Mem := pdk.AllocateString({{.Name}})
+{{- end}}
-	defer {{.Name}}Mem.Free()
+	}
-{{- else if isBytes .Type}}
+	reqBytes, err := json.Marshal(req)
-	{{.Name}}Mem := pdk.AllocateBytes({{.Name}})
-	defer {{.Name}}Mem.Free()
-{{- else if needsJSON .Type}}
-	{{.Name}}Bytes, err := json.Marshal({{.Name}})
 	if err != nil {
 		return nil, err
 	}
-	{{.Name}}Mem := pdk.AllocateBytes({{.Name}}Bytes)
+	reqMem := pdk.AllocateBytes(reqBytes)
-	defer {{.Name}}Mem.Free()
+	defer reqMem.Free()
-{{- end}}
+{{- else}}
+	// No parameters - allocate empty JSON object
+	reqMem := pdk.AllocateBytes([]byte("{}"))
+	defer reqMem.Free()
 {{- end}}
 
 	// Call the host function
-	responsePtr := {{exportName .}}({{range $i, $p := .Params}}{{if $i}}, {{end}}{{clientCallArg $p}}{{end}})
+	responsePtr := {{exportName .}}(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -82,56 +84,5 @@ func {{$.Service.Name}}{{.Name}}({{range $i, $p := .Params}}{{if $i}}, {{end}}{{
 	}
 
 	return &response, nil
-{{- else if isErrorOnly .}}
-{{- /* Error-only response - string result */}}
-{{- range .Params}}
-{{- if isString .Type}}
-	{{.Name}}Mem := pdk.AllocateString({{.Name}})
-	defer {{.Name}}Mem.Free()
-{{- else if isBytes .Type}}
-	{{.Name}}Mem := pdk.AllocateBytes({{.Name}})
-	defer {{.Name}}Mem.Free()
-{{- else if needsJSON .Type}}
-	{{.Name}}Bytes, err := json.Marshal({{.Name}})
-	if err != nil {
-		return err
-	}
-	{{.Name}}Mem := pdk.AllocateBytes({{.Name}}Bytes)
-	defer {{.Name}}Mem.Free()
-{{- end}}
-{{- end}}
-
-	// Call the host function
-	responsePtr := {{exportName .}}({{range $i, $p := .Params}}{{if $i}}, {{end}}{{clientCallArg $p}}{{end}})
-
-	// Read the response from memory
-	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
-
-	if errStr != "" {
-		return errors.New(errStr)
-	}
-
-	return nil
-{{- else}}
-{{- /* Simple return types - direct stack values */}}
-{{- range .Params}}
-{{- if isString .Type}}
-	{{.Name}}Mem := pdk.AllocateString({{.Name}})
-	defer {{.Name}}Mem.Free()
-{{- else if isBytes .Type}}
-	{{.Name}}Mem := pdk.AllocateBytes({{.Name}})
-	defer {{.Name}}Mem.Free()
-{{- end}}
-{{- end}}
-
-	// Call the host function
-{{- if .HasReturns}}
-	result := {{exportName .}}({{range $i, $p := .Params}}{{if $i}}, {{end}}{{clientCallArg $p}}{{end}})
-	return {{decodeResult (index .Returns 0) "result"}}
-{{- else}}
-	{{exportName .}}({{range $i, $p := .Params}}{{if $i}}, {{end}}{{clientCallArg $p}}{{end}})
-{{- end}}
-{{- end}}
 }
 {{- end}}

plugins/cmd/hostgen/internal/templates/host.go.tmpl

@@ -4,16 +4,14 @@ package {{.Package}}
 
 import (
 	"context"
-{{- if .NeedsJSON}}
 	"encoding/json"
-{{- end}}
 
 	extism "github.com/extism/go-sdk"
 )
 
-{{- /* Generate request/response types only when needed */ -}}
+{{- /* Generate request/response types for all methods */ -}}
 {{range .Service.Methods}}
-{{- if needsRequestType .}}
+{{- if .HasParams}}
 
 // {{requestType .}} is the request type for {{$.Service.Name}}.{{.Name}}.
 type {{requestType .}} struct {
@@ -22,7 +20,6 @@ type {{requestType .}} struct {
 {{- end}}
 }
 {{- end}}
-{{- if needsRespType .}}
 
 // {{responseType .}} is the response type for {{$.Service.Name}}.{{.Name}}.
 type {{responseType .}} struct {
@@ -31,7 +28,6 @@ type {{responseType .}} struct {
 {{- end}}
 	Error string `json:"error,omitempty"`
 }
-{{- end}}
 {{end}}
 
 // Register{{.Service.Name}}HostFunctions registers {{.Service.Name}} service host functions.
@@ -50,7 +46,6 @@ func new{{$.Service.Name}}{{.Name}}HostFunction(service {{$.Service.Interface}})
 		"{{exportName .}}",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
 {{- if .HasParams}}
-{{- if needsRequestType .}}
 			// Read JSON request from plugin memory
 			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
@@ -62,47 +57,28 @@ func new{{$.Service.Name}}{{.Name}}HostFunction(service {{$.Service.Interface}})
 				{{$.Service.Name | lower}}WriteError(p, stack, err)
 				return
 			}
-{{- else}}
-			// Read parameters from stack
-{{- range $i, $p := .Params}}
-			{{readParam $p $i}}
-{{- end}}
-{{- end}}
 {{- end}}
 
 			// Call the service method
-{{- $m := .}}
 {{- if .HasReturns}}
 {{- if .HasError}}
-			{{range $i, $r := .Returns}}{{if $i}}, {{end}}{{lower $r.Name}}{{end}}, err := service.{{.Name}}(ctx{{range .Params}}, {{if needsRequestType $m}}req.{{title .Name}}{{else}}{{.Name}}{{end}}{{end}})
+			{{range $i, $r := .Returns}}{{if $i}}, {{end}}{{lower $r.Name}}{{end}}, svcErr := service.{{.Name}}(ctx{{range .Params}}, req.{{title .Name}}{{end}})
-{{- else}}
+			if svcErr != nil {
-			{{range $i, $r := .Returns}}{{if $i}}, {{end}}{{lower $r.Name}}{{end}} := service.{{.Name}}(ctx{{range .Params}}, {{if needsRequestType $m}}req.{{title .Name}}{{else}}{{.Name}}{{end}}{{end}})
+				{{$.Service.Name | lower}}WriteError(p, stack, svcErr)
-{{- end}}
-{{- else if .HasError}}
-			err {{if hasErrFromRead .}}={{else}}:={{end}} service.{{.Name}}(ctx{{range .Params}}, {{if needsRequestType $m}}req.{{title .Name}}{{else}}{{.Name}}{{end}}{{end}})
-{{- else}}
-			service.{{.Name}}(ctx{{range .Params}}, {{if needsRequestType $m}}req.{{title .Name}}{{else}}{{.Name}}{{end}}{{end}})
-{{- end}}
-{{- if .HasError}}
-			if err != nil {
-{{- if isErrorOnly .}}
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
-{{- else if needsRespType .}}
-				{{$.Service.Name | lower}}WriteError(p, stack, err)
-{{- end}}
 				return
 			}
+{{- else}}
+			{{range $i, $r := .Returns}}{{if $i}}, {{end}}{{lower $r.Name}}{{end}} := service.{{.Name}}(ctx{{range .Params}}, req.{{title .Name}}{{end}})
+{{- end}}
+{{- else if .HasError}}
+			if svcErr := service.{{.Name}}(ctx{{range .Params}}, req.{{title .Name}}{{end}}); svcErr != nil {
+				{{$.Service.Name | lower}}WriteError(p, stack, svcErr)
+				return
+			}
+{{- else}}
+			service.{{.Name}}(ctx{{range .Params}}, req.{{title .Name}}{{end}})
 {{- end}}
 
-{{- if isErrorOnly .}}
-			// Write empty string to indicate success
-			if ptr, err := p.WriteString(""); err == nil {
-				stack[0] = ptr
-			}
-{{- else if needsRespType .}}
 			// Write JSON response to plugin memory
 			resp := {{responseType .}}{
 {{- range .Returns}}
@@ -110,27 +86,12 @@ func new{{$.Service.Name}}{{.Name}}HostFunction(service {{$.Service.Interface}})
 {{- end}}
 			}
 			{{$.Service.Name | lower}}WriteResponse(p, stack, resp)
-{{- else if .HasReturns}}
-			// Write return values to stack
-{{- range $i, $r := .Returns}}
-			{{writeReturn $r $i (lower $r.Name)}}
-{{- end}}
-{{- end}}
 		},
-{{- if needsRequestType $m}}
 		[]extism.ValueType{extism.ValueTypePTR},
-{{- else}}
-		[]extism.ValueType{ {{- range $i, $p := .Params}}{{if $i}}, {{end}}{{valueType $p.Type}}{{end}}{{if not .HasParams}}{{end}} },
-{{- end}}
-{{- if or (needsRespType .) (isErrorOnly .)}}
 		[]extism.ValueType{extism.ValueTypePTR},
-{{- else}}
-		[]extism.ValueType{ {{- range $i, $r := .Returns}}{{if $i}}, {{end}}{{valueType $r.Type}}{{end}}{{if not .HasReturns}}{{end}} },
-{{- end}}
 	)
 }
 {{end}}
-{{- if .NeedsWriteHelper}}
 
 // {{.Service.Name | lower}}WriteResponse writes a JSON response to plugin memory.
 func {{.Service.Name | lower}}WriteResponse(p *extism.CurrentPlugin, stack []uint64, resp any) {
@@ -146,8 +107,6 @@ func {{.Service.Name | lower}}WriteResponse(p *extism.CurrentPlugin, stack []uin
 	}
 	stack[0] = respPtr
 }
-{{- end}}
-{{- if .NeedsErrorHelper}}
 
 // {{.Service.Name | lower}}WriteError writes an error response to plugin memory.
 func {{.Service.Name | lower}}WriteError(p *extism.CurrentPlugin, stack []uint64, err error) {
@@ -158,4 +117,3 @@ func {{.Service.Name | lower}}WriteError(p *extism.CurrentPlugin, stack []uint64
 	respPtr, _ := p.WriteBytes(respBytes)
 	stack[0] = respPtr
 }
-{{- end}}

plugins/cmd/hostgen/internal/types.go

@@ -77,128 +77,6 @@ func NewParam(name, typ string) Param {
 	}
 }
 
-// IsSimple returns true if the type can be passed directly on the WASM stack
-// without JSON serialization (primitive numeric types).
-func (p Param) IsSimple() bool {
-	return IsSimpleType(p.Type)
-}
-
-// IsPTR returns true if the type should be passed via memory pointer
-// (strings, bytes, and complex types that need JSON serialization).
-func (p Param) IsPTR() bool {
-	return !p.IsSimple()
-}
-
-// ValueType returns the Extism ValueType constant name for this parameter.
-func (p Param) ValueType() string {
-	return GoTypeToValueType(p.Type)
-}
-
-// IsSimpleType returns true if a Go type can be passed directly on WASM stack.
-func IsSimpleType(typ string) bool {
-	switch typ {
-	case "int32", "uint32", "int64", "uint64", "float32", "float64", "bool":
-		return true
-	default:
-		return false
-	}
-}
-
-// IsStringType returns true if the type is a string.
-func IsStringType(typ string) bool {
-	return typ == "string"
-}
-
-// IsBytesType returns true if the type is []byte.
-func IsBytesType(typ string) bool {
-	return typ == "[]byte"
-}
-
-// NeedsJSON returns true if the type requires JSON serialization.
-func NeedsJSON(typ string) bool {
-	if IsSimpleType(typ) || IsStringType(typ) || IsBytesType(typ) {
-		return false
-	}
-	return true
-}
-
-// GoTypeToValueType returns the Extism ValueType constant for a Go type.
-func GoTypeToValueType(typ string) string {
-	switch typ {
-	case "int32", "uint32":
-		return "extism.ValueTypeI32"
-	case "int64", "uint64":
-		return "extism.ValueTypeI64"
-	case "float32":
-		return "extism.ValueTypeF32"
-	case "float64":
-		return "extism.ValueTypeF64"
-	case "bool":
-		return "extism.ValueTypeI32" // bool as i32
-	default:
-		// strings, []byte, structs, maps, slices all use PTR (i64)
-		return "extism.ValueTypePTR"
-	}
-}
-
-// AllParamsSimple returns true if all params can be passed on the stack.
-func (m Method) AllParamsSimple() bool {
-	for _, p := range m.Params {
-		if !p.IsSimple() {
-			return false
-		}
-	}
-	return true
-}
-
-// AllReturnsSimple returns true if all returns can be passed on the stack.
-func (m Method) AllReturnsSimple() bool {
-	for _, r := range m.Returns {
-		if !r.IsSimple() {
-			return false
-		}
-	}
-	return true
-}
-
-// NeedsRequestType returns true if a request struct is needed.
-// Only needed when we have complex params that require JSON.
-func (m Method) NeedsRequestType() bool {
-	if !m.HasParams() {
-		return false
-	}
-	for _, p := range m.Params {
-		if NeedsJSON(p.Type) {
-			return true
-		}
-	}
-	return false
-}
-
-// NeedsResponseType returns true if a response struct is needed.
-// Needed when we have complex returns that require JSON (but not for error-only methods).
-func (m Method) NeedsResponseType() bool {
-	// Error-only methods return a simple string, not JSON
-	if m.IsErrorOnly() {
-		return false
-	}
-	// If there's an error with other returns, we need a response type
-	if m.HasError && m.HasReturns() {
-		return true
-	}
-	for _, r := range m.Returns {
-		if NeedsJSON(r.Type) {
-			return true
-		}
-	}
-	return false
-}
-
-// IsErrorOnly returns true if the method only returns an error (no other return values).
-func (m Method) IsErrorOnly() bool {
-	return m.HasError && !m.HasReturns()
-}
-
 // toJSONName converts a Go identifier to camelCase JSON field name.
 func toJSONName(name string) string {
 	if name == "" {

plugins/cmd/hostgen/testdata/codec_client_expected.go

@@ -18,6 +18,11 @@ import (
 //go:wasmimport extism:host/user codec_encode
 func codec_encode(uint64) uint64
 
+// CodecEncodeRequest is the request type for Codec.Encode.
+type CodecEncodeRequest struct {
+	Data []byte `json:"data"`
+}
+
 // CodecEncodeResponse is the response type for Codec.Encode.
 type CodecEncodeResponse struct {
 	Result []byte `json:"result,omitempty"`
@@ -26,11 +31,19 @@ type CodecEncodeResponse struct {
 
 // CodecEncode calls the codec_encode host function.
 func CodecEncode(data []byte) (*CodecEncodeResponse, error) {
-	dataMem := pdk.AllocateBytes(data)
+	// Marshal request to JSON
-	defer dataMem.Free()
+	req := CodecEncodeRequest{
+		Data: data,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := codec_encode(dataMem.Offset())
+	responsePtr := codec_encode(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/cmd/hostgen/testdata/codec_expected.go

@@ -9,6 +9,11 @@ import (
 	extism "github.com/extism/go-sdk"
 )
 
+// CodecEncodeRequest is the request type for Codec.Encode.
+type CodecEncodeRequest struct {
+	Data []byte `json:"data"`
+}
+
 // CodecEncodeResponse is the response type for Codec.Encode.
 type CodecEncodeResponse struct {
 	Result []byte `json:"result,omitempty"`
@@ -27,18 +32,25 @@ func newCodecEncodeHostFunction(service CodecService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"codec_encode",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			data, err := p.ReadBytes(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			result, err := service.Encode(ctx, data)
 			if err != nil {
 				codecWriteError(p, stack, err)
 				return
 			}
+			var req CodecEncodeRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				codecWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			result, svcErr := service.Encode(ctx, req.Data)
+			if svcErr != nil {
+				codecWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := CodecEncodeResponse{
 				Result: result,

plugins/cmd/hostgen/testdata/counter_client_expected.go

@@ -8,20 +8,52 @@
 package main
 
 import (
+	"encoding/json"
+
 	"github.com/extism/go-pdk"
 )
 
 // counter_count is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user counter_count
-func counter_count(uint64) int32
+func counter_count(uint64) uint64
+
+// CounterCountRequest is the request type for Counter.Count.
+type CounterCountRequest struct {
+	Name string `json:"name"`
+}
+
+// CounterCountResponse is the response type for Counter.Count.
+type CounterCountResponse struct {
+	Value int32  `json:"value,omitempty"`
+	Error string `json:"error,omitempty"`
+}
 
 // CounterCount calls the counter_count host function.
-func CounterCount(name string) int32 {
+func CounterCount(name string) (*CounterCountResponse, error) {
-	nameMem := pdk.AllocateString(name)
+	// Marshal request to JSON
-	defer nameMem.Free()
+	req := CounterCountRequest{
+		Name: name,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	result := counter_count(nameMem.Offset())
+	responsePtr := counter_count(reqMem.Offset())
-	return int32(result)
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response CounterCountResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
 }

plugins/cmd/hostgen/testdata/counter_expected.go

@@ -4,10 +4,22 @@ package testpkg
 
 import (
 	"context"
+	"encoding/json"
 
 	extism "github.com/extism/go-sdk"
 )
 
+// CounterCountRequest is the request type for Counter.Count.
+type CounterCountRequest struct {
+	Name string `json:"name"`
+}
+
+// CounterCountResponse is the response type for Counter.Count.
+type CounterCountResponse struct {
+	Value int32  `json:"value,omitempty"`
+	Error string `json:"error,omitempty"`
+}
+
 // RegisterCounterHostFunctions registers Counter service host functions.
 // The returned host functions should be added to the plugin's configuration.
 func RegisterCounterHostFunctions(service CounterService) []extism.HostFunction {
@@ -20,18 +32,53 @@ func newCounterCountHostFunction(service CounterService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"counter_count",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			name, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
+				counterWriteError(p, stack, err)
+				return
+			}
+			var req CounterCountRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				counterWriteError(p, stack, err)
 				return
 			}
 
 			// Call the service method
-			value := service.Count(ctx, name)
+			value := service.Count(ctx, req.Name)
-			// Write return values to stack
+
-			stack[0] = extism.EncodeI32(value)
+			// Write JSON response to plugin memory
+			resp := CounterCountResponse{
+				Value: value,
+			}
+			counterWriteResponse(p, stack, resp)
 		},
 		[]extism.ValueType{extism.ValueTypePTR},
-		[]extism.ValueType{extism.ValueTypeI32},
+		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
+
+// counterWriteResponse writes a JSON response to plugin memory.
+func counterWriteResponse(p *extism.CurrentPlugin, stack []uint64, resp any) {
+	respBytes, err := json.Marshal(resp)
+	if err != nil {
+		counterWriteError(p, stack, err)
+		return
+	}
+	respPtr, err := p.WriteBytes(respBytes)
+	if err != nil {
+		stack[0] = 0
+		return
+	}
+	stack[0] = respPtr
+}
+
+// counterWriteError writes an error response to plugin memory.
+func counterWriteError(p *extism.CurrentPlugin, stack []uint64, err error) {
+	errResp := struct {
+		Error string `json:"error"`
+	}{Error: err.Error()}
+	respBytes, _ := json.Marshal(errResp)
+	respPtr, _ := p.WriteBytes(respBytes)
+	stack[0] = respPtr
+}

plugins/cmd/hostgen/testdata/echo_client_expected.go

@@ -18,6 +18,11 @@ import (
 //go:wasmimport extism:host/user echo_echo
 func echo_echo(uint64) uint64
 
+// EchoEchoRequest is the request type for Echo.Echo.
+type EchoEchoRequest struct {
+	Message string `json:"message"`
+}
+
 // EchoEchoResponse is the response type for Echo.Echo.
 type EchoEchoResponse struct {
 	Reply string `json:"reply,omitempty"`
@@ -26,11 +31,19 @@ type EchoEchoResponse struct {
 
 // EchoEcho calls the echo_echo host function.
 func EchoEcho(message string) (*EchoEchoResponse, error) {
-	messageMem := pdk.AllocateString(message)
+	// Marshal request to JSON
-	defer messageMem.Free()
+	req := EchoEchoRequest{
+		Message: message,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := echo_echo(messageMem.Offset())
+	responsePtr := echo_echo(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/cmd/hostgen/testdata/echo_expected.go

@@ -9,6 +9,11 @@ import (
 	extism "github.com/extism/go-sdk"
 )
 
