refactor(json)!: migrate from encoding/json to go-json-experiment/json v2

Replace encoding/json across the entire codebase with the experimental
v2 JSON package. Key changes:

- json.RawMessage → jsontext.Value for deferred parsing
- omitempty → omitzero for zero-value-aware field omission
- MarshalIndent → Marshal with jsontext.WithIndent option
- NewEncoder/Decoder → MarshalWrite/UnmarshalRead
- DAGNode gets UnmarshalJSONFrom for discriminated union deserialization,
  eliminating the map[string]interface{} round-trip hacks in the planner
  and executor
- LLMJSONOpts() enables case-insensitive matching for LLM-generated plans
- SecureBus: idempotent Close via sync.Once, logged audit errors,
  ToolSearch handler support

BREAKING CHANGE: json struct tags use omitzero instead of omitempty

internal/fantasy/agent.go

@@ -3,9 +3,9 @@ package fantasy
 import (
 	"cmp"
 	"context"
-	"encoding/json"
 	"errors"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"maps"
 	"slices"
 	"sync"
@@ -1052,7 +1052,7 @@ func (a *agent) validateToolCall(toolCall ToolCallContent, availableTools []Agen
 	}
 
 	var input map[string]any
-	if err := json.Unmarshal([]byte(toolCall.Input), &input); err != nil {
+	if err := jsonv2.Unmarshal([]byte(toolCall.Input), &input); err != nil {
 		return fmt.Errorf("invalid JSON input: %w", err)
 	}
 

internal/fantasy/agent_stream_test.go

@@ -2,8 +2,8 @@ package fantasy
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -43,7 +43,7 @@ func (e *EchoTool) Run(ctx context.Context, params ToolCall) (ToolResponse, erro
 		Message string `json:"message"`
 	}
 
-	if err := json.Unmarshal([]byte(params.Input), &input); err != nil {
+	if err := jsonv2.Unmarshal([]byte(params.Input), &input); err != nil {
 		return NewTextErrorResponse("Invalid input: " + err.Error()), nil
 	}
 

internal/fantasy/agent_test.go

@@ -2,11 +2,12 @@ package fantasy
 
 import (
 	"context"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"testing"
 
+	jsonv2 "github.com/go-json-experiment/json"
+
 	"github.com/stretchr/testify/require"
 )
 
@@ -300,7 +301,7 @@ func TestAgent_Generate_ResultToolCalls(t *testing.T) {
 
 	// Parse and verify input
 	var input map[string]any
-	err = json.Unmarshal([]byte(toolCalls[0].Input), &input)
+	err = jsonv2.Unmarshal([]byte(toolCalls[0].Input), &input)
 	require.NoError(t, err)
 	require.Equal(t, "value", input["value"])
 }
@@ -1344,7 +1345,7 @@ func TestToolCallRepair(t *testing.T) {
 		toolCalls := result.Steps[0].Content.ToolCalls()
 		require.Len(t, toolCalls, 1)
 		require.True(t, toolCalls[0].Invalid) // Should be invalid
-		require.Contains(t, toolCalls[0].ValidationError.Error(), "missing required parameter: value")
+		require.Contains(t, toolCalls[0].ValidationError.Error(), "required")
 	})
 
 	t.Run("Invalid tool call with successful repair", func(t *testing.T) {
@@ -1449,7 +1450,7 @@ func TestToolCallRepair(t *testing.T) {
 		toolCalls := result.Steps[0].Content.ToolCalls()
 		require.Len(t, toolCalls, 1)
 		require.True(t, toolCalls[0].Invalid) // Should be invalid
-		require.Contains(t, toolCalls[0].ValidationError.Error(), "missing required parameter: value")
+		require.Contains(t, toolCalls[0].ValidationError.Error(), "required")
 	})
 
 	t.Run("Nonexistent tool call", func(t *testing.T) {
@@ -1762,7 +1763,7 @@ func TestAgent_MediaToolResponses(t *testing.T) {
 		require.NotEmpty(t, toolResults[0].ClientMetadata)
 
 		var metadata ImageMetadata
-		err = json.Unmarshal([]byte(toolResults[0].ClientMetadata), &metadata)
+		err = jsonv2.Unmarshal([]byte(toolResults[0].ClientMetadata), &metadata)
 		require.NoError(t, err)
 		require.Equal(t, 800, metadata.Width)
 		require.Equal(t, 600, metadata.Height)

internal/fantasy/content.go

@@ -1,10 +1,10 @@
 package fantasy
 
-import "encoding/json"
+// No imports needed — json method signatures are defined inline.
 
 // ProviderOptionsData is an interface for provider-specific options data.
-// All implementations MUST also implement encoding/json.Marshaler and
+// All implementations MUST also implement jsonv2.MarshalerV2 and
-// encoding/json.Unmarshaler interfaces to ensure proper JSON serialization
+// jsonv2.UnmarshalerV2 interfaces to ensure proper JSON serialization
 // with the provider registry system.
 //
 // Recommended implementation pattern using generic helpers:
@@ -20,7 +20,7 @@ import "encoding/json"
 //	func init() {
 //	    fantasy.RegisterProviderType(TypeMyProviderOptions, func(data []byte) (fantasy.ProviderOptionsData, error) {
 //	        var opts MyProviderOptions
-//	        if err := json.Unmarshal(data, &opts); err != nil {
+//	        if err := jsonv2.Unmarshal(data, &opts); err != nil {
 //	            return nil, err
 //	        }
 //	        return &opts, nil
@@ -30,28 +30,27 @@ import "encoding/json"
 //	// Implement ProviderOptionsData interface
 //	func (*MyProviderOptions) Options() {}
 //
-//	// Implement json.Marshaler using the generic helper
+//	// Implement jsonv2.MarshalerTo using the generic helper
-//	func (m MyProviderOptions) MarshalJSON() ([]byte, error) {
+//	func (m MyProviderOptions) MarshalJSONTo(enc *jsontext.Encoder) error {
 //	    type plain MyProviderOptions
-//	    return fantasy.MarshalProviderType(TypeMyProviderOptions, plain(m))
+//	    return fantasy.MarshalProviderTypeTo(enc, TypeMyProviderOptions, plain(m))
 //	}
 //
-//	// Implement json.Unmarshaler using the generic helper
+//	// Implement jsonv2.UnmarshalerFrom using the generic helper
 //	// Note: Receives inner data after type routing by the registry.
-//	func (m *MyProviderOptions) UnmarshalJSON(data []byte) error {
+//	func (m *MyProviderOptions) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 //	    type plain MyProviderOptions
 //	    var p plain
-//	    if err := fantasy.UnmarshalProviderType(data, &p); err != nil {
+//	    if err := fantasy.UnmarshalProviderTypeFrom(dec, &p); err != nil {
 //	        return err
 //	    }
 //	    *m = MyProviderOptions(p)
 //	    return nil
 //	}
 type ProviderOptionsData interface {
-	// Options is a marker method that identifies types implementing this interface.
 	Options()
-	json.Marshaler
+	MarshalJSON() ([]byte, error)
-	json.Unmarshaler
+	UnmarshalJSON([]byte) error
 }
 
 // ProviderMetadata represents additional provider-specific metadata.
@@ -308,7 +307,7 @@ func (t ToolResultOutputContentError) GetType() ToolResultContentType {
 type ToolResultOutputContentMedia struct {
 	Data      string `json:"data"`          // for media type (base64)
 	MediaType string `json:"media_type"`    // for media type
-	Text      string `json:"text,omitempty"` // optional text content accompanying the media
+	Text      string `json:"text,omitzero"` // optional text content accompanying the media
 }
 
 // GetType returns the type of the tool result output content media.
@@ -434,9 +433,9 @@ type ToolCallContent struct {
 	// Additional provider-specific metadata for the tool call.
 	ProviderMetadata ProviderMetadata `json:"provider_metadata"`
 	// Whether this tool call is invalid (failed validation/parsing)
-	Invalid bool `json:"invalid,omitempty"`
+	Invalid bool `json:"invalid,omitzero"`
 	// Error that occurred during validation/parsing (only set if Invalid is true)
-	ValidationError error `json:"validation_error,omitempty"`
+	ValidationError error `json:"validation_error,omitzero"`
 }
 
 // GetType returns the type of the tool call content.

internal/fantasy/content_json.go

@@ -1,38 +1,39 @@
 package fantasy
 
 import (
-	"encoding/json"
 	"errors"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 )
 
 // contentJSON is a helper type for JSON serialization of Content in Response.
 type contentJSON struct {
 	Type string         `json:"type"`
-	Data json.RawMessage `json:"data"`
+	Data jsontext.Value `json:"data"`
 }
 
 // messagePartJSON is a helper type for JSON serialization of MessagePart.
 type messagePartJSON struct {
 	Type string         `json:"type"`
-	Data json.RawMessage `json:"data"`
+	Data jsontext.Value `json:"data"`
 }
 
 // toolResultOutputJSON is a helper type for JSON serialization of ToolResultOutputContent.
 type toolResultOutputJSON struct {
 	Type string         `json:"type"`
-	Data json.RawMessage `json:"data"`
+	Data jsontext.Value `json:"data"`
 }
 
 // toolJSON is a helper type for JSON serialization of Tool.
 type toolJSON struct {
 	Type string         `json:"type"`
-	Data json.RawMessage `json:"data"`
+	Data jsontext.Value `json:"data"`
 }
 
 // MarshalJSON implements json.Marshaler for TextContent.
 func (t TextContent) MarshalJSON() ([]byte, error) {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		Text             string           `json:"text"`
 		ProviderMetadata ProviderMetadata `json:"provider_metadata,omitempty"`
 	}{
@@ -43,25 +44,25 @@ func (t TextContent) MarshalJSON() ([]byte, error) {
 		return nil, err
 	}
 
-	return json.Marshal(contentJSON{
+	return jsonv2.Marshal(contentJSON{
 		Type: string(ContentTypeText),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
 // UnmarshalJSON implements json.Unmarshaler for TextContent.
 func (t *TextContent) UnmarshalJSON(data []byte) error {
 	var cj contentJSON
-	if err := json.Unmarshal(data, &cj); err != nil {
+	if err := jsonv2.Unmarshal(data, &cj); err != nil {
 		return err
 	}
 
 	var aux struct {
 		Text             string                    `json:"text"`
-		ProviderMetadata map[string]json.RawMessage `json:"provider_metadata,omitempty"`
+		ProviderMetadata map[string]jsontext.Value `json:"provider_metadata,omitempty"`
 	}
 
-	if err := json.Unmarshal(cj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal(cj.Data, &aux); err != nil {
 		return err
 	}
 
@@ -80,7 +81,7 @@ func (t *TextContent) UnmarshalJSON(data []byte) error {
 
 // MarshalJSON implements json.Marshaler for ReasoningContent.
 func (r ReasoningContent) MarshalJSON() ([]byte, error) {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		Text             string           `json:"text"`
 		ProviderMetadata ProviderMetadata `json:"provider_metadata,omitempty"`
 	}{
@@ -91,25 +92,25 @@ func (r ReasoningContent) MarshalJSON() ([]byte, error) {
 		return nil, err
 	}
 
-	return json.Marshal(contentJSON{
+	return jsonv2.Marshal(contentJSON{
 		Type: string(ContentTypeReasoning),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
 // UnmarshalJSON implements json.Unmarshaler for ReasoningContent.
 func (r *ReasoningContent) UnmarshalJSON(data []byte) error {
 	var cj contentJSON
-	if err := json.Unmarshal(data, &cj); err != nil {
+	if err := jsonv2.Unmarshal(data, &cj); err != nil {
 		return err
 	}
 
 	var aux struct {
 		Text             string                    `json:"text"`
-		ProviderMetadata map[string]json.RawMessage `json:"provider_metadata,omitempty"`
+		ProviderMetadata map[string]jsontext.Value `json:"provider_metadata,omitempty"`
 	}
 
-	if err := json.Unmarshal(cj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal(cj.Data, &aux); err != nil {
 		return err
 	}
 
@@ -126,41 +127,41 @@ func (r *ReasoningContent) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for FileContent.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for FileContent.
-func (f FileContent) MarshalJSON() ([]byte, error) {
+func (f FileContent) MarshalJSONTo(enc *jsontext.Encoder) error {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		MediaType        string           `json:"media_type"`
 		Data             []byte           `json:"data"`
-		ProviderMetadata ProviderMetadata `json:"provider_metadata,omitempty"`
+		ProviderMetadata ProviderMetadata `json:"provider_metadata,omitzero"`
 	}{
 		MediaType:        f.MediaType,
 		Data:             f.Data,
 		ProviderMetadata: f.ProviderMetadata,
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(contentJSON{
+	return jsonv2.MarshalEncode(enc, contentJSON{
 		Type: string(ContentTypeFile),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
 // UnmarshalJSON implements json.Unmarshaler for FileContent.
 func (f *FileContent) UnmarshalJSON(data []byte) error {
 	var cj contentJSON
-	if err := json.Unmarshal(data, &cj); err != nil {
+	if err := jsonv2.Unmarshal(data, &cj); err != nil {
 		return err
 	}
 
 	var aux struct {
 		MediaType        string                    `json:"media_type"`
 		Data             []byte                    `json:"data"`
-		ProviderMetadata map[string]json.RawMessage `json:"provider_metadata,omitempty"`
+		ProviderMetadata map[string]jsontext.Value `json:"provider_metadata,omitempty"`
 	}
 
-	if err := json.Unmarshal(cj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal(cj.Data, &aux); err != nil {
 		return err
 	}
 
@@ -180,7 +181,7 @@ func (f *FileContent) UnmarshalJSON(data []byte) error {
 
 // MarshalJSON implements json.Marshaler for SourceContent.
 func (s SourceContent) MarshalJSON() ([]byte, error) {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		SourceType       SourceType       `json:"source_type"`
 		ID               string           `json:"id"`
 		URL              string           `json:"url,omitempty"`
@@ -201,16 +202,16 @@ func (s SourceContent) MarshalJSON() ([]byte, error) {
 		return nil, err
 	}
 
-	return json.Marshal(contentJSON{
+	return jsonv2.Marshal(contentJSON{
 		Type: string(ContentTypeSource),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
 // UnmarshalJSON implements json.Unmarshaler for SourceContent.
 func (s *SourceContent) UnmarshalJSON(data []byte) error {
 	var cj contentJSON
-	if err := json.Unmarshal(data, &cj); err != nil {
+	if err := jsonv2.Unmarshal(data, &cj); err != nil {
 		return err
 	}
 
@@ -221,10 +222,10 @@ func (s *SourceContent) UnmarshalJSON(data []byte) error {
 		Title            string                    `json:"title,omitempty"`
 		MediaType        string                    `json:"media_type,omitempty"`
 		Filename         string                    `json:"filename,omitempty"`
-		ProviderMetadata map[string]json.RawMessage `json:"provider_metadata,omitempty"`
+		ProviderMetadata map[string]jsontext.Value `json:"provider_metadata,omitempty"`
 	}
 
-	if err := json.Unmarshal(cj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal(cj.Data, &aux); err != nil {
 		return err
 	}
 
@@ -253,7 +254,7 @@ func (t ToolCallContent) MarshalJSON() ([]byte, error) {
 		msg := t.ValidationError.Error()
 		validationErrMsg = &msg
 	}
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		ToolCallID       string           `json:"tool_call_id"`
 		ToolName         string           `json:"tool_name"`
 		Input            string           `json:"input"`
@@ -274,16 +275,16 @@ func (t ToolCallContent) MarshalJSON() ([]byte, error) {
 		return nil, err
 	}
 
-	return json.Marshal(contentJSON{
+	return jsonv2.Marshal(contentJSON{
 		Type: string(ContentTypeToolCall),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for ToolCallContent.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for ToolCallContent.
-func (t *ToolCallContent) UnmarshalJSON(data []byte) error {
+func (t *ToolCallContent) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var cj contentJSON
-	if err := json.Unmarshal(data, &cj); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &cj); err != nil {
 		return err
 	}
 
@@ -292,12 +293,12 @@ func (t *ToolCallContent) UnmarshalJSON(data []byte) error {
 		ToolName         string                    `json:"tool_name"`
 		Input            string                    `json:"input"`
 		ProviderExecuted bool                      `json:"provider_executed"`
-		ProviderMetadata map[string]json.RawMessage `json:"provider_metadata,omitempty"`
+		ProviderMetadata map[string]jsontext.Value `json:"provider_metadata,omitzero"`
-		Invalid          bool                       `json:"invalid,omitempty"`
+		Invalid          bool                      `json:"invalid,omitzero"`
-		ValidationError  *string                    `json:"validation_error,omitempty"`
+		ValidationError  *string                   `json:"validation_error,omitzero"`
 	}
 
-	if err := json.Unmarshal(cj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal(cj.Data, &aux); err != nil {
 		return err
 	}
 
@@ -321,15 +322,15 @@ func (t *ToolCallContent) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for ToolResultContent.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for ToolResultContent.
-func (t ToolResultContent) MarshalJSON() ([]byte, error) {
+func (t ToolResultContent) MarshalJSONTo(enc *jsontext.Encoder) error {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		ToolCallID       string                  `json:"tool_call_id"`
 		ToolName         string                  `json:"tool_name"`
 		Result           ToolResultOutputContent `json:"result"`
-		ClientMetadata   string                  `json:"client_metadata,omitempty"`
+		ClientMetadata   string                  `json:"client_metadata,omitzero"`
 		ProviderExecuted bool                    `json:"provider_executed"`
-		ProviderMetadata ProviderMetadata        `json:"provider_metadata,omitempty"`
+		ProviderMetadata ProviderMetadata        `json:"provider_metadata,omitzero"`
 	}{
 		ToolCallID:       t.ToolCallID,
 		ToolName:         t.ToolName,
@@ -339,32 +340,32 @@ func (t ToolResultContent) MarshalJSON() ([]byte, error) {
 		ProviderMetadata: t.ProviderMetadata,
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(contentJSON{
+	return jsonv2.MarshalEncode(enc, contentJSON{
 		Type: string(ContentTypeToolResult),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for ToolResultContent.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for ToolResultContent.
-func (t *ToolResultContent) UnmarshalJSON(data []byte) error {
+func (t *ToolResultContent) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var cj contentJSON
-	if err := json.Unmarshal(data, &cj); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &cj); err != nil {
 		return err
 	}
 
 	var aux struct {
 		ToolCallID       string                    `json:"tool_call_id"`
 		ToolName         string                    `json:"tool_name"`
-		Result           json.RawMessage            `json:"result"`
+		Result           jsontext.Value            `json:"result"`
-		ClientMetadata   string                     `json:"client_metadata,omitempty"`
+		ClientMetadata   string                    `json:"client_metadata,omitzero"`
 		ProviderExecuted bool                      `json:"provider_executed"`
-		ProviderMetadata map[string]json.RawMessage `json:"provider_metadata,omitempty"`
+		ProviderMetadata map[string]jsontext.Value `json:"provider_metadata,omitzero"`
 	}
 
-	if err := json.Unmarshal(cj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal(cj.Data, &aux); err != nil {
 		return err
 	}
 
@@ -374,7 +375,7 @@ func (t *ToolResultContent) UnmarshalJSON(data []byte) error {
 	t.ProviderExecuted = aux.ProviderExecuted
 
 	// Unmarshal the Result field
-	result, err := UnmarshalToolResultOutputContent(aux.Result)
+	result, err := UnmarshalToolResultOutputContent([]byte(aux.Result))
 	if err != nil {
 		return fmt.Errorf("failed to unmarshal tool result output: %w", err)
 	}
@@ -391,31 +392,31 @@ func (t *ToolResultContent) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for ToolResultOutputContentText.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for ToolResultOutputContentText.
-func (t ToolResultOutputContentText) MarshalJSON() ([]byte, error) {
+func (t ToolResultOutputContentText) MarshalJSONTo(enc *jsontext.Encoder) error {
 	type alias ToolResultOutputContentText
-	dataBytes, err := json.Marshal(alias(t))
+	dataBytes, err := jsonv2.Marshal(alias(t))
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(toolResultOutputJSON{
+	return jsonv2.MarshalEncode(enc, toolResultOutputJSON{
 		Type: string(ToolResultContentTypeText),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for ToolResultOutputContentText.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for ToolResultOutputContentText.
-func (t *ToolResultOutputContentText) UnmarshalJSON(data []byte) error {
+func (t *ToolResultOutputContentText) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var tr toolResultOutputJSON
-	if err := json.Unmarshal(data, &tr); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &tr); err != nil {
 		return err
 	}
 
 	type alias ToolResultOutputContentText
 	var temp alias
 
-	if err := json.Unmarshal(tr.Data, &temp); err != nil {
+	if err := jsonv2.Unmarshal([]byte(tr.Data), &temp); err != nil {
 		return err
 	}
 
@@ -423,31 +424,31 @@ func (t *ToolResultOutputContentText) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for ToolResultOutputContentError.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for ToolResultOutputContentError.
-func (t ToolResultOutputContentError) MarshalJSON() ([]byte, error) {
+func (t ToolResultOutputContentError) MarshalJSONTo(enc *jsontext.Encoder) error {
 	errMsg := ""
 	if t.Error != nil {
 		errMsg = t.Error.Error()
 	}
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		Error string `json:"error"`
 	}{
 		Error: errMsg,
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(toolResultOutputJSON{
+	return jsonv2.MarshalEncode(enc, toolResultOutputJSON{
 		Type: string(ToolResultContentTypeError),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for ToolResultOutputContentError.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for ToolResultOutputContentError.
-func (t *ToolResultOutputContentError) UnmarshalJSON(data []byte) error {
+func (t *ToolResultOutputContentError) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var tr toolResultOutputJSON
-	if err := json.Unmarshal(data, &tr); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &tr); err != nil {
 		return err
 	}
 
@@ -455,7 +456,7 @@ func (t *ToolResultOutputContentError) UnmarshalJSON(data []byte) error {
 		Error string `json:"error"`
 	}
 
-	if err := json.Unmarshal(tr.Data, &temp); err != nil {
+	if err := jsonv2.Unmarshal([]byte(tr.Data), &temp); err != nil {
 		return err
 	}
 	if temp.Error != "" {
@@ -464,31 +465,31 @@ func (t *ToolResultOutputContentError) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for ToolResultOutputContentMedia.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for ToolResultOutputContentMedia.
-func (t ToolResultOutputContentMedia) MarshalJSON() ([]byte, error) {
+func (t ToolResultOutputContentMedia) MarshalJSONTo(enc *jsontext.Encoder) error {
 	type alias ToolResultOutputContentMedia
-	dataBytes, err := json.Marshal(alias(t))
+	dataBytes, err := jsonv2.Marshal(alias(t))
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(toolResultOutputJSON{
+	return jsonv2.MarshalEncode(enc, toolResultOutputJSON{
 		Type: string(ToolResultContentTypeMedia),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for ToolResultOutputContentMedia.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for ToolResultOutputContentMedia.
-func (t *ToolResultOutputContentMedia) UnmarshalJSON(data []byte) error {
+func (t *ToolResultOutputContentMedia) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var tr toolResultOutputJSON
-	if err := json.Unmarshal(data, &tr); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &tr); err != nil {
 		return err
 	}
 
 	type alias ToolResultOutputContentMedia
 	var temp alias
 
-	if err := json.Unmarshal(tr.Data, &temp); err != nil {
+	if err := jsonv2.Unmarshal([]byte(tr.Data), &temp); err != nil {
 		return err
 	}
 
@@ -496,38 +497,38 @@ func (t *ToolResultOutputContentMedia) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for TextPart.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for TextPart.
-func (t TextPart) MarshalJSON() ([]byte, error) {
+func (t TextPart) MarshalJSONTo(enc *jsontext.Encoder) error {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		Text            string          `json:"text"`
-		ProviderOptions ProviderOptions `json:"provider_options,omitempty"`
+		ProviderOptions ProviderOptions `json:"provider_options,omitzero"`
 	}{
 		Text:            t.Text,
 		ProviderOptions: t.ProviderOptions,
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(messagePartJSON{
+	return jsonv2.MarshalEncode(enc, messagePartJSON{
 		Type: string(ContentTypeText),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for TextPart.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for TextPart.
-func (t *TextPart) UnmarshalJSON(data []byte) error {
+func (t *TextPart) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var mpj messagePartJSON
-	if err := json.Unmarshal(data, &mpj); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &mpj); err != nil {
 		return err
 	}
 
 	var aux struct {
 		Text            string                    `json:"text"`
-		ProviderOptions map[string]json.RawMessage `json:"provider_options,omitempty"`
+		ProviderOptions map[string]jsontext.Value `json:"provider_options,omitzero"`
 	}
 
-	if err := json.Unmarshal(mpj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal([]byte(mpj.Data), &aux); err != nil {
 		return err
 	}
 
@@ -544,38 +545,38 @@ func (t *TextPart) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for ReasoningPart.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for ReasoningPart.
-func (r ReasoningPart) MarshalJSON() ([]byte, error) {
+func (r ReasoningPart) MarshalJSONTo(enc *jsontext.Encoder) error {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		Text            string          `json:"text"`
-		ProviderOptions ProviderOptions `json:"provider_options,omitempty"`
+		ProviderOptions ProviderOptions `json:"provider_options,omitzero"`
 	}{
 		Text:            r.Text,
 		ProviderOptions: r.ProviderOptions,
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(messagePartJSON{
+	return jsonv2.MarshalEncode(enc, messagePartJSON{
 		Type: string(ContentTypeReasoning),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for ReasoningPart.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for ReasoningPart.
-func (r *ReasoningPart) UnmarshalJSON(data []byte) error {
+func (r *ReasoningPart) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var mpj messagePartJSON
-	if err := json.Unmarshal(data, &mpj); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &mpj); err != nil {
 		return err
 	}
 
 	var aux struct {
 		Text            string                    `json:"text"`
-		ProviderOptions map[string]json.RawMessage `json:"provider_options,omitempty"`
+		ProviderOptions map[string]jsontext.Value `json:"provider_options,omitzero"`
 	}
 
-	if err := json.Unmarshal(mpj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal([]byte(mpj.Data), &aux); err != nil {
 		return err
 	}
 
@@ -592,13 +593,13 @@ func (r *ReasoningPart) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for FilePart.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for FilePart.
-func (f FilePart) MarshalJSON() ([]byte, error) {
+func (f FilePart) MarshalJSONTo(enc *jsontext.Encoder) error {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		Filename        string          `json:"filename"`
 		Data            []byte          `json:"data"`
 		MediaType       string          `json:"media_type"`
-		ProviderOptions ProviderOptions `json:"provider_options,omitempty"`
+		ProviderOptions ProviderOptions `json:"provider_options,omitzero"`
 	}{
 		Filename:        f.Filename,
 		Data:            f.Data,
@@ -606,19 +607,19 @@ func (f FilePart) MarshalJSON() ([]byte, error) {
 		ProviderOptions: f.ProviderOptions,
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(messagePartJSON{
+	return jsonv2.MarshalEncode(enc, messagePartJSON{
 		Type: string(ContentTypeFile),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for FilePart.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for FilePart.
-func (f *FilePart) UnmarshalJSON(data []byte) error {
+func (f *FilePart) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var mpj messagePartJSON
-	if err := json.Unmarshal(data, &mpj); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &mpj); err != nil {
 		return err
 	}
 
@@ -626,10 +627,10 @@ func (f *FilePart) UnmarshalJSON(data []byte) error {
 		Filename        string                    `json:"filename"`
 		Data            []byte                    `json:"data"`
 		MediaType       string                    `json:"media_type"`
-		ProviderOptions map[string]json.RawMessage `json:"provider_options,omitempty"`
+		ProviderOptions map[string]jsontext.Value `json:"provider_options,omitzero"`
 	}
 
-	if err := json.Unmarshal(mpj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal([]byte(mpj.Data), &aux); err != nil {
 		return err
 	}
 
@@ -648,14 +649,14 @@ func (f *FilePart) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for ToolCallPart.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for ToolCallPart.
-func (t ToolCallPart) MarshalJSON() ([]byte, error) {
+func (t ToolCallPart) MarshalJSONTo(enc *jsontext.Encoder) error {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		ToolCallID       string          `json:"tool_call_id"`
 		ToolName         string          `json:"tool_name"`
 		Input            string          `json:"input"`
 		ProviderExecuted bool            `json:"provider_executed"`
-		ProviderOptions  ProviderOptions `json:"provider_options,omitempty"`
+		ProviderOptions  ProviderOptions `json:"provider_options,omitzero"`
 	}{
 		ToolCallID:       t.ToolCallID,
 		ToolName:         t.ToolName,
@@ -664,19 +665,19 @@ func (t ToolCallPart) MarshalJSON() ([]byte, error) {
 		ProviderOptions:  t.ProviderOptions,
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(messagePartJSON{
+	return jsonv2.MarshalEncode(enc, messagePartJSON{
 		Type: string(ContentTypeToolCall),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for ToolCallPart.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for ToolCallPart.
-func (t *ToolCallPart) UnmarshalJSON(data []byte) error {
+func (t *ToolCallPart) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var mpj messagePartJSON
-	if err := json.Unmarshal(data, &mpj); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &mpj); err != nil {
 		return err
 	}
 
@@ -685,10 +686,10 @@ func (t *ToolCallPart) UnmarshalJSON(data []byte) error {
 		ToolName         string                    `json:"tool_name"`
 		Input            string                    `json:"input"`
 		ProviderExecuted bool                      `json:"provider_executed"`
-		ProviderOptions  map[string]json.RawMessage `json:"provider_options,omitempty"`
+		ProviderOptions  map[string]jsontext.Value `json:"provider_options,omitzero"`
 	}
 
-	if err := json.Unmarshal(mpj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal([]byte(mpj.Data), &aux); err != nil {
 		return err
 	}
 
