diff --git a/workspace-server/internal/handlers/workspace_broadcast.go b/workspace-server/internal/handlers/workspace_broadcast.go
index 6afd21e0a..668475661 100644
--- a/workspace-server/internal/handlers/workspace_broadcast.go
+++ b/workspace-server/internal/handlers/workspace_broadcast.go
@@ -3,7 +3,7 @@ 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:
+// non-removed agent workspace in the SAME ORG.  The message is:
 //
 //   • Persisted in each recipient's activity_logs (type='broadcast_receive')
 //     so poll-mode agents pick it up via GET /activity.
@@ -16,6 +16,11 @@ package handlers
 // 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.
+//
+// Org isolation (OFFSEC-015): recipients are scoped to the sender's org using
+// a recursive CTE that walks the parent_id chain to find the org root. This
+// prevents a compromised or misconfigured workspace from broadcasting to
+// workspaces in other tenants' orgs.
 
 import (
 	"log"
@@ -74,11 +79,49 @@ func (h *BroadcastHandler) Broadcast(c *gin.Context) {
 		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,
-	)
+	// Find the sender's org root by walking the parent_id chain.
+	// Workspaces with parent_id = NULL are org roots; every other workspace
+	// belongs to the org identified by its topmost ancestor.
+	var orgRootID string
+	err = db.DB.QueryRowContext(ctx, `
+		WITH RECURSIVE org_chain AS (
+			SELECT id, parent_id, id AS root_id
+			FROM workspaces
+			WHERE id = $1
+			UNION ALL
+			SELECT w.id, w.parent_id, c.root_id
+			FROM workspaces w
+			JOIN org_chain c ON w.id = c.parent_id
+		)
+		SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1
+	`, senderID).Scan(&orgRootID)
+	if err != nil {
+		log.Printf("Broadcast: org root lookup for %s: %v", senderID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "internal error"})
+		return
+	}
+
+	// Collect all non-removed agent workspaces in the SAME ORG (same root_id),
+	// excluding the sender itself.
+	rows, err := db.DB.QueryContext(ctx, `
+		WITH RECURSIVE org_chain AS (
+			SELECT id, parent_id, id AS root_id
+			FROM workspaces
+			WHERE parent_id IS NULL
+			UNION ALL
+			SELECT w.id, w.parent_id, c.root_id
+			FROM workspaces w
+			JOIN org_chain c ON w.parent_id = c.id
+		)
+		SELECT c.id
+		FROM org_chain c
+		WHERE c.root_id = $1
+		  AND c.id != $2
+		  AND EXISTS (
+			  SELECT 1 FROM workspaces w
+			  WHERE w.id = c.id AND w.status != 'removed'
+		  )
+	`, orgRootID, senderID)
 	if err != nil {
 		log.Printf("Broadcast: recipient query failed for %s: %v", senderID, err)
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "internal error"})
diff --git a/workspace-server/internal/handlers/workspace_broadcast_test.go b/workspace-server/internal/handlers/workspace_broadcast_test.go
new file mode 100644
index 000000000..81ca3d1e9
--- /dev/null
+++ b/workspace-server/internal/handlers/workspace_broadcast_test.go
@@ -0,0 +1,666 @@
+package handlers
+
+import (
+	"bytes"
+	"context"
+	"database/sql"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/db"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/events"
+	"github.com/Molecule-AI/molecule-monorepo/platform/internal/ws"
+	"github.com/gin-gonic/gin"
+)
+
+// setupBroadcastDB uses QueryMatcherEqual so SQL strings with quoted literals
+// (e.g. status != 'removed') are compared verbatim, not as regex.
+func setupBroadcastDB(t *testing.T) sqlmock.Sqlmock {
+	t.Helper()
+	mockDB, mock, err := sqlmock.New(sqlmock.QueryMatcherOption(sqlmock.QueryMatcherEqual))
+	if err != nil {
+		t.Fatalf("failed to create sqlmock: %v", err)
+	}
+	prevDB := db.DB
+	db.DB = mockDB
+	t.Cleanup(func() { db.DB = prevDB; mockDB.Close() })
+	return mock
+}
+
+// broadcastTestUUID is a properly formatted test UUID.