+// EchoEchoRequest is the request type for Echo.Echo.
+type EchoEchoRequest struct {
+	Message string `json:"message"`
+}
+
 // EchoEchoResponse is the response type for Echo.Echo.
 type EchoEchoResponse struct {
 	Reply string `json:"reply,omitempty"`
@@ -27,18 +32,25 @@ func newEchoEchoHostFunction(service EchoService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"echo_echo",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			message, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			reply, err := service.Echo(ctx, message)
 			if err != nil {
 				echoWriteError(p, stack, err)
 				return
 			}
+			var req EchoEchoRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				echoWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			reply, svcErr := service.Echo(ctx, req.Message)
+			if svcErr != nil {
+				echoWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := EchoEchoResponse{
 				Reply: reply,

plugins/cmd/hostgen/testdata/list_client_expected.go

@@ -16,7 +16,13 @@ import (
 // list_items is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user list_items
-func list_items(uint64, uint64) uint64
+func list_items(uint64) uint64
+
+// ListItemsRequest is the request type for List.Items.
+type ListItemsRequest struct {
+	Name   string `json:"name"`
+	Filter Filter `json:"filter"`
+}
 
 // ListItemsResponse is the response type for List.Items.
 type ListItemsResponse struct {
@@ -26,17 +32,20 @@ type ListItemsResponse struct {
 
 // ListItems calls the list_items host function.
 func ListItems(name string, filter Filter) (*ListItemsResponse, error) {
-	nameMem := pdk.AllocateString(name)
+	// Marshal request to JSON
-	defer nameMem.Free()
+	req := ListItemsRequest{
-	filterBytes, err := json.Marshal(filter)
+		Name:   name,
+		Filter: filter,
+	}
+	reqBytes, err := json.Marshal(req)
 	if err != nil {
 		return nil, err
 	}
-	filterMem := pdk.AllocateBytes(filterBytes)
+	reqMem := pdk.AllocateBytes(reqBytes)
-	defer filterMem.Free()
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := list_items(nameMem.Offset(), filterMem.Offset())
+	responsePtr := list_items(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/cmd/hostgen/testdata/list_expected.go

@@ -46,11 +46,12 @@ func newListItemsHostFunction(service ListService) extism.HostFunction {
 			}
 
 			// Call the service method
-			count, err := service.Items(ctx, req.Name, req.Filter)
+			count, svcErr := service.Items(ctx, req.Name, req.Filter)
-			if err != nil {
+			if svcErr != nil {
-				listWriteError(p, stack, err)
+				listWriteError(p, stack, svcErr)
 				return
 			}
+
 			// Write JSON response to plugin memory
 			resp := ListItemsResponse{
 				Count: count,

plugins/cmd/hostgen/testdata/math_client_expected.go

@@ -16,7 +16,13 @@ import (
 // math_add is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user math_add
-func math_add(int32, int32) uint64
+func math_add(uint64) uint64
+
+// MathAddRequest is the request type for Math.Add.
+type MathAddRequest struct {
+	A int32 `json:"a"`
+	B int32 `json:"b"`
+}
 
 // MathAddResponse is the response type for Math.Add.
 type MathAddResponse struct {
@@ -26,9 +32,20 @@ type MathAddResponse struct {
 
 // MathAdd calls the math_add host function.
 func MathAdd(a int32, b int32) (*MathAddResponse, error) {
+	// Marshal request to JSON
+	req := MathAddRequest{
+		A: a,
+		B: b,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := math_add(a, b)
+	responsePtr := math_add(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/cmd/hostgen/testdata/math_expected.go

@@ -9,6 +9,12 @@ import (
 	extism "github.com/extism/go-sdk"
 )
 
+// MathAddRequest is the request type for Math.Add.
+type MathAddRequest struct {
+	A int32 `json:"a"`
+	B int32 `json:"b"`
+}
+
 // MathAddResponse is the response type for Math.Add.
 type MathAddResponse struct {
 	Result int32  `json:"result,omitempty"`
@@ -27,23 +33,32 @@ func newMathAddHostFunction(service MathService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"math_add",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			a := extism.DecodeI32(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			b := extism.DecodeI32(stack[1])
-
-			// Call the service method
-			result, err := service.Add(ctx, a, b)
 			if err != nil {
 				mathWriteError(p, stack, err)
 				return
 			}
+			var req MathAddRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				mathWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			result, svcErr := service.Add(ctx, req.A, req.B)
+			if svcErr != nil {
+				mathWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := MathAddResponse{
 				Result: result,
 			}
 			mathWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypeI32, extism.ValueTypeI32},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }

plugins/cmd/hostgen/testdata/meta_client_expected.go

@@ -9,7 +9,6 @@ package main
 
 import (
 	"encoding/json"
-	"errors"
 
 	"github.com/extism/go-pdk"
 )
@@ -24,19 +23,42 @@ func meta_get(uint64) uint64
 //go:wasmimport extism:host/user meta_set
 func meta_set(uint64) uint64
 
+// MetaGetRequest is the request type for Meta.Get.
+type MetaGetRequest struct {
+	Key string `json:"key"`
+}
+
 // MetaGetResponse is the response type for Meta.Get.
 type MetaGetResponse struct {
 	Value any    `json:"value,omitempty"`
 	Error string `json:"error,omitempty"`
 }
 
+// MetaSetRequest is the request type for Meta.Set.
+type MetaSetRequest struct {
+	Data map[string]any `json:"data"`
+}
+
+// MetaSetResponse is the response type for Meta.Set.
+type MetaSetResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // MetaGet calls the meta_get host function.
 func MetaGet(key string) (*MetaGetResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := MetaGetRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := meta_get(keyMem.Offset())
+	responsePtr := meta_get(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -52,24 +74,30 @@ func MetaGet(key string) (*MetaGetResponse, error) {
 }
 
 // MetaSet calls the meta_set host function.
-func MetaSet(data map[string]any) error {
+func MetaSet(data map[string]any) (*MetaSetResponse, error) {
-	dataBytes, err := json.Marshal(data)
+	// Marshal request to JSON
-	if err != nil {
+	req := MetaSetRequest{
-		return err
+		Data: data,
 	}
-	dataMem := pdk.AllocateBytes(dataBytes)
+	reqBytes, err := json.Marshal(req)
-	defer dataMem.Free()
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := meta_set(dataMem.Offset())
+	responsePtr := meta_set(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response MetaSetResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }

plugins/cmd/hostgen/testdata/meta_expected.go

@@ -9,6 +9,11 @@ import (
 	extism "github.com/extism/go-sdk"
 )
 
+// MetaGetRequest is the request type for Meta.Get.
+type MetaGetRequest struct {
+	Key string `json:"key"`
+}
+
 // MetaGetResponse is the response type for Meta.Get.
 type MetaGetResponse struct {
 	Value any    `json:"value,omitempty"`
@@ -20,6 +25,11 @@ type MetaSetRequest struct {
 	Data map[string]any `json:"data"`
 }
 
+// MetaSetResponse is the response type for Meta.Set.
+type MetaSetResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // RegisterMetaHostFunctions registers Meta service host functions.
 // The returned host functions should be added to the plugin's configuration.
 func RegisterMetaHostFunctions(service MetaService) []extism.HostFunction {
@@ -33,18 +43,25 @@ func newMetaGetHostFunction(service MetaService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"meta_get",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			value, err := service.Get(ctx, key)
 			if err != nil {
 				metaWriteError(p, stack, err)
 				return
 			}
+			var req MetaGetRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				metaWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			value, svcErr := service.Get(ctx, req.Key)
+			if svcErr != nil {
+				metaWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := MetaGetResponse{
 				Value: value,
@@ -73,18 +90,14 @@ func newMetaSetHostFunction(service MetaService) extism.HostFunction {
 			}
 
 			// Call the service method
-			err = service.Set(ctx, req.Data)
+			if svcErr := service.Set(ctx, req.Data); svcErr != nil {
-			if err != nil {
+				metaWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := MetaSetResponse{}
-			}
+			metaWriteResponse(p, stack, resp)
 		},
 		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},

plugins/cmd/hostgen/testdata/ping_client_expected.go

@@ -8,7 +8,7 @@
 package main
 
 import (
-	"errors"
+	"encoding/json"
 
 	"github.com/extism/go-pdk"
 )
@@ -16,21 +16,31 @@ import (
 // ping_ping is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user ping_ping
-func ping_ping() uint64
+func ping_ping(uint64) uint64
+
+// PingPingResponse is the response type for Ping.Ping.
+type PingPingResponse struct {
+	Error string `json:"error,omitempty"`
+}
 
 // PingPing calls the ping_ping host function.
-func PingPing() error {
+func PingPing() (*PingPingResponse, error) {
+	// No parameters - allocate empty JSON object
+	reqMem := pdk.AllocateBytes([]byte("{}"))
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := ping_ping()
+	responsePtr := ping_ping(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response PingPingResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }

plugins/cmd/hostgen/testdata/ping_expected.go

@@ -4,10 +4,16 @@ package testpkg
 
 import (
 	"context"
+	"encoding/json"
 
 	extism "github.com/extism/go-sdk"
 )
 
+// PingPingResponse is the response type for Ping.Ping.
+type PingPingResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // RegisterPingHostFunctions registers Ping service host functions.
 // The returned host functions should be added to the plugin's configuration.
 func RegisterPingHostFunctions(service PingService) []extism.HostFunction {
@@ -22,20 +28,41 @@ func newPingPingHostFunction(service PingService) extism.HostFunction {
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
 
 			// Call the service method
-			err := service.Ping(ctx)
+			if svcErr := service.Ping(ctx); svcErr != nil {
-			if err != nil {
+				pingWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := PingPingResponse{}
-			}
+			pingWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
+
+// pingWriteResponse writes a JSON response to plugin memory.
+func pingWriteResponse(p *extism.CurrentPlugin, stack []uint64, resp any) {
+	respBytes, err := json.Marshal(resp)
+	if err != nil {
+		pingWriteError(p, stack, err)
+		return
+	}
+	respPtr, err := p.WriteBytes(respBytes)
+	if err != nil {
+		stack[0] = 0
+		return
+	}
+	stack[0] = respPtr
+}
+
+// pingWriteError writes an error response to plugin memory.
+func pingWriteError(p *extism.CurrentPlugin, stack []uint64, err error) {
+	errResp := struct {
+		Error string `json:"error"`
+	}{Error: err.Error()}
+	respBytes, _ := json.Marshal(errResp)
+	respPtr, _ := p.WriteBytes(respBytes)
+	stack[0] = respPtr
+}

plugins/cmd/hostgen/testdata/search_client_expected.go

@@ -18,6 +18,11 @@ import (
 //go:wasmimport extism:host/user search_find
 func search_find(uint64) uint64
 
+// SearchFindRequest is the request type for Search.Find.
+type SearchFindRequest struct {
+	Query string `json:"query"`
+}
+
 // SearchFindResponse is the response type for Search.Find.
 type SearchFindResponse struct {
 	Results []Result `json:"results,omitempty"`
@@ -27,11 +32,19 @@ type SearchFindResponse struct {
 
 // SearchFind calls the search_find host function.
 func SearchFind(query string) (*SearchFindResponse, error) {
-	queryMem := pdk.AllocateString(query)
+	// Marshal request to JSON
-	defer queryMem.Free()
+	req := SearchFindRequest{
+		Query: query,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := search_find(queryMem.Offset())
+	responsePtr := search_find(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/cmd/hostgen/testdata/search_expected.go

@@ -9,6 +9,11 @@ import (
 	extism "github.com/extism/go-sdk"
 )
 
+// SearchFindRequest is the request type for Search.Find.
+type SearchFindRequest struct {
+	Query string `json:"query"`
+}
+
 // SearchFindResponse is the response type for Search.Find.
 type SearchFindResponse struct {
 	Results []Result `json:"results,omitempty"`
@@ -28,18 +33,25 @@ func newSearchFindHostFunction(service SearchService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"search_find",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			query, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			results, total, err := service.Find(ctx, query)
 			if err != nil {
 				searchWriteError(p, stack, err)
 				return
 			}
+			var req SearchFindRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				searchWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			results, total, svcErr := service.Find(ctx, req.Query)
+			if svcErr != nil {
+				searchWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := SearchFindResponse{
 				Results: results,

plugins/cmd/hostgen/testdata/store_client_expected.go

@@ -18,6 +18,11 @@ import (
 //go:wasmimport extism:host/user store_save
 func store_save(uint64) uint64
 
+// StoreSaveRequest is the request type for Store.Save.
+type StoreSaveRequest struct {
+	Item Item `json:"item"`
+}
+
 // StoreSaveResponse is the response type for Store.Save.
 type StoreSaveResponse struct {
 	Id    string `json:"id,omitempty"`
@@ -26,15 +31,19 @@ type StoreSaveResponse struct {
 
 // StoreSave calls the store_save host function.
 func StoreSave(item Item) (*StoreSaveResponse, error) {
-	itemBytes, err := json.Marshal(item)
+	// Marshal request to JSON
+	req := StoreSaveRequest{
+		Item: item,
+	}
+	reqBytes, err := json.Marshal(req)
 	if err != nil {
 		return nil, err
 	}
-	itemMem := pdk.AllocateBytes(itemBytes)
+	reqMem := pdk.AllocateBytes(reqBytes)
-	defer itemMem.Free()
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := store_save(itemMem.Offset())
+	responsePtr := store_save(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/cmd/hostgen/testdata/store_expected.go

@@ -45,11 +45,12 @@ func newStoreSaveHostFunction(service StoreService) extism.HostFunction {
 			}
 
 			// Call the service method
-			id, err := service.Save(ctx, req.Item)
+			id, svcErr := service.Save(ctx, req.Item)
-			if err != nil {
+			if svcErr != nil {
-				storeWriteError(p, stack, err)
+				storeWriteError(p, stack, svcErr)
 				return
 			}
+
 			// Write JSON response to plugin memory
 			resp := StoreSaveResponse{
 				Id: id,

plugins/cmd/hostgen/testdata/users_client_expected.go

@@ -16,7 +16,13 @@ import (
 // users_get is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user users_get
-func users_get(uint64, uint64) uint64
+func users_get(uint64) uint64
+
+// UsersGetRequest is the request type for Users.Get.
+type UsersGetRequest struct {
+	Id     *string `json:"id"`
+	Filter *User   `json:"filter"`
+}
 
 // UsersGetResponse is the response type for Users.Get.
 type UsersGetResponse struct {
@@ -26,21 +32,20 @@ type UsersGetResponse struct {
 
 // UsersGet calls the users_get host function.
 func UsersGet(id *string, filter *User) (*UsersGetResponse, error) {
-	idBytes, err := json.Marshal(id)
+	// Marshal request to JSON
+	req := UsersGetRequest{
+		Id:     id,
+		Filter: filter,
+	}
+	reqBytes, err := json.Marshal(req)
 	if err != nil {
 		return nil, err
 	}
-	idMem := pdk.AllocateBytes(idBytes)
+	reqMem := pdk.AllocateBytes(reqBytes)
-	defer idMem.Free()
+	defer reqMem.Free()
-	filterBytes, err := json.Marshal(filter)
-	if err != nil {
-		return nil, err
-	}
-	filterMem := pdk.AllocateBytes(filterBytes)
-	defer filterMem.Free()
 
 	// Call the host function
-	responsePtr := users_get(idMem.Offset(), filterMem.Offset())
+	responsePtr := users_get(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/cmd/hostgen/testdata/users_expected.go

@@ -46,11 +46,12 @@ func newUsersGetHostFunction(service UsersService) extism.HostFunction {
 			}
 
 			// Call the service method
-			result, err := service.Get(ctx, req.Id, req.Filter)
+			result, svcErr := service.Get(ctx, req.Id, req.Filter)
-			if err != nil {
+			if svcErr != nil {
-				usersWriteError(p, stack, err)
+				usersWriteError(p, stack, svcErr)
 				return
 			}
+
 			// Write JSON response to plugin memory
 			resp := UsersGetResponse{
 				Result: result,

plugins/examples/crypto-ticker/main.go

@@ -176,11 +176,14 @@ func parseTickerSymbols(tickerConfig string) []string {
 // connectAndSubscribe connects to Coinbase WebSocket and subscribes to tickers
 func connectAndSubscribe(tickers []string) error {
 	// Connect to WebSocket using host function
-	connID, err := WebSocketConnect(coinbaseWSEndpoint, nil, connectionID)
+	resp, err := WebSocketConnect(coinbaseWSEndpoint, nil, connectionID)
 	if err != nil {
 		return fmt.Errorf("WebSocket connection error: %v", err)
 	}
-	pdk.Log(pdk.LogInfo, fmt.Sprintf("Connected to Coinbase WebSocket API (connection: %s)", connID))
+	if resp.Error != "" {
+		return fmt.Errorf("WebSocket connection error: %s", resp.Error)
+	}
+	pdk.Log(pdk.LogInfo, fmt.Sprintf("Connected to Coinbase WebSocket API (connection: %s)", resp.NewConnectionID))
 
 	// Subscribe to ticker channel
 	subscription := CoinbaseSubscription{
@@ -195,10 +198,13 @@ func connectAndSubscribe(tickers []string) error {
 	}
 
 	// Send subscription message
-	err = WebSocketSendText(connectionID, string(subscriptionJSON))
+	sendResp, err := WebSocketSendText(connectionID, string(subscriptionJSON))
 	if err != nil {
 		return fmt.Errorf("WebSocket send error: %v", err)
 	}
+	if sendResp.Error != "" {
+		return fmt.Errorf("WebSocket send error: %s", sendResp.Error)
+	}
 
 	pdk.Log(pdk.LogInfo, "Subscription message sent to Coinbase WebSocket API")
 	return nil
@@ -266,9 +272,11 @@ func NdWebsocketOnClose(input OnCloseInput) (OnCloseOutput, error) {
 		pdk.Log(pdk.LogInfo, "Scheduling reconnection attempt in 5 seconds...")
 