@@ -708,48 +709,48 @@ func (t *ToolCallPart) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for ToolResultPart.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for ToolResultPart.
-func (t ToolResultPart) MarshalJSON() ([]byte, error) {
+func (t ToolResultPart) MarshalJSONTo(enc *jsontext.Encoder) error {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		ToolCallID      string                  `json:"tool_call_id"`
 		Output          ToolResultOutputContent `json:"output"`
-		ProviderOptions ProviderOptions         `json:"provider_options,omitempty"`
+		ProviderOptions ProviderOptions         `json:"provider_options,omitzero"`
 	}{
 		ToolCallID:      t.ToolCallID,
 		Output:          t.Output,
 		ProviderOptions: t.ProviderOptions,
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(messagePartJSON{
+	return jsonv2.MarshalEncode(enc, messagePartJSON{
 		Type: string(ContentTypeToolResult),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for ToolResultPart.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for ToolResultPart.
-func (t *ToolResultPart) UnmarshalJSON(data []byte) error {
+func (t *ToolResultPart) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var mpj messagePartJSON
-	if err := json.Unmarshal(data, &mpj); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &mpj); err != nil {
 		return err
 	}
 
 	var aux struct {
 		ToolCallID      string                    `json:"tool_call_id"`
-		Output          json.RawMessage            `json:"output"`
+		Output          jsontext.Value            `json:"output"`
-		ProviderOptions map[string]json.RawMessage `json:"provider_options,omitempty"`
+		ProviderOptions map[string]jsontext.Value `json:"provider_options,omitzero"`
 	}
 
-	if err := json.Unmarshal(mpj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal([]byte(mpj.Data), &aux); err != nil {
 		return err
 	}
 
 	t.ToolCallID = aux.ToolCallID
 
 	// Unmarshal the Output field
-	output, err := UnmarshalToolResultOutputContent(aux.Output)
+	output, err := UnmarshalToolResultOutputContent([]byte(aux.Output))
 	if err != nil {
 		return fmt.Errorf("failed to unmarshal tool result output: %w", err)
 	}
@@ -766,15 +767,15 @@ func (t *ToolResultPart) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// UnmarshalJSON implements json.Unmarshaler for Message.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for Message.
-func (m *Message) UnmarshalJSON(data []byte) error {
+func (m *Message) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var aux struct {
 		Role            MessageRole               `json:"role"`
-		Content         []json.RawMessage          `json:"content"`
+		Content         []jsontext.Value          `json:"content"`
-		ProviderOptions map[string]json.RawMessage `json:"provider_options"`
+		ProviderOptions map[string]jsontext.Value `json:"provider_options"`
 	}
 
-	if err := json.Unmarshal(data, &aux); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &aux); err != nil {
 		return err
 	}
 
@@ -782,7 +783,7 @@ func (m *Message) UnmarshalJSON(data []byte) error {
 
 	m.Content = make([]MessagePart, len(aux.Content))
 	for i, rawPart := range aux.Content {
-		part, err := UnmarshalMessagePart(rawPart)
+		part, err := UnmarshalMessagePart([]byte(rawPart))
 		if err != nil {
 			return fmt.Errorf("failed to unmarshal message part at index %d: %w", i, err)
 		}
@@ -800,13 +801,13 @@ func (m *Message) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for FunctionTool.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for FunctionTool.
-func (f FunctionTool) MarshalJSON() ([]byte, error) {
+func (f FunctionTool) MarshalJSONTo(enc *jsontext.Encoder) error {
-	dataBytes, err := json.Marshal(struct {
+	dataBytes, err := jsonv2.Marshal(struct {
 		Name            string          `json:"name"`
 		Description     string          `json:"description"`
 		InputSchema     map[string]any  `json:"input_schema"`
-		ProviderOptions ProviderOptions `json:"provider_options,omitempty"`
+		ProviderOptions ProviderOptions `json:"provider_options,omitzero"`
 	}{
 		Name:            f.Name,
 		Description:     f.Description,
@@ -814,19 +815,19 @@ func (f FunctionTool) MarshalJSON() ([]byte, error) {
 		ProviderOptions: f.ProviderOptions,
 	})
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(toolJSON{
+	return jsonv2.MarshalEncode(enc, toolJSON{
 		Type: string(ToolTypeFunction),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for FunctionTool.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for FunctionTool.
-func (f *FunctionTool) UnmarshalJSON(data []byte) error {
+func (f *FunctionTool) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var tj toolJSON
-	if err := json.Unmarshal(data, &tj); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &tj); err != nil {
 		return err
 	}
 
@@ -834,10 +835,10 @@ func (f *FunctionTool) UnmarshalJSON(data []byte) error {
 		Name            string                    `json:"name"`
 		Description     string                    `json:"description"`
 		InputSchema     map[string]any            `json:"input_schema"`
-		ProviderOptions map[string]json.RawMessage `json:"provider_options,omitempty"`
+		ProviderOptions map[string]jsontext.Value `json:"provider_options,omitzero"`
 	}
 
-	if err := json.Unmarshal(tj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal([]byte(tj.Data), &aux); err != nil {
 		return err
 	}
 
@@ -856,31 +857,31 @@ func (f *FunctionTool) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for ProviderDefinedTool.
+// MarshalJSONV2 implements jsonv2.MarshalerTo for ProviderDefinedTool.
-func (p ProviderDefinedTool) MarshalJSON() ([]byte, error) {
+func (p ProviderDefinedTool) MarshalJSONTo(enc *jsontext.Encoder) error {
 	type alias ProviderDefinedTool
-	dataBytes, err := json.Marshal(alias(p))
+	dataBytes, err := jsonv2.Marshal(alias(p))
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return json.Marshal(toolJSON{
+	return jsonv2.MarshalEncode(enc, toolJSON{
 		Type: string(ToolTypeProviderDefined),
-		Data: json.RawMessage(dataBytes),
+		Data: jsontext.Value(dataBytes),
 	})
 }
 
-// UnmarshalJSON implements json.Unmarshaler for ProviderDefinedTool.
+// UnmarshalJSONV2 implements jsonv2.UnmarshalerFrom for ProviderDefinedTool.
-func (p *ProviderDefinedTool) UnmarshalJSON(data []byte) error {
+func (p *ProviderDefinedTool) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var tj toolJSON
-	if err := json.Unmarshal(data, &tj); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &tj); err != nil {
 		return err
 	}
 
 	type alias ProviderDefinedTool
 	var aux alias
 
-	if err := json.Unmarshal(tj.Data, &aux); err != nil {
+	if err := jsonv2.Unmarshal([]byte(tj.Data), &aux); err != nil {
 		return err
 	}
 
@@ -892,20 +893,20 @@ func (p *ProviderDefinedTool) UnmarshalJSON(data []byte) error {
 // UnmarshalTool unmarshals JSON into the appropriate Tool type.
 func UnmarshalTool(data []byte) (Tool, error) {
 	var tj toolJSON
-	if err := json.Unmarshal(data, &tj); err != nil {
+	if err := jsonv2.Unmarshal(data, &tj); err != nil {
 		return nil, err
 	}
 
 	switch ToolType(tj.Type) {
 	case ToolTypeFunction:
 		var tool FunctionTool
-		if err := tool.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &tool); err != nil {
 			return nil, err
 		}
 		return tool, nil
 	case ToolTypeProviderDefined:
 		var tool ProviderDefinedTool
-		if err := tool.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &tool); err != nil {
 			return nil, err
 		}
 		return tool, nil
@@ -917,44 +918,44 @@ func UnmarshalTool(data []byte) (Tool, error) {
 // UnmarshalContent unmarshals JSON into the appropriate Content type.
 func UnmarshalContent(data []byte) (Content, error) {
 	var cj contentJSON
-	if err := json.Unmarshal(data, &cj); err != nil {
+	if err := jsonv2.Unmarshal(data, &cj); err != nil {
 		return nil, err
 	}
 
 	switch ContentType(cj.Type) {
 	case ContentTypeText:
 		var content TextContent
-		if err := content.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &content); err != nil {
 			return nil, err
 		}
 		return content, nil
 	case ContentTypeReasoning:
 		var content ReasoningContent
-		if err := content.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &content); err != nil {
 			return nil, err
 		}
 		return content, nil
 	case ContentTypeFile:
 		var content FileContent
-		if err := content.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &content); err != nil {
 			return nil, err
 		}
 		return content, nil
 	case ContentTypeSource:
 		var content SourceContent
-		if err := content.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &content); err != nil {
 			return nil, err
 		}
 		return content, nil
 	case ContentTypeToolCall:
 		var content ToolCallContent
-		if err := content.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &content); err != nil {
 			return nil, err
 		}
 		return content, nil
 	case ContentTypeToolResult:
 		var content ToolResultContent
-		if err := content.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &content); err != nil {
 			return nil, err
 		}
 		return content, nil
@@ -966,38 +967,38 @@ func UnmarshalContent(data []byte) (Content, error) {
 // UnmarshalMessagePart unmarshals JSON into the appropriate MessagePart type.
 func UnmarshalMessagePart(data []byte) (MessagePart, error) {
 	var mpj messagePartJSON
-	if err := json.Unmarshal(data, &mpj); err != nil {
+	if err := jsonv2.Unmarshal(data, &mpj); err != nil {
 		return nil, err
 	}
 
 	switch ContentType(mpj.Type) {
 	case ContentTypeText:
 		var part TextPart
-		if err := part.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &part); err != nil {
 			return nil, err
 		}
 		return part, nil
 	case ContentTypeReasoning:
 		var part ReasoningPart
-		if err := part.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &part); err != nil {
 			return nil, err
 		}
 		return part, nil
 	case ContentTypeFile:
 		var part FilePart
-		if err := part.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &part); err != nil {
 			return nil, err
 		}
 		return part, nil
 	case ContentTypeToolCall:
 		var part ToolCallPart
-		if err := part.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &part); err != nil {
 			return nil, err
 		}
 		return part, nil
 	case ContentTypeToolResult:
 		var part ToolResultPart
-		if err := part.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &part); err != nil {
 			return nil, err
 		}
 		return part, nil
@@ -1009,26 +1010,26 @@ func UnmarshalMessagePart(data []byte) (MessagePart, error) {
 // UnmarshalToolResultOutputContent unmarshals JSON into the appropriate ToolResultOutputContent type.
 func UnmarshalToolResultOutputContent(data []byte) (ToolResultOutputContent, error) {
 	var troj toolResultOutputJSON
-	if err := json.Unmarshal(data, &troj); err != nil {
+	if err := jsonv2.Unmarshal(data, &troj); err != nil {
 		return nil, err
 	}
 
 	switch ToolResultContentType(troj.Type) {
 	case ToolResultContentTypeText:
 		var content ToolResultOutputContentText
-		if err := content.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &content); err != nil {
 			return nil, err
 		}
 		return content, nil
 	case ToolResultContentTypeError:
 		var content ToolResultOutputContentError
-		if err := content.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &content); err != nil {
 			return nil, err
 		}
 		return content, nil
 	case ToolResultContentTypeMedia:
 		var content ToolResultOutputContentMedia
-		if err := content.UnmarshalJSON(data); err != nil {
+		if err := jsonv2.Unmarshal(data, &content); err != nil {
 			return nil, err
 		}
 		return content, nil

internal/fantasy/json_test.go

@@ -1,8 +1,8 @@
 package fantasy
 
 import (
-	"encoding/json"
 	"errors"
+	jsonv2 "github.com/go-json-experiment/json"
 	"reflect"
 	"testing"
 )
@@ -156,14 +156,14 @@ func TestMessageJSONSerialization(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			// Marshal the message
-			data, err := json.Marshal(tt.message)
+			data, err := jsonv2.Marshal(tt.message)
 			if err != nil {
 				t.Fatalf("failed to marshal message: %v", err)
 			}
 
 			// Unmarshal back
 			var decoded Message
-			err = json.Unmarshal(data, &decoded)
+			err = jsonv2.Unmarshal(data, &decoded)
 			if err != nil {
 				t.Fatalf("failed to unmarshal message: %v", err)
 			}
@@ -286,13 +286,13 @@ func TestHelperFunctions(t *testing.T) {
 	t.Run("NewUserMessage - text only", func(t *testing.T) {
 		msg := NewUserMessage("Hello")
 
-		data, err := json.Marshal(msg)
+		data, err := jsonv2.Marshal(msg)
 		if err != nil {
 			t.Fatalf("failed to marshal: %v", err)
 		}
 
 		var decoded Message
-		if err := json.Unmarshal(data, &decoded); err != nil {
+		if err := jsonv2.Unmarshal(data, &decoded); err != nil {
 			t.Fatalf("failed to unmarshal: %v", err)
 		}
 
@@ -324,13 +324,13 @@ func TestHelperFunctions(t *testing.T) {
 			},
 		)
 
-		data, err := json.Marshal(msg)
+		data, err := jsonv2.Marshal(msg)
 		if err != nil {
 			t.Fatalf("failed to marshal: %v", err)
 		}
 
 		var decoded Message
-		if err := json.Unmarshal(data, &decoded); err != nil {
+		if err := jsonv2.Unmarshal(data, &decoded); err != nil {
 			t.Fatalf("failed to unmarshal: %v", err)
 		}
 
@@ -360,13 +360,13 @@ func TestHelperFunctions(t *testing.T) {
 	t.Run("NewSystemMessage - single prompt", func(t *testing.T) {
 		msg := NewSystemMessage("You are a helpful assistant.")
 
-		data, err := json.Marshal(msg)
+		data, err := jsonv2.Marshal(msg)
 		if err != nil {
 			t.Fatalf("failed to marshal: %v", err)
 		}
 
 		var decoded Message
-		if err := json.Unmarshal(data, &decoded); err != nil {
+		if err := jsonv2.Unmarshal(data, &decoded); err != nil {
 			t.Fatalf("failed to unmarshal: %v", err)
 		}
 
@@ -387,13 +387,13 @@ func TestHelperFunctions(t *testing.T) {
 	t.Run("NewSystemMessage - multiple prompts", func(t *testing.T) {
 		msg := NewSystemMessage("First instruction", "Second instruction", "Third instruction")
 
-		data, err := json.Marshal(msg)
+		data, err := jsonv2.Marshal(msg)
 		if err != nil {
 			t.Fatalf("failed to marshal: %v", err)
 		}
 
 		var decoded Message
-		if err := json.Unmarshal(data, &decoded); err != nil {
+		if err := jsonv2.Unmarshal(data, &decoded); err != nil {
 			t.Fatalf("failed to unmarshal: %v", err)
 		}
 
@@ -420,13 +420,13 @@ func TestEdgeCases(t *testing.T) {
 			},
 		}
 
-		data, err := json.Marshal(msg)
+		data, err := jsonv2.Marshal(msg)
 		if err != nil {
 			t.Fatalf("failed to marshal: %v", err)
 		}
 
 		var decoded Message
-		if err := json.Unmarshal(data, &decoded); err != nil {
+		if err := jsonv2.Unmarshal(data, &decoded); err != nil {
 			t.Fatalf("failed to unmarshal: %v", err)
 		}
 
@@ -449,13 +449,13 @@ func TestEdgeCases(t *testing.T) {
 			},
 		}
 
-		data, err := json.Marshal(msg)
+		data, err := jsonv2.Marshal(msg)
 		if err != nil {
 			t.Fatalf("failed to marshal: %v", err)
 		}
 
 		var decoded Message
-		if err := json.Unmarshal(data, &decoded); err != nil {
+		if err := jsonv2.Unmarshal(data, &decoded); err != nil {
 			t.Fatalf("failed to unmarshal: %v", err)
 		}
 
@@ -478,13 +478,13 @@ func TestEdgeCases(t *testing.T) {
 			},
 		}
 
-		data, err := json.Marshal(msg)
+		data, err := jsonv2.Marshal(msg)
 		if err != nil {
 			t.Fatalf("failed to marshal: %v", err)
 		}
 
 		var decoded Message
-		if err := json.Unmarshal(data, &decoded); err != nil {
+		if err := jsonv2.Unmarshal(data, &decoded); err != nil {
 			t.Fatalf("failed to unmarshal: %v", err)
 		}
 
@@ -502,13 +502,13 @@ func TestEdgeCases(t *testing.T) {
 			},
 		}
 
-		data, err := json.Marshal(msg)
+		data, err := jsonv2.Marshal(msg)
 		if err != nil {
 			t.Fatalf("failed to marshal: %v", err)
 		}
 
 		var decoded Message
-		if err := json.Unmarshal(data, &decoded); err != nil {
+		if err := jsonv2.Unmarshal(data, &decoded); err != nil {
 			t.Fatalf("failed to unmarshal: %v", err)
 		}
 
@@ -533,7 +533,7 @@ func TestInvalidJSONHandling(t *testing.T) {
 		}`
 
 		var msg Message
-		err := json.Unmarshal([]byte(invalidJSON), &msg)
+		err := jsonv2.Unmarshal([]byte(invalidJSON), &msg)
 		if err == nil {
 			t.Error("expected error for unknown message part type, got nil")
 		}
@@ -559,7 +559,7 @@ func TestInvalidJSONHandling(t *testing.T) {
 		}`
 
 		var msg Message
-		err := json.Unmarshal([]byte(invalidJSON), &msg)
+		err := jsonv2.Unmarshal([]byte(invalidJSON), &msg)
 		if err == nil {
 			t.Error("expected error for unknown tool result output type, got nil")
 		}
@@ -569,7 +569,7 @@ func TestInvalidJSONHandling(t *testing.T) {
 		invalidJSON := `{"role": "user", "content": [`
 
 		var msg Message
-		err := json.Unmarshal([]byte(invalidJSON), &msg)
+		err := jsonv2.Unmarshal([]byte(invalidJSON), &msg)
 		if err == nil {
 			t.Error("expected error for malformed JSON, got nil")
 		}
@@ -584,7 +584,7 @@ type mockProviderData struct {
 func (m mockProviderData) Options()     {}
 func (m mockProviderData) Type() string { return "mock" }
 func (m mockProviderData) MarshalJSON() ([]byte, error) {
-	return json.Marshal(struct {
+	return jsonv2.Marshal(struct {
 		Type string `json:"type"`
 		mockProviderData
 	}{
@@ -598,7 +598,7 @@ func (m *mockProviderData) UnmarshalJSON(data []byte) error {
 		Type string `json:"type"`
 		mockProviderData
 	}
-	if err := json.Unmarshal(data, &aux); err != nil {
+	if err := jsonv2.Unmarshal(data, &aux); err != nil {
 		return err
 	}
 	*m = aux.mockProviderData
@@ -618,13 +618,13 @@ func TestPromptSerialization(t *testing.T) {
 			},
 		}
 
-		data, err := json.Marshal(prompt)
+		data, err := jsonv2.Marshal(prompt)
 		if err != nil {
 			t.Fatalf("failed to marshal prompt: %v", err)
 		}
 
 		var decoded Prompt
-		if err := json.Unmarshal(data, &decoded); err != nil {
+		if err := jsonv2.Unmarshal(data, &decoded); err != nil {
 			t.Fatalf("failed to unmarshal prompt: %v", err)
 		}
 
@@ -672,14 +672,14 @@ func TestStreamPartErrorSerialization(t *testing.T) {
 		}
 
 		// Marshal the stream part
-		data, err := json.Marshal(streamPart)
+		data, err := jsonv2.Marshal(streamPart)
 		if err != nil {
 			t.Fatalf("failed to marshal stream part: %v", err)
 		}
 
 		// Unmarshal back
 		var decoded StreamPart
-		err = json.Unmarshal(data, &decoded)
+		err = jsonv2.Unmarshal(data, &decoded)
 		if err != nil {
 			t.Fatalf("failed to unmarshal stream part: %v", err)
 		}
@@ -728,7 +728,7 @@ func TestStreamPartErrorSerialization(t *testing.T) {
 		}`
 
 		var streamPart StreamPart
-		err := json.Unmarshal([]byte(jsonData), &streamPart)
+		err := jsonv2.Unmarshal([]byte(jsonData), &streamPart)
 		if err != nil {
 			t.Fatalf("failed to unmarshal stream part: %v", err)
 		}

internal/fantasy/jsonrepair/jsonrepair.go

@@ -3,7 +3,6 @@ package jsonrepair
 
 import (
 	"bytes"
-	"encoding/json"
 	"errors"
 	"reflect"
 	"slices"
@@ -1521,7 +1520,7 @@ func normalizeValue(value any) any {
 		}
 		return items
 	case numberValue:
-		return json.Number(v.raw)
+		return v
 	default:
 		return v
 	}
@@ -1541,8 +1540,6 @@ func writeValue(buf *bytes.Buffer, value any, ensureASCII bool) {
 		buf.WriteByte('"')
 	case numberValue:
 		buf.WriteString(v.raw)
-	case json.Number:
-		buf.WriteString(v.String())
 	case bool:
 		if v {
 			buf.WriteString("true")

internal/fantasy/jsonrepair/jsonrepair_test.go

@@ -1,7 +1,6 @@
 package jsonrepair
 
 import (
-	"encoding/json"
 	"reflect"
 	"strings"
 	"testing"
@@ -227,7 +226,7 @@ func TestLoads(t *testing.T) {
 			input: "{\"name\": \"John\", \"age\": 30, \"city\": \"New York\"}",
 			want: map[string]any{
 				"name": "John",
-				"age":  json.Number("30"),
+				"age":  numberValue{raw: "30"},
 				"city": "New York",
 			},
 		},
@@ -235,10 +234,10 @@ func TestLoads(t *testing.T) {
 			name:  "array_numbers",
 			input: "[1, 2, 3, 4]",
 			want: []any{
-				json.Number("1"),
+				numberValue{raw: "1"},
-				json.Number("2"),
+				numberValue{raw: "2"},
-				json.Number("3"),
+				numberValue{raw: "3"},
-				json.Number("4"),
+				numberValue{raw: "4"},
 			},
 		},
 		{
@@ -453,10 +452,10 @@ func TestParseArrayObjects(t *testing.T) {
 			name:  "numbers_array",
 			input: "[1, 2, 3, 4]",
 			want: []any{
-				json.Number("1"),
+				numberValue{raw: "1"},
-				json.Number("2"),
+				numberValue{raw: "2"},
-				json.Number("3"),
+				numberValue{raw: "3"},
-				json.Number("4"),
+				numberValue{raw: "4"},
 			},
 		},
 		{
@@ -721,25 +720,25 @@ func TestParseNumber(t *testing.T) {
 		{
 			name:  "integer",
 			input: "1",
-			want:  json.Number("1"),
+			want:  numberValue{raw: "1"},
 		},
 		{
 			name:  "float",
 			input: "1.2",
-			want:  json.Number("1.2"),
+			want:  numberValue{raw: "1.2"},
 		},
 		{
 			name:  "underscored_integer",
 			input: "{\"value\": 82_461_110}",
 			want: map[string]any{
-				"value": json.Number("82461110"),
+				"value": numberValue{raw: "82461110"},
 			},
 		},
 		{
 			name:  "underscored_float",
 			input: "{\"value\": 1_234.5_6}",
 			want: map[string]any{
-				"value": json.Number("1234.56"),
+				"value": numberValue{raw: "1234.56"},
 			},
 		},
 	}
@@ -879,7 +878,7 @@ func TestParseObjectObjects(t *testing.T) {
 			input: "{ \"key\": \"value\", \"key2\": 1, \"key3\": True }",
 			want: map[string]any{
 				"key":  "value",
-				"key2": json.Number("1"),
+				"key2": numberValue{raw: "1"},
 				"key3": true,
 			},
 		},
@@ -893,7 +892,7 @@ func TestParseObjectObjects(t *testing.T) {
 			input: "{ \"key\": value, \"key2\": 1 \"key3\": null }",
 			want: map[string]any{
 				"key":  "value",
-				"key2": json.Number("1"),
+				"key2": numberValue{raw: "1"},
 				"key3": nil,
 			},
 		},

internal/fantasy/model_json.go

@@ -1,12 +1,13 @@
 package fantasy
 
 import (
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 )
 
-// UnmarshalJSON implements json.Unmarshaler for Call.
+// UnmarshalJSONFrom implements jsonv2.UnmarshalerFrom for Call.
-func (c *Call) UnmarshalJSON(data []byte) error {
+func (c *Call) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var aux struct {
 		Prompt           Prompt                    `json:"prompt"`
 		MaxOutputTokens  *int64                    `json:"max_output_tokens"`
@@ -15,12 +16,12 @@ func (c *Call) UnmarshalJSON(data []byte) error {
 		TopK             *int64                    `json:"top_k"`
 		PresencePenalty  *float64                  `json:"presence_penalty"`
 		FrequencyPenalty *float64                  `json:"frequency_penalty"`
-		Tools            []json.RawMessage          `json:"tools"`
+		Tools            []jsontext.Value          `json:"tools"`
 		ToolChoice       *ToolChoice               `json:"tool_choice"`
-		ProviderOptions  map[string]json.RawMessage `json:"provider_options"`
+		ProviderOptions  map[string]jsontext.Value `json:"provider_options"`
 	}
 
-	if err := json.Unmarshal(data, &aux); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &aux); err != nil {
 		return err
 	}
 
@@ -36,7 +37,7 @@ func (c *Call) UnmarshalJSON(data []byte) error {
 	// Unmarshal Tools slice
 	c.Tools = make([]Tool, len(aux.Tools))
 	for i, rawTool := range aux.Tools {
-		tool, err := UnmarshalTool(rawTool)
+		tool, err := UnmarshalTool([]byte(rawTool))
 		if err != nil {
 			return fmt.Errorf("failed to unmarshal tool at index %d: %w", i, err)
 		}
@@ -55,17 +56,17 @@ func (c *Call) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// UnmarshalJSON implements json.Unmarshaler for Response.
+// UnmarshalJSONFrom implements jsonv2.UnmarshalerFrom for Response.
-func (r *Response) UnmarshalJSON(data []byte) error {
+func (r *Response) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	var aux struct {
-		Content          json.RawMessage            `json:"content"`
+		Content          jsontext.Value            `json:"content"`
 		FinishReason     FinishReason              `json:"finish_reason"`
 		Usage            Usage                     `json:"usage"`
 		Warnings         []CallWarning             `json:"warnings"`
-		ProviderMetadata map[string]json.RawMessage `json:"provider_metadata"`
+		ProviderMetadata map[string]jsontext.Value `json:"provider_metadata"`
 	}
 
-	if err := json.Unmarshal(data, &aux); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &aux); err != nil {
 		return err
 	}
 
@@ -73,16 +74,14 @@ func (r *Response) UnmarshalJSON(data []byte) error {
 	r.Usage = aux.Usage
 	r.Warnings = aux.Warnings
 
-	// Unmarshal ResponseContent (need to know the type definition)
+	var rawContent []jsontext.Value
-	// If ResponseContent is []Content:
+	if err := jsonv2.Unmarshal([]byte(aux.Content), &rawContent); err != nil {
-	var rawContent []json.RawMessage
-	if err := json.Unmarshal(aux.Content, &rawContent); err != nil {
 		return err
 	}
 
 	content := make([]Content, len(rawContent))
 	for i, rawItem := range rawContent {
-		item, err := UnmarshalContent(rawItem)
+		item, err := UnmarshalContent([]byte(rawItem))
 		if err != nil {
 			return fmt.Errorf("failed to unmarshal content at index %d: %w", i, err)
 		}
@@ -102,48 +101,44 @@ func (r *Response) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// MarshalJSON implements json.Marshaler for StreamPart.
+// MarshalJSONTo implements jsonv2.MarshalerTo for StreamPart.
-func (s StreamPart) MarshalJSON() ([]byte, error) {
+func (s StreamPart) MarshalJSONTo(enc *jsontext.Encoder) error {
 	type alias StreamPart
 	aux := struct {
 		alias
-		Error string `json:"error,omitempty"`
+		Error string `json:"error,omitzero"`
 	}{
 		alias: (alias)(s),
 	}
 
-	// Marshal error to string
 	if s.Error != nil {
 		aux.Error = s.Error.Error()
 	}
 
-	// Clear the original Error field to avoid duplicate marshaling
 	aux.alias.Error = nil
 
-	return json.Marshal(aux)
+	return jsonv2.MarshalEncode(enc, aux)
 }
 
-// UnmarshalJSON implements json.Unmarshaler for StreamPart.
+// UnmarshalJSONFrom implements jsonv2.UnmarshalerFrom for StreamPart.
-func (s *StreamPart) UnmarshalJSON(data []byte) error {
+func (s *StreamPart) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
 	type alias StreamPart
 	aux := struct {
 		*alias
 		Error            string                    `json:"error"`
-		ProviderMetadata map[string]json.RawMessage `json:"provider_metadata"`
+		ProviderMetadata map[string]jsontext.Value `json:"provider_metadata"`
 	}{
 		alias: (*alias)(s),
 	}
 
-	if err := json.Unmarshal(data, &aux); err != nil {
+	if err := jsonv2.UnmarshalDecode(dec, &aux); err != nil {
 		return err
 	}
 
-	// Unmarshal error string back to error type
 	if aux.Error != "" {
 		s.Error = fmt.Errorf("%s", aux.Error)
 	}
 
-	// Unmarshal ProviderMetadata
 	if len(aux.ProviderMetadata) > 0 {
 		metadata, err := UnmarshalProviderMetadata(aux.ProviderMetadata)
 		if err != nil {

internal/fantasy/object.go

@@ -2,8 +2,8 @@ package fantasy
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"iter"
 	"reflect"
 
@@ -175,7 +175,7 @@ func (s *StreamObjectResult[T]) Object() (*ObjectResult[T], error) {
 			if part.Object != nil {
 				if err := unmarshalObject(part.Object, &finalObject); err == nil {
 					hasObject = true
-					if jsonBytes, err := json.Marshal(part.Object); err == nil {
+					if jsonBytes, err := jsonv2.Marshal(part.Object); err == nil {
 						rawText = string(jsonBytes)
 					}
 				}
@@ -220,12 +220,12 @@ func (s *StreamObjectResult[T]) Object() (*ObjectResult[T], error) {
 }
 
 func unmarshalObject(obj any, target any) error {
-	jsonBytes, err := json.Marshal(obj)
+	jsonBytes, err := jsonv2.Marshal(obj)
 	if err != nil {
 		return fmt.Errorf("failed to marshal object: %w", err)
 	}
 
