feat(workspace): add broadcast and talk-to-user platform abilities

Two new workspace-level ability flags (broadcast_enabled, talk_to_user_enabled)
with full backend enforcement, MCP tool, and canvas UI:

- Migration: adds broadcast_enabled (default false) and talk_to_user_enabled
  (default true) columns to workspaces table
- PATCH /workspaces/:id/abilities (AdminAuth) toggles either flag independently
- POST /workspaces/:id/broadcast (WorkspaceAuth) fans out a broadcast_receive
  activity_log entry + WS BROADCAST_MESSAGE event to all non-removed peers;
  requires broadcast_enabled=true on the sender
- AgentMessageWriter checks talk_to_user_enabled; returns ErrTalkToUserDisabled
  which surfaces as HTTP 403 on /notify and the send_message_to_user MCP tool
- broadcast_message MCP tool added to registry + a2a_tools_messaging.py
- Canvas ChatTab shows "Agent is not enabled to chat with you" banner with
  Enable button when talkToUserEnabled=false on the workspace node

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

canvas/src/components/tabs/ChatTab.tsx

@@ -962,6 +962,32 @@ function MyChatPanel({ workspaceId, data }: Props) {
           </div>
         </div>
       )}
+      {/* talk_to_user disabled banner — shown when the workspace has
+           talk_to_user_enabled=false. The agent cannot send canvas messages;
+           the user can re-enable the ability from here without opening settings. */}
+      {data.talkToUserEnabled === false && (
+        <div className="flex items-center gap-2 px-3 py-2 bg-surface-sunken border-b border-line/40 shrink-0">
+          <svg width="14" height="14" viewBox="0 0 16 16" fill="none" aria-hidden="true" className="shrink-0 text-ink-mid">
+            <path d="M8 1a7 7 0 1 0 0 14A7 7 0 0 0 8 1Zm0 10.5a.75.75 0 1 1 0-1.5.75.75 0 0 1 0 1.5ZM8 4a.75.75 0 0 1 .75.75v4a.75.75 0 0 1-1.5 0v-4A.75.75 0 0 1 8 4Z" fill="currentColor"/>
+          </svg>
+          <span className="text-[10px] text-ink-mid flex-1">
+            Agent is not enabled to chat with you.
+          </span>
+          <button
+            onClick={async () => {
+              try {
+                await api.patch(`/workspaces/${workspaceId}/abilities`, { talk_to_user_enabled: true });
+                useCanvasStore.getState().updateNodeData(workspaceId, { talkToUserEnabled: true });
+              } catch {
+                // ignore — user will see no change and can retry
+              }
+            }}
+            className="px-2 py-0.5 text-[10px] font-medium bg-accent/10 hover:bg-accent/20 text-accent rounded border border-accent/30 transition-colors shrink-0"
+          >
+            Enable
+          </button>
+        </div>
+      )}
       {/* Messages */}
       <div ref={containerRef} className="flex-1 overflow-y-auto p-3 space-y-3">
         {loading && (

canvas/src/store/canvas-topology.ts

@@ -519,6 +519,10 @@ export function buildNodesAndEdges(
         // #2054 — server-declared per-workspace provisioning timeout.
         // Falls through to the runtime profile when null/absent.
         provisionTimeoutMs: ws.provision_timeout_ms ?? null,
+        // Workspace abilities — defaults preserved for old platform versions
+        // that don't yet include these columns in the GET response.
+        broadcastEnabled: ws.broadcast_enabled ?? false,
+        talkToUserEnabled: ws.talk_to_user_enabled ?? true,
       },
     };
     if (hasParent) {

canvas/src/store/canvas.ts

@@ -99,6 +99,13 @@ export interface WorkspaceNodeData extends Record<string, unknown> {
    *  @/lib/runtimeProfiles. Lets a slow runtime declare its cold-boot
    *  expectation without a canvas release. */
   provisionTimeoutMs?: number | null;
+  /** When true the workspace may POST /broadcast to send org-wide messages.
+   *  Default false. Toggled by user/admin via PATCH /workspaces/:id/abilities. */
+  broadcastEnabled?: boolean;
+  /** When false the workspace cannot deliver canvas chat messages.
+   *  send_message_to_user / POST /notify return 403 and the canvas
+   *  shows a "not enabled" state with a button to re-enable. Default true. */
+  talkToUserEnabled?: boolean;
 }
 
 export type PanelTab = "details" | "skills" | "chat" | "terminal" | "config" | "schedule" | "channels" | "files" | "memory" | "traces" | "events" | "activity" | "audit";

canvas/src/store/socket.ts

@@ -299,6 +299,9 @@ export interface WorkspaceData {
    *  `@/lib/runtimeProfiles` when absent (the default behavior for any
    *  template that hasn't yet declared the field). */
   provision_timeout_ms?: number | null;
+  /** Workspace ability flags (migration 20260514). */
+  broadcast_enabled?: boolean;
+  talk_to_user_enabled?: boolean;
 }
 
 let socket: ReconnectingSocket | null = null;

workspace-server/internal/handlers/activity.go

@@ -482,6 +482,13 @@ func (h *ActivityHandler) Notify(c *gin.Context) {
 			c.JSON(http.StatusNotFound, gin.H{"error": "workspace not found"})
 			return
 		}
+		if errors.Is(err, ErrTalkToUserDisabled) {
+			c.JSON(http.StatusForbidden, gin.H{
+				"error": "talk_to_user_disabled",
+				"hint":  "This workspace is not allowed to send messages directly to the user. Forward your update to a parent workspace using delegate_task — they may be able to reach the user.",
+			})
+			return
+		}
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "internal error"})
 		return
 	}

workspace-server/internal/handlers/activity_test.go

@@ -464,9 +464,9 @@ func TestNotify_PersistsToActivityLogsForReloadRecovery(t *testing.T) {
 	t.Cleanup(func() { db.DB = prevDB; mockDB.Close() })
 
 	// Workspace existence check
-	mock.ExpectQuery(`SELECT name FROM workspaces`).
+	mock.ExpectQuery(`SELECT name, talk_to_user_enabled FROM workspaces`).
 		WithArgs("ws-notify").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("DD"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("DD", true))
 
 	// Persistence INSERT — verify shape
 	mock.ExpectExec(`INSERT INTO activity_logs`).
@@ -511,9 +511,9 @@ func TestNotify_WithAttachments_PersistsFilePartsForReload(t *testing.T) {
 	db.DB = mockDB
 	t.Cleanup(func() { db.DB = prevDB; mockDB.Close() })
 