 		// Schedule a one-time reconnection attempt
-		_, err := SchedulerScheduleOneTime(5, "reconnect", reconnectScheduleID)
+		resp, err := SchedulerScheduleOneTime(5, "reconnect", reconnectScheduleID)
 		if err != nil {
 			pdk.Log(pdk.LogError, fmt.Sprintf("Failed to schedule reconnection: %v", err))
+		} else if resp.Error != "" {
+			pdk.Log(pdk.LogError, fmt.Sprintf("Failed to schedule reconnection: %s", resp.Error))
 		}
 	}
 
@@ -317,9 +325,11 @@ func ndSchedulerCallback() int32 {
 		pdk.Log(pdk.LogError, fmt.Sprintf("Reconnection failed: %v - will retry in 10 seconds", err))
 
 		// Schedule another attempt
-		_, err = SchedulerScheduleOneTime(10, "reconnect", reconnectScheduleID)
+		resp, err := SchedulerScheduleOneTime(10, "reconnect", reconnectScheduleID)
 		if err != nil {
 			pdk.Log(pdk.LogError, fmt.Sprintf("Failed to schedule retry: %v", err))
+		} else if resp.Error != "" {
+			pdk.Log(pdk.LogError, fmt.Sprintf("Failed to schedule retry: %s", resp.Error))
 		}
 	} else {
 		pdk.Log(pdk.LogInfo, "Successfully reconnected!")

plugins/examples/crypto-ticker/nd_host.go

@@ -1,188 +0,0 @@
-// Host function wrappers for Navidrome plugin services.
-// These allow the plugin to call host functions provided by Navidrome.
-package main
-
-import (
-	"encoding/json"
-	"errors"
-
-	pdk "github.com/extism/go-pdk"
-)
-
-// WebSocket host functions
-
-//go:wasmimport extism:host/user websocket_connect
-func websocket_connect(uint64) uint64
-
-//go:wasmimport extism:host/user websocket_sendtext
-func websocket_sendtext(connectionID uint64, message uint64) uint64
-
-//go:wasmimport extism:host/user websocket_closeconnection
-func websocket_closeconnection(connectionID uint64, code int32, reason uint64) uint64
-
-// WebSocketConnectRequest is the request type for WebSocket.Connect
-type WebSocketConnectRequest struct {
-	Url          string            `json:"url"`
-	Headers      map[string]string `json:"headers,omitempty"`
-	ConnectionID string            `json:"connectionID,omitempty"`
-}
-
-// WebSocketConnectResponse is the response type for WebSocket.Connect
-type WebSocketConnectResponse struct {
-	NewConnectionID string `json:"newConnectionID,omitempty"`
-	Error           string `json:"error,omitempty"`
-}
-
-// WebSocketConnect establishes a WebSocket connection to the specified URL.
-func WebSocketConnect(url string, headers map[string]string, connectionID string) (string, error) {
-	req := WebSocketConnectRequest{
-		Url:          url,
-		Headers:      headers,
-		ConnectionID: connectionID,
-	}
-	reqBytes, err := json.Marshal(req)
-	if err != nil {
-		return "", err
-	}
-
-	reqMem := pdk.AllocateBytes(reqBytes)
-	defer reqMem.Free()
-
-	responsePtr := websocket_connect(reqMem.Offset())
-	responseMem := pdk.FindMemory(responsePtr)
-	responseBytes := responseMem.ReadBytes()
-
-	var resp WebSocketConnectResponse
-	if err := json.Unmarshal(responseBytes, &resp); err != nil {
-		return "", err
-	}
-
-	if resp.Error != "" {
-		return "", errors.New(resp.Error)
-	}
-
-	return resp.NewConnectionID, nil
-}
-
-// WebSocketSendText sends a text message over an established WebSocket connection.
-func WebSocketSendText(connectionID, message string) error {
-	connMem := pdk.AllocateString(connectionID)
-	defer connMem.Free()
-	msgMem := pdk.AllocateString(message)
-	defer msgMem.Free()
-
-	responsePtr := websocket_sendtext(connMem.Offset(), msgMem.Offset())
-	if responsePtr != 0 {
-		responseMem := pdk.FindMemory(responsePtr)
-		errStr := string(responseMem.ReadBytes())
-		if errStr != "" {
-			return errors.New(errStr)
-		}
-	}
-	return nil
-}
-
-// WebSocketCloseConnection gracefully closes a WebSocket connection.
-func WebSocketCloseConnection(connectionID string, code int32, reason string) error {
-	connMem := pdk.AllocateString(connectionID)
-	defer connMem.Free()
-	reasonMem := pdk.AllocateString(reason)
-	defer reasonMem.Free()
-
-	responsePtr := websocket_closeconnection(connMem.Offset(), code, reasonMem.Offset())
-	if responsePtr != 0 {
-		responseMem := pdk.FindMemory(responsePtr)
-		errStr := string(responseMem.ReadBytes())
-		if errStr != "" {
-			return errors.New(errStr)
-		}
-	}
-	return nil
-}
-
-// Scheduler host functions
-
-//go:wasmimport extism:host/user scheduler_scheduleonetime
-func scheduler_scheduleonetime(delaySeconds int32, payload uint64, scheduleID uint64) uint64
-
-//go:wasmimport extism:host/user scheduler_schedulerecurring
-func scheduler_schedulerecurring(cronExpression uint64, payload uint64, scheduleID uint64) uint64
-
-//go:wasmimport extism:host/user scheduler_cancelschedule
-func scheduler_cancelschedule(scheduleID uint64) uint64
-
-// SchedulerScheduleOneTimeResponse is the response type for Scheduler.ScheduleOneTime
-type SchedulerScheduleOneTimeResponse struct {
-	NewScheduleID string `json:"newScheduleID,omitempty"`
-	Error         string `json:"error,omitempty"`
-}
-
-// SchedulerScheduleRecurringResponse is the response type for Scheduler.ScheduleRecurring
-type SchedulerScheduleRecurringResponse struct {
-	NewScheduleID string `json:"newScheduleID,omitempty"`
-	Error         string `json:"error,omitempty"`
-}
-
-// SchedulerScheduleOneTime schedules a one-time task to run after delaySeconds.
-func SchedulerScheduleOneTime(delaySeconds int32, payload, scheduleID string) (string, error) {
-	payloadMem := pdk.AllocateString(payload)
-	defer payloadMem.Free()
-	scheduleIDMem := pdk.AllocateString(scheduleID)
-	defer scheduleIDMem.Free()
-
-	responsePtr := scheduler_scheduleonetime(delaySeconds, payloadMem.Offset(), scheduleIDMem.Offset())
-	responseMem := pdk.FindMemory(responsePtr)
-	responseBytes := responseMem.ReadBytes()
-
-	var resp SchedulerScheduleOneTimeResponse
-	if err := json.Unmarshal(responseBytes, &resp); err != nil {
-		return "", err
-	}
-
-	if resp.Error != "" {
-		return "", errors.New(resp.Error)
-	}
-
-	return resp.NewScheduleID, nil
-}
-
-// SchedulerScheduleRecurring schedules a recurring task using a cron expression.
-func SchedulerScheduleRecurring(cronExpression, payload, scheduleID string) (string, error) {
-	cronMem := pdk.AllocateString(cronExpression)
-	defer cronMem.Free()
-	payloadMem := pdk.AllocateString(payload)
-	defer payloadMem.Free()
-	scheduleIDMem := pdk.AllocateString(scheduleID)
-	defer scheduleIDMem.Free()
-
-	responsePtr := scheduler_schedulerecurring(cronMem.Offset(), payloadMem.Offset(), scheduleIDMem.Offset())
-	responseMem := pdk.FindMemory(responsePtr)
-	responseBytes := responseMem.ReadBytes()
-
-	var resp SchedulerScheduleRecurringResponse
-	if err := json.Unmarshal(responseBytes, &resp); err != nil {
-		return "", err
-	}
-
-	if resp.Error != "" {
-		return "", errors.New(resp.Error)
-	}
-
-	return resp.NewScheduleID, nil
-}
-
-// SchedulerCancelSchedule cancels a scheduled task.
-func SchedulerCancelSchedule(scheduleID string) error {
-	scheduleIDMem := pdk.AllocateString(scheduleID)
-	defer scheduleIDMem.Free()
-
-	responsePtr := scheduler_cancelschedule(scheduleIDMem.Offset())
-	if responsePtr != 0 {
-		responseMem := pdk.FindMemory(responsePtr)
-		errStr := string(responseMem.ReadBytes())
-		if errStr != "" {
-			return errors.New(errStr)
-		}
-	}
-	return nil
-}

plugins/examples/crypto-ticker/nd_host_scheduler.go

@@ -0,0 +1,180 @@
+// Code generated by hostgen. DO NOT EDIT.
+//
+// This file contains client wrappers for the Scheduler host service.
+// It is intended for use in Navidrome plugins built with TinyGo.
+//
+//go:build wasip1
+
+package main
+
+import (
+	"encoding/json"
+
+	"github.com/extism/go-pdk"
+)
+
+// scheduler_scheduleonetime is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user scheduler_scheduleonetime
+func scheduler_scheduleonetime(uint64) uint64
+
+// scheduler_schedulerecurring is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user scheduler_schedulerecurring
+func scheduler_schedulerecurring(uint64) uint64
+
+// scheduler_cancelschedule is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user scheduler_cancelschedule
+func scheduler_cancelschedule(uint64) uint64
+
+// SchedulerScheduleOneTimeRequest is the request type for Scheduler.ScheduleOneTime.
+type SchedulerScheduleOneTimeRequest struct {
+	DelaySeconds int32  `json:"delaySeconds"`
+	Payload      string `json:"payload"`
+	ScheduleID   string `json:"scheduleID"`
+}
+
+// SchedulerScheduleOneTimeResponse is the response type for Scheduler.ScheduleOneTime.
+type SchedulerScheduleOneTimeResponse struct {
+	NewScheduleID string `json:"newScheduleID,omitempty"`
+	Error         string `json:"error,omitempty"`
+}
+
+// SchedulerScheduleRecurringRequest is the request type for Scheduler.ScheduleRecurring.
+type SchedulerScheduleRecurringRequest struct {
+	CronExpression string `json:"cronExpression"`
+	Payload        string `json:"payload"`
+	ScheduleID     string `json:"scheduleID"`
+}
+
+// SchedulerScheduleRecurringResponse is the response type for Scheduler.ScheduleRecurring.
+type SchedulerScheduleRecurringResponse struct {
+	NewScheduleID string `json:"newScheduleID,omitempty"`
+	Error         string `json:"error,omitempty"`
+}
+
+// SchedulerCancelScheduleRequest is the request type for Scheduler.CancelSchedule.
+type SchedulerCancelScheduleRequest struct {
+	ScheduleID string `json:"scheduleID"`
+}
+
+// SchedulerCancelScheduleResponse is the response type for Scheduler.CancelSchedule.
+type SchedulerCancelScheduleResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// SchedulerScheduleOneTime calls the scheduler_scheduleonetime host function.
+// ScheduleOneTime schedules a one-time event to be triggered after the specified delay.
+// Plugins that use this function must also implement the SchedulerCallback capability
+//
+// Parameters:
+//   - delaySeconds: Number of seconds to wait before triggering the event
+//   - payload: Data to be passed to the scheduled event handler
+//   - scheduleID: Optional unique identifier for the scheduled job. If empty, one will be generated
+//
+// Returns the schedule ID that can be used to cancel the job, or an error if scheduling fails.
+func SchedulerScheduleOneTime(delaySeconds int32, payload string, scheduleID string) (*SchedulerScheduleOneTimeResponse, error) {
+	// Marshal request to JSON
+	req := SchedulerScheduleOneTimeRequest{
+		DelaySeconds: delaySeconds,
+		Payload:      payload,
+		ScheduleID:   scheduleID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := scheduler_scheduleonetime(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response SchedulerScheduleOneTimeResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}
+
+// SchedulerScheduleRecurring calls the scheduler_schedulerecurring host function.
+// ScheduleRecurring schedules a recurring event using a cron expression.
+// Plugins that use this function must also implement the SchedulerCallback capability
+//
+// Parameters:
+//   - cronExpression: Standard cron format expression (e.g., "0 0 * * *" for daily at midnight)
+//   - payload: Data to be passed to each scheduled event handler invocation
+//   - scheduleID: Optional unique identifier for the scheduled job. If empty, one will be generated
+//
+// Returns the schedule ID that can be used to cancel the job, or an error if scheduling fails.
+func SchedulerScheduleRecurring(cronExpression string, payload string, scheduleID string) (*SchedulerScheduleRecurringResponse, error) {
+	// Marshal request to JSON
+	req := SchedulerScheduleRecurringRequest{
+		CronExpression: cronExpression,
+		Payload:        payload,
+		ScheduleID:     scheduleID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := scheduler_schedulerecurring(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response SchedulerScheduleRecurringResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}
+
+// SchedulerCancelSchedule calls the scheduler_cancelschedule host function.
+// CancelSchedule cancels a scheduled job identified by its schedule ID.
+//
+// This works for both one-time and recurring schedules. Once cancelled, the job will not trigger
+// any future events.
+//
+// Returns an error if the schedule ID is not found or if cancellation fails.
+func SchedulerCancelSchedule(scheduleID string) (*SchedulerCancelScheduleResponse, error) {
+	// Marshal request to JSON
+	req := SchedulerCancelScheduleRequest{
+		ScheduleID: scheduleID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := scheduler_cancelschedule(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response SchedulerCancelScheduleResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}

plugins/examples/crypto-ticker/nd_host_websocket.go

@@ -0,0 +1,237 @@
+// Code generated by hostgen. DO NOT EDIT.
+//
+// This file contains client wrappers for the WebSocket host service.
+// It is intended for use in Navidrome plugins built with TinyGo.
+//
+//go:build wasip1
+
+package main
+
+import (
+	"encoding/json"
+
+	"github.com/extism/go-pdk"
+)
+
+// websocket_connect is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user websocket_connect
+func websocket_connect(uint64) uint64
+
+// websocket_sendtext is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user websocket_sendtext
+func websocket_sendtext(uint64) uint64
+
+// websocket_sendbinary is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user websocket_sendbinary
+func websocket_sendbinary(uint64) uint64
+
+// websocket_closeconnection is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user websocket_closeconnection
+func websocket_closeconnection(uint64) uint64
+
+// WebSocketConnectRequest is the request type for WebSocket.Connect.
+type WebSocketConnectRequest struct {
+	Url          string            `json:"url"`
+	Headers      map[string]string `json:"headers"`
+	ConnectionID string            `json:"connectionID"`
+}
+
+// WebSocketConnectResponse is the response type for WebSocket.Connect.
+type WebSocketConnectResponse struct {
+	NewConnectionID string `json:"newConnectionID,omitempty"`
+	Error           string `json:"error,omitempty"`
+}
+
+// WebSocketSendTextRequest is the request type for WebSocket.SendText.
+type WebSocketSendTextRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Message      string `json:"message"`
+}
+
+// WebSocketSendTextResponse is the response type for WebSocket.SendText.
+type WebSocketSendTextResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketSendBinaryRequest is the request type for WebSocket.SendBinary.
+type WebSocketSendBinaryRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Data         []byte `json:"data"`
+}
+
+// WebSocketSendBinaryResponse is the response type for WebSocket.SendBinary.
+type WebSocketSendBinaryResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketCloseConnectionRequest is the request type for WebSocket.CloseConnection.
+type WebSocketCloseConnectionRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Code         int32  `json:"code"`
+	Reason       string `json:"reason"`
+}
+
+// WebSocketCloseConnectionResponse is the response type for WebSocket.CloseConnection.
+type WebSocketCloseConnectionResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketConnect calls the websocket_connect host function.
+// Connect establishes a WebSocket connection to the specified URL.
+//
+// Plugins that use this function must also implement the WebSocketCallback capability
+// to receive incoming messages and connection events.
+//
+// Parameters:
+//   - url: The WebSocket URL to connect to (ws:// or wss://)
+//   - headers: Optional HTTP headers to include in the handshake request
+//   - connectionID: Optional unique identifier for the connection. If empty, one will be generated
+//
+// Returns the connection ID that can be used to send messages or close the connection,
+// or an error if the connection fails.
+func WebSocketConnect(url string, headers map[string]string, connectionID string) (*WebSocketConnectResponse, error) {
+	// Marshal request to JSON
+	req := WebSocketConnectRequest{
+		Url:          url,
+		Headers:      headers,
+		ConnectionID: connectionID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := websocket_connect(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response WebSocketConnectResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}
+
+// WebSocketSendText calls the websocket_sendtext host function.
+// SendText sends a text message over an established WebSocket connection.
+//
+// Parameters:
+//   - connectionID: The connection identifier returned by Connect
+//   - message: The text message to send
+//
+// Returns an error if the connection is not found or if sending fails.
+func WebSocketSendText(connectionID string, message string) (*WebSocketSendTextResponse, error) {
+	// Marshal request to JSON
+	req := WebSocketSendTextRequest{
+		ConnectionID: connectionID,
+		Message:      message,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := websocket_sendtext(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response WebSocketSendTextResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}
+
+// WebSocketSendBinary calls the websocket_sendbinary host function.
+// SendBinary sends binary data over an established WebSocket connection.
+//
+// Parameters:
+//   - connectionID: The connection identifier returned by Connect
+//   - data: The binary data to send
+//
+// Returns an error if the connection is not found or if sending fails.
+func WebSocketSendBinary(connectionID string, data []byte) (*WebSocketSendBinaryResponse, error) {
+	// Marshal request to JSON
+	req := WebSocketSendBinaryRequest{
+		ConnectionID: connectionID,
+		Data:         data,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := websocket_sendbinary(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response WebSocketSendBinaryResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}
+
+// WebSocketCloseConnection calls the websocket_closeconnection host function.
+// CloseConnection gracefully closes a WebSocket connection.
+//
+// Parameters:
+//   - connectionID: The connection identifier returned by Connect
+//   - code: WebSocket close status code (e.g., 1000 for normal closure)
+//   - reason: Optional human-readable reason for closing
+//
+// Returns an error if the connection is not found or if closing fails.
+func WebSocketCloseConnection(connectionID string, code int32, reason string) (*WebSocketCloseConnectionResponse, error) {
+	// Marshal request to JSON
+	req := WebSocketCloseConnectionRequest{
+		ConnectionID: connectionID,
+		Code:         code,
+		Reason:       reason,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := websocket_closeconnection(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response WebSocketCloseConnectionResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}

plugins/examples/discord-rich-presence/main.go

@@ -181,7 +181,7 @@ func NdScrobblerNowPlaying(input NowPlayingInput) (ScrobblerOutput, error) {
 	}
 
 	// Cancel any existing completion schedule
-	_ = SchedulerCancelSchedule(fmt.Sprintf("%s-clear", input.Username))
+	_, _ = SchedulerCancelSchedule(fmt.Sprintf("%s-clear", input.Username))
 
 	// Calculate timestamps
 	now := time.Now().Unix()

plugins/examples/discord-rich-presence/nd_host_artwork.go

@@ -16,22 +16,28 @@ import (
 // artwork_getartisturl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_getartisturl
-func artwork_getartisturl(uint64, int32) uint64
+func artwork_getartisturl(uint64) uint64
 
 // artwork_getalbumurl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_getalbumurl
-func artwork_getalbumurl(uint64, int32) uint64
+func artwork_getalbumurl(uint64) uint64
 
 // artwork_gettrackurl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_gettrackurl
-func artwork_gettrackurl(uint64, int32) uint64
+func artwork_gettrackurl(uint64) uint64
 
 // artwork_getplaylisturl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_getplaylisturl
-func artwork_getplaylisturl(uint64, int32) uint64
+func artwork_getplaylisturl(uint64) uint64
+
+// ArtworkGetArtistUrlRequest is the request type for Artwork.GetArtistUrl.
+type ArtworkGetArtistUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
 
 // ArtworkGetArtistUrlResponse is the response type for Artwork.GetArtistUrl.
 type ArtworkGetArtistUrlResponse struct {
@@ -39,18 +45,36 @@ type ArtworkGetArtistUrlResponse struct {
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetAlbumUrlRequest is the request type for Artwork.GetAlbumUrl.
+type ArtworkGetAlbumUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetAlbumUrlResponse is the response type for Artwork.GetAlbumUrl.
 type ArtworkGetAlbumUrlResponse struct {
 	Url   string `json:"url,omitempty"`
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetTrackUrlRequest is the request type for Artwork.GetTrackUrl.
+type ArtworkGetTrackUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetTrackUrlResponse is the response type for Artwork.GetTrackUrl.
 type ArtworkGetTrackUrlResponse struct {
 	Url   string `json:"url,omitempty"`
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetPlaylistUrlRequest is the request type for Artwork.GetPlaylistUrl.
+type ArtworkGetPlaylistUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetPlaylistUrlResponse is the response type for Artwork.GetPlaylistUrl.
 type ArtworkGetPlaylistUrlResponse struct {
 	Url   string `json:"url,omitempty"`
@@ -66,11 +90,20 @@ type ArtworkGetPlaylistUrlResponse struct {
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetArtistUrl(id string, size int32) (*ArtworkGetArtistUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetArtistUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_getartisturl(idMem.Offset(), size)
+	responsePtr := artwork_getartisturl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -94,11 +127,20 @@ func ArtworkGetArtistUrl(id string, size int32) (*ArtworkGetArtistUrlResponse, e
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetAlbumUrl(id string, size int32) (*ArtworkGetAlbumUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetAlbumUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_getalbumurl(idMem.Offset(), size)
+	responsePtr := artwork_getalbumurl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -122,11 +164,20 @@ func ArtworkGetAlbumUrl(id string, size int32) (*ArtworkGetAlbumUrlResponse, err
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetTrackUrl(id string, size int32) (*ArtworkGetTrackUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetTrackUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_gettrackurl(idMem.Offset(), size)
+	responsePtr := artwork_gettrackurl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -150,11 +201,20 @@ func ArtworkGetTrackUrl(id string, size int32) (*ArtworkGetTrackUrlResponse, err
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetPlaylistUrl(id string, size int32) (*ArtworkGetPlaylistUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetPlaylistUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_getplaylisturl(idMem.Offset(), size)
+	responsePtr := artwork_getplaylisturl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/examples/discord-rich-presence/nd_host_cache.go

@@ -9,7 +9,6 @@ package main
 
 import (
 	"encoding/json"
-	"errors"
 
 	"github.com/extism/go-pdk"
 )
@@ -17,7 +16,7 @@ import (
 // cache_setstring is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setstring
-func cache_setstring(uint64, uint64, int64) uint64
+func cache_setstring(uint64) uint64
 
 // cache_getstring is the host function provided by Navidrome.
 //
@@ -27,7 +26,7 @@ func cache_getstring(uint64) uint64
 // cache_setint is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setint
-func cache_setint(uint64, int64, int64) uint64
+func cache_setint(uint64) uint64
 
 // cache_getint is the host function provided by Navidrome.
 //
@@ -37,7 +36,7 @@ func cache_getint(uint64) uint64
 // cache_setfloat is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setfloat
-func cache_setfloat(uint64, float64, int64) uint64
+func cache_setfloat(uint64) uint64
 