-	if err := json.Unmarshal(jsonBytes, target); err != nil {
+	if err := jsonv2.Unmarshal(jsonBytes, target); err != nil {
 		return fmt.Errorf("failed to unmarshal into target type: %w", err)
 	}
 

internal/fantasy/object/object.go

@@ -4,8 +4,8 @@ package object
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"reflect"
 
 	"charm.land/fantasy"
@@ -171,7 +171,7 @@ func GenerateWithText(
 	model fantasy.LanguageModel,
 	call fantasy.ObjectCall,
 ) (*fantasy.ObjectResponse, error) {
-	jsonSchemaBytes, err := json.Marshal(call.Schema)
+	jsonSchemaBytes, err := jsonv2.Marshal(call.Schema)
 	if err != nil {
 		return nil, fmt.Errorf("failed to marshal schema: %w", err)
 	}
@@ -462,7 +462,7 @@ func StreamWithText(
 	call fantasy.ObjectCall,
 ) (fantasy.ObjectStreamResponse, error) {
 	jsonSchemaMap := schema.ToMap(call.Schema)
-	jsonSchemaBytes, err := json.Marshal(jsonSchemaMap)
+	jsonSchemaBytes, err := jsonv2.Marshal(jsonSchemaMap)
 	if err != nil {
 		return nil, fmt.Errorf("failed to marshal schema: %w", err)
 	}
@@ -603,12 +603,12 @@ func StreamWithText(
 }
 
 func unmarshal(obj any, target any) error {
-	jsonBytes, err := json.Marshal(obj)
+	jsonBytes, err := jsonv2.Marshal(obj)
 	if err != nil {
 		return fmt.Errorf("failed to marshal object: %w", err)
 	}
 
-	if err := json.Unmarshal(jsonBytes, target); err != nil {
+	if err := jsonv2.Unmarshal(jsonBytes, target); err != nil {
 		return fmt.Errorf("failed to unmarshal into target type: %w", err)
 	}
 

internal/fantasy/provider_registry.go

@@ -1,15 +1,16 @@
 package fantasy
 
 import (
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 	"sync"
 )
 
 // providerDataJSON is the serialized wrapper used by the registry.
 type providerDataJSON struct {
 	Type string         `json:"type"`
-	Data json.RawMessage `json:"data"`
+	Data jsontext.Value `json:"data"`
 }
 
 // UnmarshalFunc converts raw JSON into a ProviderOptionsData implementation.
@@ -29,7 +30,7 @@ func RegisterProviderType(typeID string, unmarshalFn UnmarshalFunc) {
 // unmarshalProviderData routes a typed payload to the correct constructor.
 func unmarshalProviderData(data []byte) (ProviderOptionsData, error) {
 	var pj providerDataJSON
-	if err := json.Unmarshal(data, &pj); err != nil {
+	if err := jsonv2.Unmarshal(data, &pj); err != nil {
 		return nil, err
 	}
 
@@ -43,7 +44,7 @@ func unmarshalProviderData(data []byte) (ProviderOptionsData, error) {
 }
 
 // unmarshalProviderDataMap is a helper for unmarshaling maps of provider data.
-func unmarshalProviderDataMap(data map[string]json.RawMessage) (map[string]ProviderOptionsData, error) {
+func unmarshalProviderDataMap(data map[string]jsontext.Value) (map[string]ProviderOptionsData, error) {
 	result := make(map[string]ProviderOptionsData)
 	for provider, rawData := range data {
 		providerData, err := unmarshalProviderData(rawData)
@@ -56,12 +57,12 @@ func unmarshalProviderDataMap(data map[string]json.RawMessage) (map[string]Provi
 }
 
 // UnmarshalProviderOptions unmarshals a map of provider options by type.
-func UnmarshalProviderOptions(data map[string]json.RawMessage) (ProviderOptions, error) {
+func UnmarshalProviderOptions(data map[string]jsontext.Value) (ProviderOptions, error) {
 	return unmarshalProviderDataMap(data)
 }
 
 // UnmarshalProviderMetadata unmarshals a map of provider metadata by type.
-func UnmarshalProviderMetadata(data map[string]json.RawMessage) (ProviderMetadata, error) {
+func UnmarshalProviderMetadata(data map[string]jsontext.Value) (ProviderMetadata, error) {
 	return unmarshalProviderDataMap(data)
 }
 
@@ -75,14 +76,14 @@ func UnmarshalProviderMetadata(data map[string]json.RawMessage) (ProviderMetadat
 //	    return fantasy.MarshalProviderType(TypeProviderOptions, plain(o))
 //	}
 func MarshalProviderType[T any](typeID string, data T) ([]byte, error) {
-	rawData, err := json.Marshal(data)
+	rawData, err := jsonv2.Marshal(data)
 	if err != nil {
 		return nil, err
 	}
 
-	return json.Marshal(providerDataJSON{
+	return jsonv2.Marshal(providerDataJSON{
 		Type: typeID,
-		Data: json.RawMessage(rawData),
+		Data: jsontext.Value(rawData),
 	})
 }
 
@@ -102,5 +103,5 @@ func MarshalProviderType[T any](typeID string, data T) ([]byte, error) {
 //	    return nil
 //	}
 func UnmarshalProviderType[T any](data []byte, target *T) error {
-	return json.Unmarshal(data, target)
+	return jsonv2.Unmarshal(data, target)
 }

internal/fantasy/providers/anthropic/anthropic.go

@@ -5,9 +5,9 @@ import (
 	"cmp"
 	"context"
 	"encoding/base64"
-	"encoding/json"
 	"errors"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"io"
 	"maps"
 	"strings"
@@ -777,7 +777,7 @@ func toPrompt(prompt fantasy.Prompt, sendReasoningData bool) ([]anthropic.TextBl
 						// in the Anthropic assistant message; the ProviderExecuted flag
 						// is only informational metadata about who ran the tool.
 						var inputMap map[string]any
-						if err := json.Unmarshal([]byte(toolCall.Input), &inputMap); err != nil {
+						if err := jsonv2.Unmarshal([]byte(toolCall.Input), &inputMap); err != nil {
 							continue
 						}
 						toolUseBlock := anthropic.NewToolUseBlock(toolCall.ToolCallID, inputMap, toolCall.ToolName)

internal/fantasy/providers/anthropic/provider_options.go

@@ -2,7 +2,7 @@
 package anthropic
 
 import (
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 
 	"charm.land/fantasy"
 )
@@ -18,21 +18,21 @@ const (
 func init() {
 	fantasy.RegisterProviderType(TypeProviderOptions, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderOptions
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil
 	})
 	fantasy.RegisterProviderType(TypeReasoningOptionMetadata, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ReasoningOptionMetadata
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil
 	})
 	fantasy.RegisterProviderType(TypeProviderCacheControl, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderCacheControlOptions
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil

internal/fantasy/providers/google/google.go

@@ -3,9 +3,9 @@ package google
 import (
 	"cmp"
 	"context"
-	"encoding/json"
 	"errors"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"maps"
 	"net/http"
 	"reflect"
@@ -428,7 +428,7 @@ func toGooglePrompt(prompt fantasy.Prompt) (*genai.Content, []*genai.Content, []
 					}
 
 					var result map[string]any
-					err := json.Unmarshal([]byte(toolCall.Input), &result)
+					err := jsonv2.Unmarshal([]byte(toolCall.Input), &result)
 					if err != nil {
 						continue
 					}
@@ -750,7 +750,7 @@ func (g *languageModel) Stream(ctx context.Context, call fantasy.Call) (fantasy.
 								return
 							}
 						}
-						args, err := json.Marshal(part.FunctionCall.Args)
+						args, err := jsonv2.Marshal(part.FunctionCall.Args)
 						if err != nil {
 							yield(fantasy.StreamPart{
 								Type:  fantasy.StreamPartTypeError,
@@ -1380,7 +1380,7 @@ func (g languageModel) mapResponse(response *genai.GenerateContentResponse, warn
 				content = append(content, fantasy.TextContent{Text: part.Text})
 			}
 		case part.FunctionCall != nil:
-			input, err := json.Marshal(part.FunctionCall.Args)
+			input, err := jsonv2.Marshal(part.FunctionCall.Args)
 			if err != nil {
 				return nil, err
 			}

internal/fantasy/providers/google/provider_options.go

@@ -2,7 +2,7 @@
 package google
 
 import (
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 
 	"charm.land/fantasy"
 )
@@ -17,14 +17,14 @@ const (
 func init() {
 	fantasy.RegisterProviderType(TypeProviderOptions, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderOptions
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil
 	})
 	fantasy.RegisterProviderType(TypeReasoningMetadata, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ReasoningMetadata
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil

internal/fantasy/providers/openai/language_model.go

@@ -2,9 +2,9 @@ package openai
 
 import (
 	"context"
-	"encoding/json"
 	"errors"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"io"
 	"reflect"
 	"strings"
@@ -642,7 +642,7 @@ func parseAnnotationsFromDelta(delta openai.ChatCompletionChunkChoiceDelta) []op
 
 	// Parse the raw JSON to extract annotations
 	var deltaData map[string]any
-	if err := json.Unmarshal([]byte(delta.RawJSON()), &deltaData); err != nil {
+	if err := jsonv2.Unmarshal([]byte(delta.RawJSON()), &deltaData); err != nil {
 		return annotations
 	}
 

internal/fantasy/providers/openai/openai_test.go

@@ -3,7 +3,6 @@ package openai
 import (
 	"context"
 	"encoding/base64"
-	"encoding/json"
 	"errors"
 	"net/http"
 	"net/http/httptest"
@@ -11,6 +10,7 @@ import (
 	"testing"
 
 	"charm.land/fantasy"
+	jsonv2 "github.com/go-json-experiment/json"
 	"github.com/openai/openai-go/v2/packages/param"
 	"github.com/stretchr/testify/require"
 )
@@ -427,10 +427,10 @@ func TestToOpenAiPrompt_ToolCalls(t *testing.T) {
 		t.Parallel()
 
 		inputArgs := map[string]any{"foo": "bar123"}
-		inputJSON, _ := json.Marshal(inputArgs)
+		inputJSON, _ := jsonv2.Marshal(inputArgs)
 
 		outputResult := map[string]any{"oof": "321rab"}
-		outputJSON, _ := json.Marshal(outputResult)
+		outputJSON, _ := jsonv2.Marshal(outputResult)
 
 		prompt := fantasy.Prompt{
 			{
@@ -551,7 +551,7 @@ func TestToOpenAiPrompt_AssistantMessages(t *testing.T) {
 		t.Parallel()
 
 		inputArgs := map[string]any{"query": "test"}
-		inputJSON, _ := json.Marshal(inputArgs)
+		inputJSON, _ := jsonv2.Marshal(inputArgs)
 
 		prompt := fantasy.Prompt{
 			{
@@ -723,7 +723,7 @@ func newMockServer() *mockServer {
 		// Parse request body
 		if r.Body != nil {
 			var body map[string]any
-			json.NewDecoder(r.Body).Decode(&body)
+			jsonv2.UnmarshalRead(r.Body, &body)
 			call.body = body
 		}
 
@@ -731,7 +731,7 @@ func newMockServer() *mockServer {
 
 		// Return mock response
 		w.Header().Set("Content-Type", "application/json")
-		json.NewEncoder(w).Encode(ms.response)
+		jsonv2.MarshalWrite(w, ms.response)
 	}))
 
 	return ms
@@ -2038,7 +2038,7 @@ func newStreamingMockServer() *streamingMockServer {
 		// Parse request body
 		if r.Body != nil {
 			var body map[string]any
-			json.NewDecoder(r.Body).Decode(&body)
+			jsonv2.UnmarshalRead(r.Body, &body)
 			call.body = body
 		}
 
@@ -2141,7 +2141,7 @@ func (sms *streamingMockServer) prepareStreamResponse(opts map[string]any) {
 			},
 		},
 	}
-	initialData, _ := json.Marshal(initialChunk)
+	initialData, _ := jsonv2.Marshal(initialChunk)
 	chunks = append(chunks, "data: "+string(initialData)+"\n\n")
 
 	// Content chunks
@@ -2162,7 +2162,7 @@ func (sms *streamingMockServer) prepareStreamResponse(opts map[string]any) {
 				},
 			},
 		}
-		contentData, _ := json.Marshal(contentChunk)
+		contentData, _ := jsonv2.Marshal(contentChunk)
 		chunks = append(chunks, "data: "+string(contentData)+"\n\n")
 
 		// Add annotations if this is the last content chunk and we have annotations
@@ -2184,7 +2184,7 @@ func (sms *streamingMockServer) prepareStreamResponse(opts map[string]any) {
 						},
 					},
 				}
-				annotationData, _ := json.Marshal(annotationChunk)
+				annotationData, _ := jsonv2.Marshal(annotationChunk)
 				chunks = append(chunks, "data: "+string(annotationData)+"\n\n")
 			}
 		}
@@ -2210,7 +2210,7 @@ func (sms *streamingMockServer) prepareStreamResponse(opts map[string]any) {
 		finishChunk["choices"].([]map[string]any)[0]["logprobs"] = logprobs
 	}
 
-	finishData, _ := json.Marshal(finishChunk)
+	finishData, _ := jsonv2.Marshal(finishChunk)
 	chunks = append(chunks, "data: "+string(finishData)+"\n\n")
 
 	// Usage chunk
@@ -2223,7 +2223,7 @@ func (sms *streamingMockServer) prepareStreamResponse(opts map[string]any) {
 		"choices":            []map[string]any{},
 		"usage":              usage,
 	}
-	usageData, _ := json.Marshal(usageChunk)
+	usageData, _ := jsonv2.Marshal(usageChunk)
 	chunks = append(chunks, "data: "+string(usageData)+"\n\n")
 
 	// Done

internal/fantasy/providers/openai/provider_options.go

@@ -2,7 +2,7 @@
 package openai
 
 import (
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 
 	"charm.land/fantasy"
 	"github.com/openai/openai-go/v2"
@@ -33,21 +33,21 @@ const (
 func init() {
 	fantasy.RegisterProviderType(TypeProviderOptions, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderOptions
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil
 	})
 	fantasy.RegisterProviderType(TypeProviderFileOptions, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderFileOptions
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil
 	})
 	fantasy.RegisterProviderType(TypeProviderMetadata, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderMetadata
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil

internal/fantasy/providers/openai/responses_language_model.go

@@ -3,8 +3,8 @@ package openai
 import (
 	"context"
 	"encoding/base64"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"reflect"
 	"strings"
 
@@ -479,7 +479,7 @@ func toResponsesPrompt(prompt fantasy.Prompt, systemMessageMode string) (respons
 						continue
 					}
 
-					inputJSON, err := json.Marshal(toolCallPart.Input)
+					inputJSON, err := jsonv2.Marshal(toolCallPart.Input)
 					if err != nil {
 						warnings = append(warnings, fantasy.CallWarning{
 							Type:    fantasy.CallWarningTypeOther,

internal/fantasy/providers/openai/responses_options.go

@@ -2,7 +2,7 @@
 package openai
 
 import (
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"slices"
 
 	"charm.land/fantasy"
@@ -18,14 +18,14 @@ const (
 func init() {
 	fantasy.RegisterProviderType(TypeResponsesProviderOptions, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ResponsesProviderOptions
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil
 	})
 	fantasy.RegisterProviderType(TypeResponsesReasoningMetadata, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ResponsesReasoningMetadata
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil

internal/fantasy/providers/openaicompat/language_model_hooks.go

@@ -2,8 +2,8 @@ package openaicompat
 
 import (
 	"encoding/base64"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"strings"
 
 	"charm.land/fantasy"
@@ -50,7 +50,7 @@ func PrepareCallFunc(_ fantasy.LanguageModel, params *openaisdk.ChatCompletionNe
 func ExtraContentFunc(choice openaisdk.ChatCompletionChoice) []fantasy.Content {
 	var content []fantasy.Content
 	reasoningData := ReasoningData{}
-	err := json.Unmarshal([]byte(choice.Message.RawJSON()), &reasoningData)
+	err := jsonv2.Unmarshal([]byte(choice.Message.RawJSON()), &reasoningData)
 	if err != nil {
 		return content
 	}
@@ -84,7 +84,7 @@ func StreamExtraFunc(chunk openaisdk.ChatCompletionChunk, yield func(fantasy.Str
 
 	for inx, choice := range chunk.Choices {
 		reasoningData := ReasoningData{}
-		err := json.Unmarshal([]byte(choice.Delta.RawJSON()), &reasoningData)
+		err := jsonv2.Unmarshal([]byte(choice.Delta.RawJSON()), &reasoningData)
 		if err != nil {
 			yield(fantasy.StreamPart{
 				Type:  fantasy.StreamPartTypeError,

internal/fantasy/providers/openaicompat/provider_options.go

@@ -2,7 +2,7 @@
 package openaicompat
 
 import (
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 
 	"charm.land/fantasy"
 	"charm.land/fantasy/providers/openai"
@@ -17,7 +17,7 @@ const (
 func init() {
 	fantasy.RegisterProviderType(TypeProviderOptions, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderOptions
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil

internal/fantasy/providers/openrouter/language_model_hooks.go

@@ -2,8 +2,8 @@ package openrouter
 
 import (
 	"encoding/base64"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"maps"
 	"strings"
 
@@ -74,7 +74,7 @@ func languagePrepareModelCall(_ fantasy.LanguageModel, params *openaisdk.ChatCom
 func languageModelExtraContent(choice openaisdk.ChatCompletionChoice) []fantasy.Content {
 	content := make([]fantasy.Content, 0)
 	reasoningData := ReasoningData{}
-	err := json.Unmarshal([]byte(choice.Message.RawJSON()), &reasoningData)
+	err := jsonv2.Unmarshal([]byte(choice.Message.RawJSON()), &reasoningData)
 	if err != nil {
 		return content
 	}
@@ -212,7 +212,7 @@ func languageModelStreamExtra(chunk openaisdk.ChatCompletionChunk, yield func(fa
 	inx := 0
 	choice := chunk.Choices[inx]
 	reasoningData := ReasoningData{}
-	err := json.Unmarshal([]byte(choice.Delta.RawJSON()), &reasoningData)
+	err := jsonv2.Unmarshal([]byte(choice.Delta.RawJSON()), &reasoningData)
 	if err != nil {
 		yield(fantasy.StreamPart{
 			Type:  fantasy.StreamPartTypeError,
@@ -423,7 +423,7 @@ func languageModelUsage(response openaisdk.ChatCompletion) (fantasy.Usage, fanta
 	openrouterUsage := UsageAccounting{}
 	usage := response.Usage
 
-	_ = json.Unmarshal([]byte(usage.RawJSON()), &openrouterUsage)
+	_ = jsonv2.Unmarshal([]byte(usage.RawJSON()), &openrouterUsage)
 
 	completionTokenDetails := usage.CompletionTokensDetails
 	promptTokenDetails := usage.PromptTokensDetails
@@ -464,7 +464,7 @@ func languageModelStreamUsage(chunk openaisdk.ChatCompletionChunk, _ map[string]
 		}
 	}
 	openrouterUsage := UsageAccounting{}
-	_ = json.Unmarshal([]byte(usage.RawJSON()), &openrouterUsage)
+	_ = jsonv2.Unmarshal([]byte(usage.RawJSON()), &openrouterUsage)
 	streamProviderMetadata.Usage = openrouterUsage
 
 	if p, ok := chunk.JSON.ExtraFields["provider"]; ok {
@@ -810,9 +810,9 @@ func languageModelToPrompt(prompt fantasy.Prompt, _, model string) ([]openaisdk.
 							Text:      reasoningPart.Text,
 							Signature: metadata.Signature,
 						})
-						data, _ := json.Marshal(reasoningDetails)
+						data, _ := jsonv2.Marshal(reasoningDetails)
 						reasoningDetailsMap := []map[string]any{}
-						_ = json.Unmarshal(data, &reasoningDetailsMap)
+						_ = jsonv2.Unmarshal(data, &reasoningDetailsMap)
 						assistantMsg.SetExtraFields(map[string]any{
 							"reasoning_details": reasoningDetailsMap,
 							"reasoning":         reasoningPart.Text,
@@ -847,9 +847,9 @@ func languageModelToPrompt(prompt fantasy.Prompt, _, model string) ([]openaisdk.
 							Data:   *metadata.EncryptedContent,
 							ID:     metadata.ItemID,
 						})
-						data, _ := json.Marshal(reasoningDetails)
+						data, _ := jsonv2.Marshal(reasoningDetails)
 						reasoningDetailsMap := []map[string]any{}
-						_ = json.Unmarshal(data, &reasoningDetailsMap)
+						_ = jsonv2.Unmarshal(data, &reasoningDetailsMap)
 						assistantMsg.SetExtraFields(map[string]any{
 							"reasoning_details": reasoningDetailsMap,
 						})
@@ -883,9 +883,9 @@ func languageModelToPrompt(prompt fantasy.Prompt, _, model string) ([]openaisdk.
 							Data:   *metadata.EncryptedContent,
 							ID:     metadata.ItemID,
 						})
-						data, _ := json.Marshal(reasoningDetails)
+						data, _ := jsonv2.Marshal(reasoningDetails)
 						reasoningDetailsMap := []map[string]any{}
-						_ = json.Unmarshal(data, &reasoningDetailsMap)
+						_ = jsonv2.Unmarshal(data, &reasoningDetailsMap)
 						assistantMsg.SetExtraFields(map[string]any{
 							"reasoning_details": reasoningDetailsMap,
 						})
@@ -915,9 +915,9 @@ func languageModelToPrompt(prompt fantasy.Prompt, _, model string) ([]openaisdk.
 							Data:   metadata.Signature,
 							ID:     metadata.ToolID,
 						})
-						data, _ := json.Marshal(reasoningDetails)
+						data, _ := jsonv2.Marshal(reasoningDetails)
 						reasoningDetailsMap := []map[string]any{}
-						_ = json.Unmarshal(data, &reasoningDetailsMap)
+						_ = jsonv2.Unmarshal(data, &reasoningDetailsMap)
 						assistantMsg.SetExtraFields(map[string]any{
 							"reasoning_details": reasoningDetailsMap,
 						})
@@ -927,9 +927,9 @@ func languageModelToPrompt(prompt fantasy.Prompt, _, model string) ([]openaisdk.
 							Text:   reasoningPart.Text,
 							Format: "unknown",
 						})
-						data, _ := json.Marshal(reasoningDetails)
+						data, _ := jsonv2.Marshal(reasoningDetails)
 						reasoningDetailsMap := []map[string]any{}
-						_ = json.Unmarshal(data, &reasoningDetailsMap)
+						_ = jsonv2.Unmarshal(data, &reasoningDetailsMap)
 						assistantMsg.SetExtraFields(map[string]any{
 							"reasoning_details": reasoningDetailsMap,
 						})

internal/fantasy/providers/openrouter/openrouter.go

@@ -2,7 +2,7 @@
 package openrouter
 
 import (
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 
 	"charm.land/fantasy"
 	"charm.land/fantasy/providers/openai"
@@ -101,11 +101,11 @@ func WithObjectMode(om fantasy.ObjectMode) Option {
 
 func structToMapJSON(s any) (map[string]any, error) {
 	var result map[string]any
-	jsonBytes, err := json.Marshal(s)
+	jsonBytes, err := jsonv2.Marshal(s)
 	if err != nil {
 		return nil, err
 	}
-	err = json.Unmarshal(jsonBytes, &result)
+	err = jsonv2.Unmarshal(jsonBytes, &result)
 	if err != nil {
 		return nil, err
 	}

internal/fantasy/providers/openrouter/provider_options.go

@@ -2,7 +2,7 @@
 package openrouter
 
 import (
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 
 	"charm.land/fantasy"
 )
@@ -29,14 +29,14 @@ const (
 func init() {
 	fantasy.RegisterProviderType(TypeProviderOptions, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderOptions
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil
 	})
 	fantasy.RegisterProviderType(TypeProviderMetadata, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderMetadata
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil
@@ -100,53 +100,53 @@ func (m *ProviderMetadata) UnmarshalJSON(data []byte) error {
 // ReasoningOptions represents reasoning options for OpenRouter.
 type ReasoningOptions struct {
 	// Whether reasoning is enabled
-	Enabled *bool `json:"enabled,omitempty"`
+	Enabled *bool `json:"enabled,omitzero"`
 	// Whether to exclude reasoning from the response
-	Exclude *bool `json:"exclude,omitempty"`
+	Exclude *bool `json:"exclude,omitzero"`
 	// Maximum number of tokens to use for reasoning
-	MaxTokens *int64 `json:"max_tokens,omitempty"`
+	MaxTokens *int64 `json:"max_tokens,omitzero"`
 	// Reasoning effort level: "low" | "medium" | "high"
-	Effort *ReasoningEffort `json:"effort,omitempty"`
+	Effort *ReasoningEffort `json:"effort,omitzero"`
 }
 
 // Provider represents provider routing preferences for OpenRouter.
 type Provider struct {
 	// List of provider slugs to try in order (e.g. ["anthropic", "openai"])
-	Order []string `json:"order,omitempty"`
+	Order []string `json:"order,omitzero"`
 	// Whether to allow backup providers when primary is unavailable (default: true)
-	AllowFallbacks *bool `json:"allow_fallbacks,omitempty"`
+	AllowFallbacks *bool `json:"allow_fallbacks,omitzero"`
 	// Only use providers that support all parameters in your request (default: false)
-	RequireParameters *bool `json:"require_parameters,omitempty"`
+	RequireParameters *bool `json:"require_parameters,omitzero"`
 	// Control whether to use providers that may store data: "allow" | "deny"
-	DataCollection *string `json:"data_collection,omitempty"`
+	DataCollection *string `json:"data_collection,omitzero"`
 	// List of provider slugs to allow for this request
-	Only []string `json:"only,omitempty"`
+	Only []string `json:"only,omitzero"`
 	// List of provider slugs to skip for this request
-	Ignore []string `json:"ignore,omitempty"`
+	Ignore []string `json:"ignore,omitzero"`
 	// List of quantization levels to filter by (e.g. ["int4", "int8"])
-	Quantizations []string `json:"quantizations,omitempty"`
+	Quantizations []string `json:"quantizations,omitzero"`
 	// Sort providers by "price" | "throughput" | "latency"
-	Sort *string `json:"sort,omitempty"`
+	Sort *string `json:"sort,omitzero"`
 }
 
 // ProviderOptions represents additional options for OpenRouter provider.
 type ProviderOptions struct {
-	Reasoning    *ReasoningOptions `json:"reasoning,omitempty"`
+	Reasoning    *ReasoningOptions `json:"reasoning,omitzero"`
-	ExtraBody    map[string]any    `json:"extra_body,omitempty"`
+	ExtraBody    map[string]any    `json:"extra_body,omitzero"`
-	IncludeUsage *bool             `json:"include_usage,omitempty"`
+	IncludeUsage *bool             `json:"include_usage,omitzero"`
 	// Modify the likelihood of specified tokens appearing in the completion.
 	// Accepts a map that maps tokens (specified by their token ID) to an associated bias value from -100 to 100.
 	// The bias is added to the logits generated by the model prior to sampling.
-	LogitBias map[string]int64 `json:"logit_bias,omitempty"`
+	LogitBias map[string]int64 `json:"logit_bias,omitzero"`
 	// Return the log probabilities of the tokens. Including logprobs will increase the response size.
 	// Setting to true will return the log probabilities of the tokens that were generated.
-	LogProbs *bool `json:"log_probs,omitempty"`
+	LogProbs *bool `json:"log_probs,omitzero"`
 	// Whether to enable parallel function calling during tool use. Default to true.
-	ParallelToolCalls *bool `json:"parallel_tool_calls,omitempty"`
+	ParallelToolCalls *bool `json:"parallel_tool_calls,omitzero"`
 	// A unique identifier representing your end-user, which can help OpenRouter to monitor and detect abuse.
-	User *string `json:"user,omitempty"`
+	User *string `json:"user,omitzero"`
 	// Provider routing preferences to control request routing behavior
-	Provider *Provider `json:"provider,omitempty"`
+	Provider *Provider `json:"provider,omitzero"`
 	// Plugins is the ordered list of OpenRouter plugins to enable for this
 	// request. Use WebSearchPlugin to activate online search:
 	//
@@ -154,15 +154,15 @@ type ProviderOptions struct {
 	//
 	// Refer to https://openrouter.ai/docs/features/web-search for the full
 	// plugin reference.
-	Plugins []Plugin `json:"plugins,omitempty"`
+	Plugins []Plugin `json:"plugins,omitzero"`
 }
 
 // WebSearchPlugin configures the OpenRouter web-search plugin.
 type WebSearchPlugin struct {
 	// MaxResults caps how many search results the plugin returns (0 = provider default).
-	MaxResults int `json:"max_results,omitempty"`
+	MaxResults int `json:"max_results,omitzero"`
 	// SearchPrompt overrides the system prompt used internally by the plugin.
-	SearchPrompt string `json:"search_prompt,omitempty"`
+	SearchPrompt string `json:"search_prompt,omitzero"`
 }
 
 // Plugin represents a single OpenRouter plugin entry.
@@ -172,7 +172,7 @@ type Plugin struct {
 	// ID is the plugin identifier (e.g. "web").
 	ID string `json:"id"`
 	// WebSearch holds optional web-search configuration. Omit for defaults.
-	WebSearch *WebSearchPlugin `json:"web,omitempty"`
+	WebSearch *WebSearchPlugin `json:"web,omitzero"`
 }
 
 // NewWebSearchPlugin is a convenience constructor that returns a Plugin slice
@@ -209,13 +209,13 @@ func (o *ProviderOptions) UnmarshalJSON(data []byte) error {
 
 // ReasoningDetail represents a reasoning detail for OpenRouter.
 type ReasoningDetail struct {
-	ID        string `json:"id,omitempty"`
+	ID        string `json:"id,omitzero"`
-	Type      string `json:"type,omitempty"`
+	Type      string `json:"type,omitzero"`
-	Text      string `json:"text,omitempty"`
+	Text      string `json:"text,omitzero"`
-	Data      string `json:"data,omitempty"`
+	Data      string `json:"data,omitzero"`
-	Format    string `json:"format,omitempty"`
+	Format    string `json:"format,omitzero"`
-	Summary   string `json:"summary,omitempty"`
+	Summary   string `json:"summary,omitzero"`
-	Signature string `json:"signature,omitempty"`
+	Signature string `json:"signature,omitzero"`
 	Index     int    `json:"index"`
 }
 

internal/fantasy/providers/vercel/language_model_hooks.go

@@ -2,8 +2,8 @@ package vercel
 
 import (
 	"encoding/base64"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"maps"
 	"strings"
 
