feat(agent): add StrictContextMock test double for unified Context

README-v2.md

@@ -0,0 +1,27 @@
+# Agent Development Kit (ADK) for Go v 2.0
+
+[![License](https://img.shields.io/badge/License-Apache_2.0-blue.svg)](LICENSE)
+
+
+## Breaking changes
+
+### Mocks update required for unified contexts 
+PR https://github.com/google/adk-go/pull/945 merges ToolContext and CallbackContext into single Context. 
+ToolContext and CallbackContext became aliases to Context. 
+
+This introduces a problem for mock contexts - new functions (ToolContext-related) are missing if the mock was created for the previous version of CallbackContext. 
+Solution:
+Add those functions to your mock:
+```go
+func (m *MockCallbackContext) Actions() *session.EventActions                       { return nil }
+func (m *MockCallbackContext) FunctionCallID() string                               { return "" }
+func (m *MockCallbackContext) ToolConfirmation() *toolconfirmation.ToolConfirmation { return nil }
+func (m *MockCallbackContext) RequestConfirmation(hint string, payload any) error {
+	return fmt.Errorf("RequestConfirmation() is not supported for MockCallbackContext")
+}
+func (m *MockCallbackContext) SearchMemory(ctx context.Context, query string) (*memory.SearchResponse, error) {
+	return nil, fmt.Errorf("SearchMemory() is not supported for MockCallbackContext")
+}
+
+var _ agent.CallbackContext = (*MockCallbackContext)(nil)
+```

agent/agent.go

@@ -161,7 +161,7 @@ func (a *agent) SubAgents() []Agent {
 
 func (a *agent) Run(ctx InvocationContext) iter.Seq2[*session.Event, error] {
 	return func(yield func(*session.Event, error) bool) {
-		spanCtx, span := telemetry.StartInvokeAgentSpan(ctx, a, ctx.Session().ID(), ctx.InvocationID())
+		spanCtx, span := telemetry.StartNodeSpan(ctx, ctx, telemetry.OperationAgent{Agent: a})
 		yield, endSpan := telemetry.WrapYield(span, yield, func(span trace.Span, event *session.Event, err error) {
 			telemetry.TraceAgentResult(span, telemetry.TraceAgentResultParams{
 				ResponseEvent: event,
@@ -170,44 +170,48 @@ func (a *agent) Run(ctx InvocationContext) iter.Seq2[*session.Event, error] {
 		})
 		defer endSpan()
 		// TODO: verify&update the setup here. Should we branch etc.
-		ctx := &invocationContext{
+
+		ic := &invocationContext{
 			Context:   ctx.WithContext(spanCtx),
 			agent:     a,
 			artifacts: ctx.Artifacts(),
 			memory:    ctx.Memory(),
 			session:   ctx.Session(),
 
-			invocationID:  ctx.InvocationID(),
-			branch:        ctx.Branch(),
-			userContent:   ctx.UserContent(),
-			runConfig:     ctx.RunConfig(),
-			endInvocation: ctx.Ended(),
+			invocationID:   ctx.InvocationID(),
+			branch:         ctx.Branch(),
+			isolationScope: ctx.IsolationScope(),
+			userContent:    ctx.UserContent(),
+			runConfig:      ctx.RunConfig(),
+			endInvocation:  ctx.Ended(),
 		}
-		event, err := runBeforeAgentCallbacks(ctx)
+		nodeCtx := NewNodeContext(ic, nil)
+
+		event, err := runBeforeAgentCallbacks(nodeCtx)
 		if event != nil || err != nil {
 			if !yield(event, err) {
 				return
 			}
 		}
 
-		if ctx.Ended() {
+		if ic.Ended() {
 			return
 		}
 
-		for event, err := range a.run(ctx) {
+		for event, err := range a.run(nodeCtx) {
 			if event != nil && event.Author == "" {
-				event.Author = getAuthorForEvent(ctx, event)
+				event.Author = getAuthorForEvent(ic, event)
 			}
 			if !yield(event, err) {
 				return
 			}
 		}
 
-		if ctx.Ended() {
+		if ic.Ended() {
 			return
 		}
 
-		event, err = runAfterAgentCallbacks(ctx)
+		event, err = runAfterAgentCallbacks(ic)
 		if event != nil || err != nil {
 			yield(event, err)
 		}
@@ -367,11 +371,12 @@ type invocationContext struct {
 	memory    Memory
 	session   session.Session
 
-	invocationID  string
-	branch        string
-	userContent   *genai.Content
-	runConfig     *RunConfig
-	endInvocation bool
+	invocationID   string
+	branch         string
+	isolationScope string
+	userContent    *genai.Content
+	runConfig      *RunConfig
+	endInvocation  bool
 }
 
 func (c *invocationContext) Agent() Agent {
@@ -398,6 +403,10 @@ func (c *invocationContext) Branch() string {
 	return c.branch
 }
 
+func (c *invocationContext) IsolationScope() string {
+	return c.isolationScope
+}
+
 func (c *invocationContext) UserContent() *genai.Content {
 	return c.userContent
 }
@@ -420,6 +429,11 @@ func (c *invocationContext) WithContext(ctx context.Context) InvocationContext {
 	return &newCtx
 }
 
+// ResumedInput always returns (nil, false) for the base
+// invocation context. Implementations that carry a resume payload
+// override this method.
+func (c *invocationContext) ResumedInput(string) (any, bool) { return nil, false }
+
 func pluginManagerFromContext(ctx context.Context) pluginManager {
 	a := ctx.Value(plugincontext.PluginManagerCtxKey)
 	m, ok := a.(pluginManager)