 // cache_getfloat is the host function provided by Navidrome.
 //
@@ -47,7 +46,7 @@ func cache_getfloat(uint64) uint64
 // cache_setbytes is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setbytes
-func cache_setbytes(uint64, uint64, int64) uint64
+func cache_setbytes(uint64) uint64
 
 // cache_getbytes is the host function provided by Navidrome.
 //
@@ -64,6 +63,23 @@ func cache_has(uint64) uint64
 //go:wasmimport extism:host/user cache_remove
 func cache_remove(uint64) uint64
 
+// CacheSetStringRequest is the request type for Cache.SetString.
+type CacheSetStringRequest struct {
+	Key        string `json:"key"`
+	Value      string `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetStringResponse is the response type for Cache.SetString.
+type CacheSetStringResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetStringRequest is the request type for Cache.GetString.
+type CacheGetStringRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetStringResponse is the response type for Cache.GetString.
 type CacheGetStringResponse struct {
 	Value  string `json:"value,omitempty"`
@@ -71,6 +87,23 @@ type CacheGetStringResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheSetIntRequest is the request type for Cache.SetInt.
+type CacheSetIntRequest struct {
+	Key        string `json:"key"`
+	Value      int64  `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetIntResponse is the response type for Cache.SetInt.
+type CacheSetIntResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetIntRequest is the request type for Cache.GetInt.
+type CacheGetIntRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetIntResponse is the response type for Cache.GetInt.
 type CacheGetIntResponse struct {
 	Value  int64  `json:"value,omitempty"`
@@ -78,6 +111,23 @@ type CacheGetIntResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheSetFloatRequest is the request type for Cache.SetFloat.
+type CacheSetFloatRequest struct {
+	Key        string  `json:"key"`
+	Value      float64 `json:"value"`
+	TtlSeconds int64   `json:"ttlSeconds"`
+}
+
+// CacheSetFloatResponse is the response type for Cache.SetFloat.
+type CacheSetFloatResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetFloatRequest is the request type for Cache.GetFloat.
+type CacheGetFloatRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetFloatResponse is the response type for Cache.GetFloat.
 type CacheGetFloatResponse struct {
 	Value  float64 `json:"value,omitempty"`
@@ -85,6 +135,23 @@ type CacheGetFloatResponse struct {
 	Error  string  `json:"error,omitempty"`
 }
 
+// CacheSetBytesRequest is the request type for Cache.SetBytes.
+type CacheSetBytesRequest struct {
+	Key        string `json:"key"`
+	Value      []byte `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetBytesResponse is the response type for Cache.SetBytes.
+type CacheSetBytesResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetBytesRequest is the request type for Cache.GetBytes.
+type CacheGetBytesRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetBytesResponse is the response type for Cache.GetBytes.
 type CacheGetBytesResponse struct {
 	Value  []byte `json:"value,omitempty"`
@@ -92,12 +159,27 @@ type CacheGetBytesResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheHasRequest is the request type for Cache.Has.
+type CacheHasRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheHasResponse is the response type for Cache.Has.
 type CacheHasResponse struct {
 	Exists bool   `json:"exists,omitempty"`
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheRemoveRequest is the request type for Cache.Remove.
+type CacheRemoveRequest struct {
+	Key string `json:"key"`
+}
+
+// CacheRemoveResponse is the response type for Cache.Remove.
+type CacheRemoveResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // CacheSetString calls the cache_setstring host function.
 // SetString stores a string value in the cache.
 //
@@ -107,24 +189,34 @@ type CacheHasResponse struct {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetString(key string, value string, ttlSeconds int64) error {
+func CacheSetString(key string, value string, ttlSeconds int64) (*CacheSetStringResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetStringRequest{
-	valueMem := pdk.AllocateString(value)
+		Key:        key,
-	defer valueMem.Free()
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setstring(keyMem.Offset(), valueMem.Offset(), ttlSeconds)
+	responsePtr := cache_setstring(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetStringResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetString calls the cache_getstring host function.
@@ -136,11 +228,19 @@ func CacheSetString(key string, value string, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not a string, exists will be false.
 func CacheGetString(key string) (*CacheGetStringResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetStringRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getstring(keyMem.Offset())
+	responsePtr := cache_getstring(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -164,22 +264,34 @@ func CacheGetString(key string) (*CacheGetStringResponse, error) {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetInt(key string, value int64, ttlSeconds int64) error {
+func CacheSetInt(key string, value int64, ttlSeconds int64) (*CacheSetIntResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetIntRequest{
+		Key:        key,
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setint(keyMem.Offset(), value, ttlSeconds)
+	responsePtr := cache_setint(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetIntResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetInt calls the cache_getint host function.
@@ -191,11 +303,19 @@ func CacheSetInt(key string, value int64, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not an integer, exists will be false.
 func CacheGetInt(key string) (*CacheGetIntResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetIntRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getint(keyMem.Offset())
+	responsePtr := cache_getint(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -219,22 +339,34 @@ func CacheGetInt(key string) (*CacheGetIntResponse, error) {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetFloat(key string, value float64, ttlSeconds int64) error {
+func CacheSetFloat(key string, value float64, ttlSeconds int64) (*CacheSetFloatResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetFloatRequest{
+		Key:        key,
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setfloat(keyMem.Offset(), value, ttlSeconds)
+	responsePtr := cache_setfloat(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetFloatResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetFloat calls the cache_getfloat host function.
@@ -246,11 +378,19 @@ func CacheSetFloat(key string, value float64, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not a float, exists will be false.
 func CacheGetFloat(key string) (*CacheGetFloatResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetFloatRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getfloat(keyMem.Offset())
+	responsePtr := cache_getfloat(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -274,24 +414,34 @@ func CacheGetFloat(key string) (*CacheGetFloatResponse, error) {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetBytes(key string, value []byte, ttlSeconds int64) error {
+func CacheSetBytes(key string, value []byte, ttlSeconds int64) (*CacheSetBytesResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetBytesRequest{
-	valueMem := pdk.AllocateBytes(value)
+		Key:        key,
-	defer valueMem.Free()
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setbytes(keyMem.Offset(), valueMem.Offset(), ttlSeconds)
+	responsePtr := cache_setbytes(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetBytesResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetBytes calls the cache_getbytes host function.
@@ -303,11 +453,19 @@ func CacheSetBytes(key string, value []byte, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not a byte slice, exists will be false.
 func CacheGetBytes(key string) (*CacheGetBytesResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetBytesRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getbytes(keyMem.Offset())
+	responsePtr := cache_getbytes(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -330,11 +488,19 @@ func CacheGetBytes(key string) (*CacheGetBytesResponse, error) {
 //
 // Returns true if the key exists and has not expired.
 func CacheHas(key string) (*CacheHasResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheHasRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_has(keyMem.Offset())
+	responsePtr := cache_has(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -356,20 +522,30 @@ func CacheHas(key string) (*CacheHasResponse, error) {
 //   - key: The cache key (will be namespaced with plugin ID)
 //
 // Returns an error if the operation fails. Does not return an error if the key doesn't exist.
-func CacheRemove(key string) error {
+func CacheRemove(key string) (*CacheRemoveResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheRemoveRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_remove(keyMem.Offset())
+	responsePtr := cache_remove(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheRemoveResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }

plugins/examples/discord-rich-presence/nd_host_scheduler.go

@@ -9,7 +9,6 @@ package main
 
 import (
 	"encoding/json"
-	"errors"
 
 	"github.com/extism/go-pdk"
 )
@@ -17,30 +16,54 @@ import (
 // scheduler_scheduleonetime is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user scheduler_scheduleonetime
-func scheduler_scheduleonetime(int32, uint64, uint64) uint64
+func scheduler_scheduleonetime(uint64) uint64
 
 // scheduler_schedulerecurring is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user scheduler_schedulerecurring
-func scheduler_schedulerecurring(uint64, uint64, uint64) uint64
+func scheduler_schedulerecurring(uint64) uint64
 
 // scheduler_cancelschedule is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user scheduler_cancelschedule
 func scheduler_cancelschedule(uint64) uint64
 
+// SchedulerScheduleOneTimeRequest is the request type for Scheduler.ScheduleOneTime.
+type SchedulerScheduleOneTimeRequest struct {
+	DelaySeconds int32  `json:"delaySeconds"`
+	Payload      string `json:"payload"`
+	ScheduleID   string `json:"scheduleID"`
+}
+
 // SchedulerScheduleOneTimeResponse is the response type for Scheduler.ScheduleOneTime.
 type SchedulerScheduleOneTimeResponse struct {
 	NewScheduleID string `json:"newScheduleID,omitempty"`
 	Error         string `json:"error,omitempty"`
 }
 
+// SchedulerScheduleRecurringRequest is the request type for Scheduler.ScheduleRecurring.
+type SchedulerScheduleRecurringRequest struct {
+	CronExpression string `json:"cronExpression"`
+	Payload        string `json:"payload"`
+	ScheduleID     string `json:"scheduleID"`
+}
+
 // SchedulerScheduleRecurringResponse is the response type for Scheduler.ScheduleRecurring.
 type SchedulerScheduleRecurringResponse struct {
 	NewScheduleID string `json:"newScheduleID,omitempty"`
 	Error         string `json:"error,omitempty"`
 }
 
+// SchedulerCancelScheduleRequest is the request type for Scheduler.CancelSchedule.
+type SchedulerCancelScheduleRequest struct {
+	ScheduleID string `json:"scheduleID"`
+}
+
+// SchedulerCancelScheduleResponse is the response type for Scheduler.CancelSchedule.
+type SchedulerCancelScheduleResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // SchedulerScheduleOneTime calls the scheduler_scheduleonetime host function.
 // ScheduleOneTime schedules a one-time event to be triggered after the specified delay.
 // Plugins that use this function must also implement the SchedulerCallback capability
@@ -52,13 +75,21 @@ type SchedulerScheduleRecurringResponse struct {
 //
 // Returns the schedule ID that can be used to cancel the job, or an error if scheduling fails.
 func SchedulerScheduleOneTime(delaySeconds int32, payload string, scheduleID string) (*SchedulerScheduleOneTimeResponse, error) {
-	payloadMem := pdk.AllocateString(payload)
+	// Marshal request to JSON
-	defer payloadMem.Free()
+	req := SchedulerScheduleOneTimeRequest{
-	scheduleIDMem := pdk.AllocateString(scheduleID)
+		DelaySeconds: delaySeconds,
-	defer scheduleIDMem.Free()
+		Payload:      payload,
+		ScheduleID:   scheduleID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := scheduler_scheduleonetime(delaySeconds, payloadMem.Offset(), scheduleIDMem.Offset())
+	responsePtr := scheduler_scheduleonetime(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -84,15 +115,21 @@ func SchedulerScheduleOneTime(delaySeconds int32, payload string, scheduleID str
 //
 // Returns the schedule ID that can be used to cancel the job, or an error if scheduling fails.
 func SchedulerScheduleRecurring(cronExpression string, payload string, scheduleID string) (*SchedulerScheduleRecurringResponse, error) {
-	cronExpressionMem := pdk.AllocateString(cronExpression)
+	// Marshal request to JSON
-	defer cronExpressionMem.Free()
+	req := SchedulerScheduleRecurringRequest{
-	payloadMem := pdk.AllocateString(payload)
+		CronExpression: cronExpression,
-	defer payloadMem.Free()
+		Payload:        payload,
-	scheduleIDMem := pdk.AllocateString(scheduleID)
+		ScheduleID:     scheduleID,
-	defer scheduleIDMem.Free()
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := scheduler_schedulerecurring(cronExpressionMem.Offset(), payloadMem.Offset(), scheduleIDMem.Offset())
+	responsePtr := scheduler_schedulerecurring(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -114,20 +151,30 @@ func SchedulerScheduleRecurring(cronExpression string, payload string, scheduleI
 // any future events.
 //
 // Returns an error if the schedule ID is not found or if cancellation fails.
-func SchedulerCancelSchedule(scheduleID string) error {
+func SchedulerCancelSchedule(scheduleID string) (*SchedulerCancelScheduleResponse, error) {
-	scheduleIDMem := pdk.AllocateString(scheduleID)
+	// Marshal request to JSON
-	defer scheduleIDMem.Free()
+	req := SchedulerCancelScheduleRequest{
+		ScheduleID: scheduleID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := scheduler_cancelschedule(scheduleIDMem.Offset())
+	responsePtr := scheduler_cancelschedule(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response SchedulerCancelScheduleResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }

plugins/examples/discord-rich-presence/nd_host_websocket.go

@@ -9,13 +9,11 @@ package main
 
 import (
 	"encoding/json"
-	"errors"
 
 	"github.com/extism/go-pdk"
 )
 
 // websocket_connect is the host function provided by Navidrome.
-// Takes a single JSON request pointer containing url, headers, and connectionID.
 //
 //go:wasmimport extism:host/user websocket_connect
 func websocket_connect(uint64) uint64
@@ -23,17 +21,17 @@ func websocket_connect(uint64) uint64
 // websocket_sendtext is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user websocket_sendtext
-func websocket_sendtext(uint64, uint64) uint64
+func websocket_sendtext(uint64) uint64
 
 // websocket_sendbinary is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user websocket_sendbinary
-func websocket_sendbinary(uint64, uint64) uint64
+func websocket_sendbinary(uint64) uint64
 
 // websocket_closeconnection is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user websocket_closeconnection
-func websocket_closeconnection(uint64, int32, uint64) uint64
+func websocket_closeconnection(uint64) uint64
 
 // WebSocketConnectRequest is the request type for WebSocket.Connect.
 type WebSocketConnectRequest struct {
@@ -48,6 +46,40 @@ type WebSocketConnectResponse struct {
 	Error           string `json:"error,omitempty"`
 }
 
+// WebSocketSendTextRequest is the request type for WebSocket.SendText.
+type WebSocketSendTextRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Message      string `json:"message"`
+}
+
+// WebSocketSendTextResponse is the response type for WebSocket.SendText.
+type WebSocketSendTextResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketSendBinaryRequest is the request type for WebSocket.SendBinary.
+type WebSocketSendBinaryRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Data         []byte `json:"data"`
+}
+
+// WebSocketSendBinaryResponse is the response type for WebSocket.SendBinary.
+type WebSocketSendBinaryResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketCloseConnectionRequest is the request type for WebSocket.CloseConnection.
+type WebSocketCloseConnectionRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Code         int32  `json:"code"`
+	Reason       string `json:"reason"`
+}
+
+// WebSocketCloseConnectionResponse is the response type for WebSocket.CloseConnection.
+type WebSocketCloseConnectionResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // WebSocketConnect calls the websocket_connect host function.
 // Connect establishes a WebSocket connection to the specified URL.
 //
@@ -62,7 +94,7 @@ type WebSocketConnectResponse struct {
 // Returns the connection ID that can be used to send messages or close the connection,
 // or an error if the connection fails.
 func WebSocketConnect(url string, headers map[string]string, connectionID string) (*WebSocketConnectResponse, error) {
-	// Create JSON request with all parameters
+	// Marshal request to JSON
 	req := WebSocketConnectRequest{
 		Url:          url,
 		Headers:      headers,
@@ -75,7 +107,7 @@ func WebSocketConnect(url string, headers map[string]string, connectionID string
 	reqMem := pdk.AllocateBytes(reqBytes)
 	defer reqMem.Free()
 
-	// Call the host function with single JSON request
+	// Call the host function
 	responsePtr := websocket_connect(reqMem.Offset())
 
 	// Read the response from memory
@@ -99,24 +131,33 @@ func WebSocketConnect(url string, headers map[string]string, connectionID string
 //   - message: The text message to send
 //
 // Returns an error if the connection is not found or if sending fails.
-func WebSocketSendText(connectionID string, message string) error {
+func WebSocketSendText(connectionID string, message string) (*WebSocketSendTextResponse, error) {
-	connectionIDMem := pdk.AllocateString(connectionID)
+	// Marshal request to JSON
-	defer connectionIDMem.Free()
+	req := WebSocketSendTextRequest{
-	messageMem := pdk.AllocateString(message)
+		ConnectionID: connectionID,
-	defer messageMem.Free()
+		Message:      message,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := websocket_sendtext(connectionIDMem.Offset(), messageMem.Offset())
+	responsePtr := websocket_sendtext(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response WebSocketSendTextResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // WebSocketSendBinary calls the websocket_sendbinary host function.
@@ -127,24 +168,33 @@ func WebSocketSendText(connectionID string, message string) error {
 //   - data: The binary data to send
 //
 // Returns an error if the connection is not found or if sending fails.
-func WebSocketSendBinary(connectionID string, data []byte) error {
+func WebSocketSendBinary(connectionID string, data []byte) (*WebSocketSendBinaryResponse, error) {
-	connectionIDMem := pdk.AllocateString(connectionID)
+	// Marshal request to JSON
-	defer connectionIDMem.Free()
+	req := WebSocketSendBinaryRequest{
-	dataMem := pdk.AllocateBytes(data)
+		ConnectionID: connectionID,
-	defer dataMem.Free()
+		Data:         data,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := websocket_sendbinary(connectionIDMem.Offset(), dataMem.Offset())
+	responsePtr := websocket_sendbinary(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response WebSocketSendBinaryResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // WebSocketCloseConnection calls the websocket_closeconnection host function.
@@ -156,22 +206,32 @@ func WebSocketSendBinary(connectionID string, data []byte) error {
 //   - reason: Optional human-readable reason for closing
 //
 // Returns an error if the connection is not found or if closing fails.
-func WebSocketCloseConnection(connectionID string, code int32, reason string) error {
+func WebSocketCloseConnection(connectionID string, code int32, reason string) (*WebSocketCloseConnectionResponse, error) {
-	connectionIDMem := pdk.AllocateString(connectionID)
+	// Marshal request to JSON
-	defer connectionIDMem.Free()
+	req := WebSocketCloseConnectionRequest{
-	reasonMem := pdk.AllocateString(reason)
+		ConnectionID: connectionID,
-	defer reasonMem.Free()
+		Code:         code,
+		Reason:       reason,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := websocket_closeconnection(connectionIDMem.Offset(), code, reasonMem.Offset())
+	responsePtr := websocket_closeconnection(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response WebSocketCloseConnectionResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }

plugins/examples/discord-rich-presence/rpc.go

@@ -140,7 +140,7 @@ func processImage(imageURL, clientID, token string, isDefaultImage bool) (string
 		ttl = 48 * 60 * 60 // 48 hours for default image
 	}
 
-	_ = CacheSetString(cacheKey, processedImage, ttl)
+	_, _ = CacheSetString(cacheKey, processedImage, ttl)
 	pdk.Log(pdk.LogDebug, fmt.Sprintf("Cached processed image URL for %s (TTL: %ds)", imageURL, ttl))
 
 	return processedImage, nil
@@ -183,9 +183,13 @@ func sendMessage(username string, opCode int, payload any) error {
 		return fmt.Errorf("failed to marshal message: %w", err)
 	}
 
-	if err := WebSocketSendText(username, string(b)); err != nil {
+	resp, err := WebSocketSendText(username, string(b))
+	if err != nil {
 		return fmt.Errorf("failed to send message: %w", err)
 	}
+	if resp.Error != "" {
+		return fmt.Errorf("failed to send message: %s", resp.Error)
+	}
 	return nil
 }
 
@@ -220,17 +224,21 @@ func cleanupFailedConnection(username string) {
 	pdk.Log(pdk.LogInfo, fmt.Sprintf("Cleaning up failed connection for user %s", username))
 
 	// Cancel the heartbeat schedule
-	if err := SchedulerCancelSchedule(username); err != nil {
+	if resp, err := SchedulerCancelSchedule(username); err != nil {
 		pdk.Log(pdk.LogWarn, fmt.Sprintf("Failed to cancel heartbeat schedule for user %s: %v", username, err))
+	} else if resp.Error != "" {
+		pdk.Log(pdk.LogWarn, fmt.Sprintf("Failed to cancel heartbeat schedule for user %s: %s", username, resp.Error))
 	}
 
 	// Close the WebSocket connection
-	if err := WebSocketCloseConnection(username, 1000, "Connection lost"); err != nil {
+	if resp, err := WebSocketCloseConnection(username, 1000, "Connection lost"); err != nil {
 		pdk.Log(pdk.LogWarn, fmt.Sprintf("Failed to close WebSocket connection for user %s: %v", username, err))
+	} else if resp.Error != "" {
+		pdk.Log(pdk.LogWarn, fmt.Sprintf("Failed to close WebSocket connection for user %s: %s", username, resp.Error))
 	}
 