-	mock.ExpectQuery(`SELECT name FROM workspaces`).
+	mock.ExpectQuery(`SELECT name, talk_to_user_enabled FROM workspaces`).
 		WithArgs("ws-attach").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("DD"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("DD", true))
 
 	// Capture the JSONB arg so we can assert on the persisted shape
 	// AFTER the call (must include parts[].kind=file so reload
@@ -640,9 +640,9 @@ func TestNotify_DBFailure_StillBroadcastsAnd200(t *testing.T) {
 	db.DB = mockDB
 	t.Cleanup(func() { db.DB = prevDB; mockDB.Close() })
 
-	mock.ExpectQuery(`SELECT name FROM workspaces`).
+	mock.ExpectQuery(`SELECT name, talk_to_user_enabled FROM workspaces`).
 		WithArgs("ws-x").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("DD"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("DD", true))
 	mock.ExpectExec(`INSERT INTO activity_logs`).
 		WillReturnError(fmt.Errorf("simulated db hiccup"))
 

workspace-server/internal/handlers/agent_message_writer.go

@@ -54,6 +54,11 @@ import (
 // timeout) surface as wrapped errors and should be treated as 503.
 var ErrWorkspaceNotFound = errors.New("agent_message: workspace not found")
 
+// ErrTalkToUserDisabled is returned when the workspace has
+// talk_to_user_enabled=false. Callers surface HTTP 403 so the Python tool
+// can detect it and suggest forwarding to a parent workspace.
+var ErrTalkToUserDisabled = errors.New("agent_message: talk_to_user disabled")
+
 // AgentMessageAttachment is one file attached to an agent → user
 // message. Identical to handlers.NotifyAttachment in field set; kept
 // distinct so the writer's API doesn't import a handler type with HTTP
@@ -107,16 +112,20 @@ func (w *AgentMessageWriter) Send(
 	// notify call surfaced as "workspace not found" and masked real
 	// incidents in the alert path.
 	var wsName string
+	var talkToUserEnabled bool
 	err := w.db.QueryRowContext(ctx,
-		`SELECT name FROM workspaces WHERE id = $1 AND status != 'removed'`,
+		`SELECT name, talk_to_user_enabled FROM workspaces WHERE id = $1 AND status != 'removed'`,
 		workspaceID,
-	).Scan(&wsName)
+	).Scan(&wsName, &talkToUserEnabled)
 	if errors.Is(err, sql.ErrNoRows) {
 		return ErrWorkspaceNotFound
 	}
 	if err != nil {
 		return fmt.Errorf("agent_message: workspace lookup: %w", err)
 	}
+	if !talkToUserEnabled {
+		return ErrTalkToUserDisabled
+	}
 
 	// 2. Build broadcast payload + WS-emit. Same shape that ChatTab's
 	//    AGENT_MESSAGE handler in canvas/src/store/canvas-events.ts has

workspace-server/internal/handlers/agent_message_writer_test.go

@@ -88,9 +88,9 @@ func TestAgentMessageWriter_Send_Success_NoAttachments(t *testing.T) {
 	mock := setupTestDB(t)
 	w := NewAgentMessageWriter(db.DB, newTestBroadcaster())
 
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-1").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("CEO Ryan PC"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("CEO Ryan PC", true))
 
 	mock.ExpectExec(`INSERT INTO activity_logs.*'a2a_receive'.*'notify'`).
 		WithArgs(
@@ -116,9 +116,9 @@ func TestAgentMessageWriter_Send_Success_WithAttachments(t *testing.T) {
 	mock := setupTestDB(t)
 	w := NewAgentMessageWriter(db.DB, newTestBroadcaster())
 
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-att").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("Ryan"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("Ryan", true))
 
 	mock.ExpectExec(`INSERT INTO activity_logs.*'a2a_receive'.*'notify'`).
 		WithArgs(
@@ -173,9 +173,9 @@ func TestAgentMessageWriter_Send_WorkspaceNotFound(t *testing.T) {
 	emitter := &capturingEmitter{}
 	w := NewAgentMessageWriter(db.DB, emitter)
 
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-missing").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}))
 
 	err := w.Send(context.Background(), "ws-missing", "lost in the void", nil)
 	if !errors.Is(err, ErrWorkspaceNotFound) {
@@ -202,9 +202,9 @@ func TestAgentMessageWriter_Send_DBInsertFailureStillReturnsNil(t *testing.T) {
 	mock := setupTestDB(t)
 	w := NewAgentMessageWriter(db.DB, newTestBroadcaster())
 
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-dbfail").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("CEO Ryan PC"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("CEO Ryan PC", true))
 
 	mock.ExpectExec(`INSERT INTO activity_logs`).
 		WillReturnError(errors.New("transient db error"))
@@ -223,9 +223,9 @@ func TestAgentMessageWriter_Send_PreviewTruncation(t *testing.T) {
 	mock := setupTestDB(t)
 	w := NewAgentMessageWriter(db.DB, newTestBroadcaster())
 
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-trunc").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("Ryan"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("Ryan", true))
 
 	longMsg := strings.Repeat("x", 200)
 	mock.ExpectExec(`INSERT INTO activity_logs`).
@@ -263,9 +263,9 @@ func TestAgentMessageWriter_Send_BroadcastsAgentMessageEvent(t *testing.T) {
 	emitter := &capturingEmitter{}
 	w := NewAgentMessageWriter(db.DB, emitter)
 
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-bc").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("Workspace Name"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("Workspace Name", true))
 	mock.ExpectExec(`INSERT INTO activity_logs`).
 		WillReturnResult(sqlmock.NewResult(1, 1))
 
@@ -315,7 +315,7 @@ func TestAgentMessageWriter_Send_DBErrorOnLookupReturnsWrapped(t *testing.T) {
 	w := NewAgentMessageWriter(db.DB, newTestBroadcaster())
 
 	transientErr := errors.New("connection refused")
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-dbdown").
 		WillReturnError(transientErr)
 
@@ -350,9 +350,9 @@ func TestAgentMessageWriter_Send_NonASCIIMessagePersists(t *testing.T) {
 	// the byte-slice bug.
 	msg := strings.Repeat("你", 200)
 
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-cjk").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("CEO Ryan PC"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("CEO Ryan PC", true))
 
 	mock.ExpectExec(`INSERT INTO activity_logs`).
 		WithArgs(
@@ -395,9 +395,9 @@ func TestAgentMessageWriter_Send_OmitsAttachmentsKeyWhenEmpty(t *testing.T) {
 	emitter := &capturingEmitter{}
 	w := NewAgentMessageWriter(db.DB, emitter)
 