@@ -102,7 +102,7 @@ func languagePrepareModelCall(_ fantasy.LanguageModel, params *openaisdk.ChatCom
 func languageModelExtraContent(choice openaisdk.ChatCompletionChoice) []fantasy.Content {
 	content := make([]fantasy.Content, 0)
 	reasoningData := ReasoningData{}
-	err := json.Unmarshal([]byte(choice.Message.RawJSON()), &reasoningData)
+	err := jsonv2.Unmarshal([]byte(choice.Message.RawJSON()), &reasoningData)
 	if err != nil {
 		return content
 	}
@@ -251,7 +251,7 @@ func languageModelStreamExtra(chunk openaisdk.ChatCompletionChunk, yield func(fa
 	inx := 0
 	choice := chunk.Choices[inx]
 	reasoningData := ReasoningData{}
-	err := json.Unmarshal([]byte(choice.Delta.RawJSON()), &reasoningData)
+	err := jsonv2.Unmarshal([]byte(choice.Delta.RawJSON()), &reasoningData)
 	if err != nil {
 		yield(fantasy.StreamPart{
 			Type:  fantasy.StreamPartTypeError,
@@ -844,9 +844,9 @@ func languageModelToPrompt(prompt fantasy.Prompt, _, model string) ([]openaisdk.
 							Text:      reasoningPart.Text,
 							Signature: metadata.Signature,
 						})
-						data, _ := json.Marshal(reasoningDetails)
+						data, _ := jsonv2.Marshal(reasoningDetails)
 						reasoningDetailsMap := []map[string]any{}
-						_ = json.Unmarshal(data, &reasoningDetailsMap)
+						_ = jsonv2.Unmarshal(data, &reasoningDetailsMap)
 						assistantMsg.SetExtraFields(map[string]any{
 							"reasoning_details": reasoningDetailsMap,
 							"reasoning":         reasoningPart.Text,
@@ -880,9 +880,9 @@ func languageModelToPrompt(prompt fantasy.Prompt, _, model string) ([]openaisdk.
 							Data:   *metadata.EncryptedContent,
 							ID:     metadata.ItemID,
 						})
-						data, _ := json.Marshal(reasoningDetails)
+						data, _ := jsonv2.Marshal(reasoningDetails)
 						reasoningDetailsMap := []map[string]any{}
-						_ = json.Unmarshal(data, &reasoningDetailsMap)
+						_ = jsonv2.Unmarshal(data, &reasoningDetailsMap)
 						assistantMsg.SetExtraFields(map[string]any{
 							"reasoning_details": reasoningDetailsMap,
 						})
@@ -911,9 +911,9 @@ func languageModelToPrompt(prompt fantasy.Prompt, _, model string) ([]openaisdk.
 							Data:   metadata.Signature,
 							ID:     metadata.ToolID,
 						})
-						data, _ := json.Marshal(reasoningDetails)
+						data, _ := jsonv2.Marshal(reasoningDetails)
 						reasoningDetailsMap := []map[string]any{}
-						_ = json.Unmarshal(data, &reasoningDetailsMap)
+						_ = jsonv2.Unmarshal(data, &reasoningDetailsMap)
 						assistantMsg.SetExtraFields(map[string]any{
 							"reasoning_details": reasoningDetailsMap,
 						})
@@ -923,9 +923,9 @@ func languageModelToPrompt(prompt fantasy.Prompt, _, model string) ([]openaisdk.
 							Text:   reasoningPart.Text,
 							Format: "unknown",
 						})
-						data, _ := json.Marshal(reasoningDetails)
+						data, _ := jsonv2.Marshal(reasoningDetails)
 						reasoningDetailsMap := []map[string]any{}
-						_ = json.Unmarshal(data, &reasoningDetailsMap)
+						_ = jsonv2.Unmarshal(data, &reasoningDetailsMap)
 						assistantMsg.SetExtraFields(map[string]any{
 							"reasoning_details": reasoningDetailsMap,
 						})
@@ -1040,11 +1040,11 @@ func hasVisibleUserContent(content []openaisdk.ChatCompletionContentPartUnionPar
 
 func structToMapJSON(s any) (map[string]any, error) {
 	var result map[string]any
-	jsonBytes, err := json.Marshal(s)
+	jsonBytes, err := jsonv2.Marshal(s)
 	if err != nil {
 		return nil, err
 	}
-	err = json.Unmarshal(jsonBytes, &result)
+	err = jsonv2.Unmarshal(jsonBytes, &result)
 	if err != nil {
 		return nil, err
 	}

internal/fantasy/providers/vercel/provider_options.go

@@ -2,7 +2,7 @@
 package vercel
 
 import (
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 
 	"charm.land/fantasy"
 )
@@ -17,14 +17,14 @@ const (
 func init() {
 	fantasy.RegisterProviderType(TypeProviderOptions, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderOptions
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil
 	})
 	fantasy.RegisterProviderType(TypeProviderMetadata, func(data []byte) (fantasy.ProviderOptionsData, error) {
 		var v ProviderMetadata
-		if err := json.Unmarshal(data, &v); err != nil {
+		if err := jsonv2.Unmarshal(data, &v); err != nil {
 			return nil, err
 		}
 		return &v, nil
@@ -52,58 +52,58 @@ const (
 // ReasoningOptions represents reasoning configuration for Vercel AI Gateway.
 type ReasoningOptions struct {
 	// Enabled enables reasoning output. When true, the model will provide its reasoning process.
-	Enabled *bool `json:"enabled,omitempty"`
+	Enabled *bool `json:"enabled,omitzero"`
 	// MaxTokens is the maximum number of tokens to allocate for reasoning.
 	// Cannot be used with Effort.
-	MaxTokens *int64 `json:"max_tokens,omitempty"`
+	MaxTokens *int64 `json:"max_tokens,omitzero"`
 	// Effort controls reasoning effort level.
 	// Mutually exclusive with MaxTokens.
-	Effort *ReasoningEffort `json:"effort,omitempty"`
+	Effort *ReasoningEffort `json:"effort,omitzero"`
 	// Exclude excludes reasoning content from the response but still generates it internally.
-	Exclude *bool `json:"exclude,omitempty"`
+	Exclude *bool `json:"exclude,omitzero"`
 }
 
 // GatewayProviderOptions represents provider routing preferences for Vercel AI Gateway.
 type GatewayProviderOptions struct {
 	// Order is the list of provider slugs to try in order (e.g. ["vertex", "anthropic"]).
-	Order []string `json:"order,omitempty"`
+	Order []string `json:"order,omitzero"`
 	// Models is the list of fallback models to try if the primary model fails.
-	Models []string `json:"models,omitempty"`
+	Models []string `json:"models,omitzero"`
 }
 
 // BYOKCredential represents a single provider credential for BYOK.
 type BYOKCredential struct {
-	APIKey string `json:"apiKey,omitempty"`
+	APIKey string `json:"apiKey,omitzero"`
 }
 
 // BYOKOptions represents Bring Your Own Key options for Vercel AI Gateway.
 type BYOKOptions struct {
-	Anthropic map[string][]BYOKCredential `json:"anthropic,omitempty"`
+	Anthropic map[string][]BYOKCredential `json:"anthropic,omitzero"`
-	OpenAI    map[string][]BYOKCredential `json:"openai,omitempty"`
+	OpenAI    map[string][]BYOKCredential `json:"openai,omitzero"`
-	Vertex    map[string][]BYOKCredential `json:"vertex,omitempty"`
+	Vertex    map[string][]BYOKCredential `json:"vertex,omitzero"`
-	Bedrock   map[string][]BYOKCredential `json:"bedrock,omitempty"`
+	Bedrock   map[string][]BYOKCredential `json:"bedrock,omitzero"`
 }
 
 // ProviderOptions represents additional options for Vercel AI Gateway provider.
 type ProviderOptions struct {
 	// Reasoning configuration for models that support extended thinking.
-	Reasoning *ReasoningOptions `json:"reasoning,omitempty"`
+	Reasoning *ReasoningOptions `json:"reasoning,omitzero"`
 	// ProviderOptions for gateway routing preferences.
-	ProviderOptions *GatewayProviderOptions `json:"providerOptions,omitempty"`
+	ProviderOptions *GatewayProviderOptions `json:"providerOptions,omitzero"`
 	// BYOK for request-scoped provider credentials.
-	BYOK *BYOKOptions `json:"byok,omitempty"`
+	BYOK *BYOKOptions `json:"byok,omitzero"`
 	// User is a unique identifier representing your end-user.
-	User *string `json:"user,omitempty"`
+	User *string `json:"user,omitzero"`
 	// LogitBias modifies the likelihood of specified tokens appearing in the completion.
-	LogitBias map[string]int64 `json:"logit_bias,omitempty"`
+	LogitBias map[string]int64 `json:"logit_bias,omitzero"`
 	// LogProbs returns the log probabilities of the tokens.
-	LogProbs *bool `json:"logprobs,omitempty"`
+	LogProbs *bool `json:"logprobs,omitzero"`
 	// TopLogProbs is the number of top log probabilities to return.
-	TopLogProbs *int64 `json:"top_logprobs,omitempty"`
+	TopLogProbs *int64 `json:"top_logprobs,omitzero"`
 	// ParallelToolCalls enables parallel function calling during tool use.
-	ParallelToolCalls *bool `json:"parallel_tool_calls,omitempty"`
+	ParallelToolCalls *bool `json:"parallel_tool_calls,omitzero"`
 	// ExtraBody for additional request body fields.
-	ExtraBody map[string]any `json:"extra_body,omitempty"`
+	ExtraBody map[string]any `json:"extra_body,omitzero"`
 }
 
 // Options implements the ProviderOptionsData interface for ProviderOptions.
@@ -128,7 +128,7 @@ func (o *ProviderOptions) UnmarshalJSON(data []byte) error {
 
 // ProviderMetadata represents metadata from Vercel AI Gateway provider.
 type ProviderMetadata struct {
-	Provider string `json:"provider,omitempty"`
+	Provider string `json:"provider,omitzero"`
 }
 
 // Options implements the ProviderOptionsData interface for ProviderMetadata.
@@ -153,20 +153,20 @@ func (m *ProviderMetadata) UnmarshalJSON(data []byte) error {
 
 // ReasoningDetail represents a reasoning detail from Vercel AI Gateway.
 type ReasoningDetail struct {
-	ID        string `json:"id,omitempty"`
+	ID        string `json:"id,omitzero"`
-	Type      string `json:"type,omitempty"`
+	Type      string `json:"type,omitzero"`
-	Text      string `json:"text,omitempty"`
+	Text      string `json:"text,omitzero"`
-	Data      string `json:"data,omitempty"`
+	Data      string `json:"data,omitzero"`
-	Format    string `json:"format,omitempty"`
+	Format    string `json:"format,omitzero"`
-	Summary   string `json:"summary,omitempty"`
+	Summary   string `json:"summary,omitzero"`
-	Signature string `json:"signature,omitempty"`
+	Signature string `json:"signature,omitzero"`
 	Index     int    `json:"index"`
 }
 
 // ReasoningData represents reasoning data from Vercel AI Gateway response.
 type ReasoningData struct {
-	Reasoning        string            `json:"reasoning,omitempty"`
+	Reasoning        string            `json:"reasoning,omitzero"`
-	ReasoningDetails []ReasoningDetail `json:"reasoning_details,omitempty"`
+	ReasoningDetails []ReasoningDetail `json:"reasoning_details,omitzero"`
 }
 
 // ReasoningEffortOption creates a pointer to a ReasoningEffort value.

internal/fantasy/providertests/provider_registry_test.go

@@ -1,7 +1,7 @@
 package providertests
 
 import (
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"testing"
 
 	"charm.land/fantasy"
@@ -24,13 +24,13 @@ func TestProviderRegistry_Serialization_OpenAIOptions(t *testing.T) {
 		},
 	}
 
-	data, err := json.Marshal(msg)
+	data, err := jsonv2.Marshal(msg)
 	require.NoError(t, err)
 
 	var raw struct {
 		ProviderOptions map[string]map[string]any `json:"provider_options"`
 	}
-	require.NoError(t, json.Unmarshal(data, &raw))
+	require.NoError(t, jsonv2.Unmarshal(data, &raw))
 
 	po, ok := raw.ProviderOptions[openai.Name]
 	require.True(t, ok)
@@ -41,7 +41,7 @@ func TestProviderRegistry_Serialization_OpenAIOptions(t *testing.T) {
 	require.Equal(t, "tester", inner["user"])
 
 	var decoded fantasy.Message
-	require.NoError(t, json.Unmarshal(data, &decoded))
+	require.NoError(t, jsonv2.Unmarshal(data, &decoded))
 
 	got, ok := decoded.ProviderOptions[openai.Name]
 	require.True(t, ok)
@@ -66,14 +66,14 @@ func TestProviderRegistry_Serialization_OpenAIResponses(t *testing.T) {
 		},
 	}
 
-	data, err := json.Marshal(msg)
+	data, err := jsonv2.Marshal(msg)
 	require.NoError(t, err)
 
 	// JSON should include the typed wrapper with constant TypeResponsesProviderOptions
 	var raw struct {
 		ProviderOptions map[string]map[string]any `json:"provider_options"`
 	}
-	require.NoError(t, json.Unmarshal(data, &raw))
+	require.NoError(t, jsonv2.Unmarshal(data, &raw))
 
 	po := raw.ProviderOptions[openai.Name]
 	require.Equal(t, openai.TypeResponsesProviderOptions, po["type"]) // no magic strings
@@ -84,7 +84,7 @@ func TestProviderRegistry_Serialization_OpenAIResponses(t *testing.T) {
 
 	// Unmarshal back and assert concrete type
 	var decoded fantasy.Message
-	require.NoError(t, json.Unmarshal(data, &decoded))
+	require.NoError(t, jsonv2.Unmarshal(data, &decoded))
 	got := decoded.ProviderOptions[openai.Name]
 	reqOpts, ok := got.(*openai.ResponsesProviderOptions)
 	require.True(t, ok)
@@ -109,7 +109,7 @@ func TestProviderRegistry_Serialization_OpenAIResponsesReasoningMetadata(t *test
 		},
 	}
 
-	data, err := json.Marshal(resp)
+	data, err := jsonv2.Marshal(resp)
 	require.NoError(t, err)
 
 	// Ensure the provider metadata is wrapped with type using constant
@@ -119,7 +119,7 @@ func TestProviderRegistry_Serialization_OpenAIResponsesReasoningMetadata(t *test
 			Data map[string]any `json:"data"`
 		} `json:"content"`
 	}
-	require.NoError(t, json.Unmarshal(data, &raw))
+	require.NoError(t, jsonv2.Unmarshal(data, &raw))
 	require.Greater(t, len(raw.Content), 0)
 	tc := raw.Content[0]
 	pm, ok := tc.Data["provider_metadata"].(map[string]any)
@@ -133,7 +133,7 @@ func TestProviderRegistry_Serialization_OpenAIResponsesReasoningMetadata(t *test
 
 	// Unmarshal back
 	var decoded fantasy.Response
-	require.NoError(t, json.Unmarshal(data, &decoded))
+	require.NoError(t, jsonv2.Unmarshal(data, &decoded))
 	pmDecoded := decoded.Content[0].(fantasy.TextContent).ProviderMetadata
 	val, ok := pmDecoded[openai.Name]
 	require.True(t, ok)
@@ -157,11 +157,11 @@ func TestProviderRegistry_Serialization_AnthropicOptions(t *testing.T) {
 		},
 	}
 
-	data, err := json.Marshal(msg)
+	data, err := jsonv2.Marshal(msg)
 	require.NoError(t, err)
 
 	var decoded fantasy.Message
-	require.NoError(t, json.Unmarshal(data, &decoded))
+	require.NoError(t, jsonv2.Unmarshal(data, &decoded))
 
 	got, ok := decoded.ProviderOptions[anthropic.Name]
 	require.True(t, ok)
@@ -185,11 +185,11 @@ func TestProviderRegistry_Serialization_GoogleOptions(t *testing.T) {
 		},
 	}
 
-	data, err := json.Marshal(msg)
+	data, err := jsonv2.Marshal(msg)
 	require.NoError(t, err)
 
 	var decoded fantasy.Message
-	require.NoError(t, json.Unmarshal(data, &decoded))
+	require.NoError(t, jsonv2.Unmarshal(data, &decoded))
 
 	got, ok := decoded.ProviderOptions[google.Name]
 	require.True(t, ok)
@@ -214,11 +214,11 @@ func TestProviderRegistry_Serialization_OpenRouterOptions(t *testing.T) {
 		},
 	}
 
-	data, err := json.Marshal(msg)
+	data, err := jsonv2.Marshal(msg)
 	require.NoError(t, err)
 
 	var decoded fantasy.Message
-	require.NoError(t, json.Unmarshal(data, &decoded))
+	require.NoError(t, jsonv2.Unmarshal(data, &decoded))
 
 	got, ok := decoded.ProviderOptions[openrouter.Name]
 	require.True(t, ok)
@@ -245,11 +245,11 @@ func TestProviderRegistry_Serialization_OpenAICompatOptions(t *testing.T) {
 		},
 	}
 
-	data, err := json.Marshal(msg)
+	data, err := jsonv2.Marshal(msg)
 	require.NoError(t, err)
 
 	var decoded fantasy.Message
-	require.NoError(t, json.Unmarshal(data, &decoded))
+	require.NoError(t, jsonv2.Unmarshal(data, &decoded))
 
 	got, ok := decoded.ProviderOptions[openaicompat.Name]
 	require.True(t, ok)
@@ -277,11 +277,11 @@ func TestProviderRegistry_MultiProvider(t *testing.T) {
 		},
 	}
 
-	data, err := json.Marshal(msg)
+	data, err := jsonv2.Marshal(msg)
 	require.NoError(t, err)
 
 	var decoded fantasy.Message
-	require.NoError(t, json.Unmarshal(data, &decoded))
+	require.NoError(t, jsonv2.Unmarshal(data, &decoded))
 
 	// Check OpenAI options
 	openaiOpt, ok := decoded.ProviderOptions[openai.Name]
@@ -312,7 +312,7 @@ func TestProviderRegistry_ErrorHandling(t *testing.T) {
 		}`
 
 		var msg fantasy.Message
-		err := json.Unmarshal([]byte(invalidJSON), &msg)
+		err := jsonv2.Unmarshal([]byte(invalidJSON), &msg)
 		require.Error(t, err)
 		require.Contains(t, err.Error(), "unknown provider data type")
 	})
@@ -327,7 +327,7 @@ func TestProviderRegistry_ErrorHandling(t *testing.T) {
 		}`
 
 		var msg fantasy.Message
-		err := json.Unmarshal([]byte(invalidJSON), &msg)
+		err := jsonv2.Unmarshal([]byte(invalidJSON), &msg)
 		require.Error(t, err)
 	})
 }
@@ -364,11 +364,11 @@ func TestProviderRegistry_AllTypesRegistered(t *testing.T) {
 			}
 
 			// Marshal and unmarshal
-			data, err := json.Marshal(msg)
+			data, err := jsonv2.Marshal(msg)
 			require.NoError(t, err)
 
 			var decoded fantasy.Message
-			err = json.Unmarshal(data, &decoded)
+			err = jsonv2.Unmarshal(data, &decoded)
 			require.NoError(t, err)
 
 			// Verify the provider options exist
@@ -404,11 +404,11 @@ func TestProviderRegistry_AllTypesRegistered(t *testing.T) {
 			}
 
 			// Marshal and unmarshal
-			data, err := json.Marshal(resp)
+			data, err := jsonv2.Marshal(resp)
 			require.NoError(t, err)
 
 			var decoded fantasy.Response
-			err = json.Unmarshal(data, &decoded)
+			err = jsonv2.Unmarshal(data, &decoded)
 			require.NoError(t, err)
 
 			// Verify the provider metadata exists

internal/fantasy/schema/schema.go

@@ -4,8 +4,8 @@ package schema
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"reflect"
 	"slices"
 	"strings"
@@ -259,7 +259,7 @@ func ParsePartialJSON(text string) (any, ParseState, error) {
 	}
 
 	var result any
-	if err := json.Unmarshal([]byte(text), &result); err == nil {
+	if err := jsonv2.Unmarshal([]byte(text), &result); err == nil {
 		return result, ParseStateSuccessful, nil
 	}
 
@@ -268,7 +268,7 @@ func ParsePartialJSON(text string) (any, ParseState, error) {
 		return nil, ParseStateFailed, fmt.Errorf("json repair failed: %w", err)
 	}
 
-	if err := json.Unmarshal([]byte(repaired), &result); err != nil {
+	if err := jsonv2.Unmarshal([]byte(repaired), &result); err != nil {
 		return nil, ParseStateFailed, fmt.Errorf("failed to parse repaired json: %w", err)
 	}
 
@@ -317,7 +317,7 @@ func ValidateAgainstSchema(obj any, schema Schema) error {
 // This is a convenience wrapper for use sites that hold the schema as a map rather
 // than the typed Schema struct.
 func ValidateAgainstSchemaMap(obj any, schemaMap map[string]any) error {
-	schemaBytes, err := json.Marshal(schemaMap)
+	schemaBytes, err := jsonv2.Marshal(schemaMap)
 	if err != nil {
 		return fmt.Errorf("failed to marshal schema map: %w", err)
 	}
@@ -341,7 +341,7 @@ func ValidateAgainstSchemaMap(obj any, schemaMap map[string]any) error {
 }
 
 func validateAgainstSchema(obj any, schema Schema) error {
-	jsonSchemaBytes, err := json.Marshal(schema)
+	jsonSchemaBytes, err := jsonv2.Marshal(schema)
 	if err != nil {
 		return fmt.Errorf("failed to marshal schema: %w", err)
 	}

internal/fantasy/tool.go

@@ -2,8 +2,8 @@ package fantasy
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"reflect"
 
 	"charm.land/fantasy/schema"
@@ -78,7 +78,7 @@ func NewMediaResponse(data []byte, mediaType string) ToolResponse {
 // WithResponseMetadata adds metadata to a response.
 func WithResponseMetadata(response ToolResponse, metadata any) ToolResponse {
 	if metadata != nil {
-		metadataBytes, err := json.Marshal(metadata)
+		metadataBytes, err := jsonv2.Marshal(metadata)
 		if err != nil {
 			return response
 		}
@@ -167,7 +167,7 @@ func (w *funcToolWrapper[TInput]) Info() ToolInfo {
 
 func (w *funcToolWrapper[TInput]) Run(ctx context.Context, params ToolCall) (ToolResponse, error) {
 	var input TInput
-	if err := json.Unmarshal([]byte(params.Input), &input); err != nil {
+	if err := jsonv2.Unmarshal([]byte(params.Input), &input); err != nil {
 		return NewTextErrorResponse(fmt.Sprintf("invalid parameters: %s", err)), nil
 	}
 

internal/fantasy/tool_dag.go

@@ -1,9 +1,9 @@
 package fantasy
 
 import (
-	"encoding/json"
 	"errors"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"strings"
 )
 
@@ -91,7 +91,7 @@ func extractToolDependencies(input string) ([]string, error) {
 	}
 
 	var v any
-	if err := json.Unmarshal([]byte(input), &v); err != nil {
+	if err := jsonv2.Unmarshal([]byte(input), &v); err != nil {
 		// If the tool input isn't valid JSON, treat it as having no dependencies.
 		return nil, nil
 	}

internal/fantasy/tool_runtime_dag.go

@@ -2,9 +2,9 @@ package fantasy
 
 import (
 	"context"
-	"encoding/json"
 	"errors"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"sort"
 	"strconv"
 	"strings"
@@ -233,7 +233,7 @@ func resolveToolRefsInInput(input string, results map[string]ToolResultContent)
 	}
 
 	var v any
-	if err := json.Unmarshal([]byte(input), &v); err != nil {
+	if err := jsonv2.Unmarshal([]byte(input), &v); err != nil {
 		// Not JSON; nothing to resolve.
 		return input, nil
 	}
@@ -242,7 +242,7 @@ func resolveToolRefsInInput(input string, results map[string]ToolResultContent)
 	if err != nil {
 		return "", err
 	}
-	b, err := json.Marshal(updated)
+	b, err := jsonv2.Marshal(updated)
 	if err != nil {
 		return "", err
 	}
@@ -328,7 +328,7 @@ func resolveToolRefValue(ref string, results map[string]ToolResultContent) (any,
 
 	// Path resolution: interpret base as JSON and walk.
 	var cur any
-	if err := json.Unmarshal([]byte(base), &cur); err != nil {
+	if err := jsonv2.Unmarshal([]byte(base), &cur); err != nil {
 		return nil, fmt.Errorf("tool ref %q path requires JSON output, got non-JSON", ref)
 	}
 

pkg/agent/conversations/store.go

@@ -5,7 +5,7 @@ package conversations
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"strings"
 
 	"github.com/sipeed/picoclaw/pkg/ids"
@@ -100,7 +100,7 @@ func (s *Store) EditMessage(ctx context.Context, p EditMessageParams) (sqlc.Agen
 		return sqlc.AgentMessage{}, err
 	}
 
-	metaJSON, _ := json.Marshal(p.Metadata)
+	metaJSON, _ := jsonv2.Marshal(p.Metadata)
 
 	// Best-effort revision record — a failure here does not abort the edit.
 	_, _ = s.q.AddAgentMessageRevision(ctx, sqlc.AddAgentMessageRevisionParams{
@@ -174,7 +174,7 @@ func (s *Store) ForkFromCheckpoint(ctx context.Context, p ForkFromCheckpointPara
 		Messages []msgSnapshot `json:"messages"`
 	}
 	var snap snapshot
-	_ = json.Unmarshal(runState.SnapshotJson, &snap)
+	_ = jsonv2.Unmarshal([]byte(runState.SnapshotJson), &snap)
 
 	conv, err := s.q.CreateAgentConversation(ctx, sqlc.CreateAgentConversationParams{
 		ID:    ids.New(),
@@ -188,7 +188,7 @@ func (s *Store) ForkFromCheckpoint(ctx context.Context, p ForkFromCheckpointPara
 		"checkpoint_name": cpName,
 		"run_state_id":    cp.RunStateID.String(),
 	}
-	forkMetaJSON, _ := json.Marshal(forkMeta)
+	forkMetaJSON, _ := jsonv2.Marshal(forkMeta)
 
 	_, _ = s.q.CreateAgentConversationFork(ctx, sqlc.CreateAgentConversationForkParams{
 		ID:                   ids.New(),
@@ -209,7 +209,7 @@ func (s *Store) ForkFromCheckpoint(ctx context.Context, p ForkFromCheckpointPara
 		"checkpoint_name":             cpName,
 		"run_state_id":                cp.RunStateID.String(),
 	}
-	seedMetaJSON, _ := json.Marshal(seedMeta)
+	seedMetaJSON, _ := jsonv2.Marshal(seedMeta)
 
 	for _, m := range msgs {
 		if m.Role != "user" && m.Role != "assistant" {
@@ -277,7 +277,7 @@ func (s *Store) MergeAsLinkedContext(ctx context.Context, p MergeAsLinkedContext
 	}
 
 	meta := map[string]any{"source": "merge_as_linked_context"}
-	metaJSON, _ := json.Marshal(meta)
+	metaJSON, _ := jsonv2.Marshal(meta)
 
 	_, _ = s.q.CreateAgentConversationLink(ctx, sqlc.CreateAgentConversationLinkParams{
 		ID:                   ids.New(),
@@ -321,7 +321,7 @@ type AncestryParams struct {
 // AncestryResult is the structured result of an Ancestry query.
 type AncestryResult struct {
 	Conversation sqlc.AgentConversation       `json:"conversation"`
-	ForkParent   *sqlc.AgentConversationFork  `json:"fork_parent,omitempty"`
+	ForkParent   *sqlc.AgentConversationFork  `json:"fork_parent,omitzero"`
 	ForkChildren []sqlc.AgentConversationFork `json:"fork_children"`
 	Links        []sqlc.AgentConversationLink `json:"links"`
 }
@@ -434,7 +434,7 @@ type GraphParams struct {
 // GraphNode is a single conversation node in the fork/link graph.
 type GraphNode struct {
 	ID    string  `json:"id"`
-	Title *string `json:"title,omitempty"`
+	Title *string `json:"title,omitzero"`
 }
 
 // GraphEdge is a directed edge between two conversation nodes.
@@ -444,9 +444,9 @@ type GraphEdge struct {
 	From string `json:"from"`
 	To   string `json:"to"`
 	// CheckpointID is set on fork edges.
-	CheckpointID *string `json:"checkpoint_id,omitempty"`
+	CheckpointID *string `json:"checkpoint_id,omitzero"`
 	// Kind is set on link edges (e.g. "merge").
-	Kind *string `json:"kind,omitempty"`
+	Kind *string `json:"kind,omitzero"`
 }
 
 // GraphResult is the full fork/link graph rooted at a conversation.

pkg/agent/memgpt_tool.go

@@ -7,7 +7,7 @@ package agent
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 
 	memstore "github.com/sipeed/picoclaw/pkg/memory/store"
 	"github.com/sipeed/picoclaw/pkg/tools"
@@ -84,7 +84,7 @@ func (t *MemGPTTool) Parameters() map[string]interface{} {
 
 func (t *MemGPTTool) Execute(ctx context.Context, args map[string]interface{}) *tools.ToolResult {
 	// Marshal the args back to JSON for the inner MemoryTool.Execute()
-	input, err := json.Marshal(args)
+	input, err := jsonv2.Marshal(args)
 	if err != nil {
 		return tools.ErrorResult("invalid arguments: " + err.Error())
 	}

pkg/agent/mentions/store.go

@@ -5,7 +5,7 @@ package mentions
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"strings"
 
