feat: enable sharing of chat sessions

Closes #1933

Signed-off-by: Brian Fox <878612+onematchfox@users.noreply.github.com>

Author: onematchfox

go/adk/cmd/main.go

@@ -173,7 +173,7 @@ func main() {
 		logger.Info("Memory service enabled", "appName", appName)
 	}
 
-	runnerConfig, subagentSessionIDs, err := runnerpkg.CreateRunnerConfig(ctx, agentConfig, sessionService, appName, memoryService)
+	runnerConfig, subagentSessionIDs, err := runnerpkg.CreateRunnerConfig(ctx, agentConfig, sessionService, appName, memoryService, kagentURL, httpClient)
 	if err != nil {
 		logger.Error(err, "Failed to create Google ADK Runner config")
 		os.Exit(1)

go/adk/pkg/runner/adapter.go

@@ -3,6 +3,7 @@ package runner
 import (
 	"context"
 	"fmt"
+	"net/http"
 	"os"
 	"strings"
 
@@ -11,6 +12,7 @@ import (
 	kagentmemory "github.com/kagent-dev/kagent/go/adk/pkg/memory"
 	"github.com/kagent-dev/kagent/go/adk/pkg/session"
 	"github.com/kagent-dev/kagent/go/adk/pkg/sts"
+	"github.com/kagent-dev/kagent/go/adk/pkg/tools"
 	"github.com/kagent-dev/kagent/go/api/adk"
 	adkmemory "google.golang.org/adk/memory"
 	adkplugin "google.golang.org/adk/plugin"
@@ -34,6 +36,8 @@ func CreateRunnerConfig(
 	sessionService *session.KAgentSessionService,
 	appName string,
 	memoryService *kagentmemory.KagentMemoryService,
+	kagentURL string,
+	httpClient *http.Client,
 ) (runner.Config, map[string]string, error) {
 	log := logr.FromContextOrDiscard(ctx)
 
@@ -46,6 +50,23 @@ func CreateRunnerConfig(
 		extraTools = append(extraTools, saveTool)
 	}
 
+	if agentConfig.ShareTools != nil && *agentConfig.ShareTools && kagentURL != "" && httpClient != nil {
+		createTool, err := tools.NewCreateShareLinkTool(httpClient, kagentURL, appName)
+		if err != nil {
+			return runner.Config{}, nil, fmt.Errorf("failed to create create_share_link tool: %w", err)
+		}
+		listTool, err := tools.NewListShareLinksTool(httpClient, kagentURL, appName)
+		if err != nil {
+			return runner.Config{}, nil, fmt.Errorf("failed to create list_share_links tool: %w", err)
+		}
+		deleteTool, err := tools.NewDeleteShareLinkTool(httpClient, kagentURL, appName)
+		if err != nil {
+			return runner.Config{}, nil, fmt.Errorf("failed to create delete_share_link tool: %w", err)
+		}
+		extraTools = append(extraTools, createTool, listTool, deleteTool)
+		log.Info("Share link tools enabled")
+	}
+
 	stsPlugin, err := buildTokenPropagationPlugin(ctx, log)
 	if err != nil {
 		return runner.Config{}, nil, err