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-noatt").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("X"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("X", true))
 	mock.ExpectExec(`INSERT INTO activity_logs`).
 		WillReturnResult(sqlmock.NewResult(1, 1))
 

workspace-server/internal/handlers/handlers_additional_test.go

@@ -230,20 +230,21 @@ func TestWorkspaceList_WithData(t *testing.T) {
 	broadcaster := newTestBroadcaster()
 	handler := NewWorkspaceHandler(broadcaster, nil, "http://localhost:8080", t.TempDir())
 
-	// 21 cols — see scanWorkspaceRow for order (max_concurrent_tasks
-	// lands between active_tasks and last_error_rate).
+	// 23 cols — broadcast_enabled + talk_to_user_enabled added after monthly_spend
+	// (migration 20260514). Column order must match scanWorkspaceRow exactly.
 	columns := []string{
 		"id", "name", "role", "tier", "status", "agent_card", "url",
 		"parent_id", "active_tasks", "max_concurrent_tasks",
 		"last_error_rate", "last_sample_error",
 		"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 		"budget_limit", "monthly_spend",
+		"broadcast_enabled", "talk_to_user_enabled",
 	}
 	rows := sqlmock.NewRows(columns).
 		AddRow("ws-1", "Agent One", "worker", 1, "online", []byte(`{"name":"agent1"}`), "http://localhost:8001",
-			nil, 3, 1, 0.02, "", 7200, "processing", "langgraph", "", 10.0, 20.0, false, nil, int64(0)).
+			nil, 3, 1, 0.02, "", 7200, "processing", "langgraph", "", 10.0, 20.0, false, nil, int64(0), false, true).
 		AddRow("ws-2", "Agent Two", "", 2, "degraded", []byte("null"), "",
-			nil, 0, 1, 0.6, "timeout", 100, "", "claude-code", "", 50.0, 60.0, true, nil, int64(0))
+			nil, 0, 1, 0.6, "timeout", 100, "", "claude-code", "", 50.0, 60.0, true, nil, int64(0), false, true)
 
 	mock.ExpectQuery("SELECT w.id, w.name").
 		WillReturnRows(rows)

workspace-server/internal/handlers/handlers_test.go

@@ -392,21 +392,21 @@ func TestWorkspaceList(t *testing.T) {
 	broadcaster := newTestBroadcaster()
 	handler := NewWorkspaceHandler(broadcaster, nil, "http://localhost:8080", "/tmp/configs")
 
-	// 21 cols: `max_concurrent_tasks` added between active_tasks and
-	// last_error_rate (see scanWorkspaceRow + COALESCE(w.max_concurrent_tasks, 1)
-	// in workspace.go). Column order must match that scan exactly.
+	// 23 cols: broadcast_enabled + talk_to_user_enabled added after monthly_spend
+	// (migration 20260514). Column order must match scanWorkspaceRow exactly.
 	columns := []string{
 		"id", "name", "role", "tier", "status", "agent_card", "url",
 		"parent_id", "active_tasks", "max_concurrent_tasks",
 		"last_error_rate", "last_sample_error",
 		"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 		"budget_limit", "monthly_spend",
+		"broadcast_enabled", "talk_to_user_enabled",
 	}
 	rows := sqlmock.NewRows(columns).
 		AddRow("ws-1", "Agent One", "worker", 1, "online", []byte("null"), "http://localhost:8001",
-			nil, 0, 1, 0.0, "", 100, "", "claude-code", "", 10.0, 20.0, false, nil, int64(0)).
+			nil, 0, 1, 0.0, "", 100, "", "claude-code", "", 10.0, 20.0, false, nil, int64(0), false, true).
 		AddRow("ws-2", "Agent Two", "manager", 2, "provisioning", []byte("null"), "",
-			nil, 0, 1, 0.0, "", 0, "", "langgraph", "", 50.0, 60.0, false, nil, int64(0))
+			nil, 0, 1, 0.0, "", 0, "", "langgraph", "", 50.0, 60.0, false, nil, int64(0), false, true)
 
 	mock.ExpectQuery("SELECT w.id, w.name").
 		WillReturnRows(rows)
@@ -1120,13 +1120,14 @@ func TestWorkspaceGet_CurrentTask(t *testing.T) {
 		"parent_id", "active_tasks", "max_concurrent_tasks", "last_error_rate", "last_sample_error",
 		"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 		"budget_limit", "monthly_spend",
+		"broadcast_enabled", "talk_to_user_enabled",
 	}
 	mock.ExpectQuery("SELECT w.id, w.name").
 		WithArgs("dddddddd-0004-0000-0000-000000000000").
 		WillReturnRows(sqlmock.NewRows(columns).AddRow(
 			"dddddddd-0004-0000-0000-000000000000", "Task Worker", "worker", 1, "online", []byte("null"), "http://localhost:9000",
 			nil, 2, 1, 0.0, "", 300, "Analyzing document", "langgraph", "", 10.0, 20.0, false,
-			nil, int64(0),
+			nil, int64(0), false, true,
 		))
 
 	w := httptest.NewRecorder()

workspace-server/internal/handlers/mcp_test.go

@@ -751,9 +751,9 @@ func TestMCPHandler_SendMessageToUser_DBErrorLogsAndStill200s(t *testing.T) {
 	t.Setenv("MOLECULE_MCP_ALLOW_SEND_MESSAGE", "true")
 	h, mock := newMCPHandler(t)
 
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-err").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("CEO Ryan PC"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("CEO Ryan PC", true))
 
 	// INSERT fails — must NOT abort the tool response.
 	mock.ExpectExec(`INSERT INTO activity_logs.*'a2a_receive'.*'notify'`).
@@ -802,9 +802,9 @@ func TestMCPHandler_SendMessageToUser_ResponseBodyShape(t *testing.T) {
 
 	const userMessage = "Hi there from the agent"
 
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-shape").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("CEO Ryan PC"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("CEO Ryan PC", true))
 