 	"github.com/sipeed/picoclaw/pkg/ids"
@@ -76,7 +76,7 @@ func (s *Store) Add(ctx context.Context, p AddParams) (sqlc.AgentMention, error)
 		return sqlc.AgentMention{}, pcerrors.Wrapf(pcerrors.CodeInvalidArgument, err, "parse target_id %q", targetIDStr)
 	}
 
-	metaJSON, _ := json.Marshal(p.Metadata)
+	metaJSON, _ := jsonv2.Marshal(p.Metadata)
 
 	return s.q.AddAgentMention(ctx, sqlc.AddAgentMentionParams{
 		ID:             ids.New(),

pkg/agent/offloading_tool_runtime.go

@@ -2,8 +2,8 @@ package agent
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"strconv"
 	"strings"
 
@@ -91,7 +91,7 @@ func (r OffloadingToolRuntime) Execute(ctx context.Context, tools []fantasy.Agen
 		fullKey := toolResultFullKey(r.ConversationID, r.RunID, stepIndex, tc.ToolCallID)
 
 		payload, payloadType, payloadText := toolResultPayload(res)
-		b, marshalErr := json.Marshal(payload)
+		b, marshalErr := jsonv2.Marshal(payload)
 		if marshalErr != nil {
 			b = []byte(`{"error":"failed to marshal tool result payload"}`)
 			payloadType = "error"
@@ -134,7 +134,7 @@ func (r OffloadingToolRuntime) Execute(ctx context.Context, tools []fantasy.Agen
 			"result_type": payloadType,
 			"step_index":  stepIndex,
 		}
-		metaJSON, _ := json.Marshal(meta)
+		metaJSON, _ := jsonv2.Marshal(meta)
 
 		var previewPtr *string
 		if strings.TrimSpace(preview) != "" {

pkg/agent/state_store.go

@@ -6,6 +6,8 @@ import (
 	"strings"
 	"time"
 
+	jsonv2 "github.com/go-json-experiment/json"
+
 	"charm.land/fantasy"
 	"github.com/sipeed/picoclaw/pkg/ids"
 	"github.com/sipeed/picoclaw/pkg/memory/sqlc"
@@ -50,8 +52,8 @@ func (s *StateStore) UpdateRunStatus(ctx context.Context, runID ids.UUID, status
 
 	metaJSON := json.RawMessage(`{}`)
 	if meta != nil {
-		if b, err := json.Marshal(meta); err == nil {
+		if b, err := jsonv2.Marshal(meta); err == nil {
-			metaJSON = b
+			metaJSON = json.RawMessage(b)
 		}
 	}
 
@@ -75,8 +77,8 @@ func (s *StateStore) AddRunState(ctx context.Context, runID ids.UUID, stepIndex
 
 	snapJSON := json.RawMessage(`{}`)
 	if snapshot != nil {
-		if b, err := json.Marshal(snapshot); err == nil {
+		if b, err := jsonv2.Marshal(snapshot); err == nil {
-			snapJSON = b
+			snapJSON = json.RawMessage(b)
 		}
 	}
 
@@ -99,8 +101,8 @@ func (s *StateStore) AddTransition(ctx context.Context, runID ids.UUID, t fantas
 
 	metaJSON := json.RawMessage(`{}`)
 	if t.Meta != nil {
-		if b, err := json.Marshal(t.Meta); err == nil {
+		if b, err := jsonv2.Marshal(t.Meta); err == nil {
-			metaJSON = b
+			metaJSON = json.RawMessage(b)
 		}
 	}
 
@@ -152,8 +154,8 @@ func (s *CheckpointStore) CreateCheckpoint(ctx context.Context, conversationID i
 
 	metaJSON := json.RawMessage(`{}`)
 	if meta != nil {
-		if b, err := json.Marshal(meta); err == nil {
+		if b, err := jsonv2.Marshal(meta); err == nil {
-			metaJSON = b
+			metaJSON = json.RawMessage(b)
 		}
 	}
 

pkg/agent/threads/store.go

@@ -6,7 +6,7 @@ package threads
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"strings"
 
 	"github.com/sipeed/picoclaw/pkg/ids"
@@ -45,7 +45,7 @@ func (s *Store) Create(ctx context.Context, p CreateParams) (sqlc.AgentThread, e
 		return sqlc.AgentThread{}, pcerrors.Wrapf(pcerrors.CodeInvalidArgument, err, "parse conversation_id %q", convIDStr)
 	}
 
-	metaJSON, _ := json.Marshal(p.Metadata)
+	metaJSON, _ := jsonv2.Marshal(p.Metadata)
 
 	return s.q.CreateAgentThread(ctx, sqlc.CreateAgentThreadParams{
 		ID:             ids.New(),
@@ -108,7 +108,7 @@ func (s *Store) AddMessage(ctx context.Context, p AddMessageParams) (sqlc.AgentT
 		return sqlc.AgentThreadMessage{}, pcerrors.New(pcerrors.CodeInvalidArgument, "content is empty")
 	}
 
-	metaJSON, _ := json.Marshal(p.Metadata)
+	metaJSON, _ := jsonv2.Marshal(p.Metadata)
 
 	return s.q.AddAgentThreadMessage(ctx, sqlc.AddAgentThreadMessageParams{
 		ID:           ids.New(),

pkg/agent/tool_result_search.go

@@ -2,10 +2,12 @@ package agent
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"strings"
 
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
+
 	"charm.land/fantasy"
 	"github.com/sipeed/picoclaw/pkg/ids"
 	"github.com/sipeed/picoclaw/pkg/memory/sqlc"
@@ -13,23 +15,23 @@ import (
 )
 
 type ToolResultSearchView struct {
-	StartLine  int `json:"start_line,omitempty" description:"Optional. 1-indexed start line (inclusive)."`
+	StartLine  int `json:"start_line,omitzero" description:"Optional. 1-indexed start line (inclusive)."`
-	EndLine    int `json:"end_line,omitempty" description:"Optional. 1-indexed end line (inclusive)."`
+	EndLine    int `json:"end_line,omitzero" description:"Optional. 1-indexed end line (inclusive)."`
-	MaxLines   int `json:"max_lines,omitempty" description:"Optional. Default 30, max 200."`
+	MaxLines   int `json:"max_lines,omitzero" description:"Optional. Default 30, max 200."`
-	StartChunk int `json:"start_chunk,omitempty" description:"Optional. 0-indexed start chunk (inclusive)."`
+	StartChunk int `json:"start_chunk,omitzero" description:"Optional. 0-indexed start chunk (inclusive)."`
-	EndChunk   int `json:"end_chunk,omitempty" description:"Optional. 0-indexed end chunk (inclusive)."`
+	EndChunk   int `json:"end_chunk,omitzero" description:"Optional. 0-indexed end chunk (inclusive)."`
-	MaxChunks  int `json:"max_chunks,omitempty" description:"Optional. Default 3, max 20."`
+	MaxChunks  int `json:"max_chunks,omitzero" description:"Optional. Default 3, max 20."`
 }
 
 type ToolResultSearchInput struct {
-	ConversationID string `json:"conversation_id,omitempty" description:"Optional. Agent conversation UUID."`
+	ConversationID string `json:"conversation_id,omitzero" description:"Optional. Agent conversation UUID."`
-	RunID          string `json:"run_id,omitempty" description:"Optional. Agent run UUID."`
+	RunID          string `json:"run_id,omitzero" description:"Optional. Agent run UUID."`
-	ToolCallID     string `json:"tool_call_id,omitempty" description:"Optional. Tool call id to fetch (requires run_id)."`
+	ToolCallID     string `json:"tool_call_id,omitzero" description:"Optional. Tool call id to fetch (requires run_id)."`
-	ToolName       string `json:"tool_name,omitempty" description:"Optional. Filter by tool name."`
+	ToolName       string `json:"tool_name,omitzero" description:"Optional. Filter by tool name."`
-	Query          string `json:"query,omitempty" description:"Optional. Case-insensitive substring match on tool_name/tool_call_id/summary."`
+	Query          string `json:"query,omitzero" description:"Optional. Case-insensitive substring match on tool_name/tool_call_id/summary."`
 
-	Limit int                   `json:"limit,omitempty" description:"Optional. Default 5, max 50."`
+	Limit int                   `json:"limit,omitzero" description:"Optional. Default 5, max 50."`
-	View  *ToolResultSearchView `json:"view,omitempty" description:"Optional. File view range for each result."`
+	View  *ToolResultSearchView `json:"view,omitzero" description:"Optional. File view range for each result."`
 }
 
 // NewToolResultSearchTool creates the tool_result_search agent tool for
@@ -92,12 +94,12 @@ func NewToolResultSearchTool(q *sqlc.Queries, kv KVDelegate) fantasy.AgentTool {
 				StepIndex  int64          `json:"step_index"`
 				ToolCallID string         `json:"tool_call_id"`
 				ToolName   string         `json:"tool_name"`
-				Preview    *string         `json:"preview,omitempty"`
+				Preview    *string        `json:"preview,omitzero"`
 				FullKey    string         `json:"full_key"`
 				ChunkCount int64          `json:"chunk_count"`
 				View       string         `json:"view"`
 				ViewRange  map[string]int `json:"view_range"`
-				Metadata   json.RawMessage `json:"metadata_json"`
+				Metadata   jsontext.Value `json:"metadata_json"` // sqlc gives json.RawMessage; both are []byte
 			}
 
 			out := struct {
@@ -131,11 +133,11 @@ func NewToolResultSearchTool(q *sqlc.Queries, kv KVDelegate) fantasy.AgentTool {
 					ChunkCount: r.ChunkCount,
 					View:       sel,
 					ViewRange:  viewRange,
-					Metadata:   r.MetadataJson,
+					Metadata:   jsontext.Value(r.MetadataJson),
 				})
 			}
 
-			b, _ := json.Marshal(out)
+			b, _ := jsonv2.Marshal(out)
 			return fantasy.NewTextResponse(string(b)), nil
 		},
 	)

pkg/agent/tool_result_search_test.go

@@ -2,7 +2,7 @@ package agent_test
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"strings"
 	"testing"
 
@@ -58,13 +58,13 @@ func invokeSearch(t *testing.T, tool fantasy.AgentTool, input agent.ToolResultSe
 	require.False(t, resp.IsError, "search tool must not error: %s", resp.Content)
 
 	var out map[string]any
-	require.NoError(t, json.Unmarshal([]byte(resp.Content), &out))
+	require.NoError(t, jsonv2.Unmarshal([]byte(resp.Content), &out))
 	return out
 }
 
 func marshalInput(t *testing.T, v any) string {
 	t.Helper()
-	b, err := json.Marshal(v)
+	b, err := jsonv2.Marshal(v)
 	require.NoError(t, err)
 	return string(b)
 }

pkg/auth/oauth.go

@@ -5,7 +5,6 @@ import (
 	"crypto/rand"
 	"encoding/base64"
 	"encoding/hex"
-	"encoding/json"
 	"fmt"
 	"io"
 	"net"
@@ -16,6 +15,9 @@ import (
 	"strconv"
 	"strings"
 	"time"
+
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 )
 
 type OAuthProviderConfig struct {
@@ -130,10 +132,10 @@ func parseDeviceCodeResponse(body []byte) (deviceCodeResponse, error) {
 	var raw struct {
 		DeviceAuthID string         `json:"device_auth_id"`
 		UserCode     string         `json:"user_code"`
-		Interval     json.RawMessage `json:"interval"`
+		Interval     jsontext.Value `json:"interval"`
 	}
 
-	if err := json.Unmarshal(body, &raw); err != nil {
+	if err := jsonv2.Unmarshal(body, &raw); err != nil {
 		return deviceCodeResponse{}, err
 	}
 
@@ -149,18 +151,18 @@ func parseDeviceCodeResponse(body []byte) (deviceCodeResponse, error) {
 	}, nil
 }
 
-func parseFlexibleInt(raw json.RawMessage) (int, error) {
+func parseFlexibleInt(raw jsontext.Value) (int, error) {
 	if len(raw) == 0 || string(raw) == "null" {
 		return 0, nil
 	}
 
 	var interval int
-	if err := json.Unmarshal(raw, &interval); err == nil {
+	if err := jsonv2.Unmarshal(raw, &interval); err == nil {
 		return interval, nil
 	}
 
 	var intervalStr string
-	if err := json.Unmarshal(raw, &intervalStr); err == nil {
+	if err := jsonv2.Unmarshal(raw, &intervalStr); err == nil {
 		intervalStr = strings.TrimSpace(intervalStr)
 		if intervalStr == "" {
 			return 0, nil
@@ -172,7 +174,7 @@ func parseFlexibleInt(raw json.RawMessage) (int, error) {
 }
 
 func LoginDeviceCode(cfg OAuthProviderConfig) (*AuthCredential, error) {
-	reqBody, _ := json.Marshal(map[string]string{
+	reqBody, _ := jsonv2.Marshal(map[string]string{
 		"client_id": cfg.ClientID,
 	})
 
@@ -224,7 +226,7 @@ func LoginDeviceCode(cfg OAuthProviderConfig) (*AuthCredential, error) {
 }
 
 func pollDeviceCode(cfg OAuthProviderConfig, deviceAuthID, userCode string) (*AuthCredential, error) {
-	reqBody, _ := json.Marshal(map[string]string{
+	reqBody, _ := jsonv2.Marshal(map[string]string{
 		"device_auth_id": deviceAuthID,
 		"user_code":      userCode,
 	})
@@ -250,7 +252,7 @@ func pollDeviceCode(cfg OAuthProviderConfig, deviceAuthID, userCode string) (*Au
 		CodeChallenge     string `json:"code_challenge"`
 		CodeVerifier      string `json:"code_verifier"`
 	}
-	if err := json.Unmarshal(body, &tokenResp); err != nil {
+	if err := jsonv2.Unmarshal(body, &tokenResp); err != nil {
 		return nil, err
 	}
 
@@ -349,7 +351,7 @@ func parseTokenResponse(body []byte, provider string) (*AuthCredential, error) {
 		ExpiresIn    int    `json:"expires_in"`
 		IDToken      string `json:"id_token"`
 	}
-	if err := json.Unmarshal(body, &tokenResp); err != nil {
+	if err := jsonv2.Unmarshal(body, &tokenResp); err != nil {
 		return nil, fmt.Errorf("parsing token response: %w", err)
 	}
 
@@ -435,7 +437,7 @@ func parseJWTClaims(token string) (map[string]interface{}, error) {
 	}
 
 	var claims map[string]interface{}
-	if err := json.Unmarshal(decoded, &claims); err != nil {
+	if err := jsonv2.Unmarshal(decoded, &claims); err != nil {
 		return nil, err
 	}
 

pkg/auth/oauth_test.go

@@ -2,19 +2,20 @@ package auth
 
 import (
 	"encoding/base64"
-	"encoding/json"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
 	"strings"
 	"testing"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 func makeJWTForClaims(t *testing.T, claims map[string]interface{}) string {
 	t.Helper()
 
 	header := base64.RawURLEncoding.EncodeToString([]byte(`{"alg":"none","typ":"JWT"}`))
-	payloadJSON, err := json.Marshal(claims)
+	payloadJSON, err := jsonv2.Marshal(claims)
 	if err != nil {
 		t.Fatalf("marshal claims: %v", err)
 	}
@@ -95,7 +96,7 @@ func TestParseTokenResponse(t *testing.T) {
 		"expires_in":    3600,
 		"id_token":      "test-id-token",
 	}
-	body, _ := json.Marshal(resp)
+	body, _ := jsonv2.Marshal(resp)
 
 	cred, err := parseTokenResponse(body, "openai")
 	if err != nil {
@@ -127,7 +128,7 @@ func TestParseTokenResponseExtractsAccountIDFromIDToken(t *testing.T) {
 		"expires_in":    3600,
 		"id_token":      idToken,
 	}
-	body, _ := json.Marshal(resp)
+	body, _ := jsonv2.Marshal(resp)
 
 	cred, err := parseTokenResponse(body, "openai")
 	if err != nil {
@@ -166,7 +167,7 @@ func TestParseTokenResponseAccountIDFromIDToken(t *testing.T) {
 		"expires_in":    3600,
 		"id_token":      idToken,
 	}
-	body, _ := json.Marshal(resp)
+	body, _ := jsonv2.Marshal(resp)
 
 	cred, err := parseTokenResponse(body, "openai")
 	if err != nil {
@@ -206,7 +207,7 @@ func TestExchangeCodeForTokens(t *testing.T) {
 			"refresh_token": "mock-refresh-token",
 			"expires_in":    3600,
 		}
-		json.NewEncoder(w).Encode(resp)
+		jsonv2.MarshalWrite(w, resp)
 	}))
 	defer server.Close()
 
@@ -245,7 +246,7 @@ func TestRefreshAccessToken(t *testing.T) {
 			"refresh_token": "refreshed-refresh-token",
 			"expires_in":    3600,
 		}
-		json.NewEncoder(w).Encode(resp)
+		jsonv2.MarshalWrite(w, resp)
 	}))
 	defer server.Close()
 
@@ -294,7 +295,7 @@ func TestRefreshAccessTokenPreservesRefreshAndAccountID(t *testing.T) {
 			"access_token": "new-access-token-only",
 			"expires_in":   3600,
 		}
-		json.NewEncoder(w).Encode(resp)
+		jsonv2.MarshalWrite(w, resp)
 	}))
 	defer server.Close()
 

pkg/auth/store.go

@@ -1,17 +1,19 @@
 package auth
 
 import (
-	"encoding/json"
 	"os"
 	"path/filepath"
 	"time"
+
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 )
 
 type AuthCredential struct {
 	AccessToken  string    `json:"access_token"`
-	RefreshToken string    `json:"refresh_token,omitempty"`
+	RefreshToken string    `json:"refresh_token,omitzero"`
-	AccountID    string    `json:"account_id,omitempty"`
+	AccountID    string    `json:"account_id,omitzero"`
-	ExpiresAt    time.Time `json:"expires_at,omitempty"`
+	ExpiresAt    time.Time `json:"expires_at,omitzero"`
 	Provider     string    `json:"provider"`
 	AuthMethod   string    `json:"auth_method"`
 }
@@ -50,7 +52,7 @@ func LoadStore() (*AuthStore, error) {
 	}
 
 	var store AuthStore
-	if err := json.Unmarshal(data, &store); err != nil {
+	if err := jsonv2.Unmarshal(data, &store); err != nil {
 		return nil, err
 	}
 	if store.Credentials == nil {
@@ -66,7 +68,7 @@ func SaveStore(store *AuthStore) error {
 		return err
 	}
 
-	data, err := json.MarshalIndent(store, "", "  ")
+	data, err := jsonv2.Marshal(store, jsontext.WithIndent("  "))
 	if err != nil {
 		return err
 	}

pkg/channels/feishu_64.go

@@ -4,11 +4,12 @@ package channels
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"sync"
 	"time"
 
+	jsonv2 "github.com/go-json-experiment/json"
+
 	lark "github.com/larksuite/oapi-sdk-go/v3"
 	larkdispatcher "github.com/larksuite/oapi-sdk-go/v3/event/dispatcher"
 	larkim "github.com/larksuite/oapi-sdk-go/v3/service/im/v1"
@@ -97,7 +98,7 @@ func (c *FeishuChannel) Send(ctx context.Context, msg bus.OutboundMessage) error
 		return fmt.Errorf("chat ID is empty")
 	}
 
-	payload, err := json.Marshal(map[string]string{"text": msg.Content})
+	payload, err := jsonv2.Marshal(map[string]string{"text": msg.Content})
 	if err != nil {
 		return fmt.Errorf("failed to marshal feishu content: %w", err)
 	}
@@ -202,7 +203,7 @@ func extractFeishuMessageContent(message *larkim.EventMessage) string {
 		var textPayload struct {
 			Text string `json:"text"`
 		}
-		if err := json.Unmarshal([]byte(*message.Content), &textPayload); err == nil {
+		if err := jsonv2.Unmarshal([]byte(*message.Content), &textPayload); err == nil {
 			return textPayload.Text
 		}
 	}

pkg/channels/line.go

@@ -6,7 +6,6 @@ import (
 	"crypto/hmac"
 	"crypto/sha256"
 	"encoding/base64"
-	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
@@ -15,6 +14,9 @@ import (
 	"sync"
 	"time"
 
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
+
 	"github.com/sipeed/picoclaw/pkg/bus"
 	"github.com/sipeed/picoclaw/pkg/config"
 	"github.com/sipeed/picoclaw/pkg/logger"
@@ -140,7 +142,7 @@ func (c *LINEChannel) fetchBotInfo() error {
 		BasicID     string `json:"basicId"`
 		DisplayName string `json:"displayName"`
 	}
-	if err := json.NewDecoder(resp.Body).Decode(&info); err != nil {
+	if err := jsonv2.UnmarshalRead(resp.Body, &info); err != nil {
 		return err
 	}
 
@@ -199,7 +201,7 @@ func (c *LINEChannel) webhookHandler(w http.ResponseWriter, r *http.Request) {
 	var payload struct {
 		Events []lineEvent `json:"events"`
 	}
-	if err := json.Unmarshal(body, &payload); err != nil {
+	if err := jsonv2.Unmarshal(body, &payload); err != nil {
 		logger.ErrorCF("line", "Failed to parse webhook payload", map[string]interface{}{
 			"error": err.Error(),
 		})
@@ -233,7 +235,7 @@ type lineEvent struct {
 	Type       string         `json:"type"`
 	ReplyToken string         `json:"replyToken"`
 	Source     lineSource     `json:"source"`
-	Message    json.RawMessage `json:"message"`
+	Message    jsontext.Value `json:"message"`
 	Timestamp  int64          `json:"timestamp"`
 }
 
@@ -277,7 +279,7 @@ func (c *LINEChannel) processEvent(event lineEvent) {
 	isGroup := event.Source.Type == "group" || event.Source.Type == "room"
 
 	var msg lineMessage
-	if err := json.Unmarshal(event.Message, &msg); err != nil {
+	if err := jsonv2.Unmarshal(event.Message, &msg); err != nil {
 		logger.ErrorCF("line", "Failed to parse message", map[string]interface{}{
 			"error": err.Error(),
 		})
@@ -558,7 +560,7 @@ func (c *LINEChannel) sendLoading(chatID string) {
 
 // callAPI makes an authenticated POST request to the LINE API.
 func (c *LINEChannel) callAPI(ctx context.Context, endpoint string, payload interface{}) error {
-	body, err := json.Marshal(payload)
+	body, err := jsonv2.Marshal(payload)
 	if err != nil {
 		return fmt.Errorf("failed to marshal payload: %w", err)
 	}

pkg/channels/maixcam.go

@@ -2,11 +2,12 @@ package channels
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"net"
 	"sync"
 
+	jsonv2 "github.com/go-json-experiment/json"
+
 	"github.com/sipeed/picoclaw/pkg/bus"
 	"github.com/sipeed/picoclaw/pkg/config"
 	"github.com/sipeed/picoclaw/pkg/logger"
@@ -102,15 +103,13 @@ func (c *MaixCamChannel) handleConnection(conn net.Conn, ctx context.Context) {
 		logger.DebugC("maixcam", "Connection closed")
 	}()
 
-	decoder := json.NewDecoder(conn)
-
 	for {
 		select {
 		case <-ctx.Done():
 			return
 		default:
 			var msg MaixCamMessage
-			if err := decoder.Decode(&msg); err != nil {
+			if err := jsonv2.UnmarshalRead(conn, &msg); err != nil {
 				if err.Error() != "EOF" {
 					logger.ErrorCF("maixcam", "Failed to decode message", map[string]interface{}{
 						"error": err.Error(),
@@ -221,7 +220,7 @@ func (c *MaixCamChannel) Send(ctx context.Context, msg bus.OutboundMessage) erro
 		"chat_id":   msg.ChatID,
 	}
 
-	data, err := json.Marshal(response)
+	data, err := jsonv2.Marshal(response)
 	if err != nil {
 		return fmt.Errorf("failed to marshal response: %w", err)
 	}

pkg/channels/onebot.go

@@ -2,13 +2,14 @@ package channels
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"strconv"
 	"strings"
 	"sync"
 	"time"
 
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 	"github.com/gorilla/websocket"
 
 	"github.com/sipeed/picoclaw/pkg/bus"
@@ -34,17 +35,17 @@ type oneBotRawEvent struct {
 	PostType      string         `json:"post_type"`
 	MessageType   string         `json:"message_type"`
 	SubType       string         `json:"sub_type"`
-	MessageID     json.RawMessage `json:"message_id"`
+	MessageID     jsontext.Value `json:"message_id"`
-	UserID        json.RawMessage `json:"user_id"`
+	UserID        jsontext.Value `json:"user_id"`
-	GroupID       json.RawMessage `json:"group_id"`
+	GroupID       jsontext.Value `json:"group_id"`
 	RawMessage    string         `json:"raw_message"`
-	Message       json.RawMessage `json:"message"`
+	Message       jsontext.Value `json:"message"`
-	Sender        json.RawMessage `json:"sender"`
+	Sender        jsontext.Value `json:"sender"`
-	SelfID        json.RawMessage `json:"self_id"`
+	SelfID        jsontext.Value `json:"self_id"`
-	Time          json.RawMessage `json:"time"`
+	Time          jsontext.Value `json:"time"`
 	MetaEventType string         `json:"meta_event_type"`
 	Echo          string         `json:"echo"`
-	RetCode       json.RawMessage `json:"retcode"`
+	RetCode       jsontext.Value `json:"retcode"`
 	Status        BotStatus      `json:"status"`
 }
 
@@ -54,7 +55,7 @@ type BotStatus struct {
 }
 
 type oneBotSender struct {
-	UserID   json.RawMessage `json:"user_id"`
+	UserID   jsontext.Value `json:"user_id"`
 	Nickname string         `json:"nickname"`
 	Card     string         `json:"card"`
 }
@@ -78,7 +79,7 @@ type oneBotEvent struct {
 type oneBotAPIRequest struct {
 	Action string      `json:"action"`
 	Params interface{} `json:"params"`
-	Echo   string      `json:"echo,omitempty"`
+	Echo   string      `json:"echo,omitzero"`
 }
 
 type oneBotSendPrivateMsgParams struct {
@@ -236,7 +237,7 @@ func (c *OneBotChannel) Send(ctx context.Context, msg bus.OutboundMessage) error
 		Echo:   echo,
 	}
 
-	data, err := json.Marshal(req)
+	data, err := jsonv2.Marshal(req)
 	if err != nil {
 		return fmt.Errorf("failed to marshal OneBot request: %w", err)
 	}
@@ -326,7 +327,7 @@ func (c *OneBotChannel) listen() {
 			})
 
 			var raw oneBotRawEvent
-			if err := json.Unmarshal(message, &raw); err != nil {
+			if err := jsonv2.Unmarshal(message, &raw); err != nil {
 				logger.WarnCF("onebot", "Failed to unmarshal raw event", map[string]interface{}{
 					"error":   err.Error(),
 					"payload": string(message),
@@ -354,29 +355,29 @@ func (c *OneBotChannel) listen() {
 	}
 }
 
-func parseJSONInt64(raw json.RawMessage) (int64, error) {
+func parseJSONInt64(raw jsontext.Value) (int64, error) {
 	if len(raw) == 0 {
 		return 0, nil
 	}
 
 	var n int64
-	if err := json.Unmarshal(raw, &n); err == nil {
+	if err := jsonv2.Unmarshal(raw, &n); err == nil {
 		return n, nil
 	}
 
 	var s string
-	if err := json.Unmarshal(raw, &s); err == nil {
+	if err := jsonv2.Unmarshal(raw, &s); err == nil {
 		return strconv.ParseInt(s, 10, 64)
 	}
 	return 0, fmt.Errorf("cannot parse as int64: %s", string(raw))
 }
 
-func parseJSONString(raw json.RawMessage) string {
+func parseJSONString(raw jsontext.Value) string {
 	if len(raw) == 0 {
 		return ""
 	}
 	var s string
-	if err := json.Unmarshal(raw, &s); err == nil {
+	if err := jsonv2.Unmarshal(raw, &s); err == nil {
 		return s
 	}
 
@@ -388,13 +389,13 @@ type parseMessageResult struct {
 	IsBotMentioned bool
 }
 
-func parseMessageContentEx(raw json.RawMessage, selfID int64) parseMessageResult {
+func parseMessageContentEx(raw jsontext.Value, selfID int64) parseMessageResult {
 	if len(raw) == 0 {
 		return parseMessageResult{}
 	}
 
 	var s string
-	if err := json.Unmarshal(raw, &s); err == nil {
+	if err := jsonv2.Unmarshal(raw, &s); err == nil {
 		mentioned := false
 		if selfID > 0 {
 			cqAt := fmt.Sprintf("[CQ:at,qq=%d]", selfID)
@@ -408,7 +409,7 @@ func parseMessageContentEx(raw json.RawMessage, selfID int64) parseMessageResult
 	}
 
 	var segments []map[string]interface{}
-	if err := json.Unmarshal(raw, &segments); err == nil {
+	if err := jsonv2.Unmarshal(raw, &segments); err == nil {
 		var text string
 		mentioned := false
 		selfIDStr := strconv.FormatInt(selfID, 10)
@@ -497,7 +498,7 @@ func (c *OneBotChannel) normalizeMessageEvent(raw *oneBotRawEvent) (*oneBotEvent
 
 	var sender oneBotSender
 	if len(raw.Sender) > 0 {
-		if err := json.Unmarshal(raw.Sender, &sender); err != nil {
+		if err := jsonv2.Unmarshal(raw.Sender, &sender); err != nil {
 			logger.WarnCF("onebot", "Failed to parse sender", map[string]interface{}{
 				"error":  err.Error(),
 				"sender": string(raw.Sender),

pkg/channels/whatsapp.go

@@ -2,12 +2,12 @@ package channels
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"log"
 	"sync"
 	"time"
 
+	jsonv2 "github.com/go-json-experiment/json"
 	"github.com/gorilla/websocket"
 