 	// Clean up cache entries
-	_ = CacheRemove(fmt.Sprintf("discord.seq.%s", username))
+	_, _ = CacheRemove(fmt.Sprintf("discord.seq.%s", username))
 
 	pdk.Log(pdk.LogInfo, fmt.Sprintf("Cleaned up connection for user %s", username))
 }
@@ -297,12 +305,16 @@ func connect(username, token string) error {
 
 // disconnect closes the Discord connection for a user.
 func disconnect(username string) error {
-	if err := SchedulerCancelSchedule(username); err != nil {
+	if resp, err := SchedulerCancelSchedule(username); err != nil {
 		return fmt.Errorf("failed to cancel schedule: %w", err)
+	} else if resp.Error != "" {
+		return fmt.Errorf("failed to cancel schedule: %s", resp.Error)
 	}
 
-	if err := WebSocketCloseConnection(username, 1000, "Navidrome disconnect"); err != nil {
+	if resp, err := WebSocketCloseConnection(username, 1000, "Navidrome disconnect"); err != nil {
 		return fmt.Errorf("failed to close WebSocket connection: %w", err)
+	} else if resp.Error != "" {
+		return fmt.Errorf("failed to close WebSocket connection: %s", resp.Error)
 	}
 	return nil
 }
@@ -325,8 +337,10 @@ func handleWebSocketMessage(connectionID, message string) error {
 	if v := msg["s"]; v != nil {
 		seq := int64(v.(float64))
 		pdk.Log(pdk.LogTrace, fmt.Sprintf("Received sequence number for connection '%s': %d", connectionID, seq))
-		if err := CacheSetInt(fmt.Sprintf("discord.seq.%s", connectionID), seq, int64(heartbeatInterval*2)); err != nil {
+		if resp, err := CacheSetInt(fmt.Sprintf("discord.seq.%s", connectionID), seq, int64(heartbeatInterval*2)); err != nil {
 			return fmt.Errorf("failed to store sequence number for user %s: %w", connectionID, err)
+		} else if resp.Error != "" {
+			return fmt.Errorf("failed to store sequence number for user %s: %s", connectionID, resp.Error)
 		}
 	}
 	return nil

plugins/host/artwork_gen.go

@@ -9,24 +9,48 @@ import (
 	extism "github.com/extism/go-sdk"
 )
 
+// ArtworkGetArtistUrlRequest is the request type for Artwork.GetArtistUrl.
+type ArtworkGetArtistUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetArtistUrlResponse is the response type for Artwork.GetArtistUrl.
 type ArtworkGetArtistUrlResponse struct {
 	Url   string `json:"url,omitempty"`
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetAlbumUrlRequest is the request type for Artwork.GetAlbumUrl.
+type ArtworkGetAlbumUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetAlbumUrlResponse is the response type for Artwork.GetAlbumUrl.
 type ArtworkGetAlbumUrlResponse struct {
 	Url   string `json:"url,omitempty"`
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetTrackUrlRequest is the request type for Artwork.GetTrackUrl.
+type ArtworkGetTrackUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetTrackUrlResponse is the response type for Artwork.GetTrackUrl.
 type ArtworkGetTrackUrlResponse struct {
 	Url   string `json:"url,omitempty"`
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetPlaylistUrlRequest is the request type for Artwork.GetPlaylistUrl.
+type ArtworkGetPlaylistUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetPlaylistUrlResponse is the response type for Artwork.GetPlaylistUrl.
 type ArtworkGetPlaylistUrlResponse struct {
 	Url   string `json:"url,omitempty"`
@@ -48,26 +72,32 @@ func newArtworkGetArtistUrlHostFunction(service ArtworkService) extism.HostFunct
 	return extism.NewHostFunctionWithStack(
 		"artwork_getartisturl",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			id, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-			size := extism.DecodeI32(stack[1])
-
-			// Call the service method
-			url, err := service.GetArtistUrl(ctx, id, size)
 			if err != nil {
 				artworkWriteError(p, stack, err)
 				return
 			}
+			var req ArtworkGetArtistUrlRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				artworkWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			url, svcErr := service.GetArtistUrl(ctx, req.Id, req.Size)
+			if svcErr != nil {
+				artworkWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := ArtworkGetArtistUrlResponse{
 				Url: url,
 			}
 			artworkWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypeI32},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -76,26 +106,32 @@ func newArtworkGetAlbumUrlHostFunction(service ArtworkService) extism.HostFuncti
 	return extism.NewHostFunctionWithStack(
 		"artwork_getalbumurl",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			id, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-			size := extism.DecodeI32(stack[1])
-
-			// Call the service method
-			url, err := service.GetAlbumUrl(ctx, id, size)
 			if err != nil {
 				artworkWriteError(p, stack, err)
 				return
 			}
+			var req ArtworkGetAlbumUrlRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				artworkWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			url, svcErr := service.GetAlbumUrl(ctx, req.Id, req.Size)
+			if svcErr != nil {
+				artworkWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := ArtworkGetAlbumUrlResponse{
 				Url: url,
 			}
 			artworkWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypeI32},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -104,26 +140,32 @@ func newArtworkGetTrackUrlHostFunction(service ArtworkService) extism.HostFuncti
 	return extism.NewHostFunctionWithStack(
 		"artwork_gettrackurl",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			id, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-			size := extism.DecodeI32(stack[1])
-
-			// Call the service method
-			url, err := service.GetTrackUrl(ctx, id, size)
 			if err != nil {
 				artworkWriteError(p, stack, err)
 				return
 			}
+			var req ArtworkGetTrackUrlRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				artworkWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			url, svcErr := service.GetTrackUrl(ctx, req.Id, req.Size)
+			if svcErr != nil {
+				artworkWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := ArtworkGetTrackUrlResponse{
 				Url: url,
 			}
 			artworkWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypeI32},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -132,26 +174,32 @@ func newArtworkGetPlaylistUrlHostFunction(service ArtworkService) extism.HostFun
 	return extism.NewHostFunctionWithStack(
 		"artwork_getplaylisturl",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			id, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-			size := extism.DecodeI32(stack[1])
-
-			// Call the service method
-			url, err := service.GetPlaylistUrl(ctx, id, size)
 			if err != nil {
 				artworkWriteError(p, stack, err)
 				return
 			}
+			var req ArtworkGetPlaylistUrlRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				artworkWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			url, svcErr := service.GetPlaylistUrl(ctx, req.Id, req.Size)
+			if svcErr != nil {
+				artworkWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := ArtworkGetPlaylistUrlResponse{
 				Url: url,
 			}
 			artworkWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypeI32},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }

plugins/host/cache_gen.go

@@ -9,6 +9,23 @@ import (
 	extism "github.com/extism/go-sdk"
 )
 
+// CacheSetStringRequest is the request type for Cache.SetString.
+type CacheSetStringRequest struct {
+	Key        string `json:"key"`
+	Value      string `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetStringResponse is the response type for Cache.SetString.
+type CacheSetStringResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetStringRequest is the request type for Cache.GetString.
+type CacheGetStringRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetStringResponse is the response type for Cache.GetString.
 type CacheGetStringResponse struct {
 	Value  string `json:"value,omitempty"`
@@ -16,6 +33,23 @@ type CacheGetStringResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheSetIntRequest is the request type for Cache.SetInt.
+type CacheSetIntRequest struct {
+	Key        string `json:"key"`
+	Value      int64  `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetIntResponse is the response type for Cache.SetInt.
+type CacheSetIntResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetIntRequest is the request type for Cache.GetInt.
+type CacheGetIntRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetIntResponse is the response type for Cache.GetInt.
 type CacheGetIntResponse struct {
 	Value  int64  `json:"value,omitempty"`
@@ -23,6 +57,23 @@ type CacheGetIntResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheSetFloatRequest is the request type for Cache.SetFloat.
+type CacheSetFloatRequest struct {
+	Key        string  `json:"key"`
+	Value      float64 `json:"value"`
+	TtlSeconds int64   `json:"ttlSeconds"`
+}
+
+// CacheSetFloatResponse is the response type for Cache.SetFloat.
+type CacheSetFloatResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetFloatRequest is the request type for Cache.GetFloat.
+type CacheGetFloatRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetFloatResponse is the response type for Cache.GetFloat.
 type CacheGetFloatResponse struct {
 	Value  float64 `json:"value,omitempty"`
@@ -30,6 +81,23 @@ type CacheGetFloatResponse struct {
 	Error  string  `json:"error,omitempty"`
 }
 
+// CacheSetBytesRequest is the request type for Cache.SetBytes.
+type CacheSetBytesRequest struct {
+	Key        string `json:"key"`
+	Value      []byte `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetBytesResponse is the response type for Cache.SetBytes.
+type CacheSetBytesResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetBytesRequest is the request type for Cache.GetBytes.
+type CacheGetBytesRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetBytesResponse is the response type for Cache.GetBytes.
 type CacheGetBytesResponse struct {
 	Value  []byte `json:"value,omitempty"`
@@ -37,12 +105,27 @@ type CacheGetBytesResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheHasRequest is the request type for Cache.Has.
+type CacheHasRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheHasResponse is the response type for Cache.Has.
 type CacheHasResponse struct {
 	Exists bool   `json:"exists,omitempty"`
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheRemoveRequest is the request type for Cache.Remove.
+type CacheRemoveRequest struct {
+	Key string `json:"key"`
+}
+
+// CacheRemoveResponse is the response type for Cache.Remove.
+type CacheRemoveResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // RegisterCacheHostFunctions registers Cache service host functions.
 // The returned host functions should be added to the plugin's configuration.
 func RegisterCacheHostFunctions(service CacheService) []extism.HostFunction {
@@ -64,32 +147,29 @@ func newCacheSetStringHostFunction(service CacheService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"cache_setstring",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
+				cacheWriteError(p, stack, err)
 				return
 			}
-			value, err := p.ReadString(stack[1])
+			var req CacheSetStringRequest
-			if err != nil {
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				cacheWriteError(p, stack, err)
 				return
 			}
-			ttlSeconds := int64(stack[2])
 
 			// Call the service method
-			err = service.SetString(ctx, key, value, ttlSeconds)
+			if svcErr := service.SetString(ctx, req.Key, req.Value, req.TtlSeconds); svcErr != nil {
-			if err != nil {
+				cacheWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := CacheSetStringResponse{}
-			}
+			cacheWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypePTR, extism.ValueTypeI64},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -98,18 +178,25 @@ func newCacheGetStringHostFunction(service CacheService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"cache_getstring",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			value, exists, err := service.GetString(ctx, key)
 			if err != nil {
 				cacheWriteError(p, stack, err)
 				return
 			}
+			var req CacheGetStringRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				cacheWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			value, exists, svcErr := service.GetString(ctx, req.Key)
+			if svcErr != nil {
+				cacheWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := CacheGetStringResponse{
 				Value:  value,
@@ -126,29 +213,29 @@ func newCacheSetIntHostFunction(service CacheService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"cache_setint",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
+				cacheWriteError(p, stack, err)
+				return
+			}
+			var req CacheSetIntRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				cacheWriteError(p, stack, err)
 				return
 			}
-			value := int64(stack[1])
-			ttlSeconds := int64(stack[2])
 
 			// Call the service method
-			err = service.SetInt(ctx, key, value, ttlSeconds)
+			if svcErr := service.SetInt(ctx, req.Key, req.Value, req.TtlSeconds); svcErr != nil {
-			if err != nil {
+				cacheWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := CacheSetIntResponse{}
-			}
+			cacheWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypeI64, extism.ValueTypeI64},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -157,18 +244,25 @@ func newCacheGetIntHostFunction(service CacheService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"cache_getint",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			value, exists, err := service.GetInt(ctx, key)
 			if err != nil {
 				cacheWriteError(p, stack, err)
 				return
 			}
+			var req CacheGetIntRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				cacheWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			value, exists, svcErr := service.GetInt(ctx, req.Key)
+			if svcErr != nil {
+				cacheWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := CacheGetIntResponse{
 				Value:  value,
@@ -185,29 +279,29 @@ func newCacheSetFloatHostFunction(service CacheService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"cache_setfloat",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
+				cacheWriteError(p, stack, err)
+				return
+			}
+			var req CacheSetFloatRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				cacheWriteError(p, stack, err)
 				return
 			}
-			value := extism.DecodeF64(stack[1])
-			ttlSeconds := int64(stack[2])
 
 			// Call the service method
-			err = service.SetFloat(ctx, key, value, ttlSeconds)
+			if svcErr := service.SetFloat(ctx, req.Key, req.Value, req.TtlSeconds); svcErr != nil {
-			if err != nil {
+				cacheWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := CacheSetFloatResponse{}
-			}
+			cacheWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypeF64, extism.ValueTypeI64},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -216,18 +310,25 @@ func newCacheGetFloatHostFunction(service CacheService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"cache_getfloat",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			value, exists, err := service.GetFloat(ctx, key)
 			if err != nil {
 				cacheWriteError(p, stack, err)
 				return
 			}
+			var req CacheGetFloatRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				cacheWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			value, exists, svcErr := service.GetFloat(ctx, req.Key)
+			if svcErr != nil {
+				cacheWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := CacheGetFloatResponse{
 				Value:  value,
@@ -244,32 +345,29 @@ func newCacheSetBytesHostFunction(service CacheService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"cache_setbytes",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
+				cacheWriteError(p, stack, err)
 				return
 			}
-			value, err := p.ReadBytes(stack[1])
+			var req CacheSetBytesRequest
-			if err != nil {
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				cacheWriteError(p, stack, err)
 				return
 			}
-			ttlSeconds := int64(stack[2])
 
 			// Call the service method
-			err = service.SetBytes(ctx, key, value, ttlSeconds)
+			if svcErr := service.SetBytes(ctx, req.Key, req.Value, req.TtlSeconds); svcErr != nil {
-			if err != nil {
+				cacheWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := CacheSetBytesResponse{}
-			}
+			cacheWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypePTR, extism.ValueTypeI64},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -278,18 +376,25 @@ func newCacheGetBytesHostFunction(service CacheService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"cache_getbytes",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			value, exists, err := service.GetBytes(ctx, key)
 			if err != nil {
 				cacheWriteError(p, stack, err)
 				return
 			}
+			var req CacheGetBytesRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				cacheWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			value, exists, svcErr := service.GetBytes(ctx, req.Key)
+			if svcErr != nil {
+				cacheWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := CacheGetBytesResponse{
 				Value:  value,
@@ -306,18 +411,25 @@ func newCacheHasHostFunction(service CacheService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"cache_has",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			exists, err := service.Has(ctx, key)
 			if err != nil {
 				cacheWriteError(p, stack, err)
 				return
 			}
+			var req CacheHasRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				cacheWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			exists, svcErr := service.Has(ctx, req.Key)
+			if svcErr != nil {
+				cacheWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := CacheHasResponse{
 				Exists: exists,
@@ -333,25 +445,27 @@ func newCacheRemoveHostFunction(service CacheService) extism.HostFunction {
 	return extism.NewHostFunctionWithStack(
 		"cache_remove",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			key, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
+				cacheWriteError(p, stack, err)
+				return
+			}
+			var req CacheRemoveRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				cacheWriteError(p, stack, err)
 				return
 			}
 
 			// Call the service method
-			err = service.Remove(ctx, key)
+			if svcErr := service.Remove(ctx, req.Key); svcErr != nil {
-			if err != nil {
+				cacheWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := CacheRemoveResponse{}
-			}
+			cacheWriteResponse(p, stack, resp)
 		},
 		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},

plugins/host/go/nd_host_artwork.go

@@ -16,22 +16,28 @@ import (
 // artwork_getartisturl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_getartisturl
-func artwork_getartisturl(uint64, int32) uint64
+func artwork_getartisturl(uint64) uint64
 
 // artwork_getalbumurl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_getalbumurl
-func artwork_getalbumurl(uint64, int32) uint64
+func artwork_getalbumurl(uint64) uint64
 
 // artwork_gettrackurl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_gettrackurl
-func artwork_gettrackurl(uint64, int32) uint64
+func artwork_gettrackurl(uint64) uint64
 
 // artwork_getplaylisturl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_getplaylisturl
-func artwork_getplaylisturl(uint64, int32) uint64
+func artwork_getplaylisturl(uint64) uint64
+
+// ArtworkGetArtistUrlRequest is the request type for Artwork.GetArtistUrl.
+type ArtworkGetArtistUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
 
 // ArtworkGetArtistUrlResponse is the response type for Artwork.GetArtistUrl.
 type ArtworkGetArtistUrlResponse struct {
@@ -39,18 +45,36 @@ type ArtworkGetArtistUrlResponse struct {
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetAlbumUrlRequest is the request type for Artwork.GetAlbumUrl.
+type ArtworkGetAlbumUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetAlbumUrlResponse is the response type for Artwork.GetAlbumUrl.
 type ArtworkGetAlbumUrlResponse struct {
 	Url   string `json:"url,omitempty"`
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetTrackUrlRequest is the request type for Artwork.GetTrackUrl.
+type ArtworkGetTrackUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetTrackUrlResponse is the response type for Artwork.GetTrackUrl.
 type ArtworkGetTrackUrlResponse struct {
 	Url   string `json:"url,omitempty"`
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetPlaylistUrlRequest is the request type for Artwork.GetPlaylistUrl.
+type ArtworkGetPlaylistUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetPlaylistUrlResponse is the response type for Artwork.GetPlaylistUrl.
 type ArtworkGetPlaylistUrlResponse struct {
 	Url   string `json:"url,omitempty"`
@@ -66,11 +90,20 @@ type ArtworkGetPlaylistUrlResponse struct {
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetArtistUrl(id string, size int32) (*ArtworkGetArtistUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetArtistUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_getartisturl(idMem.Offset(), size)
+	responsePtr := artwork_getartisturl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -94,11 +127,20 @@ func ArtworkGetArtistUrl(id string, size int32) (*ArtworkGetArtistUrlResponse, e
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetAlbumUrl(id string, size int32) (*ArtworkGetAlbumUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetAlbumUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_getalbumurl(idMem.Offset(), size)
+	responsePtr := artwork_getalbumurl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -122,11 +164,20 @@ func ArtworkGetAlbumUrl(id string, size int32) (*ArtworkGetAlbumUrlResponse, err
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetTrackUrl(id string, size int32) (*ArtworkGetTrackUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetTrackUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_gettrackurl(idMem.Offset(), size)
+	responsePtr := artwork_gettrackurl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -150,11 +201,20 @@ func ArtworkGetTrackUrl(id string, size int32) (*ArtworkGetTrackUrlResponse, err
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetPlaylistUrl(id string, size int32) (*ArtworkGetPlaylistUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetPlaylistUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_getplaylisturl(idMem.Offset(), size)
+	responsePtr := artwork_getplaylisturl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/host/go/nd_host_cache.go

@@ -9,7 +9,6 @@ package main
 
 import (
 	"encoding/json"
-	"errors"
 
 	"github.com/extism/go-pdk"
 )
@@ -17,7 +16,7 @@ import (
 // cache_setstring is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setstring
-func cache_setstring(uint64, uint64, int64) uint64
+func cache_setstring(uint64) uint64
 
 // cache_getstring is the host function provided by Navidrome.
 //
@@ -27,7 +26,7 @@ func cache_getstring(uint64) uint64
 // cache_setint is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setint
-func cache_setint(uint64, int64, int64) uint64
+func cache_setint(uint64) uint64
 
 // cache_getint is the host function provided by Navidrome.
 //
@@ -37,7 +36,7 @@ func cache_getint(uint64) uint64
 // cache_setfloat is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setfloat
-func cache_setfloat(uint64, float64, int64) uint64
+func cache_setfloat(uint64) uint64
 
 // cache_getfloat is the host function provided by Navidrome.
 //
@@ -47,7 +46,7 @@ func cache_getfloat(uint64) uint64
 // cache_setbytes is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setbytes
-func cache_setbytes(uint64, uint64, int64) uint64
+func cache_setbytes(uint64) uint64
 
 // cache_getbytes is the host function provided by Navidrome.
 //
@@ -64,6 +63,23 @@ func cache_has(uint64) uint64
 //go:wasmimport extism:host/user cache_remove
 func cache_remove(uint64) uint64
 