 	// Capture the response_body argument and assert its exact shape.
 	mock.ExpectExec(`INSERT INTO activity_logs.*'a2a_receive'.*'notify'`).
@@ -861,9 +861,9 @@ func TestMCPHandler_SendMessageToUser_PersistsToActivityLog(t *testing.T) {
 	// before it does anything else. Returning a name lets the
 	// broadcast payload populate; the test doesn't assert on the
 	// broadcast (no observable WS in this fake), only on the DB.
-	mock.ExpectQuery("SELECT name FROM workspaces").
+	mock.ExpectQuery("SELECT name, talk_to_user_enabled FROM workspaces").
 		WithArgs("ws-msg").
-		WillReturnRows(sqlmock.NewRows([]string{"name"}).AddRow("CEO Ryan PC"))
+		WillReturnRows(sqlmock.NewRows([]string{"name", "talk_to_user_enabled"}).AddRow("CEO Ryan PC", true))
 
 	// The persistence INSERT — pin the exact shape so a future
 	// refactor that switches columns or drops `method='notify'`

workspace-server/internal/handlers/workspace.go

@@ -595,7 +595,7 @@ func scanWorkspaceRow(rows interface {
 	var id, name, role, status, url, sampleError, currentTask, runtime, workspaceDir string
 	var tier, activeTasks, maxConcurrentTasks, uptimeSeconds int
 	var errorRate, x, y float64
-	var collapsed bool
+	var collapsed, broadcastEnabled, talkToUserEnabled bool
 	var parentID *string
 	var agentCard []byte
 	var budgetLimit sql.NullInt64
@@ -604,7 +604,7 @@ func scanWorkspaceRow(rows interface {
 	err := rows.Scan(&id, &name, &role, &tier, &status, &agentCard, &url,
 		&parentID, &activeTasks, &maxConcurrentTasks, &errorRate, &sampleError, &uptimeSeconds,
 		&currentTask, &runtime, &workspaceDir, &x, &y, &collapsed,
-		&budgetLimit, &monthlySpend)
+		&budgetLimit, &monthlySpend, &broadcastEnabled, &talkToUserEnabled)
 	if err != nil {
 		return nil, err
 	}
@@ -628,6 +628,8 @@ func scanWorkspaceRow(rows interface {
 		"x":                    x,
 		"y":                    y,
 		"collapsed":            collapsed,
+		"broadcast_enabled":    broadcastEnabled,
+		"talk_to_user_enabled": talkToUserEnabled,
 	}
 
 	// budget_limit: nil when no limit set, int64 otherwise
@@ -663,7 +665,8 @@ const workspaceListQuery = `
 		   COALESCE(w.current_task, ''), COALESCE(w.runtime, 'langgraph'),
 		   COALESCE(w.workspace_dir, ''),
 		   COALESCE(cl.x, 0), COALESCE(cl.y, 0), COALESCE(cl.collapsed, false),
-		   w.budget_limit, COALESCE(w.monthly_spend, 0)
+		   w.budget_limit, COALESCE(w.monthly_spend, 0),
+		   w.broadcast_enabled, w.talk_to_user_enabled
 	FROM workspaces w
 	LEFT JOIN canvas_layouts cl ON cl.workspace_id = w.id
 	WHERE w.status != 'removed'
@@ -723,7 +726,8 @@ func (h *WorkspaceHandler) Get(c *gin.Context) {
 			   COALESCE(w.current_task, ''), COALESCE(w.runtime, 'langgraph'),
 			   COALESCE(w.workspace_dir, ''),
 			   COALESCE(cl.x, 0), COALESCE(cl.y, 0), COALESCE(cl.collapsed, false),
-			   w.budget_limit, COALESCE(w.monthly_spend, 0)
+			   w.budget_limit, COALESCE(w.monthly_spend, 0),
+			   w.broadcast_enabled, w.talk_to_user_enabled
 		FROM workspaces w
 		LEFT JOIN canvas_layouts cl ON cl.workspace_id = w.id
 		WHERE w.id = $1

workspace-server/internal/handlers/workspace_abilities.go

@@ -0,0 +1,82 @@
+package handlers
+
+// workspace_abilities.go — PATCH /workspaces/:id/abilities
+//
+// Allows users and admin agents to toggle two workspace-level ability flags:
+//
+//   broadcast_enabled   — workspace may POST /broadcast to send org-wide messages
+//   talk_to_user_enabled — workspace may deliver canvas chat messages via
+//                          send_message_to_user / POST /notify
+//
+// Gated behind AdminAuth so workspace agents cannot self-modify their own
+// ability flags (that would let any agent grant itself broadcast rights or
+// suppress its own chat-silence constraint).
+
+import (
+	"log"
+	"net/http"
+
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/gin-gonic/gin"
+)
+
+// AbilitiesPayload carries the subset of ability flags the caller wants to
+// update. Fields are pointers so that the handler can distinguish "caller
+// supplied false" from "caller omitted the field" (omitempty semantics).
+type AbilitiesPayload struct {
+	BroadcastEnabled   *bool `json:"broadcast_enabled"`
+	TalkToUserEnabled  *bool `json:"talk_to_user_enabled"`
+}
+
+// PatchAbilities handles PATCH /workspaces/:id/abilities (AdminAuth).
+func PatchAbilities(c *gin.Context) {
+	id := c.Param("id")
+	if err := validateWorkspaceID(id); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid workspace ID"})
+		return
+	}
+
+	var body AbilitiesPayload
+	if err := c.ShouldBindJSON(&body); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid request body"})
+		return
+	}
+	if body.BroadcastEnabled == nil && body.TalkToUserEnabled == nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "at least one ability field required"})
+		return
+	}
+
+	ctx := c.Request.Context()
+
+	var exists bool
+	if err := db.DB.QueryRowContext(ctx,
+		`SELECT EXISTS(SELECT 1 FROM workspaces WHERE id = $1 AND status != 'removed')`, id,
+	).Scan(&exists); err != nil || !exists {
+		c.JSON(http.StatusNotFound, gin.H{"error": "workspace not found"})
+		return
+	}
+
+	if body.BroadcastEnabled != nil {
+		if _, err := db.DB.ExecContext(ctx,
+			`UPDATE workspaces SET broadcast_enabled = $2, updated_at = now() WHERE id = $1`,
+			id, *body.BroadcastEnabled,
+		); err != nil {
+			log.Printf("PatchAbilities broadcast_enabled for %s: %v", id, err)
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "update failed"})
+			return
+		}
+	}
+
+	if body.TalkToUserEnabled != nil {
+		if _, err := db.DB.ExecContext(ctx,
+			`UPDATE workspaces SET talk_to_user_enabled = $2, updated_at = now() WHERE id = $1`,
+			id, *body.TalkToUserEnabled,
+		); err != nil {
+			log.Printf("PatchAbilities talk_to_user_enabled for %s: %v", id, err)
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "update failed"})
+			return
+		}
+	}
+
+	c.JSON(http.StatusOK, gin.H{"status": "updated"})
+}