+const broadcastTestUUID = "bbbbbbbb-0001-0001-0001-000000000001"
+
+// buildBroadcastCtx creates a gin.Context wired for POST /workspaces/:id/broadcast.
+func buildBroadcastCtx(id, body string) (*gin.Context, *httptest.ResponseRecorder) {
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	req := httptest.NewRequest(http.MethodPost, "/workspaces/"+id+"/broadcast", bytes.NewBufferString(body))
+	req.Header.Set("Content-Type", "application/json")
+	c.Request = req.WithContext(context.Background())
+	c.Params = gin.Params{{Key: "id", Value: id}}
+	return c, w
+}
+
+// ─── Pure function ────────────────────────────────────────────────────────────
+
+func TestBroadcastTruncate(t *testing.T) {
+	tests := []struct {
+		name string
+		s    string
+		max  int
+		want string
+	}{
+		{"empty string", "", 10, ""},
+		{"under limit", "hello", 10, "hello"},
+		{"exactly at limit", "hello", 5, "hello"},
+		{"over limit", "hello world", 5, "hello…"},
+		{"unicode over limit", "こんにちは世界", 5, "こんにちは…"},
+		{"ascii over limit", "abcdefghij", 5, "abcde…"},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := broadcastTruncate(tc.s, tc.max)
+			if got != tc.want {
+				t.Errorf("broadcastTruncate(%q, %d) = %q; want %q", tc.s, tc.max, got, tc.want)
+			}
+		})
+	}
+}
+
+// ─── Validation ────────────────────────────────────────────────────────────────
+
+func TestBroadcast_InvalidWorkspaceID(t *testing.T) {
+	c, w := buildBroadcastCtx("not-a-uuid", `{"message":"hello"}`)
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("want 400, got %d: %s", w.Code, w.Body.String())
+	}
+}
+
+func TestBroadcast_MissingMessage(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{}`)
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("want 400, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+func TestBroadcast_MalformedJSON(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `not json`)
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("want 400, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+// ─── Auth / Authz ─────────────────────────────────────────────────────────────
+
+func TestBroadcast_WorkspaceNotFound(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello"}`)
+
+	// Workspace lookup returns no rows.
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnError(sql.ErrNoRows)
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusNotFound {
+		t.Errorf("want 404, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+func TestBroadcast_WorkspaceLookupQueryError(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello"}`)
+
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnError(sql.ErrConnDone)
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusNotFound {
+		t.Errorf("want 404, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+func TestBroadcast_BroadcastDisabled(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello"}`)
+
+	// Workspace found but broadcast_enabled=false.
+	rows := sqlmock.NewRows([]string{"name", "broadcast_enabled"}).
+		AddRow("test-workspace", false)
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(rows)
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusForbidden {
+		t.Errorf("want 403, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+// ─── Org root lookup error (blocks cross-org broadcast) ──────────────────────
+
+func TestBroadcast_OrgRootLookupError(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello"}`)
+
+	// Workspace lookup succeeds.
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("test-workspace", true))
+
+	// Org root CTE fails — handler must NOT proceed to the recipient query
+	// (which would broadcast cross-org if org root lookup failed silently).
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(broadcastTestUUID).
+		WillReturnError(context.DeadlineExceeded)
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusInternalServerError {
+		t.Errorf("want 500, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet expectations: %v", err)
+	}
+}
+
+// ─── DB error paths ───────────────────────────────────────────────────────────
+
+func TestBroadcast_RecipientQueryError(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello"}`)
+
+	// Workspace lookup succeeds with broadcast_enabled=true.
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("test-workspace", true))
+
+	// Org root lookup succeeds.
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(broadcastTestUUID))
+
+	// Recipient query fails.
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(broadcastTestUUID, broadcastTestUUID).
+		WillReturnError(sql.ErrConnDone)
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusInternalServerError {
+		t.Errorf("want 500, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+func TestBroadcast_RecipientRowsError(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello"}`)
+
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("test-workspace", true))
+
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(broadcastTestUUID))
+
+	// Recipient query succeeds but rows.Err() fails.