go/adk/pkg/tools/share_tools.go

@@ -0,0 +1,205 @@
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+
+	"google.golang.org/adk/tool"
+	"google.golang.org/adk/tool/functiontool"
+)
+
+// shareClient holds the dependencies for share link tools, captured at construction time.
+type shareClient struct {
+	baseURL    string
+	uiURL      string // KAGENT_UI_URL, used to build full share URLs
+	appName    string
+	httpClient *http.Client
+}
+
+// parseAppName converts a Python-identifier app_name back to (namespace, name).
+// Format: "namespace__NS__agent_name" with hyphens encoded as underscores.
+func parseAppName(appName string) (namespace, name string) {
+	parts := strings.SplitN(appName, "__NS__", 2)
+	if len(parts) != 2 {
+		return "", strings.ReplaceAll(appName, "_", "-")
+	}
+	return strings.ReplaceAll(parts[0], "_", "-"), strings.ReplaceAll(parts[1], "_", "-")
+}
+
+// shareURL returns the share URL for a session token.
+// With uiURL set it returns a full absolute URL; otherwise a relative path.
+func (c *shareClient) shareURL(token, sessionID string) string {
+	ns, name := parseAppName(c.appName)
+	path := fmt.Sprintf("/agents/%s/%s/chat/%s?share=%s", ns, name, sessionID, token)
+	if c.uiURL != "" {
+		return c.uiURL + path
+	}
+	return path
+}
+
+func (c *shareClient) do(ctx context.Context, method, path string) (*http.Response, error) {
+	req, err := http.NewRequestWithContext(ctx, method, c.baseURL+path, nil)
+	if err != nil {
+		return nil, fmt.Errorf("building request %s %s: %w", method, c.baseURL+path, err)
+	}
+	req.Header.Set("X-Agent-Name", c.appName)
+	return c.httpClient.Do(req)
+}
+
+func (c *shareClient) doWithJSON(ctx context.Context, method, path string, body io.Reader) (*http.Response, error) {
+	req, err := http.NewRequestWithContext(ctx, method, c.baseURL+path, body)
+	if err != nil {
+		return nil, fmt.Errorf("building request %s %s: %w", method, c.baseURL+path, err)
+	}
+	req.Header.Set("X-Agent-Name", c.appName)
+	req.Header.Set("Content-Type", "application/json")
+	return c.httpClient.Do(req)
+}
+
+func (c *shareClient) readBody(resp *http.Response) (map[string]any, error) {
+	defer resp.Body.Close()
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("reading response: %w", err)
+	}
+	var out map[string]any
+	if err := json.Unmarshal(body, &out); err != nil {
+		return nil, fmt.Errorf("decoding response: %w", err)
+	}
+	return out, nil
+}
+
+type createShareInput struct {
+	// ReadOnly controls whether the shared link allows visitors to send messages.
+	// When nil (not provided by the model), the server defaults to true (read-only).
+	ReadOnly *bool `json:"read_only,omitempty"`
+}
+
+// NewCreateShareLinkTool creates a tool that generates a share token for the current session.
+func NewCreateShareLinkTool(httpClient *http.Client, baseURL, appName string) (tool.Tool, error) {
+	c := &shareClient{
+		baseURL:    baseURL,
+		uiURL:      strings.TrimRight(os.Getenv("KAGENT_UI_URL"), "/"),
+		appName:    appName,
+		httpClient: httpClient,
+	}
+	return functiontool.New(functiontool.Config{
+		Name: "create_share_link",
+		Description: "Creates a share link for the current chat session. " +
+			"Returns a URL any authenticated user can open to view this session. " +
+			"The link is read-only by default (visitors cannot send messages). " +
+			"Set read_only=false to allow visitors to interact. " +
+			"Each call creates a new token; existing tokens remain valid.",
+	}, func(ctx tool.Context, in createShareInput) (map[string]any, error) {
+		sessionID := ctx.SessionID()
+		if sessionID == "" {
+			return nil, fmt.Errorf("create_share_link: no session ID in context")
+		}
+		reqBody, err := json.Marshal(in)
+		if err != nil {
+			return nil, fmt.Errorf("create_share_link: encoding request: %w", err)