workspace-server/internal/handlers/workspace_broadcast.go

@@ -0,0 +1,142 @@
+package handlers
+
+// workspace_broadcast.go — POST /workspaces/:id/broadcast
+//
+// Allows a workspace with broadcast_enabled=true to send a message to every
+// non-removed agent workspace in the org.  The message is:
+//
+//   • Persisted in each recipient's activity_logs (type='broadcast_receive')
+//     so poll-mode agents pick it up via GET /activity.
+//   • Broadcast via WebSocket BROADCAST_MESSAGE event so canvas panels can
+//     show a real-time banner for each recipient workspace.
+//
+// The sender's own workspace logs a 'broadcast_sent' activity row for
+// traceability.
+//
+// Auth: WorkspaceAuth (the agent triggers this with its own bearer token).
+// The handler re-validates broadcast_enabled inside the DB lookup to prevent
+// TOCTOU — the middleware only proved the token is valid, not the ability.
+
+import (
+	"log"
+	"net/http"
+	"strconv"
+
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
+	"github.com/gin-gonic/gin"
+)
+
+// BroadcastHandler is constructed once and shared across requests.
+type BroadcastHandler struct {
+	broadcaster *events.Broadcaster
+}
+
+// NewBroadcastHandler creates a BroadcastHandler.
+func NewBroadcastHandler(b *events.Broadcaster) *BroadcastHandler {
+	return &BroadcastHandler{broadcaster: b}
+}
+
+// Broadcast handles POST /workspaces/:id/broadcast.
+func (h *BroadcastHandler) Broadcast(c *gin.Context) {
+	senderID := c.Param("id")
+	if err := validateWorkspaceID(senderID); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid workspace ID"})
+		return
+	}
+
+	var body struct {
+		Message string `json:"message" binding:"required"`
+	}
+	if err := c.ShouldBindJSON(&body); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "message is required"})
+		return
+	}
+
+	ctx := c.Request.Context()
+
+	// Verify sender exists and has broadcast_enabled=true.
+	var senderName string
+	var broadcastEnabled bool
+	err := db.DB.QueryRowContext(ctx,
+		`SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'`,
+		senderID,
+	).Scan(&senderName, &broadcastEnabled)
+	if err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "workspace not found"})
+		return
+	}
+	if !broadcastEnabled {
+		c.JSON(http.StatusForbidden, gin.H{
+			"error": "broadcast_disabled",
+			"hint":  "This workspace does not have the broadcast ability. Ask a user or admin to enable it via PATCH /workspaces/:id/abilities.",
+		})
+		return
+	}
+
+	// Collect all non-removed agent workspaces (excludes the sender itself).
+	rows, err := db.DB.QueryContext(ctx,
+		`SELECT id FROM workspaces WHERE status != 'removed' AND id != $1`,
+		senderID,
+	)
+	if err != nil {
+		log.Printf("Broadcast: recipient query failed for %s: %v", senderID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "internal error"})
+		return
+	}
+	defer rows.Close()
+
+	var recipientIDs []string
+	for rows.Next() {
+		var rid string
+		if rows.Scan(&rid) == nil {
+			recipientIDs = append(recipientIDs, rid)
+		}
+	}
+	if err := rows.Err(); err != nil {
+		log.Printf("Broadcast: recipient rows error for %s: %v", senderID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "internal error"})
+		return
+	}
+
+	broadcastPayload := map[string]interface{}{
+		"message":   body.Message,
+		"sender_id": senderID,
+		"sender":    senderName,
+	}
+
+	// Persist broadcast_receive in each recipient's activity log + emit WS event.
+	delivered := 0
+	for _, rid := range recipientIDs {
+		if _, err := db.DB.ExecContext(ctx, `
+			INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, status)
+			VALUES ($1, 'broadcast_receive', 'broadcast', $2, $3, 'ok')
+		`, rid, senderID, "Broadcast from "+senderName+": "+broadcastTruncate(body.Message, 120)); err != nil {
+			log.Printf("Broadcast: activity_logs insert for recipient %s: %v", rid, err)
+			continue
+		}
+		h.broadcaster.BroadcastOnly(rid, "BROADCAST_MESSAGE", broadcastPayload)
+		delivered++
+	}
+
+	// Record the send on the sender's own log.
+	if _, err := db.DB.ExecContext(ctx, `
+		INSERT INTO activity_logs (workspace_id, activity_type, method, summary, status)
+		VALUES ($1, 'broadcast_sent', 'broadcast', $2, 'ok')
+	`, senderID, "Broadcast sent to "+strconv.Itoa(delivered)+" workspace(s)"); err != nil {
+		log.Printf("Broadcast: sender activity_log for %s: %v", senderID, err)
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"status":    "sent",
+		"delivered": delivered,
+	})
+}
+
+func broadcastTruncate(s string, max int) string {
+	runes := []rune(s)
+	if len(runes) <= max {
+		return s
+	}
+	return string(runes[:max]) + "…"
+}

workspace-server/internal/handlers/workspace_budget_test.go

@@ -33,6 +33,7 @@ var wsColumns = []string{
 	"parent_id", "active_tasks", "max_concurrent_tasks", "last_error_rate", "last_sample_error",
 	"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 	"budget_limit", "monthly_spend",
+	"broadcast_enabled", "talk_to_user_enabled",
 }
 
 // ==================== GET — financial fields stripped from open endpoint ====================
@@ -52,8 +53,10 @@ func TestWorkspaceBudget_Get_NilLimit(t *testing.T) {
 				[]byte(`{}`), "http://localhost:9001",
 				nil, 0, 1, 0.0, "", 0, "", "langgraph", "",
 				0.0, 0.0, false,
-				nil, // budget_limit NULL
-				0))  // monthly_spend 0
+				nil,   // budget_limit NULL
+				0,     // monthly_spend 0
+				false, // broadcast_enabled
+				true)) // talk_to_user_enabled
 
 	w := httptest.NewRecorder()
 	c, _ := gin.CreateTestContext(w)
@@ -96,7 +99,8 @@ func TestWorkspaceBudget_Get_WithLimit(t *testing.T) {
 				nil, 0, 1, 0.0, "", 0, "", "langgraph", "",
 				0.0, 0.0, false,
 				int64(500),  // budget_limit = $5.00 in DB
-				int64(123))) // monthly_spend = $1.23 in DB
+				int64(123),  // monthly_spend = $1.23 in DB
+				false, true)) // broadcast_enabled, talk_to_user_enabled
 