+	badRows := sqlmock.NewRows([]string{"id"}).AddRow("ws-2").RowError(0, sql.ErrConnDone)
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(broadcastTestUUID, broadcastTestUUID).
+		WillReturnRows(badRows)
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusInternalServerError {
+		t.Errorf("want 500, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+// ─── Success paths ───────────────────────────────────────────────────────────
+
+func TestBroadcast_Success_OneRecipient(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello world"}`)
+
+	// Workspace lookup.
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("sender-workspace", true))
+
+	// Org root lookup.
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(broadcastTestUUID))
+
+	// Recipient query: one recipient.
+	recipRows := sqlmock.NewRows([]string{"id"}).AddRow("ws-recipient-1")
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(broadcastTestUUID, broadcastTestUUID).
+		WillReturnRows(recipRows)
+
+	// Activity log insert for recipient.
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, status) VALUES ($1, 'broadcast_receive', 'broadcast', $2, $3, 'ok')").
+		WithArgs("ws-recipient-1", broadcastTestUUID, sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	// Activity log insert for sender (broadcast_sent).
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, summary, status) VALUES ($1, 'broadcast_sent', 'broadcast', $2, 'ok')").
+		WithArgs(broadcastTestUUID, sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusOK {
+		t.Errorf("want 200, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+func TestBroadcast_Success_NoRecipients(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello"}`)
+
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("solo-workspace", true))
+
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(broadcastTestUUID))
+
+	// No recipients.
+	recipRows := sqlmock.NewRows([]string{"id"})
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(broadcastTestUUID, broadcastTestUUID).
+		WillReturnRows(recipRows)
+
+	// Activity log insert for sender (broadcast_sent).
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, summary, status) VALUES ($1, 'broadcast_sent', 'broadcast', $2, 'ok')").
+		WithArgs(broadcastTestUUID, sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusOK {
+		t.Errorf("want 200, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+func TestBroadcast_Success_MultipleRecipients(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello"}`)
+
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("broadcaster", true))
+
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(broadcastTestUUID))
+
+	// Three recipients.
+	recipRows := sqlmock.NewRows([]string{"id"}).
+		AddRow("ws-1").AddRow("ws-2").AddRow("ws-3")
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(broadcastTestUUID, broadcastTestUUID).
+		WillReturnRows(recipRows)
+
+	// Each recipient gets a broadcast_receive log.
+	for _, rid := range []string{"ws-1", "ws-2", "ws-3"} {
+		mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, status) VALUES ($1, 'broadcast_receive', 'broadcast', $2, $3, 'ok')").
+			WithArgs(rid, broadcastTestUUID, sqlmock.AnyArg()).
+			WillReturnResult(sqlmock.NewResult(0, 1))
+	}
+
+	// Sender log.
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, summary, status) VALUES ($1, 'broadcast_sent', 'broadcast', $2, 'ok')").
+		WithArgs(broadcastTestUUID, sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusOK {
+		t.Errorf("want 200, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+// ─── Recipient insert failure (logged, continues) ─────────────────────────────
+
+func TestBroadcast_RecipientInsertError_ContinuesAndSucceeds(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello"}`)
+
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("broadcaster", true))
+
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(broadcastTestUUID))
+
+	// Two recipients.
+	recipRows := sqlmock.NewRows([]string{"id"}).AddRow("ws-1").AddRow("ws-2")
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(broadcastTestUUID, broadcastTestUUID).
+		WillReturnRows(recipRows)
+
+	// First recipient insert fails (logged, continues).
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, status) VALUES ($1, 'broadcast_receive', 'broadcast', $2, $3, 'ok')").
+		WithArgs("ws-1", broadcastTestUUID, sqlmock.AnyArg()).
+		WillReturnError(sql.ErrConnDone)
+
+	// Second recipient insert succeeds.
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, status) VALUES ($1, 'broadcast_receive', 'broadcast', $2, $3, 'ok')").
+		WithArgs("ws-2", broadcastTestUUID, sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	// Sender log.
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, summary, status) VALUES ($1, 'broadcast_sent', 'broadcast', $2, 'ok')").
+		WithArgs(broadcastTestUUID, sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	// Handler returns 200 even though one insert failed — it logs and continues.
