Feature/auth flow

agent/remoteagent/a2a_agent_test.go

@@ -756,6 +756,7 @@ func TestRemoteAgent_EmptyResultForEmptySession(t *testing.T) {
 		cmpopts.IgnoreFields(session.Event{}, "ID"),
 		cmpopts.IgnoreFields(session.Event{}, "Timestamp"),
 		cmpopts.IgnoreFields(session.EventActions{}, "StateDelta"),
+		cmpopts.IgnoreFields(session.EventActions{}, "RequestedAuthConfigs"),
 	}
 	if diff := cmp.Diff(wantEvents, gotEvents, ignoreFields...); diff != "" {
 		t.Fatalf("agent.Run() wrong result (+got,-want):\ngot = %+v\nwant = %+v\ndiff = %s", gotEvents, wantEvents, diff)

agent/remoteagent/utils_test.go

@@ -305,6 +305,7 @@ func TestPresentAsUserMessage(t *testing.T) {
 		cmpopts.IgnoreFields(session.Event{}, "InvocationID"),
 		cmpopts.IgnoreFields(session.Event{}, "Timestamp"),
 		cmpopts.IgnoreFields(session.EventActions{}, "StateDelta"),
+		cmpopts.IgnoreFields(session.EventActions{}, "RequestedAuthConfigs"),
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {

agent/workflowagents/loopagent/agent_test.go

@@ -234,7 +234,7 @@ func TestNewLoopAgent(t *testing.T) {
 
 			ignoreFields := []cmp.Option{
 				cmpopts.IgnoreFields(session.Event{}, "ID", "InvocationID", "Timestamp"),
-				cmpopts.IgnoreFields(session.EventActions{}, "StateDelta"),
+				cmpopts.IgnoreFields(session.EventActions{}, "StateDelta", "RequestedAuthConfigs"),
 				cmpopts.IgnoreFields(genai.FunctionCall{}, "ID"),
 				cmpopts.IgnoreFields(genai.FunctionResponse{}, "ID"),
 			}

agent/workflowagents/sequentialagent/agent_test.go

@@ -254,7 +254,7 @@ func TestNewSequentialAgent(t *testing.T) {
 				for i, gotEvent := range gotEvents {
 					tt.wantEvents[i].Timestamp = gotEvent.Timestamp
 					if diff := cmp.Diff(tt.wantEvents[i], gotEvent, cmpopts.IgnoreFields(session.Event{}, "ID", "Timestamp", "InvocationID"),
-						cmpopts.IgnoreFields(session.EventActions{}, "StateDelta")); diff != "" {
+						cmpopts.IgnoreFields(session.EventActions{}, "StateDelta", "RequestedAuthConfigs")); diff != "" {
 						t.Errorf("event[i] mismatch (-want +got):\n%s", diff)
 					}
 				}