 	w := httptest.NewRecorder()
 	c, _ := gin.CreateTestContext(w)

workspace-server/internal/handlers/workspace_test.go

@@ -29,6 +29,7 @@ func TestWorkspaceGet_Success(t *testing.T) {
 		"parent_id", "active_tasks", "max_concurrent_tasks", "last_error_rate", "last_sample_error",
 		"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 		"budget_limit", "monthly_spend",
+		"broadcast_enabled", "talk_to_user_enabled",
 	}
 	mock.ExpectQuery("SELECT w.id, w.name").
 		WithArgs("cccccccc-0001-0000-0000-000000000000").
@@ -36,7 +37,7 @@ func TestWorkspaceGet_Success(t *testing.T) {
 			AddRow("cccccccc-0001-0000-0000-000000000000", "My Agent", "worker", 1, "online", []byte(`{"name":"test"}`),
 				"http://localhost:8001", nil, 2, 1, 0.05, "", 3600, "working", "langgraph",
 				"", 10.0, 20.0, false,
-				nil, 0))
+				nil, 0, false, true))
 
 	w := httptest.NewRecorder()
 	c, _ := gin.CreateTestContext(w)
@@ -118,6 +119,7 @@ func TestWorkspaceGet_RemovedReturns410(t *testing.T) {
 		"parent_id", "active_tasks", "max_concurrent_tasks", "last_error_rate", "last_sample_error",
 		"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 		"budget_limit", "monthly_spend",
+		"broadcast_enabled", "talk_to_user_enabled",
 	}
 	mock.ExpectQuery("SELECT w.id, w.name").
 		WithArgs(id).
@@ -125,7 +127,7 @@ func TestWorkspaceGet_RemovedReturns410(t *testing.T) {
 			AddRow(id, "Old Agent", "worker", 1, string(models.StatusRemoved), []byte(`null`),
 				"", nil, 0, 1, 0.0, "", 0, "", "langgraph",
 				"", 0.0, 0.0, false,
-				nil, 0))
+				nil, 0, false, true))
 	mock.ExpectQuery(`SELECT updated_at FROM workspaces`).
 		WithArgs(id).
 		WillReturnRows(sqlmock.NewRows([]string{"updated_at"}).AddRow(removedAt))
@@ -181,6 +183,7 @@ func TestWorkspaceGet_RemovedReturns410WithNullRemovedAtOnTimestampFetchFailure(
 		"parent_id", "active_tasks", "max_concurrent_tasks", "last_error_rate", "last_sample_error",
 		"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 		"budget_limit", "monthly_spend",
+		"broadcast_enabled", "talk_to_user_enabled",
 	}
 	mock.ExpectQuery("SELECT w.id, w.name").
 		WithArgs(id).
@@ -188,7 +191,7 @@ func TestWorkspaceGet_RemovedReturns410WithNullRemovedAtOnTimestampFetchFailure(
 			AddRow(id, "Vanished", "worker", 1, string(models.StatusRemoved), []byte(`null`),
 				"", nil, 0, 1, 0.0, "", 0, "", "langgraph",
 				"", 0.0, 0.0, false,
-				nil, 0))
+				nil, 0, false, true))
 	// Simulate the row vanishing between the two queries.
 	mock.ExpectQuery(`SELECT updated_at FROM workspaces`).
 		WithArgs(id).
@@ -243,6 +246,7 @@ func TestWorkspaceGet_RemovedWithIncludeQueryReturns200(t *testing.T) {
 		"parent_id", "active_tasks", "max_concurrent_tasks", "last_error_rate", "last_sample_error",
 		"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 		"budget_limit", "monthly_spend",
+		"broadcast_enabled", "talk_to_user_enabled",
 	}
 	mock.ExpectQuery("SELECT w.id, w.name").
 		WithArgs(id).
@@ -250,7 +254,7 @@ func TestWorkspaceGet_RemovedWithIncludeQueryReturns200(t *testing.T) {
 			AddRow(id, "Audit Agent", "worker", 1, string(models.StatusRemoved), []byte(`null`),
 				"", nil, 0, 1, 0.0, "", 0, "", "langgraph",
 				"", 0.0, 0.0, false,
-				nil, 0))
+				nil, 0, false, true))
 	// last_outbound_at follow-up query (existing path)
 	mock.ExpectQuery(`SELECT last_outbound_at FROM workspaces`).
 		WithArgs(id).
@@ -676,6 +680,7 @@ func TestWorkspaceList_Empty(t *testing.T) {
 			"parent_id", "active_tasks", "last_error_rate", "last_sample_error",
 			"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 			"budget_limit", "monthly_spend",
+		"broadcast_enabled", "talk_to_user_enabled",
 		}))
 
 	w := httptest.NewRecorder()
@@ -1379,6 +1384,7 @@ func TestWorkspaceGet_FinancialFieldsStripped(t *testing.T) {
 		"parent_id", "active_tasks", "max_concurrent_tasks", "last_error_rate", "last_sample_error",
 		"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 		"budget_limit", "monthly_spend",
+		"broadcast_enabled", "talk_to_user_enabled",
 	}
 	// Populate with non-zero financial values to confirm they are stripped.
 	mock.ExpectQuery("SELECT w.id, w.name").
@@ -1387,7 +1393,7 @@ func TestWorkspaceGet_FinancialFieldsStripped(t *testing.T) {
 			AddRow("cccccccc-0010-0000-0000-000000000000", "Finance Test", "worker", 1, "online", []byte(`{}`),
 				"http://localhost:9001", nil, 0, 1, 0.0, "", 0, "", "langgraph",
 				"", 0.0, 0.0, false,
-				int64(50000), int64(12500))) // budget_limit=500 USD, spend=125 USD
+				int64(50000), int64(12500), false, true)) // budget_limit=500 USD, spend=125 USD
 
 	w := httptest.NewRecorder()
 	c, _ := gin.CreateTestContext(w)
@@ -1435,6 +1441,7 @@ func TestWorkspaceGet_SensitiveFieldsStripped(t *testing.T) {
 		"parent_id", "active_tasks", "max_concurrent_tasks", "last_error_rate", "last_sample_error",
 		"uptime_seconds", "current_task", "runtime", "workspace_dir", "x", "y", "collapsed",
 		"budget_limit", "monthly_spend",
+		"broadcast_enabled", "talk_to_user_enabled",
 	}
 	mock.ExpectQuery("SELECT w.id, w.name").
 		WithArgs("cccccccc-0955-0000-0000-000000000000").
@@ -1447,7 +1454,7 @@ func TestWorkspaceGet_SensitiveFieldsStripped(t *testing.T) {
 				"langgraph",
 				"/home/user/secret-projects/client-work",
 				0.0, 0.0, false,
-				nil, 0))
+				nil, 0, false, true))
 