+// CacheSetStringRequest is the request type for Cache.SetString.
+type CacheSetStringRequest struct {
+	Key        string `json:"key"`
+	Value      string `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetStringResponse is the response type for Cache.SetString.
+type CacheSetStringResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetStringRequest is the request type for Cache.GetString.
+type CacheGetStringRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetStringResponse is the response type for Cache.GetString.
 type CacheGetStringResponse struct {
 	Value  string `json:"value,omitempty"`
@@ -71,6 +87,23 @@ type CacheGetStringResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheSetIntRequest is the request type for Cache.SetInt.
+type CacheSetIntRequest struct {
+	Key        string `json:"key"`
+	Value      int64  `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetIntResponse is the response type for Cache.SetInt.
+type CacheSetIntResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetIntRequest is the request type for Cache.GetInt.
+type CacheGetIntRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetIntResponse is the response type for Cache.GetInt.
 type CacheGetIntResponse struct {
 	Value  int64  `json:"value,omitempty"`
@@ -78,6 +111,23 @@ type CacheGetIntResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheSetFloatRequest is the request type for Cache.SetFloat.
+type CacheSetFloatRequest struct {
+	Key        string  `json:"key"`
+	Value      float64 `json:"value"`
+	TtlSeconds int64   `json:"ttlSeconds"`
+}
+
+// CacheSetFloatResponse is the response type for Cache.SetFloat.
+type CacheSetFloatResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetFloatRequest is the request type for Cache.GetFloat.
+type CacheGetFloatRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetFloatResponse is the response type for Cache.GetFloat.
 type CacheGetFloatResponse struct {
 	Value  float64 `json:"value,omitempty"`
@@ -85,6 +135,23 @@ type CacheGetFloatResponse struct {
 	Error  string  `json:"error,omitempty"`
 }
 
+// CacheSetBytesRequest is the request type for Cache.SetBytes.
+type CacheSetBytesRequest struct {
+	Key        string `json:"key"`
+	Value      []byte `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetBytesResponse is the response type for Cache.SetBytes.
+type CacheSetBytesResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetBytesRequest is the request type for Cache.GetBytes.
+type CacheGetBytesRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetBytesResponse is the response type for Cache.GetBytes.
 type CacheGetBytesResponse struct {
 	Value  []byte `json:"value,omitempty"`
@@ -92,12 +159,27 @@ type CacheGetBytesResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheHasRequest is the request type for Cache.Has.
+type CacheHasRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheHasResponse is the response type for Cache.Has.
 type CacheHasResponse struct {
 	Exists bool   `json:"exists,omitempty"`
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheRemoveRequest is the request type for Cache.Remove.
+type CacheRemoveRequest struct {
+	Key string `json:"key"`
+}
+
+// CacheRemoveResponse is the response type for Cache.Remove.
+type CacheRemoveResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // CacheSetString calls the cache_setstring host function.
 // SetString stores a string value in the cache.
 //
@@ -107,24 +189,34 @@ type CacheHasResponse struct {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetString(key string, value string, ttlSeconds int64) error {
+func CacheSetString(key string, value string, ttlSeconds int64) (*CacheSetStringResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetStringRequest{
-	valueMem := pdk.AllocateString(value)
+		Key:        key,
-	defer valueMem.Free()
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setstring(keyMem.Offset(), valueMem.Offset(), ttlSeconds)
+	responsePtr := cache_setstring(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetStringResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetString calls the cache_getstring host function.
@@ -136,11 +228,19 @@ func CacheSetString(key string, value string, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not a string, exists will be false.
 func CacheGetString(key string) (*CacheGetStringResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetStringRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getstring(keyMem.Offset())
+	responsePtr := cache_getstring(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -164,22 +264,34 @@ func CacheGetString(key string) (*CacheGetStringResponse, error) {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetInt(key string, value int64, ttlSeconds int64) error {
+func CacheSetInt(key string, value int64, ttlSeconds int64) (*CacheSetIntResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetIntRequest{
+		Key:        key,
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setint(keyMem.Offset(), value, ttlSeconds)
+	responsePtr := cache_setint(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetIntResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetInt calls the cache_getint host function.
@@ -191,11 +303,19 @@ func CacheSetInt(key string, value int64, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not an integer, exists will be false.
 func CacheGetInt(key string) (*CacheGetIntResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetIntRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getint(keyMem.Offset())
+	responsePtr := cache_getint(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -219,22 +339,34 @@ func CacheGetInt(key string) (*CacheGetIntResponse, error) {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetFloat(key string, value float64, ttlSeconds int64) error {
+func CacheSetFloat(key string, value float64, ttlSeconds int64) (*CacheSetFloatResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetFloatRequest{
+		Key:        key,
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setfloat(keyMem.Offset(), value, ttlSeconds)
+	responsePtr := cache_setfloat(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetFloatResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetFloat calls the cache_getfloat host function.
@@ -246,11 +378,19 @@ func CacheSetFloat(key string, value float64, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not a float, exists will be false.
 func CacheGetFloat(key string) (*CacheGetFloatResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetFloatRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getfloat(keyMem.Offset())
+	responsePtr := cache_getfloat(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -274,24 +414,34 @@ func CacheGetFloat(key string) (*CacheGetFloatResponse, error) {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetBytes(key string, value []byte, ttlSeconds int64) error {
+func CacheSetBytes(key string, value []byte, ttlSeconds int64) (*CacheSetBytesResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetBytesRequest{
-	valueMem := pdk.AllocateBytes(value)
+		Key:        key,
-	defer valueMem.Free()
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setbytes(keyMem.Offset(), valueMem.Offset(), ttlSeconds)
+	responsePtr := cache_setbytes(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetBytesResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetBytes calls the cache_getbytes host function.
@@ -303,11 +453,19 @@ func CacheSetBytes(key string, value []byte, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not a byte slice, exists will be false.
 func CacheGetBytes(key string) (*CacheGetBytesResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetBytesRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getbytes(keyMem.Offset())
+	responsePtr := cache_getbytes(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -330,11 +488,19 @@ func CacheGetBytes(key string) (*CacheGetBytesResponse, error) {
 //
 // Returns true if the key exists and has not expired.
 func CacheHas(key string) (*CacheHasResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheHasRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_has(keyMem.Offset())
+	responsePtr := cache_has(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -356,20 +522,30 @@ func CacheHas(key string) (*CacheHasResponse, error) {
 //   - key: The cache key (will be namespaced with plugin ID)
 //
 // Returns an error if the operation fails. Does not return an error if the key doesn't exist.
-func CacheRemove(key string) error {
+func CacheRemove(key string) (*CacheRemoveResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheRemoveRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_remove(keyMem.Offset())
+	responsePtr := cache_remove(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheRemoveResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }

plugins/host/go/nd_host_scheduler.go

@@ -9,7 +9,6 @@ package main
 
 import (
 	"encoding/json"
-	"errors"
 
 	"github.com/extism/go-pdk"
 )
@@ -17,30 +16,54 @@ import (
 // scheduler_scheduleonetime is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user scheduler_scheduleonetime
-func scheduler_scheduleonetime(int32, uint64, uint64) uint64
+func scheduler_scheduleonetime(uint64) uint64
 
 // scheduler_schedulerecurring is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user scheduler_schedulerecurring
-func scheduler_schedulerecurring(uint64, uint64, uint64) uint64
+func scheduler_schedulerecurring(uint64) uint64
 
 // scheduler_cancelschedule is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user scheduler_cancelschedule
 func scheduler_cancelschedule(uint64) uint64
 
+// SchedulerScheduleOneTimeRequest is the request type for Scheduler.ScheduleOneTime.
+type SchedulerScheduleOneTimeRequest struct {
+	DelaySeconds int32  `json:"delaySeconds"`
+	Payload      string `json:"payload"`
+	ScheduleID   string `json:"scheduleID"`
+}
+
 // SchedulerScheduleOneTimeResponse is the response type for Scheduler.ScheduleOneTime.
 type SchedulerScheduleOneTimeResponse struct {
 	NewScheduleID string `json:"newScheduleID,omitempty"`
 	Error         string `json:"error,omitempty"`
 }
 
+// SchedulerScheduleRecurringRequest is the request type for Scheduler.ScheduleRecurring.
+type SchedulerScheduleRecurringRequest struct {
+	CronExpression string `json:"cronExpression"`
+	Payload        string `json:"payload"`
+	ScheduleID     string `json:"scheduleID"`
+}
+
 // SchedulerScheduleRecurringResponse is the response type for Scheduler.ScheduleRecurring.
 type SchedulerScheduleRecurringResponse struct {
 	NewScheduleID string `json:"newScheduleID,omitempty"`
 	Error         string `json:"error,omitempty"`
 }
 
+// SchedulerCancelScheduleRequest is the request type for Scheduler.CancelSchedule.
+type SchedulerCancelScheduleRequest struct {
+	ScheduleID string `json:"scheduleID"`
+}
+
+// SchedulerCancelScheduleResponse is the response type for Scheduler.CancelSchedule.
+type SchedulerCancelScheduleResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // SchedulerScheduleOneTime calls the scheduler_scheduleonetime host function.
 // ScheduleOneTime schedules a one-time event to be triggered after the specified delay.
 // Plugins that use this function must also implement the SchedulerCallback capability
@@ -52,13 +75,21 @@ type SchedulerScheduleRecurringResponse struct {
 //
 // Returns the schedule ID that can be used to cancel the job, or an error if scheduling fails.
 func SchedulerScheduleOneTime(delaySeconds int32, payload string, scheduleID string) (*SchedulerScheduleOneTimeResponse, error) {
-	payloadMem := pdk.AllocateString(payload)
+	// Marshal request to JSON
-	defer payloadMem.Free()
+	req := SchedulerScheduleOneTimeRequest{
-	scheduleIDMem := pdk.AllocateString(scheduleID)
+		DelaySeconds: delaySeconds,
-	defer scheduleIDMem.Free()
+		Payload:      payload,
+		ScheduleID:   scheduleID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := scheduler_scheduleonetime(delaySeconds, payloadMem.Offset(), scheduleIDMem.Offset())
+	responsePtr := scheduler_scheduleonetime(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -84,15 +115,21 @@ func SchedulerScheduleOneTime(delaySeconds int32, payload string, scheduleID str
 //
 // Returns the schedule ID that can be used to cancel the job, or an error if scheduling fails.
 func SchedulerScheduleRecurring(cronExpression string, payload string, scheduleID string) (*SchedulerScheduleRecurringResponse, error) {
-	cronExpressionMem := pdk.AllocateString(cronExpression)
+	// Marshal request to JSON
-	defer cronExpressionMem.Free()
+	req := SchedulerScheduleRecurringRequest{
-	payloadMem := pdk.AllocateString(payload)
+		CronExpression: cronExpression,
-	defer payloadMem.Free()
+		Payload:        payload,
-	scheduleIDMem := pdk.AllocateString(scheduleID)
+		ScheduleID:     scheduleID,
-	defer scheduleIDMem.Free()
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := scheduler_schedulerecurring(cronExpressionMem.Offset(), payloadMem.Offset(), scheduleIDMem.Offset())
+	responsePtr := scheduler_schedulerecurring(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -114,20 +151,30 @@ func SchedulerScheduleRecurring(cronExpression string, payload string, scheduleI
 // any future events.
 //
 // Returns an error if the schedule ID is not found or if cancellation fails.
-func SchedulerCancelSchedule(scheduleID string) error {
+func SchedulerCancelSchedule(scheduleID string) (*SchedulerCancelScheduleResponse, error) {
-	scheduleIDMem := pdk.AllocateString(scheduleID)
+	// Marshal request to JSON
-	defer scheduleIDMem.Free()
+	req := SchedulerCancelScheduleRequest{
+		ScheduleID: scheduleID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := scheduler_cancelschedule(scheduleIDMem.Offset())
+	responsePtr := scheduler_cancelschedule(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response SchedulerCancelScheduleResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }

plugins/host/go/nd_host_subsonicapi.go

@@ -18,6 +18,11 @@ import (
 //go:wasmimport extism:host/user subsonicapi_call
 func subsonicapi_call(uint64) uint64
 
+// SubsonicAPICallRequest is the request type for SubsonicAPI.Call.
+type SubsonicAPICallRequest struct {
+	Uri string `json:"uri"`
+}
+
 // SubsonicAPICallResponse is the response type for SubsonicAPI.Call.
 type SubsonicAPICallResponse struct {
 	ResponseJSON string `json:"responseJSON,omitempty"`
@@ -30,11 +35,19 @@ type SubsonicAPICallResponse struct {
 // The uri parameter should be the Subsonic API path without the server prefix,
 // e.g., "getAlbumList2?type=random&size=10". The response is returned as raw JSON.
 func SubsonicAPICall(uri string) (*SubsonicAPICallResponse, error) {
-	uriMem := pdk.AllocateString(uri)
+	// Marshal request to JSON
-	defer uriMem.Free()
+	req := SubsonicAPICallRequest{
+		Uri: uri,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := subsonicapi_call(uriMem.Offset())
+	responsePtr := subsonicapi_call(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/host/go/nd_host_websocket.go

@@ -9,13 +9,11 @@ package main
 
 import (
 	"encoding/json"
-	"errors"
 
 	"github.com/extism/go-pdk"
 )
 
 // websocket_connect is the host function provided by Navidrome.
-// Takes a single JSON request pointer containing url, headers, and connectionID.
 //
 //go:wasmimport extism:host/user websocket_connect
 func websocket_connect(uint64) uint64
@@ -23,17 +21,17 @@ func websocket_connect(uint64) uint64
 // websocket_sendtext is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user websocket_sendtext
-func websocket_sendtext(uint64, uint64) uint64
+func websocket_sendtext(uint64) uint64
 
 // websocket_sendbinary is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user websocket_sendbinary
-func websocket_sendbinary(uint64, uint64) uint64
+func websocket_sendbinary(uint64) uint64
 
 // websocket_closeconnection is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user websocket_closeconnection
-func websocket_closeconnection(uint64, int32, uint64) uint64
+func websocket_closeconnection(uint64) uint64
 
 // WebSocketConnectRequest is the request type for WebSocket.Connect.
 type WebSocketConnectRequest struct {
@@ -48,6 +46,40 @@ type WebSocketConnectResponse struct {
 	Error           string `json:"error,omitempty"`
 }
 
+// WebSocketSendTextRequest is the request type for WebSocket.SendText.
+type WebSocketSendTextRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Message      string `json:"message"`
+}
+
+// WebSocketSendTextResponse is the response type for WebSocket.SendText.
+type WebSocketSendTextResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketSendBinaryRequest is the request type for WebSocket.SendBinary.
+type WebSocketSendBinaryRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Data         []byte `json:"data"`
+}
+
+// WebSocketSendBinaryResponse is the response type for WebSocket.SendBinary.
+type WebSocketSendBinaryResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketCloseConnectionRequest is the request type for WebSocket.CloseConnection.
+type WebSocketCloseConnectionRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Code         int32  `json:"code"`
+	Reason       string `json:"reason"`
+}
+
+// WebSocketCloseConnectionResponse is the response type for WebSocket.CloseConnection.
+type WebSocketCloseConnectionResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // WebSocketConnect calls the websocket_connect host function.
 // Connect establishes a WebSocket connection to the specified URL.
 //
@@ -62,7 +94,7 @@ type WebSocketConnectResponse struct {
 // Returns the connection ID that can be used to send messages or close the connection,
 // or an error if the connection fails.
 func WebSocketConnect(url string, headers map[string]string, connectionID string) (*WebSocketConnectResponse, error) {
-	// Create JSON request with all parameters
+	// Marshal request to JSON
 	req := WebSocketConnectRequest{
 		Url:          url,
 		Headers:      headers,
@@ -75,7 +107,7 @@ func WebSocketConnect(url string, headers map[string]string, connectionID string
 	reqMem := pdk.AllocateBytes(reqBytes)
 	defer reqMem.Free()
 
-	// Call the host function with single JSON request
+	// Call the host function
 	responsePtr := websocket_connect(reqMem.Offset())
 
 	// Read the response from memory
@@ -99,24 +131,33 @@ func WebSocketConnect(url string, headers map[string]string, connectionID string
 //   - message: The text message to send
 //
 // Returns an error if the connection is not found or if sending fails.
-func WebSocketSendText(connectionID string, message string) error {
+func WebSocketSendText(connectionID string, message string) (*WebSocketSendTextResponse, error) {
-	connectionIDMem := pdk.AllocateString(connectionID)
+	// Marshal request to JSON
-	defer connectionIDMem.Free()
+	req := WebSocketSendTextRequest{
-	messageMem := pdk.AllocateString(message)
+		ConnectionID: connectionID,
-	defer messageMem.Free()
+		Message:      message,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := websocket_sendtext(connectionIDMem.Offset(), messageMem.Offset())
+	responsePtr := websocket_sendtext(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response WebSocketSendTextResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // WebSocketSendBinary calls the websocket_sendbinary host function.
@@ -127,24 +168,33 @@ func WebSocketSendText(connectionID string, message string) error {
 //   - data: The binary data to send
 //
 // Returns an error if the connection is not found or if sending fails.
-func WebSocketSendBinary(connectionID string, data []byte) error {
+func WebSocketSendBinary(connectionID string, data []byte) (*WebSocketSendBinaryResponse, error) {
-	connectionIDMem := pdk.AllocateString(connectionID)
+	// Marshal request to JSON
-	defer connectionIDMem.Free()
+	req := WebSocketSendBinaryRequest{
-	dataMem := pdk.AllocateBytes(data)
+		ConnectionID: connectionID,
-	defer dataMem.Free()
+		Data:         data,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := websocket_sendbinary(connectionIDMem.Offset(), dataMem.Offset())
+	responsePtr := websocket_sendbinary(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response WebSocketSendBinaryResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // WebSocketCloseConnection calls the websocket_closeconnection host function.
@@ -156,22 +206,32 @@ func WebSocketSendBinary(connectionID string, data []byte) error {
 //   - reason: Optional human-readable reason for closing
 //
 // Returns an error if the connection is not found or if closing fails.
-func WebSocketCloseConnection(connectionID string, code int32, reason string) error {
+func WebSocketCloseConnection(connectionID string, code int32, reason string) (*WebSocketCloseConnectionResponse, error) {
-	connectionIDMem := pdk.AllocateString(connectionID)
+	// Marshal request to JSON
-	defer connectionIDMem.Free()
+	req := WebSocketCloseConnectionRequest{
-	reasonMem := pdk.AllocateString(reason)
+		ConnectionID: connectionID,
-	defer reasonMem.Free()
+		Code:         code,
+		Reason:       reason,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := websocket_closeconnection(connectionIDMem.Offset(), code, reasonMem.Offset())
+	responsePtr := websocket_closeconnection(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response WebSocketCloseConnectionResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }

plugins/host/scheduler_gen.go

@@ -9,18 +9,42 @@ import (
 	extism "github.com/extism/go-sdk"
 )
 
+// SchedulerScheduleOneTimeRequest is the request type for Scheduler.ScheduleOneTime.
+type SchedulerScheduleOneTimeRequest struct {
+	DelaySeconds int32  `json:"delaySeconds"`
+	Payload      string `json:"payload"`
+	ScheduleID   string `json:"scheduleID"`
+}
+
 // SchedulerScheduleOneTimeResponse is the response type for Scheduler.ScheduleOneTime.
 type SchedulerScheduleOneTimeResponse struct {
 	NewScheduleID string `json:"newScheduleID,omitempty"`
 	Error         string `json:"error,omitempty"`
 }
 
+// SchedulerScheduleRecurringRequest is the request type for Scheduler.ScheduleRecurring.
+type SchedulerScheduleRecurringRequest struct {
+	CronExpression string `json:"cronExpression"`
+	Payload        string `json:"payload"`
+	ScheduleID     string `json:"scheduleID"`
+}
+
 // SchedulerScheduleRecurringResponse is the response type for Scheduler.ScheduleRecurring.
 type SchedulerScheduleRecurringResponse struct {
 	NewScheduleID string `json:"newScheduleID,omitempty"`
 	Error         string `json:"error,omitempty"`
 }
 