auth/auth_config.go

@@ -0,0 +1,160 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package auth
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/json"
+	"fmt"
+	"sort"
+	"strconv"
+)
+
+// AuthConfig combines auth scheme and credentials for a tool.
+// This is passed to tools that require authentication.
+type AuthConfig struct {
+	// AuthScheme defines how the API expects authentication.
+	AuthScheme AuthScheme `json:"authScheme"`
+	// RawAuthCredential is the initial credential (e.g., client_id/secret).
+	RawAuthCredential *AuthCredential `json:"rawAuthCredential,omitempty"`
+	// ExchangedAuthCredential is the processed credential (e.g., access_token).
+	ExchangedAuthCredential *AuthCredential `json:"exchangedAuthCredential,omitempty"`
+	// CredentialKey is a unique key for persisting this credential.
+	CredentialKey string `json:"credentialKey,omitempty"`
+}
+
+// NewAuthConfig creates a new AuthConfig with the given scheme and credential.
+// If credentialKey is empty, it will be generated automatically.
+func NewAuthConfig(scheme AuthScheme, credential *AuthCredential) (*AuthConfig, error) {
+	cfg := &AuthConfig{
+		AuthScheme:        scheme,
+		RawAuthCredential: credential,
+	}
+	if cfg.CredentialKey == "" {
+		key, err := cfg.generateCredentialKey()
+		if err != nil {
+			return nil, fmt.Errorf("generate credential key: %w", err)
+		}
+		cfg.CredentialKey = key
+	}
+	return cfg, nil
+}
+
+// generateCredentialKey creates a unique key based on auth scheme and credential.
+func (c *AuthConfig) generateCredentialKey() (string, error) {
+	var schemePart, credPart string
+	if c.AuthScheme != nil {
+		schemeJSON, err := stableJSON(c.AuthScheme)
+		if err != nil {
+			return "", fmt.Errorf("marshal auth scheme: %w", err)
+		}
+		schemeType := c.AuthScheme.GetType()
+		h := sha256.Sum256([]byte(schemeJSON))
+		schemePart = fmt.Sprintf("%s_%x", schemeType, h[:8])
+	}
+	if c.RawAuthCredential != nil {
+		credJSON, err := stableJSON(c.RawAuthCredential)
+		if err != nil {
+			return "", fmt.Errorf("marshal auth credential: %w", err)
+		}
+		h := sha256.Sum256([]byte(credJSON))
+		credPart = fmt.Sprintf("%s_%x", c.RawAuthCredential.AuthType, h[:8])
+	}
+	return fmt.Sprintf("adk_%s_%s", schemePart, credPart), nil
+}
+
+// Copy creates a deep copy of the AuthConfig.
+func (c *AuthConfig) Copy() *AuthConfig {
+	if c == nil {
+		return nil
+	}
+	return &AuthConfig{
+		AuthScheme:              c.AuthScheme, // AuthScheme is typically immutable
+		RawAuthCredential:       c.RawAuthCredential.Copy(),
+		ExchangedAuthCredential: c.ExchangedAuthCredential.Copy(),
+		CredentialKey:           c.CredentialKey,
+	}
+}
+
+// stableJSON returns a deterministic JSON representation with sorted map keys.
+func stableJSON(v interface{}) (string, error) {
+	raw, err := json.Marshal(v)
+	if err != nil {
+		return "", err
+	}
+	var data interface{}
+	dec := json.NewDecoder(bytes.NewReader(raw))
+	dec.UseNumber()
+	if err := dec.Decode(&data); err != nil {
+		return "", err
+	}
+	var buf bytes.Buffer
+	if err := encodeCanonical(&buf, data); err != nil {
+		return "", err
+	}
+	return buf.String(), nil
+}
+
+func encodeCanonical(buf *bytes.Buffer, v interface{}) error {
+	switch val := v.(type) {
+	case nil:
+		buf.WriteString("null")
+	case bool:
+		if val {
+			buf.WriteString("true")
+		} else {
+			buf.WriteString("false")
+		}
+	case string:
+		buf.WriteString(strconv.Quote(val))
+	case json.Number:
+		buf.WriteString(val.String())
+	case float64:
+		buf.WriteString(strconv.FormatFloat(val, 'g', -1, 64))
+	case []interface{}:
+		buf.WriteByte('[')
+		for i, elem := range val {
+			if i > 0 {
+				buf.WriteByte(',')
+			}
+			if err := encodeCanonical(buf, elem); err != nil {
+				return err
+			}
+		}
+		buf.WriteByte(']')
+	case map[string]interface{}:
+		buf.WriteByte('{')
+		keys := make([]string, 0, len(val))
+		for k := range val {
+			keys = append(keys, k)
+		}
+		sort.Strings(keys)
+		for i, k := range keys {
+			if i > 0 {
+				buf.WriteByte(',')
+			}
+			buf.WriteString(strconv.Quote(k))
+			buf.WriteByte(':')
+			if err := encodeCanonical(buf, val[k]); err != nil {
+				return err
+			}
+		}
+		buf.WriteByte('}')
+	default:
+		return fmt.Errorf("unsupported JSON canonicalization type %T", v)
+	}
+	return nil
+}