 	w := httptest.NewRecorder()
 	c, _ := gin.CreateTestContext(w)

workspace-server/internal/models/workspace.go

@@ -36,6 +36,15 @@ type Workspace struct {
 	// to activity_logs, agent reads via GET /activity?since_id=). See
 	// migration 045 + RFC #2339.
 	DeliveryMode       string          `json:"delivery_mode" db:"delivery_mode"`
+	// BroadcastEnabled: when true the workspace may call POST /broadcast to
+	// deliver a message to all non-removed agent workspaces in the org.
+	// Default false — only privileged orchestrators should hold this ability.
+	BroadcastEnabled   bool            `json:"broadcast_enabled" db:"broadcast_enabled"`
+	// TalkToUserEnabled: when false the workspace's send_message_to_user calls
+	// and POST /notify requests are rejected with HTTP 403 so the agent is
+	// forced to route updates through a parent workspace. Default true
+	// (preserves existing behaviour for all workspaces).
+	TalkToUserEnabled  bool            `json:"talk_to_user_enabled" db:"talk_to_user_enabled"`
 	// Canvas layout fields (from JOIN)
 	X         float64 `json:"x"`
 	Y         float64 `json:"y"`

workspace-server/internal/router/router.go

@@ -146,6 +146,9 @@ func Setup(hub *ws.Hub, broadcaster *events.Broadcaster, prov *provisioner.Provi
 		wsAdmin.GET("/workspaces", wh.List)
 		wsAdmin.POST("/workspaces", wh.Create)
 		wsAdmin.DELETE("/workspaces/:id", wh.Delete)
+		// Ability toggles — admin-only so workspace agents cannot self-modify
+		// broadcast_enabled or talk_to_user_enabled.
+		wsAdmin.PATCH("/workspaces/:id/abilities", handlers.PatchAbilities)
 		// Out-of-band bootstrap signal: CP's watcher POSTs here when it
 		// detects "RUNTIME CRASHED" in a workspace EC2 console output,
 		// so the canvas flips to failed in seconds instead of waiting
@@ -201,6 +204,12 @@ func Setup(hub *ws.Hub, broadcaster *events.Broadcaster, prov *provisioner.Provi
 		// to 'hibernated'. The workspace auto-wakes on the next A2A message.
 		wsAuth.POST("/hibernate", wh.Hibernate)
 
+		// Broadcast — send a message to all non-removed workspaces in the org.
+		// Requires broadcast_enabled=true on the source workspace (checked
+		// inside the handler). WorkspaceAuth on wsAuth proves token ownership.
+		broadcastH := handlers.NewBroadcastHandler(broadcaster)
+		wsAuth.POST("/broadcast", broadcastH.Broadcast)
+
 		// External-workspace credential lifecycle (issue #319 follow-up to
 		// the Create flow). Both endpoints reject runtime ≠ external with
 		// 400 — see external_rotate.go for the rationale.

workspace-server/migrations/20260514120000_workspace_abilities.down.sql

@@ -0,0 +1,3 @@
+ALTER TABLE workspaces
+    DROP COLUMN IF EXISTS broadcast_enabled,
+    DROP COLUMN IF EXISTS talk_to_user_enabled;

workspace-server/migrations/20260514120000_workspace_abilities.up.sql

@@ -0,0 +1,16 @@
+-- Workspace abilities: opt-in flags that gate platform-level behaviours.
+--
+-- broadcast_enabled (default FALSE): when TRUE the workspace may call
+--   POST /workspaces/:id/broadcast to send a message to every non-removed
+--   agent workspace in the org. Off by default — only privileged
+--   orchestrator workspaces should hold this ability.
+--
+-- talk_to_user_enabled (default TRUE): when FALSE the workspace is not
+--   allowed to deliver messages to the canvas user via send_message_to_user /
+--   POST /notify. The platform returns HTTP 403 so the agent can forward its
+--   update to a parent workspace instead. Default TRUE preserves existing
+--   behaviour for all current workspaces.
+
+ALTER TABLE workspaces
+    ADD COLUMN IF NOT EXISTS broadcast_enabled    BOOLEAN NOT NULL DEFAULT FALSE,
+    ADD COLUMN IF NOT EXISTS talk_to_user_enabled BOOLEAN NOT NULL DEFAULT TRUE;

workspace/a2a_tools.py

@@ -137,6 +137,7 @@ from a2a_tools_delegation import (  # noqa: E402  (import after the from-a2a_cli
 # identically.
 from a2a_tools_messaging import (  # noqa: E402  (import after the top-of-module imports)
     _upload_chat_files,
+    tool_broadcast_message,
     tool_chat_history,
     tool_get_workspace_info,
     tool_list_peers,