+// SchedulerCancelScheduleRequest is the request type for Scheduler.CancelSchedule.
+type SchedulerCancelScheduleRequest struct {
+	ScheduleID string `json:"scheduleID"`
+}
+
+// SchedulerCancelScheduleResponse is the response type for Scheduler.CancelSchedule.
+type SchedulerCancelScheduleResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // RegisterSchedulerHostFunctions registers Scheduler service host functions.
 // The returned host functions should be added to the plugin's configuration.
 func RegisterSchedulerHostFunctions(service SchedulerService) []extism.HostFunction {
@@ -35,30 +59,32 @@ func newSchedulerScheduleOneTimeHostFunction(service SchedulerService) extism.Ho
 	return extism.NewHostFunctionWithStack(
 		"scheduler_scheduleonetime",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			delaySeconds := extism.DecodeI32(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			payload, err := p.ReadString(stack[1])
-			if err != nil {
-				return
-			}
-			scheduleID, err := p.ReadString(stack[2])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			newscheduleid, err := service.ScheduleOneTime(ctx, delaySeconds, payload, scheduleID)
 			if err != nil {
 				schedulerWriteError(p, stack, err)
 				return
 			}
+			var req SchedulerScheduleOneTimeRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				schedulerWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			newscheduleid, svcErr := service.ScheduleOneTime(ctx, req.DelaySeconds, req.Payload, req.ScheduleID)
+			if svcErr != nil {
+				schedulerWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := SchedulerScheduleOneTimeResponse{
 				NewScheduleID: newscheduleid,
 			}
 			schedulerWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypeI32, extism.ValueTypePTR, extism.ValueTypePTR},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -67,33 +93,32 @@ func newSchedulerScheduleRecurringHostFunction(service SchedulerService) extism.
 	return extism.NewHostFunctionWithStack(
 		"scheduler_schedulerecurring",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			cronExpression, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-			payload, err := p.ReadString(stack[1])
-			if err != nil {
-				return
-			}
-			scheduleID, err := p.ReadString(stack[2])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			newscheduleid, err := service.ScheduleRecurring(ctx, cronExpression, payload, scheduleID)
 			if err != nil {
 				schedulerWriteError(p, stack, err)
 				return
 			}
+			var req SchedulerScheduleRecurringRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				schedulerWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			newscheduleid, svcErr := service.ScheduleRecurring(ctx, req.CronExpression, req.Payload, req.ScheduleID)
+			if svcErr != nil {
+				schedulerWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := SchedulerScheduleRecurringResponse{
 				NewScheduleID: newscheduleid,
 			}
 			schedulerWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypePTR, extism.ValueTypePTR},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -102,25 +127,27 @@ func newSchedulerCancelScheduleHostFunction(service SchedulerService) extism.Hos
 	return extism.NewHostFunctionWithStack(
 		"scheduler_cancelschedule",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			scheduleID, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
+				schedulerWriteError(p, stack, err)
+				return
+			}
+			var req SchedulerCancelScheduleRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				schedulerWriteError(p, stack, err)
 				return
 			}
 
 			// Call the service method
-			err = service.CancelSchedule(ctx, scheduleID)
+			if svcErr := service.CancelSchedule(ctx, req.ScheduleID); svcErr != nil {
-			if err != nil {
+				schedulerWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := SchedulerCancelScheduleResponse{}
-			}
+			schedulerWriteResponse(p, stack, resp)
 		},
 		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},

plugins/host/subsonicapi_gen.go

@@ -9,6 +9,11 @@ import (
 	extism "github.com/extism/go-sdk"
 )
 
+// SubsonicAPICallRequest is the request type for SubsonicAPI.Call.
+type SubsonicAPICallRequest struct {
+	Uri string `json:"uri"`
+}
+
 // SubsonicAPICallResponse is the response type for SubsonicAPI.Call.
 type SubsonicAPICallResponse struct {
 	ResponseJSON string `json:"responseJSON,omitempty"`
@@ -27,18 +32,25 @@ func newSubsonicAPICallHostFunction(service SubsonicAPIService) extism.HostFunct
 	return extism.NewHostFunctionWithStack(
 		"subsonicapi_call",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			uri, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
-			if err != nil {
-				return
-			}
-
-			// Call the service method
-			responsejson, err := service.Call(ctx, uri)
 			if err != nil {
 				subsonicapiWriteError(p, stack, err)
 				return
 			}
+			var req SubsonicAPICallRequest
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				subsonicapiWriteError(p, stack, err)
+				return
+			}
+
+			// Call the service method
+			responsejson, svcErr := service.Call(ctx, req.Uri)
+			if svcErr != nil {
+				subsonicapiWriteError(p, stack, svcErr)
+				return
+			}
+
 			// Write JSON response to plugin memory
 			resp := SubsonicAPICallResponse{
 				ResponseJSON: responsejson,

plugins/host/websocket_gen.go

@@ -22,6 +22,40 @@ type WebSocketConnectResponse struct {
 	Error           string `json:"error,omitempty"`
 }
 
+// WebSocketSendTextRequest is the request type for WebSocket.SendText.
+type WebSocketSendTextRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Message      string `json:"message"`
+}
+
+// WebSocketSendTextResponse is the response type for WebSocket.SendText.
+type WebSocketSendTextResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketSendBinaryRequest is the request type for WebSocket.SendBinary.
+type WebSocketSendBinaryRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Data         []byte `json:"data"`
+}
+
+// WebSocketSendBinaryResponse is the response type for WebSocket.SendBinary.
+type WebSocketSendBinaryResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketCloseConnectionRequest is the request type for WebSocket.CloseConnection.
+type WebSocketCloseConnectionRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Code         int32  `json:"code"`
+	Reason       string `json:"reason"`
+}
+
+// WebSocketCloseConnectionResponse is the response type for WebSocket.CloseConnection.
+type WebSocketCloseConnectionResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // RegisterWebSocketHostFunctions registers WebSocket service host functions.
 // The returned host functions should be added to the plugin's configuration.
 func RegisterWebSocketHostFunctions(service WebSocketService) []extism.HostFunction {
@@ -50,11 +84,12 @@ func newWebSocketConnectHostFunction(service WebSocketService) extism.HostFuncti
 			}
 
 			// Call the service method
-			newconnectionid, err := service.Connect(ctx, req.Url, req.Headers, req.ConnectionID)
+			newconnectionid, svcErr := service.Connect(ctx, req.Url, req.Headers, req.ConnectionID)
-			if err != nil {
+			if svcErr != nil {
-				websocketWriteError(p, stack, err)
+				websocketWriteError(p, stack, svcErr)
 				return
 			}
+
 			// Write JSON response to plugin memory
 			resp := WebSocketConnectResponse{
 				NewConnectionID: newconnectionid,
@@ -70,31 +105,29 @@ func newWebSocketSendTextHostFunction(service WebSocketService) extism.HostFunct
 	return extism.NewHostFunctionWithStack(
 		"websocket_sendtext",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			connectionID, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
+				websocketWriteError(p, stack, err)
 				return
 			}
-			message, err := p.ReadString(stack[1])
+			var req WebSocketSendTextRequest
-			if err != nil {
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				websocketWriteError(p, stack, err)
 				return
 			}
 
 			// Call the service method
-			err = service.SendText(ctx, connectionID, message)
+			if svcErr := service.SendText(ctx, req.ConnectionID, req.Message); svcErr != nil {
-			if err != nil {
+				websocketWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := WebSocketSendTextResponse{}
-			}
+			websocketWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypePTR},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -103,31 +136,29 @@ func newWebSocketSendBinaryHostFunction(service WebSocketService) extism.HostFun
 	return extism.NewHostFunctionWithStack(
 		"websocket_sendbinary",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			connectionID, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
+				websocketWriteError(p, stack, err)
 				return
 			}
-			data, err := p.ReadBytes(stack[1])
+			var req WebSocketSendBinaryRequest
-			if err != nil {
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
+				websocketWriteError(p, stack, err)
 				return
 			}
 
 			// Call the service method
-			err = service.SendBinary(ctx, connectionID, data)
+			if svcErr := service.SendBinary(ctx, req.ConnectionID, req.Data); svcErr != nil {
-			if err != nil {
+				websocketWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := WebSocketSendBinaryResponse{}
-			}
+			websocketWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypePTR},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }
@@ -136,32 +167,29 @@ func newWebSocketCloseConnectionHostFunction(service WebSocketService) extism.Ho
 	return extism.NewHostFunctionWithStack(
 		"websocket_closeconnection",
 		func(ctx context.Context, p *extism.CurrentPlugin, stack []uint64) {
-			// Read parameters from stack
+			// Read JSON request from plugin memory
-			connectionID, err := p.ReadString(stack[0])
+			reqBytes, err := p.ReadBytes(stack[0])
 			if err != nil {
+				websocketWriteError(p, stack, err)
 				return
 			}
-			code := extism.DecodeI32(stack[1])
+			var req WebSocketCloseConnectionRequest
-			reason, err := p.ReadString(stack[2])
+			if err := json.Unmarshal(reqBytes, &req); err != nil {
-			if err != nil {
+				websocketWriteError(p, stack, err)
 				return
 			}
 
 			// Call the service method
-			err = service.CloseConnection(ctx, connectionID, code, reason)
+			if svcErr := service.CloseConnection(ctx, req.ConnectionID, req.Code, req.Reason); svcErr != nil {
-			if err != nil {
+				websocketWriteError(p, stack, svcErr)
-				// Write error string to plugin memory
-				if ptr, err := p.WriteString(err.Error()); err == nil {
-					stack[0] = ptr
-				}
 				return
 			}
-			// Write empty string to indicate success
+
-			if ptr, err := p.WriteString(""); err == nil {
+			// Write JSON response to plugin memory
-				stack[0] = ptr
+			resp := WebSocketCloseConnectionResponse{}
-			}
+			websocketWriteResponse(p, stack, resp)
 		},
-		[]extism.ValueType{extism.ValueTypePTR, extism.ValueTypeI32, extism.ValueTypePTR},
+		[]extism.ValueType{extism.ValueTypePTR},
 		[]extism.ValueType{extism.ValueTypePTR},
 	)
 }

plugins/testdata/fake-artwork/nd_host_artwork.go

@@ -16,22 +16,28 @@ import (
 // artwork_getartisturl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_getartisturl
-func artwork_getartisturl(uint64, int32) uint64
+func artwork_getartisturl(uint64) uint64
 
 // artwork_getalbumurl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_getalbumurl
-func artwork_getalbumurl(uint64, int32) uint64
+func artwork_getalbumurl(uint64) uint64
 
 // artwork_gettrackurl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_gettrackurl
-func artwork_gettrackurl(uint64, int32) uint64
+func artwork_gettrackurl(uint64) uint64
 
 // artwork_getplaylisturl is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user artwork_getplaylisturl
-func artwork_getplaylisturl(uint64, int32) uint64
+func artwork_getplaylisturl(uint64) uint64
+
+// ArtworkGetArtistUrlRequest is the request type for Artwork.GetArtistUrl.
+type ArtworkGetArtistUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
 
 // ArtworkGetArtistUrlResponse is the response type for Artwork.GetArtistUrl.
 type ArtworkGetArtistUrlResponse struct {
@@ -39,18 +45,36 @@ type ArtworkGetArtistUrlResponse struct {
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetAlbumUrlRequest is the request type for Artwork.GetAlbumUrl.
+type ArtworkGetAlbumUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetAlbumUrlResponse is the response type for Artwork.GetAlbumUrl.
 type ArtworkGetAlbumUrlResponse struct {
 	Url   string `json:"url,omitempty"`
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetTrackUrlRequest is the request type for Artwork.GetTrackUrl.
+type ArtworkGetTrackUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetTrackUrlResponse is the response type for Artwork.GetTrackUrl.
 type ArtworkGetTrackUrlResponse struct {
 	Url   string `json:"url,omitempty"`
 	Error string `json:"error,omitempty"`
 }
 
+// ArtworkGetPlaylistUrlRequest is the request type for Artwork.GetPlaylistUrl.
+type ArtworkGetPlaylistUrlRequest struct {
+	Id   string `json:"id"`
+	Size int32  `json:"size"`
+}
+
 // ArtworkGetPlaylistUrlResponse is the response type for Artwork.GetPlaylistUrl.
 type ArtworkGetPlaylistUrlResponse struct {
 	Url   string `json:"url,omitempty"`
@@ -66,11 +90,20 @@ type ArtworkGetPlaylistUrlResponse struct {
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetArtistUrl(id string, size int32) (*ArtworkGetArtistUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetArtistUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_getartisturl(idMem.Offset(), size)
+	responsePtr := artwork_getartisturl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -94,11 +127,20 @@ func ArtworkGetArtistUrl(id string, size int32) (*ArtworkGetArtistUrlResponse, e
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetAlbumUrl(id string, size int32) (*ArtworkGetAlbumUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetAlbumUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_getalbumurl(idMem.Offset(), size)
+	responsePtr := artwork_getalbumurl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -122,11 +164,20 @@ func ArtworkGetAlbumUrl(id string, size int32) (*ArtworkGetAlbumUrlResponse, err
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetTrackUrl(id string, size int32) (*ArtworkGetTrackUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetTrackUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_gettrackurl(idMem.Offset(), size)
+	responsePtr := artwork_gettrackurl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -150,11 +201,20 @@ func ArtworkGetTrackUrl(id string, size int32) (*ArtworkGetTrackUrlResponse, err
 //
 // Returns the public URL for the artwork, or an error if generation fails.
 func ArtworkGetPlaylistUrl(id string, size int32) (*ArtworkGetPlaylistUrlResponse, error) {
-	idMem := pdk.AllocateString(id)
+	// Marshal request to JSON
-	defer idMem.Free()
+	req := ArtworkGetPlaylistUrlRequest{
+		Id:   id,
+		Size: size,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := artwork_getplaylisturl(idMem.Offset(), size)
+	responsePtr := artwork_getplaylisturl(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/testdata/fake-scheduler/nd_host_scheduler.go

@@ -9,7 +9,6 @@ package main
 
 import (
 	"encoding/json"
-	"errors"
 
 	"github.com/extism/go-pdk"
 )
@@ -17,30 +16,54 @@ import (
 // scheduler_scheduleonetime is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user scheduler_scheduleonetime
-func scheduler_scheduleonetime(int32, uint64, uint64) uint64
+func scheduler_scheduleonetime(uint64) uint64
 
 // scheduler_schedulerecurring is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user scheduler_schedulerecurring
-func scheduler_schedulerecurring(uint64, uint64, uint64) uint64
+func scheduler_schedulerecurring(uint64) uint64
 
 // scheduler_cancelschedule is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user scheduler_cancelschedule
 func scheduler_cancelschedule(uint64) uint64
 
+// SchedulerScheduleOneTimeRequest is the request type for Scheduler.ScheduleOneTime.
+type SchedulerScheduleOneTimeRequest struct {
+	DelaySeconds int32  `json:"delaySeconds"`
+	Payload      string `json:"payload"`
+	ScheduleID   string `json:"scheduleID"`
+}
+
 // SchedulerScheduleOneTimeResponse is the response type for Scheduler.ScheduleOneTime.
 type SchedulerScheduleOneTimeResponse struct {
 	NewScheduleID string `json:"newScheduleID,omitempty"`
 	Error         string `json:"error,omitempty"`
 }
 
+// SchedulerScheduleRecurringRequest is the request type for Scheduler.ScheduleRecurring.
+type SchedulerScheduleRecurringRequest struct {
+	CronExpression string `json:"cronExpression"`
+	Payload        string `json:"payload"`
+	ScheduleID     string `json:"scheduleID"`
+}
+
 // SchedulerScheduleRecurringResponse is the response type for Scheduler.ScheduleRecurring.
 type SchedulerScheduleRecurringResponse struct {
 	NewScheduleID string `json:"newScheduleID,omitempty"`
 	Error         string `json:"error,omitempty"`
 }
 
+// SchedulerCancelScheduleRequest is the request type for Scheduler.CancelSchedule.
+type SchedulerCancelScheduleRequest struct {
+	ScheduleID string `json:"scheduleID"`
+}
+
+// SchedulerCancelScheduleResponse is the response type for Scheduler.CancelSchedule.
+type SchedulerCancelScheduleResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // SchedulerScheduleOneTime calls the scheduler_scheduleonetime host function.
 // ScheduleOneTime schedules a one-time event to be triggered after the specified delay.
 // Plugins that use this function must also implement the SchedulerCallback capability
@@ -52,13 +75,21 @@ type SchedulerScheduleRecurringResponse struct {
 //
 // Returns the schedule ID that can be used to cancel the job, or an error if scheduling fails.
 func SchedulerScheduleOneTime(delaySeconds int32, payload string, scheduleID string) (*SchedulerScheduleOneTimeResponse, error) {
-	payloadMem := pdk.AllocateString(payload)
+	// Marshal request to JSON
-	defer payloadMem.Free()
+	req := SchedulerScheduleOneTimeRequest{
-	scheduleIDMem := pdk.AllocateString(scheduleID)
+		DelaySeconds: delaySeconds,
-	defer scheduleIDMem.Free()
+		Payload:      payload,
+		ScheduleID:   scheduleID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := scheduler_scheduleonetime(delaySeconds, payloadMem.Offset(), scheduleIDMem.Offset())
+	responsePtr := scheduler_scheduleonetime(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -84,15 +115,21 @@ func SchedulerScheduleOneTime(delaySeconds int32, payload string, scheduleID str
 //
 // Returns the schedule ID that can be used to cancel the job, or an error if scheduling fails.
 func SchedulerScheduleRecurring(cronExpression string, payload string, scheduleID string) (*SchedulerScheduleRecurringResponse, error) {
-	cronExpressionMem := pdk.AllocateString(cronExpression)
+	// Marshal request to JSON
-	defer cronExpressionMem.Free()
+	req := SchedulerScheduleRecurringRequest{
-	payloadMem := pdk.AllocateString(payload)
+		CronExpression: cronExpression,
-	defer payloadMem.Free()
+		Payload:        payload,
-	scheduleIDMem := pdk.AllocateString(scheduleID)
+		ScheduleID:     scheduleID,
-	defer scheduleIDMem.Free()
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := scheduler_schedulerecurring(cronExpressionMem.Offset(), payloadMem.Offset(), scheduleIDMem.Offset())
+	responsePtr := scheduler_schedulerecurring(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -114,20 +151,30 @@ func SchedulerScheduleRecurring(cronExpression string, payload string, scheduleI
 // any future events.
 //
 // Returns an error if the schedule ID is not found or if cancellation fails.
-func SchedulerCancelSchedule(scheduleID string) error {
+func SchedulerCancelSchedule(scheduleID string) (*SchedulerCancelScheduleResponse, error) {
-	scheduleIDMem := pdk.AllocateString(scheduleID)
+	// Marshal request to JSON
-	defer scheduleIDMem.Free()
+	req := SchedulerCancelScheduleRequest{
+		ScheduleID: scheduleID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := scheduler_cancelschedule(scheduleIDMem.Offset())
+	responsePtr := scheduler_cancelschedule(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response SchedulerCancelScheduleResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }

plugins/testdata/fake-subsonicapi-plugin/nd_host_subsonicapi.go

@@ -2,6 +2,8 @@
 //
 // This file contains client wrappers for the SubsonicAPI host service.
 // It is intended for use in Navidrome plugins built with TinyGo.
+//
+//go:build wasip1
 
 package main
 
@@ -16,6 +18,11 @@ import (
 //go:wasmimport extism:host/user subsonicapi_call
 func subsonicapi_call(uint64) uint64
 
+// SubsonicAPICallRequest is the request type for SubsonicAPI.Call.
+type SubsonicAPICallRequest struct {
+	Uri string `json:"uri"`
+}
+
 // SubsonicAPICallResponse is the response type for SubsonicAPI.Call.
 type SubsonicAPICallResponse struct {
 	ResponseJSON string `json:"responseJSON,omitempty"`
@@ -28,11 +35,19 @@ type SubsonicAPICallResponse struct {
 // The uri parameter should be the Subsonic API path without the server prefix,
 // e.g., "getAlbumList2?type=random&size=10". The response is returned as raw JSON.
 func SubsonicAPICall(uri string) (*SubsonicAPICallResponse, error) {
-	uriMem := pdk.AllocateString(uri)
+	// Marshal request to JSON
-	defer uriMem.Free()
+	req := SubsonicAPICallRequest{
+		Uri: uri,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := subsonicapi_call(uriMem.Offset())
+	responsePtr := subsonicapi_call(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)

plugins/testdata/fake-websocket/main.go

@@ -4,7 +4,6 @@ package main
 
 import (
 	"encoding/json"
-	"errors"
 
 	pdk "github.com/extism/go-pdk"
 )
@@ -82,20 +81,28 @@ func ndWebSocketOnTextMessage() int32 {
 
 	switch input.Message {
 	case "echo":
-		err := webSocketSendText(input.ConnectionID, "echo:"+input.Message)
+		resp, err := WebSocketSendText(input.ConnectionID, "echo:"+input.Message)
 		if err != nil {
 			errStr := err.Error()
 			pdk.OutputJSON(OnTextMessageOutput{Error: &errStr})
 			return 0
 		}
+		if resp.Error != "" {
+			pdk.OutputJSON(OnTextMessageOutput{Error: &resp.Error})
+			return 0
+		}
 
 	case "close":
-		err := webSocketCloseConnection(input.ConnectionID)
+		resp, err := WebSocketCloseConnection(input.ConnectionID, 1000, "closed by plugin")
 		if err != nil {
 			errStr := err.Error()
 			pdk.OutputJSON(OnTextMessageOutput{Error: &errStr})
 			return 0
 		}
+		if resp.Error != "" {
+			pdk.OutputJSON(OnTextMessageOutput{Error: &resp.Error})
+			return 0
+		}
 
 	case "fail":
 		errStr := "intentional test failure"
@@ -205,48 +212,4 @@ func storeReceivedMessage(msg string) {
 	pdk.SetVar("_received_messages", []byte(msg))
 }
 