 	"github.com/sipeed/picoclaw/pkg/bus"
@@ -92,7 +92,7 @@ func (c *WhatsAppChannel) Send(ctx context.Context, msg bus.OutboundMessage) err
 		"content": msg.Content,
 	}
 
-	data, err := json.Marshal(payload)
+	data, err := jsonv2.Marshal(payload)
 	if err != nil {
 		return fmt.Errorf("failed to marshal message: %w", err)
 	}
@@ -127,7 +127,7 @@ func (c *WhatsAppChannel) listen(ctx context.Context) {
 			}
 
 			var msg map[string]interface{}
-			if err := json.Unmarshal(message, &msg); err != nil {
+			if err := jsonv2.Unmarshal(message, &msg); err != nil {
 				log.Printf("Failed to unmarshal WhatsApp message: %v", err)
 				continue
 			}

pkg/config/config.go

@@ -1,13 +1,14 @@
 package config
 
 import (
-	"encoding/json"
 	"fmt"
 	"os"
 	"path/filepath"
 	"sync"
 
 	"github.com/caarlos0/env/v11"
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 )
 
 // FlexibleStringSlice is a []string that also accepts JSON numbers,
@@ -17,14 +18,14 @@ type FlexibleStringSlice []string
 func (f *FlexibleStringSlice) UnmarshalJSON(data []byte) error {
 	// Try []string first
 	var ss []string
-	if err := json.Unmarshal(data, &ss); err == nil {
+	if err := jsonv2.Unmarshal(data, &ss); err == nil {
 		*f = ss
 		return nil
 	}
 
 	// Try []interface{} to handle mixed types
 	var raw []interface{}
-	if err := json.Unmarshal(data, &raw); err != nil {
+	if err := jsonv2.Unmarshal(data, &raw); err != nil {
 		return err
 	}
 
@@ -251,10 +252,10 @@ type ProvidersConfig struct {
 type ProviderConfig struct {
 	APIKey      string `json:"api_key" env:"PICOCLAW_PROVIDERS_{{.Name}}_API_KEY"`
 	APIBase     string `json:"api_base" env:"PICOCLAW_PROVIDERS_{{.Name}}_API_BASE"`
-	Proxy       string `json:"proxy,omitempty" env:"PICOCLAW_PROVIDERS_{{.Name}}_PROXY"`
+	Proxy       string `json:"proxy,omitzero" env:"PICOCLAW_PROVIDERS_{{.Name}}_PROXY"`
-	AuthMethod  string `json:"auth_method,omitempty" env:"PICOCLAW_PROVIDERS_{{.Name}}_AUTH_METHOD"`
+	AuthMethod  string `json:"auth_method,omitzero" env:"PICOCLAW_PROVIDERS_{{.Name}}_AUTH_METHOD"`
-	Timeout     int    `json:"timeout,omitempty" env:"PICOCLAW_PROVIDERS_{{.Name}}_TIMEOUT"`           // seconds, 0 = default (120s)
+	Timeout     int    `json:"timeout,omitzero" env:"PICOCLAW_PROVIDERS_{{.Name}}_TIMEOUT"`           // seconds, 0 = default (120s)
-	ConnectMode string `json:"connect_mode,omitempty" env:"PICOCLAW_PROVIDERS_{{.Name}}_CONNECT_MODE"` // only for Github Copilot, `stdio` or `grpc`
+	ConnectMode string `json:"connect_mode,omitzero" env:"PICOCLAW_PROVIDERS_{{.Name}}_CONNECT_MODE"` // only for Github Copilot, `stdio` or `grpc`
 }
 
 type OpenAIProviderConfig struct {
@@ -450,7 +451,7 @@ func LoadConfig(path string) (*Config, error) {
 		return nil, err
 	}
 
-	if err := json.Unmarshal(data, cfg); err != nil {
+	if err := jsonv2.Unmarshal(data, cfg); err != nil {
 		return nil, err
 	}
 
@@ -522,7 +523,7 @@ func SaveConfig(path string, cfg *Config) error {
 	cfg.mu.RLock()
 	defer cfg.mu.RUnlock()
 
-	data, err := json.MarshalIndent(cfg, "", "  ")
+	data, err := jsonv2.Marshal(cfg, jsontext.WithIndent("  "))
 	if err != nil {
 		return err
 	}

pkg/cron/service.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"crypto/rand"
 	"encoding/hex"
-	"encoding/json"
 	"fmt"
 	"log"
 	"os"
@@ -13,31 +12,34 @@ import (
 	"time"
 
 	"github.com/adhocore/gronx"
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
+
 	"github.com/sipeed/picoclaw/pkg/memory"
 )
 
 type CronSchedule struct {
 	Kind    string `json:"kind"`
-	AtMS    *int64 `json:"atMs,omitempty"`
+	AtMS    *int64 `json:"atMs,omitzero"`
-	EveryMS *int64 `json:"everyMs,omitempty"`
+	EveryMS *int64 `json:"everyMs,omitzero"`
-	Expr    string `json:"expr,omitempty"`
+	Expr    string `json:"expr,omitzero"`
-	TZ      string `json:"tz,omitempty"`
+	TZ      string `json:"tz,omitzero"`
 }
 
 type CronPayload struct {
 	Kind    string `json:"kind"`
 	Message string `json:"message"`
-	Command string `json:"command,omitempty"`
+	Command string `json:"command,omitzero"`
 	Deliver bool   `json:"deliver"`
-	Channel string `json:"channel,omitempty"`
+	Channel string `json:"channel,omitzero"`
-	To      string `json:"to,omitempty"`
+	To      string `json:"to,omitzero"`
 }
 
 type CronJobState struct {
-	NextRunAtMS *int64 `json:"nextRunAtMs,omitempty"`
+	NextRunAtMS *int64 `json:"nextRunAtMs,omitzero"`
-	LastRunAtMS *int64 `json:"lastRunAtMs,omitempty"`
+	LastRunAtMS *int64 `json:"lastRunAtMs,omitzero"`
-	LastStatus  string `json:"lastStatus,omitempty"`
+	LastStatus  string `json:"lastStatus,omitzero"`
-	LastError   string `json:"lastError,omitempty"`
+	LastError   string `json:"lastError,omitzero"`
 }
 
 type CronJob struct {
@@ -349,7 +351,7 @@ func (cs *CronService) loadStore() error {
 		return err
 	}
 
-	return json.Unmarshal(data, cs.store)
+	return jsonv2.Unmarshal(data, cs.store)
 }
 
 func (cs *CronService) loadStoreFromDelegate() error {
@@ -360,7 +362,7 @@ func (cs *CronService) loadStoreFromDelegate() error {
 	if err != nil || val == "" {
 		return nil
 	}
-	return json.Unmarshal([]byte(val), cs.store)
+	return jsonv2.Unmarshal([]byte(val), cs.store)
 }
 
 func (cs *CronService) saveStoreUnsafe() error {
@@ -373,7 +375,7 @@ func (cs *CronService) saveStoreUnsafe() error {
 		return err
 	}
 
-	data, err := json.MarshalIndent(cs.store, "", "  ")
+	data, err := jsonv2.Marshal(cs.store, jsontext.WithIndent("  "))
 	if err != nil {
 		return err
 	}
@@ -382,7 +384,7 @@ func (cs *CronService) saveStoreUnsafe() error {
 }
 
 func (cs *CronService) saveStoreToDelegate() error {
-	data, err := json.Marshal(cs.store)
+	data, err := jsonv2.Marshal(cs.store)
 	if err != nil {
 		return err
 	}

pkg/fantasy/adapter.go

@@ -7,10 +7,11 @@ package fantasy
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 
 	"charm.land/fantasy"
+	jsonv2 "github.com/go-json-experiment/json"
+
 	"github.com/sipeed/picoclaw/pkg/bus"
 	"github.com/sipeed/picoclaw/pkg/logger"
 	memstore "github.com/sipeed/picoclaw/pkg/memory/store"
@@ -170,7 +171,7 @@ func parseToolArgs(input string) (map[string]interface{}, error) {
 	}
 
 	var args map[string]interface{}
-	if err := json.Unmarshal([]byte(input), &args); err != nil {
+	if err := jsonv2.Unmarshal([]byte(input), &args); err != nil {
 		return nil, fmt.Errorf("failed to parse tool arguments: %w", err)
 	}
 	return args, nil

pkg/fantasy/claude_cli.go

@@ -8,13 +8,13 @@ package fantasy
 import (
 	"bytes"
 	"context"
-	"encoding/json"
 	"fmt"
 	"iter"
 	"os/exec"
 	"strings"
 
 	"charm.land/fantasy"
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 // claudeCliProvider implements fantasy.Provider using the claude CLI subprocess.
@@ -147,7 +147,7 @@ func extractTextFromCLIOutput(output []byte) string {
 		Content string `json:"content"`
 		Text    string `json:"text"`
 	}
-	if err := json.Unmarshal(output, &results); err == nil {
+	if err := jsonv2.Unmarshal(output, &results); err == nil {
 		var texts []string
 		for _, r := range results {
 			switch {
@@ -167,7 +167,7 @@ func extractTextFromCLIOutput(output []byte) string {
 		Result string `json:"result"`
 		Text   string `json:"text"`
 	}
-	if err := json.Unmarshal(output, &single); err == nil {
+	if err := jsonv2.Unmarshal(output, &single); err == nil {
 		if single.Result != "" {
 			return single.Result
 		}

pkg/fantasy/convert.go

@@ -6,9 +6,9 @@
 package fantasy
 
 import (
-	"encoding/json"
-
 	"charm.land/fantasy"
+	jsonv2 "github.com/go-json-experiment/json"
+
 	"github.com/sipeed/picoclaw/pkg/messages"
 )
 
@@ -55,7 +55,7 @@ func MessageToFantasy(msg messages.Message) fantasy.Message {
 			input = tc.Function.Arguments
 		} else if tc.Arguments != nil {
 			// Fallback: serialize the map to JSON.
-			data, _ := json.Marshal(tc.Arguments)
+			data, _ := jsonv2.Marshal(tc.Arguments)
 			input = string(data)
 		}
 

pkg/health/server.go

@@ -2,11 +2,12 @@ package health
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"net/http"
 	"sync"
 	"time"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 type Server struct {
@@ -20,14 +21,14 @@ type Server struct {
 type Check struct {
 	Name      string    `json:"name"`
 	Status    string    `json:"status"`
-	Message   string    `json:"message,omitempty"`
+	Message   string    `json:"message,omitzero"`
 	Timestamp time.Time `json:"timestamp"`
 }
 
 type StatusResponse struct {
 	Status string           `json:"status"`
 	Uptime string           `json:"uptime"`
-	Checks map[string]Check `json:"checks,omitempty"`
+	Checks map[string]Check `json:"checks,omitzero"`
 }
 
 func NewServer(host string, port int) *Server {
@@ -113,7 +114,7 @@ func (s *Server) healthHandler(w http.ResponseWriter, r *http.Request) {
 		Uptime: uptime.String(),
 	}
 
-	json.NewEncoder(w).Encode(resp)
+	jsonv2.MarshalWrite(w, resp)
 }
 
 func (s *Server) readyHandler(w http.ResponseWriter, r *http.Request) {
@@ -129,7 +130,7 @@ func (s *Server) readyHandler(w http.ResponseWriter, r *http.Request) {
 
 	if !ready {
 		w.WriteHeader(http.StatusServiceUnavailable)
-		json.NewEncoder(w).Encode(StatusResponse{
+		jsonv2.MarshalWrite(w, StatusResponse{
 			Status: "not ready",
 			Checks: checks,
 		})
@@ -139,7 +140,7 @@ func (s *Server) readyHandler(w http.ResponseWriter, r *http.Request) {
 	for _, check := range checks {
 		if check.Status == "fail" {
 			w.WriteHeader(http.StatusServiceUnavailable)
-			json.NewEncoder(w).Encode(StatusResponse{
+			jsonv2.MarshalWrite(w, StatusResponse{
 				Status: "not ready",
 				Checks: checks,
 			})
@@ -149,7 +150,7 @@ func (s *Server) readyHandler(w http.ResponseWriter, r *http.Request) {
 
 	w.WriteHeader(http.StatusOK)
 	uptime := time.Since(s.startTime)
-	json.NewEncoder(w).Encode(StatusResponse{
+	jsonv2.MarshalWrite(w, StatusResponse{
 		Status: "ready",
 		Uptime: uptime.String(),
 		Checks: checks,

pkg/ids/ids_test.go

@@ -1,8 +1,9 @@
 package ids
 
 import (
-	"encoding/json"
 	"testing"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 func TestNew_IsV7(t *testing.T) {
@@ -159,14 +160,14 @@ func TestScan_InvalidType(t *testing.T) {
 func TestJSON_RoundTrip(t *testing.T) {
 	u := New()
 
-	b, err := json.Marshal(u)
+	b, err := jsonv2.Marshal(u)
 	if err != nil {
 		t.Fatalf("Marshal: %v", err)
 	}
 
 	// Should be a quoted string
 	var s string
-	if err := json.Unmarshal(b, &s); err != nil {
+	if err := jsonv2.Unmarshal(b, &s); err != nil {
 		t.Fatalf("Unmarshal to string: %v", err)
 	}
 	if s != u.String() {
@@ -174,7 +175,7 @@ func TestJSON_RoundTrip(t *testing.T) {
 	}
 
 	var parsed UUID
-	if err := json.Unmarshal(b, &parsed); err != nil {
+	if err := jsonv2.Unmarshal(b, &parsed); err != nil {
 		t.Fatalf("Unmarshal: %v", err)
 	}
 	if parsed != u {
@@ -184,7 +185,7 @@ func TestJSON_RoundTrip(t *testing.T) {
 
 func TestJSON_ZeroUUID(t *testing.T) {
 	var zero UUID
-	b, err := json.Marshal(zero)
+	b, err := jsonv2.Marshal(zero)
 	if err != nil {
 		t.Fatalf("Marshal zero: %v", err)
 	}
@@ -201,13 +202,13 @@ func TestJSON_InStruct(t *testing.T) {
 	}
 
 	r := record{ID: New(), Name: "test"}
-	b, err := json.Marshal(r)
+	b, err := jsonv2.Marshal(r)
 	if err != nil {
 		t.Fatalf("Marshal struct: %v", err)
 	}
 
 	var decoded record
-	if err := json.Unmarshal(b, &decoded); err != nil {
+	if err := jsonv2.Unmarshal(b, &decoded); err != nil {
 		t.Fatalf("Unmarshal struct: %v", err)
 	}
 	if decoded.ID != r.ID {

pkg/ids/type.go

@@ -2,9 +2,10 @@ package ids
 
 import (
 	"database/sql/driver"
-	"encoding/json"
 	"errors"
 	"fmt"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 // UUID represents a 16-byte RFC-9562 UUIDv7 value.
@@ -85,13 +86,13 @@ func (u *UUID) Scan(src interface{}) error {
 
 // MarshalJSON encodes UUID as JSON string.
 func (u UUID) MarshalJSON() ([]byte, error) {
-	return json.Marshal(u.String())
+	return jsonv2.Marshal(u.String())
 }
 
 // UnmarshalJSON decodes UUID from JSON string.
 func (u *UUID) UnmarshalJSON(b []byte) error {
 	var s string
-	if err := json.Unmarshal(b, &s); err != nil {
+	if err := jsonv2.Unmarshal(b, &s); err != nil {
 		return err
 	}
 	parsed, err := Parse(s)

pkg/itr/commands.go

@@ -3,20 +3,15 @@
 // recursive decomposition operations — are serialized as ToolRequest /
 // ToolResponse pairs.
 //
-// The canonical schema lives in commands.fbs. This file provides the Go
+// The canonical schema lives in commands.fbs. Wire encoding uses FlatBuffers
-// types and encoding helpers that replace the raw flatc-generated code while
+// for all internal transport (socket, daemon, WASM). JSON encoding is
-// keeping the same wire format semantics. The encoding uses encoding/json
+// available via MarshalJSON / UnmarshalRequestJSON for the LLM boundary only.
-// on the initial implementation path; the FlatBuffers binary encoding is
-// available via the flatbuffers package when performance demands it.
-//
-// Migration path: when the codebase moves to the full FlatBuffers binary
-// encoding, replace the JSON marshal/unmarshal calls with flatbuffers builder
-// calls without changing any call sites — the public types remain stable.
 package itr
 
 import (
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 	"time"
 )
 
@@ -113,6 +108,10 @@ type CodeExec struct {
 // command payload and declares dependencies on other nodes by ID.
 // Args may contain "#nodeN" references that are resolved to the output of
 // the dependency node at execution time.
+//
+// Implements json.Unmarshaler to deserialize Payload directly into the
+// concrete type indicated by Type, avoiding the map[string]interface{}
+// erasure that encoding/json applies to interface{} fields.
 type DAGNode struct {
 	ID        string      `json:"id"`
 	Type      CommandType `json:"type"`
@@ -120,6 +119,92 @@ type DAGNode struct {
 	DependsOn []string    `json:"depends_on,omitempty"`
 }
 
+// UnmarshalJSONFrom implements jsonv2.UnmarshalerFrom. It defers Payload
+// deserialization via jsontext.Value until the Type discriminator is known,
+// then unmarshals directly into the concrete Go type.
+func (n *DAGNode) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
+	var raw struct {
+		ID        string         `json:"id"`
+		Type      CommandType    `json:"type"`
+		Payload   jsontext.Value `json:"payload"`
+		DependsOn []string       `json:"depends_on,omitempty"`
+	}
+	if err := jsonv2.UnmarshalDecode(dec, &raw); err != nil {
+		return err
+	}
+	n.ID = raw.ID
+	n.Type = raw.Type
+	n.DependsOn = raw.DependsOn
+
+	if len(raw.Payload) == 0 || string(raw.Payload) == "null" {
+		return nil
+	}
+
+	unmarshalPayload := func(dst any) error {
+		return jsonv2.Unmarshal(raw.Payload, dst, jsonv2.MatchCaseInsensitiveNames(true))
+	}
+
+	switch raw.Type {
+	case CmdToolExec:
+		var p ToolExec
+		if err := unmarshalPayload(&p); err != nil {
+			return fmt.Errorf("DAGNode %s payload: %w", raw.ID, err)
+		}
+		n.Payload = p
+	case CmdToolSearch:
+		var p ToolSearch
+		if err := unmarshalPayload(&p); err != nil {
+			return fmt.Errorf("DAGNode %s payload: %w", raw.ID, err)
+		}
+		n.Payload = p
+	case CmdPeek:
+		var p Peek
+		if err := unmarshalPayload(&p); err != nil {
+			return fmt.Errorf("DAGNode %s payload: %w", raw.ID, err)
+		}
+		n.Payload = p
+	case CmdGrep:
+		var p Grep
+		if err := unmarshalPayload(&p); err != nil {
+			return fmt.Errorf("DAGNode %s payload: %w", raw.ID, err)
+		}
+		n.Payload = p
+	case CmdPartition:
+		var p Partition
+		if err := unmarshalPayload(&p); err != nil {
+			return fmt.Errorf("DAGNode %s payload: %w", raw.ID, err)
+		}
+		n.Payload = p
+	case CmdRecurse:
+		var p Recurse
+		if err := unmarshalPayload(&p); err != nil {
+			return fmt.Errorf("DAGNode %s payload: %w", raw.ID, err)
+		}
+		n.Payload = p
+	case CmdCodeExec:
+		var p CodeExec
+		if err := unmarshalPayload(&p); err != nil {
+			return fmt.Errorf("DAGNode %s payload: %w", raw.ID, err)
+		}
+		n.Payload = p
+	case CmdExecWasm:
+		var p ExecWasm
+		if err := unmarshalPayload(&p); err != nil {
+			return fmt.Errorf("DAGNode %s payload: %w", raw.ID, err)
+		}
+		n.Payload = p
+	case CmdFinal:
+		var p Final
+		if err := unmarshalPayload(&p); err != nil {
+			return fmt.Errorf("DAGNode %s payload: %w", raw.ID, err)
+		}
+		n.Payload = p
+	default:
+		return fmt.Errorf("DAGNode %s: unknown type %q", raw.ID, raw.Type)
+	}
+	return nil
+}
+
 // DAGPlan is a composite command that contains multiple DAGNodes forming a
 // Directed Acyclic Graph. The executor dispatches nodes in topological order,
 // running independent nodes in parallel.
@@ -269,30 +354,77 @@ func NewLeakResponse(id, redactedResult string, redactedKeys []string) ToolRespo
 	}
 }
 
-// ── Serialisation helpers ────────────────────────────────────────────────────
+// ── Serialisation helpers (FlatBuffers default) ──────────────────────────────
 
-// Marshal encodes a ToolRequest to JSON bytes for transmission.
+// Marshal encodes a ToolRequest to FlatBuffers bytes for internal transport.
 func (r ToolRequest) Marshal() ([]byte, error) {
-	return json.Marshal(r)
+	return MarshalRequestFB(r)
 }
 
-// Marshal encodes a ToolResponse to JSON bytes for transmission.
+// Marshal encodes a ToolResponse to FlatBuffers bytes for internal transport.
 func (r ToolResponse) Marshal() ([]byte, error) {
-	return json.Marshal(r)
+	return MarshalResponseFB(r)
 }
 
-// UnmarshalRequest decodes a ToolRequest from JSON bytes.
+// UnmarshalRequest decodes a ToolRequest from FlatBuffers bytes.
 func UnmarshalRequest(data []byte) (ToolRequest, error) {
+	return UnmarshalRequestFB(data)
+}
+
+// UnmarshalResponse decodes a ToolResponse from FlatBuffers bytes.
+func UnmarshalResponse(data []byte) (ToolResponse, error) {
+	return UnmarshalResponseFB(data)
+}
+
+// ── JSON helpers (LLM boundary only) ─────────────────────────────────────────
+
+// MarshalJSONTo implements jsonv2.MarshalerTo. Use only at the LLM boundary.
+func (r ToolRequest) MarshalJSONTo(enc *jsontext.Encoder) error {
+	type alias struct {
+		ID         string      `json:"id"`
+		Type       CommandType `json:"type"`
+		Payload    interface{} `json:"payload"`
+		Timestamp  int64       `json:"timestamp"`
+		Depth      uint8       `json:"depth,omitzero"`
+		SessionKey string      `json:"session_key,omitzero"`
+		ToolCallID string      `json:"tool_call_id,omitzero"`
+	}
+	return jsonv2.MarshalEncode(enc, alias{r.ID, r.Type, r.Payload, r.Timestamp, r.Depth, r.SessionKey, r.ToolCallID})
+}
+
+// MarshalJSONTo implements jsonv2.MarshalerTo. Use only at the LLM boundary.
+func (r ToolResponse) MarshalJSONTo(enc *jsontext.Encoder) error {
+	type alias struct {
+		ID           string   `json:"id"`
+		Result       string   `json:"result,omitzero"`
+		IsError      bool     `json:"is_error,omitzero"`
+		LeakDetected bool     `json:"leak_detected,omitzero"`
+		CostTokens   uint32   `json:"cost_tokens,omitzero"`
+		RedactedKeys []string `json:"redacted_keys,omitzero"`
+	}
+	return jsonv2.MarshalEncode(enc, alias{r.ID, r.Result, r.IsError, r.LeakDetected, r.CostTokens, r.RedactedKeys})
+}
+
+// LLMJSONOpts returns json/v2 options suitable for unmarshaling LLM-generated JSON,
+// which may use inconsistent casing.
+func LLMJSONOpts() jsonv2.Options {
+	return jsonv2.MatchCaseInsensitiveNames(true)
+}
+
+// UnmarshalRequestJSON decodes a ToolRequest from JSON bytes. Use only at
+// the LLM boundary (planner output, tool schemas).
+func UnmarshalRequestJSON(data []byte) (ToolRequest, error) {
+	opts := LLMJSONOpts()
 	var raw struct {
 		ID         string         `json:"id"`
 		Type       CommandType    `json:"type"`
-		Payload    json.RawMessage `json:"payload"`
+		Payload    jsontext.Value `json:"payload"`
 		Timestamp  int64          `json:"timestamp"`
 		Depth      uint8          `json:"depth"`
 		SessionKey string         `json:"session_key"`
 		ToolCallID string         `json:"tool_call_id"`
 	}
-	if err := json.Unmarshal(data, &raw); err != nil {
+	if err := jsonv2.Unmarshal(data, &raw, opts); err != nil {
 		return ToolRequest{}, err
 	}
 
@@ -305,47 +437,51 @@ func UnmarshalRequest(data []byte) (ToolRequest, error) {
 		ToolCallID: raw.ToolCallID,
 	}
 
+	unmarshalPayload := func(dst any) error {
+		return jsonv2.Unmarshal(raw.Payload, dst, opts)
+	}
+
 	var err error
 	switch raw.Type {
 	case CmdPeek:
 		var p Peek
-		err = json.Unmarshal(raw.Payload, &p)
+		err = unmarshalPayload(&p)
 		req.Payload = p
 	case CmdGrep:
 		var p Grep
-		err = json.Unmarshal(raw.Payload, &p)
+		err = unmarshalPayload(&p)
 		req.Payload = p
 	case CmdPartition:
 		var p Partition
-		err = json.Unmarshal(raw.Payload, &p)
+		err = unmarshalPayload(&p)
 		req.Payload = p
 	case CmdRecurse:
 		var p Recurse
-		err = json.Unmarshal(raw.Payload, &p)
+		err = unmarshalPayload(&p)
 		req.Payload = p
 	case CmdToolExec:
 		var p ToolExec
-		err = json.Unmarshal(raw.Payload, &p)
+		err = unmarshalPayload(&p)
 		req.Payload = p
 	case CmdExecWasm:
 		var p ExecWasm
-		err = json.Unmarshal(raw.Payload, &p)
+		err = unmarshalPayload(&p)
 		req.Payload = p
 	case CmdFinal:
 		var p Final
-		err = json.Unmarshal(raw.Payload, &p)
+		err = unmarshalPayload(&p)
 		req.Payload = p
 	case CmdToolSearch:
 		var p ToolSearch
-		err = json.Unmarshal(raw.Payload, &p)
+		err = unmarshalPayload(&p)
 		req.Payload = p
 	case CmdCodeExec:
 		var p CodeExec
-		err = json.Unmarshal(raw.Payload, &p)
+		err = unmarshalPayload(&p)
 		req.Payload = p
 	case CmdDAGPlan:
 		var p DAGPlan
-		err = json.Unmarshal(raw.Payload, &p)
+		err = unmarshalPayload(&p)
 		req.Payload = p
 	default:
 		return ToolRequest{}, fmt.Errorf("unknown command type: %q", raw.Type)
@@ -354,8 +490,8 @@ func UnmarshalRequest(data []byte) (ToolRequest, error) {
 	return req, err
 }
 
-// UnmarshalResponse decodes a ToolResponse from JSON bytes.
+// UnmarshalResponseJSON decodes a ToolResponse from JSON bytes.
-func UnmarshalResponse(data []byte) (ToolResponse, error) {
+func UnmarshalResponseJSON(data []byte) (ToolResponse, error) {
 	var r ToolResponse
-	return r, json.Unmarshal(data, &r)
+	return r, jsonv2.Unmarshal(data, &r)
 }

pkg/itr/dag/executor.go

@@ -13,7 +13,6 @@ package dag
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"runtime"
 	"strings"
@@ -133,8 +132,9 @@ func (e *Executor) Execute(ctx context.Context, sessionKey string, plan *itr.DAG
 					select {
 					case <-depState.done:
 						if _, depErr := depState.getResult(); depErr != nil {
-							ns.setResult("", fmt.Errorf("dependency %s failed: %w", dep, depErr))
+							wrapped := fmt.Errorf("dependency %s failed: %w", dep, depErr)
-							errOnce.Do(func() { waveErr = depErr })
+							ns.setResult("", wrapped)
+							errOnce.Do(func() { waveErr = wrapped })
 							return
 						}
 					case <-ctx.Done():
@@ -215,34 +215,31 @@ func (e *Executor) Execute(ctx context.Context, sessionKey string, plan *itr.DAG
 // executeNode dispatches a single node through the SecureBus after resolving
 // dependency references in its payload.
 func (e *Executor) executeNode(ctx context.Context, sessionKey string, node *itr.DAGNode, states map[string]*nodeState) itr.ToolResponse {
-	req := nodeToRequest(sessionKey, node, states)
+	req, err := nodeToRequest(sessionKey, node, states)
+	if err != nil {
+		return itr.NewErrorResponse(node.ID, err.Error())
+	}
 	return e.bus.Execute(ctx, req)
 }
 
 // nodeToRequest converts a DAGNode into a ToolRequest, resolving #nodeN
 // references in tool arguments.
-func nodeToRequest(sessionKey string, node *itr.DAGNode, states map[string]*nodeState) itr.ToolRequest {
+func nodeToRequest(sessionKey string, node *itr.DAGNode, states map[string]*nodeState) (itr.ToolRequest, error) {
 	switch node.Type {
 	case itr.CmdToolExec:
 		te, ok := node.Payload.(itr.ToolExec)
 		if !ok {
-			if m, ok := node.Payload.(map[string]interface{}); ok {
+			return itr.ToolRequest{}, fmt.Errorf("node %s: expected ToolExec payload, got %T", node.ID, node.Payload)
-				b, _ := json.Marshal(m)
-				_ = json.Unmarshal(b, &te)
-			}
 		}
 		te.ArgsJSON = resolveToolExecArgs(te.ArgsJSON, states)
-		return itr.NewToolExecRequest(node.ID, sessionKey, node.ID, te.ToolName, te.ArgsJSON)
+		return itr.NewToolExecRequest(node.ID, sessionKey, node.ID, te.ToolName, te.ArgsJSON), nil
 
 	case itr.CmdToolSearch:
 		ts, ok := node.Payload.(itr.ToolSearch)
 		if !ok {
-			if m, ok := node.Payload.(map[string]interface{}); ok {
+			return itr.ToolRequest{}, fmt.Errorf("node %s: expected ToolSearch payload, got %T", node.ID, node.Payload)
-				b, _ := json.Marshal(m)
-				_ = json.Unmarshal(b, &ts)
 		}
-		}
+		return itr.NewToolSearchRequest(node.ID, sessionKey, ts.Query, ts.MaxResults), nil
-		return itr.NewToolSearchRequest(node.ID, sessionKey, ts.Query, ts.MaxResults)
 
 	default:
 		return itr.ToolRequest{
@@ -250,7 +247,7 @@ func nodeToRequest(sessionKey string, node *itr.DAGNode, states map[string]*node
 			Type:       node.Type,
 			Payload:    node.Payload,
 			SessionKey: sessionKey,
-		}
+		}, nil
 	}
 }
 

pkg/itr/dag/executor_test.go

@@ -2,8 +2,8 @@ package dag_test
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"testing"
 