+	if w.Code != http.StatusOK {
+		t.Errorf("want 200 despite insert error, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+// ─── Sender activity log insert failure (logged, still 200) ───────────────────
+
+func TestBroadcast_SenderLogInsertError_Still200(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	c, w := buildBroadcastCtx(broadcastTestUUID, `{"message":"hello"}`)
+
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("broadcaster", true))
+
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(broadcastTestUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(broadcastTestUUID))
+
+	recipRows := sqlmock.NewRows([]string{"id"}).AddRow("ws-1")
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(broadcastTestUUID, broadcastTestUUID).
+		WillReturnRows(recipRows)
+
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, status) VALUES ($1, 'broadcast_receive', 'broadcast', $2, $3, 'ok')").
+		WithArgs("ws-1", broadcastTestUUID, sqlmock.AnyArg()).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	// Sender log fails — but handler still returns 200 (logged only).
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, summary, status) VALUES ($1, 'broadcast_sent', 'broadcast', $2, 'ok')").
+		WithArgs(broadcastTestUUID, sqlmock.AnyArg()).
+		WillReturnError(sql.ErrConnDone)
+
+	handler := NewBroadcastHandler(events.NewBroadcaster(ws.NewHub(nil)))
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusOK {
+		t.Errorf("want 200 despite sender log error, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations: %v", err)
+	}
+}
+
+// ─── Org-scoped recipient query tests (OFFSEC-015) ────────────────────────────
+
+// TestBroadcast_OrgScopedRecipients verifies that a broadcast from Org-A does
+// NOT reach workspaces belonging to Org-B. This is the core regression test
+// for OFFSEC-015: the original query had no org filter, so a workspace in
+// Org-A could broadcast to every non-removed workspace in the entire DB.
+func TestBroadcast_OrgScopedRecipients(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	broadcaster := newTestBroadcaster()
+	handler := NewBroadcastHandler(broadcaster)
+
+	senderID := "00000000-0000-0000-0000-000000000001" // org-a-root
+	wsAChild := "00000000-0000-0000-0000-000000000002"
+
+	// 1. Sender lookup
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("Org-A Root", true))
+
+	// 2. Org root lookup — sender is its own root (parent_id = NULL)
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(senderID))
+
+	// 3. Org-scoped recipient query — MUST include org filter so ws-b-child is NOT included.
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(senderID, senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow(wsAChild))
+
+	// Activity log inserts
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, status) VALUES ($1, 'broadcast_receive', 'broadcast', $2, $3, 'ok')").
+		WithArgs(wsAChild, senderID, sqlmock.AnyArg()).WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, summary, status) VALUES ($1, 'broadcast_sent', 'broadcast', $2, 'ok')").
+		WithArgs(senderID, sqlmock.AnyArg()).WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: senderID}}
+	body := `{"message":"hello from org-a"}`
+	c.Request = httptest.NewRequest("POST", "/workspaces/"+senderID+"/broadcast", bytes.NewBufferString(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusOK {
+		t.Errorf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+
+	var resp map[string]interface{}
+	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("failed to unmarshal response: %v", err)
+	}
+	if resp["status"] != "sent" {
+		t.Errorf("expected status 'sent', got %v", resp["status"])
+	}
+	// ws-b-child is in a DIFFERENT org — the org-scoped query MUST NOT include it.
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet mock expectations — cross-org workspace was included: %v", err)
+	}
+}
+
+// TestBroadcast_OrgScoped_OrgRootSender verifies that when the sender IS the
+// org root (parent_id = NULL), broadcasts still reach sibling workspaces.
+func TestBroadcast_OrgScoped_OrgRootSender(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	broadcaster := newTestBroadcaster()
+	handler := NewBroadcastHandler(broadcaster)
+
+	senderID := "00000000-0000-0000-0000-000000000001"
+	siblingID := "00000000-0000-0000-0000-000000000002"
+
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("Root Agent", true))
+
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(senderID))
+
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(senderID, senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow(siblingID))
+
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, status) VALUES ($1, 'broadcast_receive', 'broadcast', $2, $3, 'ok')").