-// Host function declarations for WebSocket operations
-//
-//go:wasmimport extism:host/user websocket_sendtext
-func websocket_sendtext(connectionID uint64, message uint64) uint64
-
-//go:wasmimport extism:host/user websocket_closeconnection
-func websocket_closeconnection(connectionID uint64, code int32, reason uint64) uint64
-
-// webSocketSendText sends a text message to the specified connection.
-func webSocketSendText(connectionID, message string) error {
-	connMem := pdk.AllocateString(connectionID)
-	defer connMem.Free()
-	msgMem := pdk.AllocateString(message)
-	defer msgMem.Free()
-
-	responsePtr := websocket_sendtext(connMem.Offset(), msgMem.Offset())
-	if responsePtr != 0 {
-		responseMem := pdk.FindMemory(responsePtr)
-		errStr := string(responseMem.ReadBytes())
-		if errStr != "" {
-			return errors.New(errStr)
-		}
-	}
-	return nil
-}
-
-// webSocketCloseConnection closes the specified WebSocket connection.
-func webSocketCloseConnection(connectionID string) error {
-	connMem := pdk.AllocateString(connectionID)
-	defer connMem.Free()
-	reasonMem := pdk.AllocateString("closed by plugin")
-	defer reasonMem.Free()
-
-	responsePtr := websocket_closeconnection(connMem.Offset(), 1000, reasonMem.Offset())
-	if responsePtr != 0 {
-		responseMem := pdk.FindMemory(responsePtr)
-		errStr := string(responseMem.ReadBytes())
-		if errStr != "" {
-			return errors.New(errStr)
-		}
-	}
-	return nil
-}
-
 func main() {}

plugins/testdata/fake-websocket/nd_host_websocket.go

@@ -0,0 +1,237 @@
+// Code generated by hostgen. DO NOT EDIT.
+//
+// This file contains client wrappers for the WebSocket host service.
+// It is intended for use in Navidrome plugins built with TinyGo.
+//
+//go:build wasip1
+
+package main
+
+import (
+	"encoding/json"
+
+	"github.com/extism/go-pdk"
+)
+
+// websocket_connect is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user websocket_connect
+func websocket_connect(uint64) uint64
+
+// websocket_sendtext is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user websocket_sendtext
+func websocket_sendtext(uint64) uint64
+
+// websocket_sendbinary is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user websocket_sendbinary
+func websocket_sendbinary(uint64) uint64
+
+// websocket_closeconnection is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user websocket_closeconnection
+func websocket_closeconnection(uint64) uint64
+
+// WebSocketConnectRequest is the request type for WebSocket.Connect.
+type WebSocketConnectRequest struct {
+	Url          string            `json:"url"`
+	Headers      map[string]string `json:"headers"`
+	ConnectionID string            `json:"connectionID"`
+}
+
+// WebSocketConnectResponse is the response type for WebSocket.Connect.
+type WebSocketConnectResponse struct {
+	NewConnectionID string `json:"newConnectionID,omitempty"`
+	Error           string `json:"error,omitempty"`
+}
+
+// WebSocketSendTextRequest is the request type for WebSocket.SendText.
+type WebSocketSendTextRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Message      string `json:"message"`
+}
+
+// WebSocketSendTextResponse is the response type for WebSocket.SendText.
+type WebSocketSendTextResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketSendBinaryRequest is the request type for WebSocket.SendBinary.
+type WebSocketSendBinaryRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Data         []byte `json:"data"`
+}
+
+// WebSocketSendBinaryResponse is the response type for WebSocket.SendBinary.
+type WebSocketSendBinaryResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketCloseConnectionRequest is the request type for WebSocket.CloseConnection.
+type WebSocketCloseConnectionRequest struct {
+	ConnectionID string `json:"connectionID"`
+	Code         int32  `json:"code"`
+	Reason       string `json:"reason"`
+}
+
+// WebSocketCloseConnectionResponse is the response type for WebSocket.CloseConnection.
+type WebSocketCloseConnectionResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// WebSocketConnect calls the websocket_connect host function.
+// Connect establishes a WebSocket connection to the specified URL.
+//
+// Plugins that use this function must also implement the WebSocketCallback capability
+// to receive incoming messages and connection events.
+//
+// Parameters:
+//   - url: The WebSocket URL to connect to (ws:// or wss://)
+//   - headers: Optional HTTP headers to include in the handshake request
+//   - connectionID: Optional unique identifier for the connection. If empty, one will be generated
+//
+// Returns the connection ID that can be used to send messages or close the connection,
+// or an error if the connection fails.
+func WebSocketConnect(url string, headers map[string]string, connectionID string) (*WebSocketConnectResponse, error) {
+	// Marshal request to JSON
+	req := WebSocketConnectRequest{
+		Url:          url,
+		Headers:      headers,
+		ConnectionID: connectionID,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := websocket_connect(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response WebSocketConnectResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}
+
+// WebSocketSendText calls the websocket_sendtext host function.
+// SendText sends a text message over an established WebSocket connection.
+//
+// Parameters:
+//   - connectionID: The connection identifier returned by Connect
+//   - message: The text message to send
+//
+// Returns an error if the connection is not found or if sending fails.
+func WebSocketSendText(connectionID string, message string) (*WebSocketSendTextResponse, error) {
+	// Marshal request to JSON
+	req := WebSocketSendTextRequest{
+		ConnectionID: connectionID,
+		Message:      message,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := websocket_sendtext(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response WebSocketSendTextResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}
+
+// WebSocketSendBinary calls the websocket_sendbinary host function.
+// SendBinary sends binary data over an established WebSocket connection.
+//
+// Parameters:
+//   - connectionID: The connection identifier returned by Connect
+//   - data: The binary data to send
+//
+// Returns an error if the connection is not found or if sending fails.
+func WebSocketSendBinary(connectionID string, data []byte) (*WebSocketSendBinaryResponse, error) {
+	// Marshal request to JSON
+	req := WebSocketSendBinaryRequest{
+		ConnectionID: connectionID,
+		Data:         data,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := websocket_sendbinary(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response WebSocketSendBinaryResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}
+
+// WebSocketCloseConnection calls the websocket_closeconnection host function.
+// CloseConnection gracefully closes a WebSocket connection.
+//
+// Parameters:
+//   - connectionID: The connection identifier returned by Connect
+//   - code: WebSocket close status code (e.g., 1000 for normal closure)
+//   - reason: Optional human-readable reason for closing
+//
+// Returns an error if the connection is not found or if closing fails.
+func WebSocketCloseConnection(connectionID string, code int32, reason string) (*WebSocketCloseConnectionResponse, error) {
+	// Marshal request to JSON
+	req := WebSocketCloseConnectionRequest{
+		ConnectionID: connectionID,
+		Code:         code,
+		Reason:       reason,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := websocket_closeconnection(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response WebSocketCloseConnectionResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	return &response, nil
+}

plugins/testdata/fake_cache_plugin/main.go

@@ -81,12 +81,16 @@ func ndTestCache() int32 {
 
 	switch input.Operation {
 	case "set_string":
-		err := CacheSetString(input.Key, input.StringVal, input.TTLSeconds)
+		resp, err := CacheSetString(input.Key, input.StringVal, input.TTLSeconds)
 		if err != nil {
 			errStr := err.Error()
 			pdk.OutputJSON(TestCacheOutput{Error: &errStr})
 			return 0
 		}
+		if resp.Error != "" {
+			pdk.OutputJSON(TestCacheOutput{Error: &resp.Error})
+			return 0
+		}
 		pdk.OutputJSON(TestCacheOutput{})
 		return 0
 
@@ -105,12 +109,16 @@ func ndTestCache() int32 {
 		return 0
 
 	case "set_int":
-		err := CacheSetInt(input.Key, input.IntVal, input.TTLSeconds)
+		resp, err := CacheSetInt(input.Key, input.IntVal, input.TTLSeconds)
 		if err != nil {
 			errStr := err.Error()
 			pdk.OutputJSON(TestCacheOutput{Error: &errStr})
 			return 0
 		}
+		if resp.Error != "" {
+			pdk.OutputJSON(TestCacheOutput{Error: &resp.Error})
+			return 0
+		}
 		pdk.OutputJSON(TestCacheOutput{})
 		return 0
 
@@ -129,12 +137,16 @@ func ndTestCache() int32 {
 		return 0
 
 	case "set_float":
-		err := CacheSetFloat(input.Key, input.FloatVal, input.TTLSeconds)
+		resp, err := CacheSetFloat(input.Key, input.FloatVal, input.TTLSeconds)
 		if err != nil {
 			errStr := err.Error()
 			pdk.OutputJSON(TestCacheOutput{Error: &errStr})
 			return 0
 		}
+		if resp.Error != "" {
+			pdk.OutputJSON(TestCacheOutput{Error: &resp.Error})
+			return 0
+		}
 		pdk.OutputJSON(TestCacheOutput{})
 		return 0
 
@@ -153,12 +165,16 @@ func ndTestCache() int32 {
 		return 0
 
 	case "set_bytes":
-		err := CacheSetBytes(input.Key, input.BytesVal, input.TTLSeconds)
+		resp, err := CacheSetBytes(input.Key, input.BytesVal, input.TTLSeconds)
 		if err != nil {
 			errStr := err.Error()
 			pdk.OutputJSON(TestCacheOutput{Error: &errStr})
 			return 0
 		}
+		if resp.Error != "" {
+			pdk.OutputJSON(TestCacheOutput{Error: &resp.Error})
+			return 0
+		}
 		pdk.OutputJSON(TestCacheOutput{})
 		return 0
 
@@ -191,12 +207,16 @@ func ndTestCache() int32 {
 		return 0
 
 	case "remove":
-		err := CacheRemove(input.Key)
+		resp, err := CacheRemove(input.Key)
 		if err != nil {
 			errStr := err.Error()
 			pdk.OutputJSON(TestCacheOutput{Error: &errStr})
 			return 0
 		}
+		if resp.Error != "" {
+			pdk.OutputJSON(TestCacheOutput{Error: &resp.Error})
+			return 0
+		}
 		pdk.OutputJSON(TestCacheOutput{})
 		return 0
 

plugins/testdata/fake_cache_plugin/nd_host_cache.go

@@ -9,7 +9,6 @@ package main
 
 import (
 	"encoding/json"
-	"errors"
 
 	"github.com/extism/go-pdk"
 )
@@ -17,7 +16,7 @@ import (
 // cache_setstring is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setstring
-func cache_setstring(uint64, uint64, int64) uint64
+func cache_setstring(uint64) uint64
 
 // cache_getstring is the host function provided by Navidrome.
 //
@@ -27,7 +26,7 @@ func cache_getstring(uint64) uint64
 // cache_setint is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setint
-func cache_setint(uint64, int64, int64) uint64
+func cache_setint(uint64) uint64
 
 // cache_getint is the host function provided by Navidrome.
 //
@@ -37,7 +36,7 @@ func cache_getint(uint64) uint64
 // cache_setfloat is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setfloat
-func cache_setfloat(uint64, float64, int64) uint64
+func cache_setfloat(uint64) uint64
 
 // cache_getfloat is the host function provided by Navidrome.
 //
@@ -47,7 +46,7 @@ func cache_getfloat(uint64) uint64
 // cache_setbytes is the host function provided by Navidrome.
 //
 //go:wasmimport extism:host/user cache_setbytes
-func cache_setbytes(uint64, uint64, int64) uint64
+func cache_setbytes(uint64) uint64
 
 // cache_getbytes is the host function provided by Navidrome.
 //
@@ -64,6 +63,23 @@ func cache_has(uint64) uint64
 //go:wasmimport extism:host/user cache_remove
 func cache_remove(uint64) uint64
 
+// CacheSetStringRequest is the request type for Cache.SetString.
+type CacheSetStringRequest struct {
+	Key        string `json:"key"`
+	Value      string `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetStringResponse is the response type for Cache.SetString.
+type CacheSetStringResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetStringRequest is the request type for Cache.GetString.
+type CacheGetStringRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetStringResponse is the response type for Cache.GetString.
 type CacheGetStringResponse struct {
 	Value  string `json:"value,omitempty"`
@@ -71,6 +87,23 @@ type CacheGetStringResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheSetIntRequest is the request type for Cache.SetInt.
+type CacheSetIntRequest struct {
+	Key        string `json:"key"`
+	Value      int64  `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetIntResponse is the response type for Cache.SetInt.
+type CacheSetIntResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetIntRequest is the request type for Cache.GetInt.
+type CacheGetIntRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetIntResponse is the response type for Cache.GetInt.
 type CacheGetIntResponse struct {
 	Value  int64  `json:"value,omitempty"`
@@ -78,6 +111,23 @@ type CacheGetIntResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheSetFloatRequest is the request type for Cache.SetFloat.
+type CacheSetFloatRequest struct {
+	Key        string  `json:"key"`
+	Value      float64 `json:"value"`
+	TtlSeconds int64   `json:"ttlSeconds"`
+}
+
+// CacheSetFloatResponse is the response type for Cache.SetFloat.
+type CacheSetFloatResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetFloatRequest is the request type for Cache.GetFloat.
+type CacheGetFloatRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetFloatResponse is the response type for Cache.GetFloat.
 type CacheGetFloatResponse struct {
 	Value  float64 `json:"value,omitempty"`
@@ -85,6 +135,23 @@ type CacheGetFloatResponse struct {
 	Error  string  `json:"error,omitempty"`
 }
 
+// CacheSetBytesRequest is the request type for Cache.SetBytes.
+type CacheSetBytesRequest struct {
+	Key        string `json:"key"`
+	Value      []byte `json:"value"`
+	TtlSeconds int64  `json:"ttlSeconds"`
+}
+
+// CacheSetBytesResponse is the response type for Cache.SetBytes.
+type CacheSetBytesResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
+// CacheGetBytesRequest is the request type for Cache.GetBytes.
+type CacheGetBytesRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheGetBytesResponse is the response type for Cache.GetBytes.
 type CacheGetBytesResponse struct {
 	Value  []byte `json:"value,omitempty"`
@@ -92,12 +159,27 @@ type CacheGetBytesResponse struct {
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheHasRequest is the request type for Cache.Has.
+type CacheHasRequest struct {
+	Key string `json:"key"`
+}
+
 // CacheHasResponse is the response type for Cache.Has.
 type CacheHasResponse struct {
 	Exists bool   `json:"exists,omitempty"`
 	Error  string `json:"error,omitempty"`
 }
 
+// CacheRemoveRequest is the request type for Cache.Remove.
+type CacheRemoveRequest struct {
+	Key string `json:"key"`
+}
+
+// CacheRemoveResponse is the response type for Cache.Remove.
+type CacheRemoveResponse struct {
+	Error string `json:"error,omitempty"`
+}
+
 // CacheSetString calls the cache_setstring host function.
 // SetString stores a string value in the cache.
 //
@@ -107,24 +189,34 @@ type CacheHasResponse struct {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetString(key string, value string, ttlSeconds int64) error {
+func CacheSetString(key string, value string, ttlSeconds int64) (*CacheSetStringResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetStringRequest{
-	valueMem := pdk.AllocateString(value)
+		Key:        key,
-	defer valueMem.Free()
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setstring(keyMem.Offset(), valueMem.Offset(), ttlSeconds)
+	responsePtr := cache_setstring(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetStringResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetString calls the cache_getstring host function.
@@ -136,11 +228,19 @@ func CacheSetString(key string, value string, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not a string, exists will be false.
 func CacheGetString(key string) (*CacheGetStringResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetStringRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getstring(keyMem.Offset())
+	responsePtr := cache_getstring(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -164,22 +264,34 @@ func CacheGetString(key string) (*CacheGetStringResponse, error) {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetInt(key string, value int64, ttlSeconds int64) error {
+func CacheSetInt(key string, value int64, ttlSeconds int64) (*CacheSetIntResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetIntRequest{
+		Key:        key,
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setint(keyMem.Offset(), value, ttlSeconds)
+	responsePtr := cache_setint(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetIntResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetInt calls the cache_getint host function.
@@ -191,11 +303,19 @@ func CacheSetInt(key string, value int64, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not an integer, exists will be false.
 func CacheGetInt(key string) (*CacheGetIntResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetIntRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getint(keyMem.Offset())
+	responsePtr := cache_getint(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -219,22 +339,34 @@ func CacheGetInt(key string) (*CacheGetIntResponse, error) {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetFloat(key string, value float64, ttlSeconds int64) error {
+func CacheSetFloat(key string, value float64, ttlSeconds int64) (*CacheSetFloatResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetFloatRequest{
+		Key:        key,
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setfloat(keyMem.Offset(), value, ttlSeconds)
+	responsePtr := cache_setfloat(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetFloatResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetFloat calls the cache_getfloat host function.
@@ -246,11 +378,19 @@ func CacheSetFloat(key string, value float64, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not a float, exists will be false.
 func CacheGetFloat(key string) (*CacheGetFloatResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetFloatRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getfloat(keyMem.Offset())
+	responsePtr := cache_getfloat(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -274,24 +414,34 @@ func CacheGetFloat(key string) (*CacheGetFloatResponse, error) {
 //   - ttlSeconds: Time-to-live in seconds (0 uses default of 24 hours)
 //
 // Returns an error if the operation fails.
-func CacheSetBytes(key string, value []byte, ttlSeconds int64) error {
+func CacheSetBytes(key string, value []byte, ttlSeconds int64) (*CacheSetBytesResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheSetBytesRequest{
-	valueMem := pdk.AllocateBytes(value)
+		Key:        key,
-	defer valueMem.Free()
+		Value:      value,
+		TtlSeconds: ttlSeconds,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_setbytes(keyMem.Offset(), valueMem.Offset(), ttlSeconds)
+	responsePtr := cache_setbytes(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheSetBytesResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }
 
 // CacheGetBytes calls the cache_getbytes host function.
@@ -303,11 +453,19 @@ func CacheSetBytes(key string, value []byte, ttlSeconds int64) error {
 // Returns the value and whether the key exists. If the key doesn't exist
 // or the stored value is not a byte slice, exists will be false.
 func CacheGetBytes(key string) (*CacheGetBytesResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheGetBytesRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_getbytes(keyMem.Offset())
+	responsePtr := cache_getbytes(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -330,11 +488,19 @@ func CacheGetBytes(key string) (*CacheGetBytesResponse, error) {
 //
 // Returns true if the key exists and has not expired.
 func CacheHas(key string) (*CacheHasResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheHasRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_has(keyMem.Offset())
+	responsePtr := cache_has(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
@@ -356,20 +522,30 @@ func CacheHas(key string) (*CacheHasResponse, error) {
 //   - key: The cache key (will be namespaced with plugin ID)
 //
 // Returns an error if the operation fails. Does not return an error if the key doesn't exist.
-func CacheRemove(key string) error {
+func CacheRemove(key string) (*CacheRemoveResponse, error) {
-	keyMem := pdk.AllocateString(key)
+	// Marshal request to JSON
-	defer keyMem.Free()
+	req := CacheRemoveRequest{
+		Key: key,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
 
 	// Call the host function
-	responsePtr := cache_remove(keyMem.Offset())
+	responsePtr := cache_remove(reqMem.Offset())
 
 	// Read the response from memory
 	responseMem := pdk.FindMemory(responsePtr)
-	errStr := string(responseMem.ReadBytes())
+	responseBytes := responseMem.ReadBytes()
 
-	if errStr != "" {
+	// Parse the response
-		return errors.New(errStr)
+	var response CacheRemoveResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
 	}
 
-	return nil
+	return &response, nil
 }