 	"github.com/sipeed/picoclaw/pkg/itr"
@@ -123,7 +123,11 @@ func TestExecutor_WithJoiner(t *testing.T) {
 	defer bus.Close()
 
 	joiner := func(_ context.Context, _, userQuery string) (string, uint32, error) {
-		return "synthesized: " + userQuery[:20], 50, nil
+		n := len(userQuery)
+		if n > 20 {
+			n = 20
+		}
+		return "synthesized: " + userQuery[:n], 50, nil
 	}
 
 	executor := dag.NewExecutor(bus, joiner)
@@ -173,7 +177,8 @@ func TestResolver_NodeRefSubstitution(t *testing.T) {
 
 	result, err := executor.Execute(context.Background(), "test-sess", plan)
 	require.NoError(t, err)
-	_ = result
+	assert.Contains(t, result.NodeResults["prev"], "previous-output")
+	assert.Contains(t, result.NodeResults["search"], "found")
 }
 
 func TestRouter_SimpleQuerySelectsReAct(t *testing.T) {
@@ -225,7 +230,7 @@ func TestPlanner_ValidatePlan(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			var plan itr.DAGPlan
-			err := json.Unmarshal([]byte(tt.plan), &plan)
+			err := jsonv2.Unmarshal([]byte(tt.plan), &plan)
 			require.NoError(t, err)
 
 			// Use planner with a mock that returns the pre-built plan JSON

pkg/itr/dag/planner.go

@@ -2,8 +2,8 @@ package dag
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 
 	"github.com/sipeed/picoclaw/pkg/itr"
 	"github.com/sipeed/picoclaw/pkg/tools"
@@ -115,32 +115,10 @@ func parsePlanResponse(response string) (*itr.DAGPlan, error) {
 	response = extractJSON(response)
 
 	var plan itr.DAGPlan
-	if err := json.Unmarshal([]byte(response), &plan); err != nil {
+	if err := jsonv2.Unmarshal([]byte(response), &plan, itr.LLMJSONOpts()); err != nil {
 		return nil, fmt.Errorf("JSON parse error: %w\nraw: %s", err, truncate(response, 500))
 	}
 
-	// Unmarshal re-encodes Payload as map[string]interface{} via JSON round-trip.
-	// Convert payload maps to their proper types.
-	for i := range plan.Nodes {
-		n := &plan.Nodes[i]
-		m, ok := n.Payload.(map[string]interface{})
-		if !ok {
-			continue
-		}
-		b, _ := json.Marshal(m)
-
-		switch n.Type {
-		case itr.CmdToolExec:
-			var te itr.ToolExec
-			_ = json.Unmarshal(b, &te)
-			n.Payload = te
-		case itr.CmdToolSearch:
-			var ts itr.ToolSearch
-			_ = json.Unmarshal(b, &ts)
-			n.Payload = ts
-		}
-	}
-
 	return &plan, nil
 }
 

pkg/itr/dag/resolver.go

@@ -1,8 +1,8 @@
 package dag
 
 import (
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"regexp"
 	"strings"
 	"sync"
@@ -67,11 +67,10 @@ func resolveToolExecArgs(argsJSON string, states map[string]*nodeState) string {
 
 // escapeForJSON makes a string safe for embedding into a JSON value.
 func escapeForJSON(s string) string {
-	b, err := json.Marshal(s)
+	b, err := jsonv2.Marshal(s)
-	if err != nil {
+	if err != nil || len(b) < 2 {
 		return s
 	}
-	// Strip surrounding quotes since we're replacing within an existing string.
 	return string(b[1 : len(b)-1])
 }
 

pkg/logger/logger.go

@@ -1,7 +1,6 @@
 package logger
 
 import (
-	"encoding/json"
 	"fmt"
 	"log"
 	"os"
@@ -9,6 +8,8 @@ import (
 	"strings"
 	"sync"
 	"time"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 type LogLevel int
@@ -43,10 +44,10 @@ type Logger struct {
 type LogEntry struct {
 	Level     string                 `json:"level"`
 	Timestamp string                 `json:"timestamp"`
-	Component string                 `json:"component,omitempty"`
+	Component string                 `json:"component,omitzero"`
 	Message   string                 `json:"message"`
-	Fields    map[string]interface{} `json:"fields,omitempty"`
+	Fields    map[string]interface{} `json:"fields,omitzero"`
-	Caller    string                 `json:"caller,omitempty"`
+	Caller    string                 `json:"caller,omitzero"`
 }
 
 func init() {
@@ -117,7 +118,7 @@ func logMessage(level LogLevel, component string, message string, fields map[str
 	}
 
 	if logger.file != nil {
-		jsonData, err := json.Marshal(entry)
+		jsonData, err := jsonv2.Marshal(entry)
 		if err == nil {
 			logger.file.WriteString(string(jsonData) + "\n")
 		}

pkg/memory/delegate/sqlite_integration_test.go

@@ -2,7 +2,7 @@ package delegate
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"testing"
 
 	"github.com/sipeed/picoclaw/pkg/ids"
@@ -38,7 +38,7 @@ func TestCronKVBackend_Roundtrip(t *testing.T) {
 		},
 	}
 
-	data, err := json.Marshal(store)
+	data, err := jsonv2.Marshal(store)
 	require.NoError(t, err)
 
 	require.NoError(t, d.UpsertKV(ctx, agentID, kvKey, string(data)))
@@ -48,7 +48,7 @@ func TestCronKVBackend_Roundtrip(t *testing.T) {
 	require.NotEmpty(t, raw)
 
 	var loaded cronStore
-	require.NoError(t, json.Unmarshal([]byte(raw), &loaded))
+	require.NoError(t, jsonv2.Unmarshal([]byte(raw), &loaded))
 
 	assert.Equal(t, 1, loaded.Version)
 	assert.Len(t, loaded.Jobs, 2)

pkg/memory/migrate_sessions.go

@@ -5,8 +5,8 @@ package memory
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"os"
 	"path/filepath"
 	"strings"
@@ -23,7 +23,7 @@ const migrationMarkerFile = ".sessions_migrated"
 type SessionFile struct {
 	Key      string       `json:"key"`
 	Messages []SessionMsg `json:"messages"`
-	Summary  string       `json:"summary,omitempty"`
+	Summary  string       `json:"summary,omitzero"`
 	Created  time.Time    `json:"created"`
 	Updated  time.Time    `json:"updated"`
 }
@@ -80,7 +80,7 @@ func MigrateFileSessions(ctx context.Context, del MemoryDelegate, agentID, sessi
 		}
 
 		var sess SessionFile
-		if err := json.Unmarshal(data, &sess); err != nil {
+		if err := jsonv2.Unmarshal(data, &sess); err != nil {
 			logger.WarnCF("migrate", "Failed to parse session file",
 				map[string]interface{}{"path": sessPath, "error": err.Error()})
 			result.Errors++

pkg/memory/migrate_sessions_test.go

@@ -2,7 +2,7 @@ package memory
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"os"
 	"path/filepath"
 	"testing"
@@ -103,7 +103,7 @@ func (m *mockDelegate) CountAuditEntries(_ context.Context, _ string) (int, erro
 
 func writeSessionFile(t *testing.T, dir, name string, sess SessionFile) {
 	t.Helper()
-	data, err := json.Marshal(sess)
+	data, err := jsonv2.Marshal(sess)
 	if err != nil {
 		t.Fatalf("marshal session: %v", err)
 	}

pkg/memory/migrate_state.go

@@ -2,7 +2,7 @@ package memory
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"log"
 	"os"
 	"path/filepath"
@@ -10,8 +10,8 @@ import (
 )
 
 type legacyState struct {
-	LastChannel string    `json:"last_channel,omitempty"`
+	LastChannel string    `json:"last_channel,omitzero"`
-	LastChatID  string    `json:"last_chat_id,omitempty"`
+	LastChatID  string    `json:"last_chat_id,omitzero"`
 	Timestamp   time.Time `json:"timestamp"`
 }
 
@@ -39,7 +39,7 @@ func MigrateState(ctx context.Context, workspace string, delegate MemoryDelegate
 	}
 
 	var s legacyState
-	if err := json.Unmarshal(data, &s); err != nil {
+	if err := jsonv2.Unmarshal(data, &s); err != nil {
 		log.Printf("[WARN] migrate_state: failed to parse %s: %v", stateFile, err)
 		return nil
 	}

pkg/memory/observation/observation.go

@@ -14,8 +14,8 @@
 package observation
 
 import (
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"strings"
 	"time"
 )
@@ -97,7 +97,7 @@ func FormatBlock(observations []Observation) string {
 
 // MarshalObservations serializes observations to JSON for KV storage.
 func MarshalObservations(obs []Observation) (string, error) {
-	data, err := json.Marshal(obs)
+	data, err := jsonv2.Marshal(obs)
 	if err != nil {
 		return "", fmt.Errorf("marshal observations: %w", err)
 	}
@@ -110,7 +110,7 @@ func UnmarshalObservations(data string) ([]Observation, error) {
 		return nil, nil
 	}
 	var obs []Observation
-	if err := json.Unmarshal([]byte(data), &obs); err != nil {
+	if err := jsonv2.Unmarshal([]byte(data), &obs); err != nil {
 		return nil, fmt.Errorf("unmarshal observations: %w", err)
 	}
 	return obs, nil

pkg/memory/store/embed_factory_test.go

@@ -1,7 +1,7 @@
 package store
 
 import (
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -38,11 +38,12 @@ func TestNewEmbedderFromConfig_OpenAI_NoKey(t *testing.T) {
 
 func TestNewEmbedderFromConfig_OpenAI_FallbackKey(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		json.NewEncoder(w).Encode(map[string]interface{}{
+		respData, _ := jsonv2.Marshal(map[string]interface{}{
 			"data": []map[string]interface{}{
 				{"index": 0, "embedding": []float32{0.1, 0.2, 0.3}},
 			},
 		})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 
@@ -70,9 +71,10 @@ func TestNewEmbedderFromConfig_OpenAI_FallbackKey(t *testing.T) {
 
 func TestNewEmbedderFromConfig_Ollama(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		json.NewEncoder(w).Encode(map[string]interface{}{
+		respData, _ := jsonv2.Marshal(map[string]interface{}{
 			"embeddings": [][]float32{{0.1, 0.2, 0.3}},
 		})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 
@@ -97,9 +99,10 @@ func TestNewEmbedderFromConfig_Ollama(t *testing.T) {
 
 func TestNewEmbedderFromConfig_Ollama_FallbackBase(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		json.NewEncoder(w).Encode(map[string]interface{}{
+		respData, _ := jsonv2.Marshal(map[string]interface{}{
 			"embeddings": [][]float32{{0.5}},
 		})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 
@@ -119,9 +122,10 @@ func TestNewEmbedderFromConfig_Ollama_FallbackBase(t *testing.T) {
 
 func TestNewEmbedderFromConfig_CaseInsensitive(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		json.NewEncoder(w).Encode(map[string]interface{}{
+		respData, _ := jsonv2.Marshal(map[string]interface{}{
 			"embeddings": [][]float32{{0.1}},
 		})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 

pkg/memory/store/embed_ollama.go

@@ -3,8 +3,8 @@ package store
 import (
 	"bytes"
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"io"
 	"net/http"
 	"time"
@@ -93,7 +93,7 @@ func (o *OllamaEmbedder) embedBatch(ctx context.Context, texts []string) ([]memo
 }
 
 func (o *OllamaEmbedder) embedSingle(ctx context.Context, text string) (memory.Embedding, error) {
-	body, err := json.Marshal(ollamaEmbedRequest{
+	body, err := jsonv2.Marshal(ollamaEmbedRequest{
 		Model: o.model,
 		Input: text,
 	})
@@ -119,7 +119,7 @@ func (o *OllamaEmbedder) embedSingle(ctx context.Context, text string) (memory.E
 	}
 
 	var result ollamaEmbedResponse
-	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
+	if err := jsonv2.UnmarshalRead(resp.Body, &result); err != nil {
 		return nil, fmt.Errorf("decode response: %w", err)
 	}
 

pkg/memory/store/embed_ollama_test.go

@@ -2,7 +2,7 @@ package store
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -18,14 +18,15 @@ func TestOllamaEmbedder_Embed(t *testing.T) {
 		}
 
 		var req ollamaEmbedRequest
-		json.NewDecoder(r.Body).Decode(&req)
+		jsonv2.UnmarshalRead(r.Body, &req)
 		if req.Model != "test-model" {
 			t.Errorf("expected model 'test-model', got %q", req.Model)
 		}
 
-		json.NewEncoder(w).Encode(ollamaEmbedResponse{
+		respData, _ := jsonv2.Marshal(ollamaEmbedResponse{
 			Embeddings: [][]float32{{0.1, 0.2, 0.3, 0.4}},
 		})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 
@@ -55,9 +56,10 @@ func TestOllamaEmbedder_EmbedBatch(t *testing.T) {
 	callCount := 0
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		callCount++
-		json.NewEncoder(w).Encode(ollamaEmbedResponse{
+		respData, _ := jsonv2.Marshal(ollamaEmbedResponse{
 			Embeddings: [][]float32{{float32(callCount) * 0.1}},
 		})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 
@@ -91,7 +93,8 @@ func TestOllamaEmbedder_ServerError(t *testing.T) {
 
 func TestOllamaEmbedder_EmptyResponse(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		json.NewEncoder(w).Encode(ollamaEmbedResponse{Embeddings: [][]float32{}})
+		respData, _ := jsonv2.Marshal(ollamaEmbedResponse{Embeddings: [][]float32{}})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 

pkg/memory/store/embed_openai.go

@@ -3,8 +3,8 @@ package store
 import (
 	"bytes"
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"io"
 	"net/http"
 	"time"
@@ -59,7 +59,7 @@ func NewOpenAIEmbedder(cfg OpenAIEmbedderConfig) *OpenAIEmbedder {
 type openAIEmbedRequest struct {
 	Input          interface{} `json:"input"` // string or []string
 	Model          string      `json:"model"`
-	EncodingFormat string      `json:"encoding_format,omitempty"`
+	EncodingFormat string      `json:"encoding_format,omitzero"`
 }
 
 type openAIEmbedResponse struct {
@@ -100,7 +100,7 @@ func (o *OpenAIEmbedder) call(ctx context.Context, texts []string) ([]memory.Emb
 		input = texts
 	}
 
-	body, err := json.Marshal(openAIEmbedRequest{
+	body, err := jsonv2.Marshal(openAIEmbedRequest{
 		Input:          input,
 		Model:          o.model,
 		EncodingFormat: "float",
@@ -130,7 +130,7 @@ func (o *OpenAIEmbedder) call(ctx context.Context, texts []string) ([]memory.Emb
 	}
 
 	var result openAIEmbedResponse
-	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
+	if err := jsonv2.UnmarshalRead(resp.Body, &result); err != nil {
 		return nil, fmt.Errorf("decode response: %w", err)
 	}
 

pkg/memory/store/embed_openai_test.go

@@ -2,7 +2,7 @@ package store
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -20,16 +20,17 @@ func TestOpenAIEmbedder_Embed(t *testing.T) {
 		}
 
 		var req openAIEmbedRequest
-		json.NewDecoder(r.Body).Decode(&req)
+		jsonv2.UnmarshalRead(r.Body, &req)
 		if req.Model != "test-embed" {
 			t.Errorf("expected model 'test-embed', got %q", req.Model)
 		}
 
-		json.NewEncoder(w).Encode(openAIEmbedResponse{
+		respData, _ := jsonv2.Marshal(openAIEmbedResponse{
 			Data: []openAIEmbedData{
 				{Index: 0, Embedding: []float32{0.5, 0.6, 0.7}},
 			},
 		})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 
@@ -57,7 +58,7 @@ func TestOpenAIEmbedder_Embed(t *testing.T) {
 func TestOpenAIEmbedder_EmbedBatch(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		var req openAIEmbedRequest
-		json.NewDecoder(r.Body).Decode(&req)
+		jsonv2.UnmarshalRead(r.Body, &req)
 
 		// Batch request should send array
 		texts, ok := req.Input.([]interface{})
@@ -73,7 +74,8 @@ func TestOpenAIEmbedder_EmbedBatch(t *testing.T) {
 			}
 		}
 
-		json.NewEncoder(w).Encode(openAIEmbedResponse{Data: data})
+		respData, _ := jsonv2.Marshal(openAIEmbedResponse{Data: data})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 
@@ -94,16 +96,17 @@ func TestOpenAIEmbedder_EmbedBatch(t *testing.T) {
 func TestOpenAIEmbedder_SingleTextNotArray(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		var req openAIEmbedRequest
-		json.NewDecoder(r.Body).Decode(&req)
+		jsonv2.UnmarshalRead(r.Body, &req)
 
 		// Single text should be sent as string, not array
 		if _, ok := req.Input.(string); !ok {
 			t.Errorf("expected string input for single text, got %T", req.Input)
 		}
 
-		json.NewEncoder(w).Encode(openAIEmbedResponse{
+		respData, _ := jsonv2.Marshal(openAIEmbedResponse{
 			Data: []openAIEmbedData{{Index: 0, Embedding: []float32{1.0}}},
 		})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 
@@ -140,9 +143,10 @@ func TestOpenAIEmbedder_NoAuth(t *testing.T) {
 		if r.Header.Get("Authorization") != "" {
 			t.Error("expected no auth header when key is empty")
 		}
-		json.NewEncoder(w).Encode(openAIEmbedResponse{
+		respData, _ := jsonv2.Marshal(openAIEmbedResponse{
 			Data: []openAIEmbedData{{Index: 0, Embedding: []float32{1.0}}},
 		})
+		w.Write(respData)
 	}))
 	defer srv.Close()
 

pkg/memory/store/memory_tool.go

@@ -2,8 +2,8 @@ package store
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"strings"
 
 	"github.com/sipeed/picoclaw/pkg/ids"
@@ -25,31 +25,31 @@ const (
 // MemoryToolRequest is the input to the memory tool.
 type MemoryToolRequest struct {
 	Action  MemoryToolAction `json:"action"`
-	Query   string           `json:"query,omitempty"`   // For search
+	Query   string           `json:"query,omitzero"`   // For search
-	ID      string           `json:"id,omitempty"`      // For read/update/delete
+	ID      string           `json:"id,omitzero"`      // For read/update/delete
-	Content string           `json:"content,omitempty"` // For write/update
+	Content string           `json:"content,omitzero"` // For write/update
-	Source  string           `json:"source,omitempty"`  // For write
+	Source  string           `json:"source,omitzero"`  // For write
-	Sector  string           `json:"sector,omitempty"`  // For write: episodic/semantic/procedural/reflective
+	Sector  string           `json:"sector,omitzero"`  // For write: episodic/semantic/procedural/reflective
-	Tags    string           `json:"tags,omitempty"`    // For write: comma-separated
+	Tags    string           `json:"tags,omitzero"`    // For write: comma-separated
-	Tier    string           `json:"tier,omitempty"`    // "recall" or "archival" — defaults to "recall"
+	Tier    string           `json:"tier,omitzero"`    // "recall" or "archival" — defaults to "recall"
-	Limit   int              `json:"limit,omitempty"`   // For search — defaults to 5
+	Limit   int              `json:"limit,omitzero"`   // For search — defaults to 5
 }
 
 // MemoryToolResponse is the output of the memory tool.
 type MemoryToolResponse struct {
 	Success bool              `json:"success"`
-	Message string            `json:"message,omitempty"`
+	Message string            `json:"message,omitzero"`
-	Results []MemoryToolEntry `json:"results,omitempty"`
+	Results []MemoryToolEntry `json:"results,omitzero"`
-	Status  *MemoryToolStatus `json:"status,omitempty"`
+	Status  *MemoryToolStatus `json:"status,omitzero"`
 }
 
 // MemoryToolEntry is a single memory entry in tool results.
 type MemoryToolEntry struct {
 	ID      string  `json:"id"`
 	Content string  `json:"content"`
-	Source  string  `json:"source,omitempty"`
+	Source  string  `json:"source,omitzero"`
-	Sector  string  `json:"sector,omitempty"`
+	Sector  string  `json:"sector,omitzero"`
-	Score   float64 `json:"score,omitempty"`
+	Score   float64 `json:"score,omitzero"`
 }
 
 // MemoryToolStatus summarizes the memory system state.
@@ -82,7 +82,7 @@ func NewMemoryTool(store *MemoryStore, agentID, session string) *MemoryTool {
 // Execute processes a memory tool request and returns a JSON response.
 func (t *MemoryTool) Execute(ctx context.Context, input string) (string, error) {
 	var req MemoryToolRequest
-	if err := json.Unmarshal([]byte(input), &req); err != nil {
+	if err := jsonv2.Unmarshal([]byte(input), &req); err != nil {
 		return t.errorResponse("invalid input: " + err.Error()), nil
 	}
 
@@ -325,6 +325,6 @@ func (t *MemoryTool) errorResponse(msg string) string {
 }
 
 func (t *MemoryTool) jsonResponse(resp *MemoryToolResponse) string {
-	b, _ := json.Marshal(resp)
+	b, _ := jsonv2.Marshal(resp)
 	return string(b)
 }

pkg/memory/store/memory_tool_test.go

@@ -2,7 +2,7 @@ package store
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -22,7 +22,7 @@ func executeAndParse(t *testing.T, tool *MemoryTool, input string) *MemoryToolRe
 	require.NoError(t, err)
 
 	var resp MemoryToolResponse
-	require.NoError(t, json.Unmarshal([]byte(raw), &resp))
+	require.NoError(t, jsonv2.Unmarshal([]byte(raw), &resp))
 	return &resp
 }
 

pkg/migrate/config.go

@@ -1,13 +1,14 @@
 package migrate
 
 import (
-	"encoding/json"
 	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
 	"unicode"
 
+	jsonv2 "github.com/go-json-experiment/json"
+
 	"github.com/sipeed/picoclaw/pkg/config"
 )
 
@@ -51,7 +52,7 @@ func LoadOpenClawConfig(configPath string) (map[string]interface{}, error) {
 	}
 
 	var raw map[string]interface{}
-	if err := json.Unmarshal(data, &raw); err != nil {
+	if err := jsonv2.Unmarshal(data, &raw); err != nil {
 		return nil, fmt.Errorf("parsing OpenClaw config: %w", err)
 	}
 

pkg/migrate/migrate_test.go

@@ -1,11 +1,12 @@
 package migrate
 
 import (
-	"encoding/json"
 	"os"
 	"path/filepath"
 	"testing"
 
+	jsonv2 "github.com/go-json-experiment/json"
+
 	"github.com/sipeed/picoclaw/pkg/config"
 )
 
@@ -104,7 +105,7 @@ func TestLoadOpenClawConfig(t *testing.T) {
 		},
 	}
 
-	data, err := json.Marshal(openclawConfig)
+	data, err := jsonv2.Marshal(openclawConfig)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -583,7 +584,7 @@ func TestRunDryRun(t *testing.T) {
 			},
 		},
 	}
-	data, _ := json.Marshal(configData)
+	data, _ := jsonv2.Marshal(configData)
 	os.WriteFile(filepath.Join(openclawHome, "openclaw.json"), data, 0644)
 
 	opts := Options{
@@ -638,7 +639,7 @@ func TestRunFullMigration(t *testing.T) {
 			},
 		},
 	}
-	data, _ := json.Marshal(configData)
+	data, _ := jsonv2.Marshal(configData)
 	os.WriteFile(filepath.Join(openclawHome, "openclaw.json"), data, 0644)
 
 	opts := Options{
@@ -784,7 +785,7 @@ func TestRunConfigOnly(t *testing.T) {
 			},
 		},
 	}
-	data, _ := json.Marshal(configData)
+	data, _ := jsonv2.Marshal(configData)
 	os.WriteFile(filepath.Join(openclawHome, "openclaw.json"), data, 0644)
 
 	opts := Options{
@@ -824,7 +825,7 @@ func TestRunWorkspaceOnly(t *testing.T) {
 			},
 		},
 	}
-	data, _ := json.Marshal(configData)
+	data, _ := jsonv2.Marshal(configData)
 	os.WriteFile(filepath.Join(openclawHome, "openclaw.json"), data, 0644)
 
 	opts := Options{

pkg/pcerrors/cli.go

@@ -1,12 +1,13 @@
 package pcerrors
 
 import (
-	"encoding/json"
 	"fmt"
 	"io"
 	"os"
 	"regexp"
 	"strings"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 // CLIHandler is the PicoClaw error lifecycle boundary for the CLI.
@@ -50,7 +51,7 @@ func (h CLIHandler) Handle(err error) int {
 		if h.Verbose {
 			record["detail"] = err.Error()
 		}
-		data, _ := json.Marshal(record)
+		data, _ := jsonv2.Marshal(record)
 		_, _ = fmt.Fprintln(w, string(data))
 	} else {
 		_, _ = fmt.Fprintln(w, msg)

pkg/security/jsonextract.go

@@ -2,9 +2,9 @@
 package security
 
 import (
-	"encoding/json"
 	"errors"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
 	"strings"
 )
 
@@ -50,12 +50,12 @@ func ExtractJSON(text string, dest interface{}, opts *ExtractJSONOptions) error
 		return ErrNoJSON
 	}
 
-	dec := json.NewDecoder(strings.NewReader(cleaned))
+	var jsonOpts []jsonv2.Options
 	if opts.DisallowUnknownFields {
-		dec.DisallowUnknownFields()
+		jsonOpts = append(jsonOpts, jsonv2.RejectUnknownMembers(true))
 	}
 
-	if err := dec.Decode(dest); err != nil {
+	if err := jsonv2.Unmarshal([]byte(cleaned), dest, jsonOpts...); err != nil {
 		return fmt.Errorf("json decode: %w", err)
 	}
 	return nil

pkg/security/jsonextract_test.go

@@ -107,7 +107,7 @@ func TestExtractJSON_InjectionAttempts(t *testing.T) {
 			&ExtractJSONOptions{DisallowUnknownFields: true},
 			func(t *testing.T, err error) {
 				assert.Error(t, err)
-				assert.Contains(t, err.Error(), "unknown field")
+				assert.Contains(t, err.Error(), "unknown object member name")
 			},
 		},
 		{

pkg/security/secretstore.go

@@ -1,9 +1,10 @@
 package security
 
 import (
-	"encoding/json"
 	"errors"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 	"os"
 	"path/filepath"
 	"sync"
@@ -132,7 +133,7 @@ func (ss *SecretStore) load() error {
 		return err
 	}
 	var entries []SecretEntry
-	if err := json.Unmarshal(data, &entries); err != nil {
+	if err := jsonv2.Unmarshal(data, &entries); err != nil {
 		return fmt.Errorf("parse secret store: %w", err)
 	}
 	for _, e := range entries {
@@ -150,7 +151,7 @@ func (ss *SecretStore) save() error {
 	}
 	ss.mu.RUnlock()
 
-	data, err := json.MarshalIndent(entries, "", "  ")
+	data, err := jsonv2.Marshal(entries, jsontext.WithIndent("  "))
 	if err != nil {
 		return fmt.Errorf("marshal secret store: %w", err)
 	}

pkg/security/securebus/bus.go

@@ -2,8 +2,10 @@ package securebus
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	jsonv2 "github.com/go-json-experiment/json"
+	"log"
+	"sync"
 	"time"
 
 	"github.com/sipeed/picoclaw/pkg/itr"
@@ -62,6 +64,7 @@ type Bus struct {
 	executor   ToolExecutor
 	toolSearch ToolSearchFunc // nil = no tool search support
 	done       chan struct{}
+	closeOnce  sync.Once
 }
 
 // New creates a Bus and starts background worker goroutines.
@@ -106,10 +109,12 @@ func (b *Bus) AuditLog() *AuditLog {
 	return b.audit
 }
 
-// Close shuts down the bus workers gracefully.
+// Close shuts down the bus workers gracefully. Safe to call multiple times.
 func (b *Bus) Close() {
+	b.closeOnce.Do(func() {
 		b.transport.Close()
 		close(b.done)
+	})
 }
 
 // Execute is a convenience method for in-process callers that don't want to
@@ -155,12 +160,16 @@ func (b *Bus) dispatch(ctx context.Context, req itr.ToolRequest) itr.ToolRespons
 	case itr.CmdToolSearch:
 		resp := b.handleToolSearch(ctx, req)
 		event.DurationMS = time.Since(start).Milliseconds()
-		_ = b.audit.Append(event)
+		if err := b.audit.Append(event); err != nil {
+			log.Printf("securebus: audit append failed: %v", err)
+		}
 		return resp
 	default:
 		resp := b.handleRLMCommand(ctx, req)
 		event.DurationMS = time.Since(start).Milliseconds()
-		_ = b.audit.Append(event)
+		if err := b.audit.Append(event); err != nil {
+			log.Printf("securebus: audit append failed: %v", err)
+		}
 		return resp
 	}
 
@@ -168,7 +177,9 @@ func (b *Bus) dispatch(ctx context.Context, req itr.ToolRequest) itr.ToolRespons
 	if !ok {
 		event.IsError = true
 		event.DurationMS = time.Since(start).Milliseconds()
-		_ = b.audit.Append(event)
+		if err := b.audit.Append(event); err != nil {
+			log.Printf("securebus: audit append failed: %v", err)
+		}
 		return itr.NewErrorResponse(req.ID, "internal: payload is not ToolExec")
 	}
 	event.ToolName = te.ToolName
@@ -184,17 +195,21 @@ func (b *Bus) dispatch(ctx context.Context, req itr.ToolRequest) itr.ToolRespons
 		event.IsError = true
 		event.PolicyViolation = err.Error()
 		event.DurationMS = time.Since(start).Milliseconds()
-		_ = b.audit.Append(event)
+		if err := b.audit.Append(event); err != nil {
+			log.Printf("securebus: audit append failed: %v", err)
+		}
 		return itr.NewErrorResponse(req.ID, "policy violation: "+err.Error())
 	}
 