workspace/a2a_tools_messaging.py

@@ -101,6 +101,50 @@ async def _upload_chat_files(
     return uploaded, None
 
 
+async def tool_broadcast_message(
+    message: str,
+    workspace_id: str | None = None,
+) -> str:
+    """Send a broadcast message to ALL agent workspaces in the org.
+
+    Requires the workspace to have broadcast_enabled=true (set by a user or
+    admin via PATCH /workspaces/:id/abilities). Use for urgent org-wide
+    signals — status changes, critical alerts, coordination instructions.
+    Every non-removed workspace receives the message in its activity log so
+    poll-mode agents pick it up, and push-mode canvases get a real-time
+    BROADCAST_MESSAGE WebSocket event.
+
+    Args:
+        message: The broadcast text. Keep it concise — all agents receive
+            this, so avoid lengthy prose that floods every context.
+        workspace_id: Optional. Which registered workspace to send the
+            broadcast from. Single-workspace agents omit this.
+    """
+    if not message:
+        return "Error: message is required"
+    target_workspace_id = (workspace_id or "").strip() or WORKSPACE_ID
+    try:
+        async with httpx.AsyncClient(timeout=30.0) as client:
+            resp = await client.post(
+                f"{PLATFORM_URL}/workspaces/{target_workspace_id}/broadcast",
+                json={"message": message},
+                headers=_auth_headers_for_heartbeat(target_workspace_id),
+            )
+            if resp.status_code == 200:
+                data = resp.json()
+                delivered = data.get("delivered", "?")
+                return f"Broadcast sent to {delivered} workspace(s)"
+            if resp.status_code == 403:
+                try:
+                    hint = resp.json().get("hint", "")
+                except Exception:
+                    hint = ""
+                return f"Error: broadcast ability not enabled.{(' ' + hint) if hint else ''}"
+            return f"Error: platform returned {resp.status_code}"
+    except Exception as e:
+        return f"Error sending broadcast: {e}"
+
+
 async def tool_send_message_to_user(
     message: str,
     attachments: list[str] | None = None,
@@ -151,6 +195,20 @@ async def tool_send_message_to_user(
                 if uploaded:
                     return f"Message sent to user with {len(uploaded)} attachment(s)"
                 return "Message sent to user"
+            if resp.status_code == 403:
+                try:
+                    body = resp.json()
+                    if body.get("error") == "talk_to_user_disabled":
+                        hint = body.get("hint", "")
+                        return (
+                            "Error: this workspace is not allowed to send messages "
+                            "directly to the user (talk_to_user is disabled). "
+                            + (hint + " " if hint else "")
+                            + "Use delegate_task to forward your update to a parent "
+                            "or supervisor workspace that can reach the user."
+                        )
+                except Exception:
+                    pass
             return f"Error: platform returned {resp.status_code}"
     except Exception as e:
         return f"Error sending message: {e}"

workspace/executor_helpers.py

@@ -340,6 +340,10 @@ _CLI_A2A_COMMAND_KEYWORDS: dict[str, str | None] = {
     "delegate_task_async": "delegate --async",
     "check_task_status": "status",
     "get_workspace_info": "info",
+    # `broadcast_message` is not exposed via the CLI subprocess interface
+    # today — it's an MCP-first capability. If a2a_cli grows a `broadcast`
+    # subcommand, map it here and the alignment test will gate the change.
+    "broadcast_message": None,
     # `send_message_to_user` is not exposed via the CLI subprocess
     # interface today — it requires a structured `attachments` field
     # that wouldn't survive a positional-arg shell invocation cleanly.

workspace/platform_tools/registry.py

@@ -51,6 +51,7 @@ from dataclasses import dataclass
 from typing import Any, Literal
 
 from a2a_tools import (
+    tool_broadcast_message,
     tool_chat_history,
     tool_check_task_status,
     tool_commit_memory,
@@ -288,6 +289,44 @@ _GET_WORKSPACE_INFO = ToolSpec(
     section=A2A_SECTION,
 )
 
+_BROADCAST_MESSAGE = ToolSpec(
+    name="broadcast_message",
+    short=(
+        "Send a message to ALL agent workspaces in the org simultaneously. "
+        "Requires broadcast_enabled=true on this workspace (set by user/admin)."
+    ),
+    when_to_use=(
+        "Use for urgent, org-wide signals: critical status changes, emergency "
+        "stop instructions, coordinated task announcements. Every non-removed "
+        "workspace receives the message in its activity log (poll-mode agents "
+        "see it on their next poll; push-mode canvases get a real-time banner). "
+        "This tool returns an error if broadcast_enabled is false — a user or "
+        "admin must enable it via the workspace abilities settings first."
+    ),
+    input_schema={
+        "type": "object",
+        "properties": {
+            "message": {
+                "type": "string",
+                "description": (
+                    "The broadcast text. Keep it concise — every agent in the "
+                    "org receives this in their activity feed."
+                ),
+            },
+            "workspace_id": {
+                "type": "string",
+                "description": (
+                    "Optional. Multi-workspace mode: the registered workspace "
+                    "to broadcast from. Single-workspace agents omit this."
+                ),
+            },
+        },
+        "required": ["message"],
+    },
+    impl=tool_broadcast_message,
+    section=A2A_SECTION,
+)
+
 _SEND_MESSAGE_TO_USER = ToolSpec(
     name="send_message_to_user",
     short=(
@@ -603,6 +642,7 @@ TOOLS: list[ToolSpec] = [
     _CHECK_TASK_STATUS,
     _LIST_PEERS,
     _GET_WORKSPACE_INFO,
+    _BROADCAST_MESSAGE,
     _SEND_MESSAGE_TO_USER,
     # Inbox (standalone-only; in-container returns informational error)
     _WAIT_FOR_MESSAGE,

workspace/tests/snapshots/a2a_instructions_mcp.txt

@@ -5,6 +5,7 @@
 - **check_task_status**: Poll the status of a task started with delegate_task_async; returns result when done.
 - **list_peers**: List the workspaces this agent can communicate with — name, ID, status, role for each.
 - **get_workspace_info**: Get this workspace's own info — ID, name, role, tier, parent, status.
+- **broadcast_message**: Send a message to ALL agent workspaces in the org simultaneously. Requires broadcast_enabled=true on this workspace (set by user/admin).
 - **send_message_to_user**: Send a message directly to the user's canvas chat — pushed instantly via WebSocket. Use this to: (1) acknowledge a task immediately ('Got it, I'll start working on this'), (2) send interim progress updates while doing long work, (3) deliver follow-up results after delegation completes, (4) attach files (zip, pdf, csv, image) for the user to download via the `attachments` field (NEVER paste file URLs in `message`). The message appears in the user's chat as if you're proactively reaching out.
 - **wait_for_message**: Block until the next inbound message (canvas user OR peer agent) arrives, or until ``timeout_secs`` elapses.
 - **inbox_peek**: List pending inbound messages without removing them.
@@ -26,6 +27,9 @@ Call this first when you need to delegate but don't know the target's ID. Access
 ### get_workspace_info
 Use to introspect your own identity (e.g. before reporting back to the user, or to determine whether you're a tier-0 root that can write GLOBAL memory).
 
+### broadcast_message
+Use for urgent, org-wide signals: critical status changes, emergency stop instructions, coordinated task announcements. Every non-removed workspace receives the message in its activity log (poll-mode agents see it on their next poll; push-mode canvases get a real-time banner). This tool returns an error if broadcast_enabled is false — a user or admin must enable it via the workspace abilities settings first.
+
 ### send_message_to_user
 Use proactively across the lifecycle of a task — early to acknowledge, mid-flight to update, late to deliver. Never paste file URLs in the message body — always pass absolute paths in `attachments` so the platform serves them as download chips (works on SaaS where external file hosts are unreachable).