+		}
+		resp, err := c.doWithJSON(ctx, http.MethodPost, "/api/sessions/"+url.PathEscape(sessionID)+"/shares", strings.NewReader(string(reqBody)))
+		if err != nil {
+			return nil, fmt.Errorf("create_share_link: request failed: %w", err)
+		}
+		if resp.StatusCode != http.StatusCreated {
+			_, _ = io.Copy(io.Discard, resp.Body)
+			_ = resp.Body.Close()
+			return nil, fmt.Errorf("create_share_link: unexpected status %d", resp.StatusCode)
+		}
+		body, err := c.readBody(resp)
+		if err != nil {
+			return nil, fmt.Errorf("create_share_link: %w", err)
+		}
+		data, _ := body["data"].(map[string]any)
+		token, _ := data["token"].(string)
+		readOnly, _ := data["read_only"].(bool)
+		return map[string]any{
+			"url":       c.shareURL(token, sessionID),
+			"read_only": readOnly,
+		}, nil
+	})
+}
+
+// NewListShareLinksTool creates a tool that lists active share tokens for the current session.
+func NewListShareLinksTool(httpClient *http.Client, baseURL, appName string) (tool.Tool, error) {
+	c := &shareClient{
+		baseURL:    baseURL,
+		uiURL:      strings.TrimRight(os.Getenv("KAGENT_UI_URL"), "/"),
+		appName:    appName,
+		httpClient: httpClient,
+	}
+	return functiontool.New(functiontool.Config{
+		Name: "list_share_links",
+		Description: "Lists all active share links for the current session. " +
+			"Returns each share token and creation time. " +
+			"Use this to find a token before calling delete_share_link.",
+	}, func(ctx tool.Context, _ struct{}) (map[string]any, error) {
+		sessionID := ctx.SessionID()
+		if sessionID == "" {
+			return nil, fmt.Errorf("list_share_links: no session ID in context")
+		}
+		resp, err := c.do(ctx, http.MethodGet, "/api/sessions/"+url.PathEscape(sessionID)+"/shares")
+		if err != nil {
+			return nil, fmt.Errorf("list_share_links: request failed: %w", err)
+		}
+		if resp.StatusCode != http.StatusOK {
+			_, _ = io.Copy(io.Discard, resp.Body)
+			_ = resp.Body.Close()
+			return nil, fmt.Errorf("list_share_links: unexpected status %d", resp.StatusCode)
+		}
+		body, err := c.readBody(resp)
+		if err != nil {
+			return nil, fmt.Errorf("list_share_links: %w", err)
+		}
+		shares := body["data"]
+		if shares == nil {
+			shares = []any{}
+		}
+		return map[string]any{"shares": shares}, nil
+	})
+}
+
+type deleteShareInput struct {
+	Token string `json:"token"`
+}
+
+// NewDeleteShareLinkTool creates a tool that revokes a specific share token for the current session.
+func NewDeleteShareLinkTool(httpClient *http.Client, baseURL, appName string) (tool.Tool, error) {
+	c := &shareClient{
+		baseURL:    baseURL,
+		uiURL:      strings.TrimRight(os.Getenv("KAGENT_UI_URL"), "/"),
+		appName:    appName,
+		httpClient: httpClient,
+	}
+	return functiontool.New(functiontool.Config{
+		Name: "delete_share_link",
+		Description: "Deletes a share link by token, immediately revoking access for anyone using it. " +
+			"Use list_share_links first to find the token you want to revoke.",
+	}, func(ctx tool.Context, in deleteShareInput) (map[string]any, error) {
+		if in.Token == "" {
+			return nil, fmt.Errorf("delete_share_link: token is required")
+		}
+		sessionID := ctx.SessionID()
+		if sessionID == "" {
+			return nil, fmt.Errorf("delete_share_link: no session ID in context")
+		}
+		path := "/api/sessions/" + url.PathEscape(sessionID) + "/shares/" + url.PathEscape(in.Token)
+		resp, err := c.do(ctx, http.MethodDelete, path)
+		if err != nil {
+			return nil, fmt.Errorf("delete_share_link: request failed: %w", err)
+		}
+		defer resp.Body.Close()
+		if resp.StatusCode != http.StatusOK {
+			return nil, fmt.Errorf("delete_share_link: unexpected status %d", resp.StatusCode)
+		}
+		return map[string]any{"status": "revoked", "token": in.Token}, nil
+	})
+}