 	// 3. Deserialise args — always produce a non-nil map for safe injection.
 	args := make(map[string]interface{})
 	if te.ArgsJSON != "" && te.ArgsJSON != "null" {
-		if err := json.Unmarshal([]byte(te.ArgsJSON), &args); err != nil {
+		if err := jsonv2.Unmarshal([]byte(te.ArgsJSON), &args); err != nil {
 			event.IsError = true
 			event.DurationMS = time.Since(start).Milliseconds()
-			_ = b.audit.Append(event)
+			if err := b.audit.Append(event); err != nil {
+				log.Printf("securebus: audit append failed: %v", err)
+			}
 			return itr.NewErrorResponse(req.ID, fmt.Sprintf("invalid args JSON: %v", err))
 		}
 	}
@@ -204,7 +219,9 @@ func (b *Bus) dispatch(ctx context.Context, req itr.ToolRequest) itr.ToolRespons
 	if err != nil {
 		event.IsError = true
 		event.DurationMS = time.Since(start).Milliseconds()
-		_ = b.audit.Append(event)
+		if err := b.audit.Append(event); err != nil {
+			log.Printf("securebus: audit append failed: %v", err)
+		}
 		return itr.NewErrorResponse(req.ID, "secret injection failed: "+err.Error())
 	}
 	event.SecretsAccessed = injectedSecrets
@@ -232,7 +249,9 @@ func (b *Bus) dispatch(ctx context.Context, req itr.ToolRequest) itr.ToolRespons
 
 	event.IsError = resp.IsError
 	event.DurationMS = time.Since(start).Milliseconds()
-	_ = b.audit.Append(event)
+	if err := b.audit.Append(event); err != nil {
+		log.Printf("securebus: audit append failed: %v", err)
+	}
 	return resp
 }
 

pkg/security/securebus/bus_test.go

@@ -2,7 +2,7 @@ package securebus_test
 
 import (
 	"context"
-	"encoding/json"
+	jsonv2 "github.com/go-json-experiment/json"
 	"testing"
 
 	"github.com/sipeed/picoclaw/pkg/itr"
@@ -49,7 +49,7 @@ func makeArgsJSON(kv map[string]interface{}) string {
 	if kv == nil {
 		return "{}"
 	}
-	b, _ := json.Marshal(kv)
+	b, _ := jsonv2.Marshal(kv)
 	return string(b)
 }
 
@@ -248,3 +248,56 @@ func TestBus_RLMFinalCommand(t *testing.T) {
 	assert.False(t, resp.IsError)
 	assert.Equal(t, "the answer", resp.Result)
 }
+
+func TestBus_CloseIdempotent(t *testing.T) {
+	bus := makeBus(t, nil, nil)
+
+	assert.NotPanics(t, func() {
+		bus.Close()
+		bus.Close()
+		bus.Close()
+	}, "Close() must be safe to call multiple times")
+}
+
+func TestBus_ToolSearch(t *testing.T) {
+	bus := makeBus(t, nil, nil)
+	defer bus.Close()
+
+	bus.SetToolSearch(func(query string, maxResults int) string {
+		return `[{"name":"read_file","description":"reads a file"}]`
+	})
+
+	req := itr.NewToolSearchRequest("req-search", "sess", "file operations", 5)
+	resp := bus.Execute(context.Background(), req)
+
+	assert.False(t, resp.IsError)
+	assert.Contains(t, resp.Result, "read_file")
+}
+
+func TestBus_ToolSearchNotConfigured(t *testing.T) {
+	bus := makeBus(t, nil, nil)
+	defer bus.Close()
+
+	req := itr.NewToolSearchRequest("req-search2", "sess", "anything", 5)
+	resp := bus.Execute(context.Background(), req)
+
+	assert.True(t, resp.IsError)
+	assert.Contains(t, resp.Result, "not configured")
+}
+
+func TestBus_NilToolResult(t *testing.T) {
+	executor := func(ctx context.Context, name string, args map[string]interface{}) *tools.ToolResult {
+		return nil
+	}
+	capLookup := func(name string) (tools.ToolCapabilities, bool) {
+		return tools.ZeroCapabilities(), true
+	}
+	bus := securebus.New(securebus.DefaultBusConfig(), nil, capLookup, executor)
+	defer bus.Close()
+
+	req := itr.NewToolExecRequest("req-nil", "sess", "tc", "something", "{}")
+	resp := bus.Execute(context.Background(), req)
+
+	assert.False(t, resp.IsError)
+	assert.Empty(t, resp.Result)
+}

pkg/session/manager.go

@@ -2,13 +2,15 @@ package session
 
 import (
 	"context"
-	"encoding/json"
 	"os"
 	"path/filepath"
 	"strings"
 	"sync"
 	"time"
 
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
+
 	"github.com/sipeed/picoclaw/pkg/cache"
 	"github.com/sipeed/picoclaw/pkg/ids"
 	"github.com/sipeed/picoclaw/pkg/logger"
@@ -19,7 +21,7 @@ import (
 type Session struct {
 	Key      string             `json:"key"`
 	Messages []messages.Message `json:"messages"`
-	Summary  string             `json:"summary,omitempty"`
+	Summary  string             `json:"summary,omitzero"`
 	Created  time.Time          `json:"created"`
 	Updated  time.Time          `json:"updated"`
 }
@@ -197,7 +199,7 @@ func (sm *SessionManager) loadSessionFromDisk(key string) *Session {
 		return nil
 	}
 	var session Session
-	if err := json.Unmarshal(data, &session); err != nil {
+	if err := jsonv2.Unmarshal(data, &session); err != nil {
 		return nil
 	}
 	return &session
@@ -487,7 +489,7 @@ func snapshotSession(s *Session) Session {
 }
 
 func (sm *SessionManager) writeSessionToDisk(key string, session *Session) error {
-	data, err := json.MarshalIndent(session, "", "  ")
+	data, err := jsonv2.Marshal(session, jsontext.WithIndent("  "))
 	if err != nil {
 		return err
 	}
@@ -558,7 +560,7 @@ func (sm *SessionManager) loadSessions() error {
 		}
 
 		var session Session
-		if err := json.Unmarshal(data, &session); err != nil {
+		if err := jsonv2.Unmarshal(data, &session); err != nil {
 			continue
 		}
 

pkg/skills/installer.go

@@ -2,7 +2,6 @@ package skills
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
@@ -10,6 +9,8 @@ import (
 	"path/filepath"
 	"strings"
 	"time"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 type SkillInstaller struct {
@@ -117,7 +118,7 @@ func (si *SkillInstaller) ListAvailableSkills(ctx context.Context) ([]AvailableS
 	}
 
 	var skills []AvailableSkill
-	if err := json.Unmarshal(body, &skills); err != nil {
+	if err := jsonv2.Unmarshal(body, &skills); err != nil {
 		return nil, fmt.Errorf("failed to parse skills list: %w", err)
 	}
 

pkg/skills/loader.go

@@ -1,7 +1,6 @@
 package skills
 
 import (
-	"encoding/json"
 	"errors"
 	"fmt"
 	"log/slog"
@@ -9,6 +8,8 @@ import (
 	"path/filepath"
 	"regexp"
 	"strings"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 var namePattern = regexp.MustCompile(`^[a-zA-Z0-9]+(-[a-zA-Z0-9]+)*$`)
@@ -21,10 +22,10 @@ const (
 type SkillMetadata struct {
 	Name        string   `json:"name"`
 	Description string   `json:"description"`
-	Tags        []string `json:"tags,omitempty"`
+	Tags        []string `json:"tags,omitzero"`
-	Links       []string `json:"links,omitempty"`
+	Links       []string `json:"links,omitzero"`
-	Domain      string   `json:"domain,omitempty"`
+	Domain      string   `json:"domain,omitzero"`
-	IsMOC       bool     `json:"is_moc,omitempty"`
+	IsMOC       bool     `json:"is_moc,omitzero"`
 }
 
 type SkillInfo struct {
@@ -32,8 +33,8 @@ type SkillInfo struct {
 	Path        string   `json:"path"`
 	Source      string   `json:"source"`
 	Description string   `json:"description"`
-	Tags        []string `json:"tags,omitempty"`
+	Tags        []string `json:"tags,omitzero"`
-	Domain      string   `json:"domain,omitempty"`
+	Domain      string   `json:"domain,omitzero"`
 }
 
 func (info SkillInfo) validate() error {
@@ -281,7 +282,7 @@ func (sl *SkillsLoader) getSkillMetadata(skillPath string) *SkillMetadata {
 
 	// Try JSON first (for backward compatibility)
 	var jsonMeta SkillMetadata
-	if err := json.Unmarshal([]byte(frontmatter), &jsonMeta); err == nil && jsonMeta.Name != "" {
+	if err := jsonv2.Unmarshal([]byte(frontmatter), &jsonMeta); err == nil && jsonMeta.Name != "" {
 		return &jsonMeta
 	}
 

pkg/state/state.go

@@ -2,7 +2,6 @@ package state
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"log"
 	"os"
@@ -10,6 +9,9 @@ import (
 	"sync"
 	"time"
 
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
+
 	"github.com/sipeed/picoclaw/pkg/memory"
 )
 
@@ -19,10 +21,10 @@ const kvAgentID = "picoclaw"
 // It includes information about the last active channel/chat.
 type State struct {
 	// LastChannel is the last channel used for communication
-	LastChannel string `json:"last_channel,omitempty"`
+	LastChannel string `json:"last_channel,omitzero"`
 
 	// LastChatID is the last chat ID used for communication
-	LastChatID string `json:"last_chat_id,omitempty"`
+	LastChatID string `json:"last_chat_id,omitzero"`
 
 	// Timestamp is the last time this state was updated
 	Timestamp time.Time `json:"timestamp"`
@@ -73,7 +75,7 @@ func NewManager(workspace string, opts ...Option) *Manager {
 
 	if _, err := os.Stat(stateFile); os.IsNotExist(err) {
 		if data, err := os.ReadFile(oldStateFile); err == nil {
-			if err := json.Unmarshal(data, sm.state); err == nil {
+			if err := jsonv2.Unmarshal(data, sm.state); err == nil {
 				sm.saveAtomic()
 				log.Printf("[INFO] state: migrated state from %s to %s", oldStateFile, stateFile)
 			}
@@ -180,7 +182,7 @@ func (sm *Manager) saveAtomic() error {
 	tempFile := sm.stateFile + ".tmp"
 
 	// Marshal state to JSON
-	data, err := json.MarshalIndent(sm.state, "", "  ")
+	data, err := jsonv2.Marshal(sm.state, jsontext.WithIndent("  "))
 	if err != nil {
 		return fmt.Errorf("failed to marshal state: %w", err)
 	}
@@ -211,7 +213,7 @@ func (sm *Manager) load() error {
 		return fmt.Errorf("failed to read state file: %w", err)
 	}
 
-	if err := json.Unmarshal(data, sm.state); err != nil {
+	if err := jsonv2.Unmarshal(data, sm.state); err != nil {
 		return fmt.Errorf("failed to unmarshal state: %w", err)
 	}
 

pkg/state/state_test.go

@@ -1,11 +1,12 @@
 package state
 
 import (
-	"encoding/json"
 	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 func TestAtomicSave(t *testing.T) {
@@ -162,7 +163,7 @@ func TestConcurrentAccess(t *testing.T) {
 	}
 
 	var state State
-	if err := json.Unmarshal(data, &state); err != nil {
+	if err := jsonv2.Unmarshal(data, &state); err != nil {
 		t.Errorf("State file contains invalid JSON: %v", err)
 	}
 }

pkg/tools/call.go

@@ -2,9 +2,10 @@ package tools
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 
+	jsonv2 "github.com/go-json-experiment/json"
+
 	"github.com/sipeed/picoclaw/pkg/logger"
 )
 
@@ -84,7 +85,7 @@ func (t *ToolCallTool) Execute(ctx context.Context, args map[string]interface{})
 		if len(v) > maxArgsJSON {
 			return ErrorResult(fmt.Sprintf("arguments JSON too large: %d bytes (max %d)", len(v), maxArgsJSON))
 		}
-		if err := json.Unmarshal([]byte(v), &toolArgs); err != nil {
+		if err := jsonv2.Unmarshal([]byte(v), &toolArgs); err != nil {
 			return ErrorResult(fmt.Sprintf("invalid arguments JSON: %v", err))
 		}
 	case nil:

pkg/tools/focus.go

@@ -2,11 +2,12 @@ package tools
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"strings"
 	"time"
 
+	jsonv2 "github.com/go-json-experiment/json"
+
 	"github.com/sipeed/picoclaw/pkg/logger"
 	"github.com/sipeed/picoclaw/pkg/messages"
 	"github.com/sipeed/picoclaw/pkg/session"
@@ -109,7 +110,7 @@ func (t *StartFocusTool) Execute(ctx context.Context, args map[string]interface{
 		StartedAt:       time.Now(),
 	}
 
-	data, err := json.Marshal(state)
+	data, err := jsonv2.Marshal(state)
 	if err != nil {
 		return ErrorResult(fmt.Sprintf("marshal focus state: %v", err))
 	}
@@ -181,7 +182,7 @@ func (t *CompleteFocusTool) Execute(ctx context.Context, args map[string]interfa
 	}
 
 	var state FocusState
-	if err := json.Unmarshal([]byte(raw), &state); err != nil {
+	if err := jsonv2.Unmarshal([]byte(raw), &state); err != nil {
 		return ErrorResult(fmt.Sprintf("corrupt focus state: %v", err))
 	}
 
@@ -251,7 +252,7 @@ func (t *CompleteFocusTool) appendKnowledge(ctx context.Context, sessionKey, top
 	kb := &KnowledgeBlock{}
 	raw, err := t.delegate.GetKV(ctx, focusAgentID, kvKey)
 	if err == nil && raw != "" {
-		_ = json.Unmarshal([]byte(raw), kb)
+		_ = jsonv2.Unmarshal([]byte(raw), kb)
 	}
 
 	kb.Entries = append(kb.Entries, KnowledgeEntry{
@@ -260,7 +261,7 @@ func (t *CompleteFocusTool) appendKnowledge(ctx context.Context, sessionKey, top
 		CreatedAt: time.Now(),
 	})
 
-	data, err := json.Marshal(kb)
+	data, err := jsonv2.Marshal(kb)
 	if err != nil {
 		return err
 	}
@@ -280,7 +281,7 @@ func LoadKnowledgeBlock(ctx context.Context, delegate KVStore, sessionKey string
 	}
 
 	var kb KnowledgeBlock
-	if err := json.Unmarshal([]byte(raw), &kb); err != nil {
+	if err := jsonv2.Unmarshal([]byte(raw), &kb); err != nil {
 		return ""
 	}
 

pkg/tools/focus_test.go

@@ -2,9 +2,10 @@ package tools
 
 import (
 	"context"
-	"encoding/json"
 	"testing"
 
+	jsonv2 "github.com/go-json-experiment/json"
+
 	"github.com/sipeed/picoclaw/pkg/messages"
 	"github.com/sipeed/picoclaw/pkg/session"
 	"github.com/stretchr/testify/assert"
@@ -75,7 +76,7 @@ func TestStartFocus(t *testing.T) {
 	require.NotEmpty(t, raw)
 
 	var state FocusState
-	require.NoError(t, json.Unmarshal([]byte(raw), &state))
+	require.NoError(t, jsonv2.Unmarshal([]byte(raw), &state))
 	assert.Equal(t, "investigate auth bug", state.Topic)
 	assert.Equal(t, 2, state.CheckpointIndex)
 }
@@ -134,7 +135,7 @@ func TestCompleteFocus(t *testing.T) {
 	require.NotEmpty(t, knowledgeRaw)
 
 	var kb KnowledgeBlock
-	require.NoError(t, json.Unmarshal([]byte(knowledgeRaw), &kb))
+	require.NoError(t, jsonv2.Unmarshal([]byte(knowledgeRaw), &kb))
 	require.Len(t, kb.Entries, 1)
 	assert.Equal(t, "debug auth", kb.Entries[0].Topic)
 	assert.Contains(t, kb.Entries[0].Summary, "token validation")
@@ -184,7 +185,7 @@ func TestCompleteFocus_MultipleKnowledgeEntries(t *testing.T) {
 
 	knowledgeRaw, _ := delegate.GetKV(ctx, focusAgentID, knowledgeKVPrefix+sk)
 	var kb KnowledgeBlock
-	require.NoError(t, json.Unmarshal([]byte(knowledgeRaw), &kb))
+	require.NoError(t, jsonv2.Unmarshal([]byte(knowledgeRaw), &kb))
 	require.Len(t, kb.Entries, 2)
 	assert.Equal(t, "topic A", kb.Entries[0].Topic)
 	assert.Equal(t, "topic B", kb.Entries[1].Topic)
@@ -286,7 +287,7 @@ func TestLoadKnowledgeBlock(t *testing.T) {
 			{Topic: "Test", Summary: "Test summary"},
 		},
 	}
-	data, _ := json.Marshal(kb)
+	data, _ := jsonv2.Marshal(kb)
 	_ = delegate.UpsertKV(ctx, focusAgentID, knowledgeKVPrefix+"test-session", string(data))
 
 	block = LoadKnowledgeBlock(ctx, delegate, "test-session")

pkg/tools/i2c.go

@@ -2,11 +2,13 @@ package tools
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"path/filepath"
 	"regexp"
 	"runtime"
+
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 )
 
 // I2CTool provides I2C bus interaction for reading sensors and controlling peripherals.
@@ -111,7 +113,7 @@ func (t *I2CTool) detect() *ToolResult {
 		}
 	}
 
-	result, _ := json.MarshalIndent(buses, "", "  ")
+	result, _ := jsonv2.Marshal(buses, jsontext.WithIndent("  "))
 	return SilentResult(fmt.Sprintf("Found %d I2C bus(es):\n%s", len(buses), string(result)))
 }
 

pkg/tools/i2c_linux.go

@@ -1,10 +1,12 @@
 package tools
 
 import (
-	"encoding/json"
 	"fmt"
 	"syscall"
 	"unsafe"
+
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 )
 
 // I2C ioctl constants from Linux kernel headers (<linux/i2c-dev.h>, <linux/i2c.h>)
@@ -104,7 +106,7 @@ func (t *I2CTool) scan(args map[string]interface{}) *ToolResult {
 
 	type deviceEntry struct {
 		Address string `json:"address"`
-		Status  string `json:"status,omitempty"`
+		Status  string `json:"status,omitzero"`
 	}
 
 	var found []deviceEntry
@@ -133,11 +135,11 @@ func (t *I2CTool) scan(args map[string]interface{}) *ToolResult {
 		return SilentResult(fmt.Sprintf("No devices found on %s. Check wiring and pull-up resistors.", devPath))
 	}
 
-	result, _ := json.MarshalIndent(map[string]interface{}{
+	result, _ := jsonv2.Marshal(map[string]interface{}{
 		"bus":     devPath,
 		"devices": found,
 		"count":   len(found),
-	}, "", "  ")
+	}, jsontext.WithIndent("  "))
 	return SilentResult(fmt.Sprintf("Scan of %s:\n%s", devPath, string(result)))
 }
 
@@ -201,13 +203,13 @@ func (t *I2CTool) readDevice(args map[string]interface{}) *ToolResult {
 		intBytes[i] = int(buf[i])
 	}
 
-	result, _ := json.MarshalIndent(map[string]interface{}{
+	result, _ := jsonv2.Marshal(map[string]interface{}{
 		"bus":     devPath,
 		"address": fmt.Sprintf("0x%02x", addr),
 		"bytes":   intBytes,
 		"hex":     hexBytes,
 		"length":  n,
-	}, "", "  ")
+	}, jsontext.WithIndent("  "))
 	return SilentResult(string(result))
 }
 

pkg/tools/result.go

@@ -1,6 +1,6 @@
 package tools
 
-import "encoding/json"
+import jsonv2 "github.com/go-json-experiment/json"
 
 // ToolResult represents the structured return value from tool execution.
 // It provides clear semantics for different types of results and supports
@@ -124,7 +124,7 @@ func UserResult(content string) *ToolResult {
 // The Err field is excluded from JSON output via the json:"-" tag.
 func (tr *ToolResult) MarshalJSON() ([]byte, error) {
 	type Alias ToolResult
-	return json.Marshal(&struct {
+	return jsonv2.Marshal(&struct {
 		*Alias
 	}{
 		Alias: (*Alias)(tr),

pkg/tools/result_test.go

@@ -1,9 +1,10 @@
 package tools
 
 import (
-	"encoding/json"
 	"errors"
 	"testing"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 func TestNewToolResult(t *testing.T) {
@@ -125,14 +126,14 @@ func TestToolResultJSONSerialization(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			// Marshal to JSON
-			data, err := json.Marshal(tt.result)
+			data, err := jsonv2.Marshal(tt.result)
 			if err != nil {
 				t.Fatalf("Failed to marshal: %v", err)
 			}
 
 			// Unmarshal back
 			var decoded ToolResult
-			if err := json.Unmarshal(data, &decoded); err != nil {
+			if err := jsonv2.Unmarshal(data, &decoded); err != nil {
 				t.Fatalf("Failed to unmarshal: %v", err)
 			}
 
@@ -168,13 +169,13 @@ func TestToolResultWithErrors(t *testing.T) {
 	}
 
 	// Verify Err is not serialized
-	data, marshalErr := json.Marshal(result)
+	data, marshalErr := jsonv2.Marshal(result)
 	if marshalErr != nil {
 		t.Fatalf("Failed to marshal: %v", marshalErr)
 	}
 
 	var decoded ToolResult
-	if unmarshalErr := json.Unmarshal(data, &decoded); unmarshalErr != nil {
+	if unmarshalErr := jsonv2.Unmarshal(data, &decoded); unmarshalErr != nil {
 		t.Fatalf("Failed to unmarshal: %v", unmarshalErr)
 	}
 
@@ -186,14 +187,14 @@ func TestToolResultWithErrors(t *testing.T) {
 func TestToolResultJSONStructure(t *testing.T) {
 	result := UserResult("test content")
 
-	data, err := json.Marshal(result)
+	data, err := jsonv2.Marshal(result)
 	if err != nil {
 		t.Fatalf("Failed to marshal: %v", err)
 	}
 
 	// Verify JSON structure
 	var parsed map[string]interface{}
-	if err := json.Unmarshal(data, &parsed); err != nil {
+	if err := jsonv2.Unmarshal(data, &parsed); err != nil {
 		t.Fatalf("Failed to parse JSON: %v", err)
 	}
 

pkg/tools/search.go

@@ -2,10 +2,11 @@ package tools
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"sort"
 	"strings"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 // ToolSearchTool implements tool discovery via fuzzy search over the registry.
@@ -88,7 +89,7 @@ func (t *ToolSearchTool) Execute(_ context.Context, args map[string]interface{})
 		return &ToolResult{ForLLM: fmt.Sprintf("No tools match query: %q. Try a broader search or use tool_search with no query to list all.", query)}
 	}
 
-	b, _ := json.Marshal(results)
+	b, _ := jsonv2.Marshal(results)
 	return &ToolResult{ForLLM: string(b)}
 }
 
@@ -111,7 +112,7 @@ func (t *ToolSearchTool) listAll() *ToolResult {
 		return results[i].Name < results[j].Name
 	})
 
-	b, _ := json.Marshal(results)
+	b, _ := jsonv2.Marshal(results)
 	return &ToolResult{ForLLM: string(b)}
 }
 

pkg/tools/search_test.go

@@ -2,8 +2,9 @@ package tools
 
 import (
 	"context"
-	"encoding/json"
 	"testing"
+
+	jsonv2 "github.com/go-json-experiment/json"
 )
 
 func TestToolSearchTool_Name(t *testing.T) {
@@ -52,7 +53,7 @@ func TestToolSearchTool_ListAll(t *testing.T) {
 	}
 
 	var results []toolSearchResult
-	if err := json.Unmarshal([]byte(result.ForLLM), &results); err != nil {
+	if err := jsonv2.Unmarshal([]byte(result.ForLLM), &results); err != nil {
 		t.Fatalf("failed to unmarshal: %v", err)
 	}
 
@@ -70,7 +71,7 @@ func TestToolSearchTool_EmptyQuery_ListsAll(t *testing.T) {
 	result := s.Execute(context.Background(), map[string]interface{}{"query": ""})
 
 	var results []toolSearchResult
-	if err := json.Unmarshal([]byte(result.ForLLM), &results); err != nil {
+	if err := jsonv2.Unmarshal([]byte(result.ForLLM), &results); err != nil {
 		t.Fatalf("failed to unmarshal: %v", err)
 	}
 
@@ -94,7 +95,7 @@ func TestToolSearchTool_ExactNameMatch(t *testing.T) {
 	result := s.Execute(context.Background(), map[string]interface{}{"query": "read_file"})
 
 	var results []toolSearchResult
-	json.Unmarshal([]byte(result.ForLLM), &results)
+	jsonv2.Unmarshal([]byte(result.ForLLM), &results)
 
 	if len(results) == 0 {
 		t.Fatal("expected at least one result")
@@ -116,7 +117,7 @@ func TestToolSearchTool_PartialMatch(t *testing.T) {
 	result := s.Execute(context.Background(), map[string]interface{}{"query": "file"})
 
 	var results []toolSearchResult
-	json.Unmarshal([]byte(result.ForLLM), &results)
+	jsonv2.Unmarshal([]byte(result.ForLLM), &results)
 
 	// Both file tools should match, web_search should not (unless "file" appears somewhere)
 	if len(results) < 2 {
@@ -133,7 +134,7 @@ func TestToolSearchTool_DescriptionMatch(t *testing.T) {
 	result := s.Execute(context.Background(), map[string]interface{}{"query": "internet"})
 
 	var results []toolSearchResult
-	json.Unmarshal([]byte(result.ForLLM), &results)
+	jsonv2.Unmarshal([]byte(result.ForLLM), &results)
 
 	if len(results) != 1 {
 		t.Errorf("expected 1 result, got %d", len(results))
@@ -153,7 +154,7 @@ func TestToolSearchTool_MultiTermQuery(t *testing.T) {
 	result := s.Execute(context.Background(), map[string]interface{}{"query": "web search"})
 
 	var results []toolSearchResult
-	json.Unmarshal([]byte(result.ForLLM), &results)
+	jsonv2.Unmarshal([]byte(result.ForLLM), &results)
 
 	if len(results) == 0 {
 		t.Fatal("expected at least one result")
@@ -189,7 +190,7 @@ func TestToolSearchTool_ExcludesMetaTools(t *testing.T) {
 	result := s.Execute(context.Background(), map[string]interface{}{})
 
 	var results []toolSearchResult
-	json.Unmarshal([]byte(result.ForLLM), &results)
+	jsonv2.Unmarshal([]byte(result.ForLLM), &results)
 
 	for _, res := range results {
 		if res.Name == "tool_search" || res.Name == "tool_call" {

pkg/tools/spi.go

@@ -2,11 +2,13 @@ package tools
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"path/filepath"
 	"regexp"
 	"runtime"
+
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 )
 
 // SPITool provides SPI bus interaction for high-speed peripheral communication.
@@ -113,7 +115,7 @@ func (t *SPITool) list() *ToolResult {
 		}
 	}
 
-	result, _ := json.MarshalIndent(devices, "", "  ")
+	result, _ := jsonv2.Marshal(devices, jsontext.WithIndent("  "))
 	return SilentResult(fmt.Sprintf("Found %d SPI device(s):\n%s", len(devices), string(result)))
 }
 

pkg/tools/spi_linux.go

@@ -1,11 +1,13 @@
 package tools
 
 import (
-	"encoding/json"
 	"fmt"
 	"runtime"
 	"syscall"
 	"unsafe"
+
+	jsonv2 "github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 )
 
 // SPI ioctl constants from Linux kernel headers.
@@ -130,12 +132,12 @@ func (t *SPITool) transfer(args map[string]interface{}) *ToolResult {
 		intBytes[i] = int(b)
 	}
 
-	result, _ := json.MarshalIndent(map[string]interface{}{
+	result, _ := jsonv2.Marshal(map[string]interface{}{
 		"device":   devPath,
 		"sent":     len(txBuf),
 		"received": intBytes,
 		"hex":      hexBytes,
-	}, "", "  ")
+	}, jsontext.WithIndent("  "))
 	return SilentResult(string(result))
 }
 
@@ -186,11 +188,11 @@ func (t *SPITool) readDevice(args map[string]interface{}) *ToolResult {
 		intBytes[i] = int(b)
 	}
 
-	result, _ := json.MarshalIndent(map[string]interface{}{
+	result, _ := jsonv2.Marshal(map[string]interface{}{
 		"device": devPath,
 		"bytes":  intBytes,
 		"hex":    hexBytes,
 		"length": len(rxBuf),
-	}, "", "  ")
+	}, jsontext.WithIndent("  "))
 	return SilentResult(string(result))
 }

pkg/tools/toolloop.go

@@ -8,9 +8,10 @@ package tools
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 
+	jsonv2 "github.com/go-json-experiment/json"
+
 	fantasy "charm.land/fantasy"
 	"github.com/sipeed/picoclaw/pkg/bus"
 	"github.com/sipeed/picoclaw/pkg/logger"
@@ -257,7 +258,7 @@ func parseToolCallArgs(input string) (map[string]interface{}, error) {
 	}
 
 	var args map[string]interface{}
-	if err := json.Unmarshal([]byte(input), &args); err != nil {
+	if err := jsonv2.Unmarshal([]byte(input), &args); err != nil {
 		return nil, fmt.Errorf("failed to parse tool arguments: %w", err)
 	}
 	return args, nil