fix: return error instead of panic when ArtifactService is nil (#283)

internal/context/callback_context.go

@@ -56,14 +56,20 @@ func NewCallbackContextWithDelta(ctx agent.InvocationContext, stateDelta map[str
 func newCallbackContext(ctx agent.InvocationContext, stateDelta map[string]any) *callbackContext {
 	rCtx := NewReadonlyContext(ctx)
 	eventActions := &session.EventActions{StateDelta: stateDelta}
+
+	var artifacts *internalArtifacts
+	if ctx.Artifacts() != nil {
+		artifacts = &internalArtifacts{
+			Artifacts:    ctx.Artifacts(),
+			eventActions: eventActions,
+		}
+	}
+
 	return &callbackContext{
 		ReadonlyContext: rCtx,
 		invocationCtx:   ctx,
 		eventActions:    eventActions,
-		artifacts: &internalArtifacts{
-			Artifacts:    ctx.Artifacts(),
-			eventActions: eventActions,
-		},
+		artifacts:       artifacts,
 	}
 }
 
@@ -77,6 +83,9 @@ type callbackContext struct {
 }
 
 func (c *callbackContext) Artifacts() agent.Artifacts {
+	if c.artifacts == nil {
+		return nil
+	}
 	return c.artifacts
 }
 

internal/toolinternal/context.go

@@ -60,15 +60,20 @@ func NewToolContext(ctx agent.InvocationContext, functionCallID string, actions
 	}
 	cbCtx := contextinternal.NewCallbackContextWithDelta(ctx, actions.StateDelta)
 
+	var artifacts *internalArtifacts
+	if ctx.Artifacts() != nil {
+		artifacts = &internalArtifacts{
+			Artifacts:    ctx.Artifacts(),
+			eventActions: actions,
+		}
+	}
+
 	return &toolContext{
 		CallbackContext:   cbCtx,
 		invocationContext: ctx,
 		functionCallID:    functionCallID,
 		eventActions:      actions,
-		artifacts: &internalArtifacts{
-			Artifacts:    ctx.Artifacts(),
-			eventActions: actions,
-		},
+		artifacts:         artifacts,
 	}
 }
 
@@ -81,6 +86,9 @@ type toolContext struct {
 }
 
 func (c *toolContext) Artifacts() agent.Artifacts {
+	if c.artifacts == nil {
+		return nil
+	}
 	return c.artifacts
 }
 

tool/loadartifactstool/load_artifacts_tool.go

@@ -20,6 +20,7 @@ package loadartifactstool
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 
 	"golang.org/x/sync/errgroup"
@@ -32,6 +33,8 @@ import (
 	"google.golang.org/adk/tool"
 )
 
+var ErrArtifactServiceNotInitialized = errors.New("artifact service is not initialized")
+
 // artifactsTool is a tool that loads artifacts and adds them to the session.
 type artifactsTool struct {
 	name        string
@@ -118,6 +121,9 @@ func (t *artifactsTool) Run(ctx tool.Context, args any) (map[string]any, error)
 // ProcessRequest processes the LLM request. It packs the tool, appends initial
 // instructions, and processes any load artifacts function calls.
 func (t *artifactsTool) ProcessRequest(ctx tool.Context, req *model.LLMRequest) error {
+	if ctx.Artifacts() == nil {
+		return ErrArtifactServiceNotInitialized
+	}
 	if err := toolutils.PackTool(req, t); err != nil {
 		return err
 	}

tool/loadartifactstool/load_artifacts_tool_test.go

@@ -15,6 +15,7 @@
 package loadartifactstool_test
 
 import (
+	"errors"
 	"strings"
 	"testing"
 
@@ -293,3 +294,24 @@ func createToolContext(t *testing.T) tool.Context {
 
 	return toolinternal.NewToolContext(ctx, "", nil)
 }
+
+func TestLoadArtifactsTool_ProcessRequest_NilArtifactService(t *testing.T) {
+	loadArtifactsTool := loadartifactstool.New()
+
+	ctx := icontext.NewInvocationContext(t.Context(), icontext.InvocationContextParams{
+		Artifacts: nil,
+	})
+	tc := toolinternal.NewToolContext(ctx, "", nil)
+
+	llmRequest := &model.LLMRequest{}
+
+	requestProcessor, ok := loadArtifactsTool.(toolinternal.RequestProcessor)
+	if !ok {
+		t.Fatal("loadArtifactsTool does not implement RequestProcessor")
+	}
+
+	err := requestProcessor.ProcessRequest(tc, llmRequest)
+if !errors.Is(err, loadartifactstool.ErrArtifactServiceNotInitialized) {
+		t.Errorf("ProcessRequest() with nil artifact service returned error = %v, want %v", err, loadartifactstool.ErrArtifactServiceNotInitialized)
+	}
+}