+		WithArgs(siblingID, senderID, sqlmock.AnyArg()).WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, summary, status) VALUES ($1, 'broadcast_sent', 'broadcast', $2, 'ok')").
+		WithArgs(senderID, sqlmock.AnyArg()).WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: senderID}}
+	body := `{"message":"hello siblings"}`
+	c.Request = httptest.NewRequest("POST", "/workspaces/"+senderID+"/broadcast", bytes.NewBufferString(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusOK {
+		t.Errorf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet expectations: %v", err)
+	}
+}
+
+// TestBroadcast_OrgScoped_ChildWorkspaceSender verifies that a non-root child
+// workspace can broadcast to siblings in the same org.
+func TestBroadcast_OrgScoped_ChildWorkspaceSender(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	broadcaster := newTestBroadcaster()
+	handler := NewBroadcastHandler(broadcaster)
+
+	orgRootID := "00000000-0000-0000-0000-000000000001"
+	senderID := "00000000-0000-0000-0000-000000000002"
+	siblingID := "00000000-0000-0000-0000-000000000003"
+
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("Child Agent", true))
+
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(orgRootID))
+
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(orgRootID, senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow(siblingID))
+
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, status) VALUES ($1, 'broadcast_receive', 'broadcast', $2, $3, 'ok')").
+		WithArgs(siblingID, senderID, sqlmock.AnyArg()).WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, summary, status) VALUES ($1, 'broadcast_sent', 'broadcast', $2, 'ok')").
+		WithArgs(senderID, sqlmock.AnyArg()).WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: senderID}}
+	body := `{"message":"child broadcasting"}`
+	c.Request = httptest.NewRequest("POST", "/workspaces/"+senderID+"/broadcast", bytes.NewBufferString(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusOK {
+		t.Errorf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet expectations: %v", err)
+	}
+}
+
+// TestBroadcast_OrgScoped_SelfBroadcastExcluded verifies that broadcasting
+// from a workspace does not send a broadcast_receive to the sender itself.
+func TestBroadcast_OrgScoped_SelfBroadcastExcluded(t *testing.T) {
+	mock := setupBroadcastDB(t)
+	broadcaster := newTestBroadcaster()
+	handler := NewBroadcastHandler(broadcaster)
+
+	senderID := "00000000-0000-0000-0000-000000000001"
+	peerID := "00000000-0000-0000-0000-000000000002"
+
+	mock.ExpectQuery("SELECT name, broadcast_enabled FROM workspaces WHERE id = $1 AND status != 'removed'").
+		WithArgs(senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"name", "broadcast_enabled"}).AddRow("Root Agent", true))
+
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE id = $1 UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.id = c.parent_id ) SELECT root_id FROM org_chain WHERE parent_id IS NULL LIMIT 1").
+		WithArgs(senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"root_id"}).AddRow(senderID))
+
+	// Recipient query MUST exclude sender via id != senderID
+	mock.ExpectQuery("WITH RECURSIVE org_chain AS ( SELECT id, parent_id, id AS root_id FROM workspaces WHERE parent_id IS NULL UNION ALL SELECT w.id, w.parent_id, c.root_id FROM workspaces w JOIN org_chain c ON w.parent_id = c.id ) SELECT c.id FROM org_chain c WHERE c.root_id = $1 AND c.id != $2 AND EXISTS ( SELECT 1 FROM workspaces w WHERE w.id = c.id AND w.status != 'removed' )").
+		WithArgs(senderID, senderID).
+		WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow(peerID))
+
+	// Peer receives broadcast_receive
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, source_id, summary, status) VALUES ($1, 'broadcast_receive', 'broadcast', $2, $3, 'ok')").
+		WithArgs(peerID, senderID, sqlmock.AnyArg()).WillReturnResult(sqlmock.NewResult(0, 1))
+	// Sender logs broadcast_sent (NOT broadcast_receive)
+	mock.ExpectExec("INSERT INTO activity_logs (workspace_id, activity_type, method, summary, status) VALUES ($1, 'broadcast_sent', 'broadcast', $2, 'ok')").
+		WithArgs(senderID, sqlmock.AnyArg()).WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: senderID}}
+	body := `{"message":"no echo to self"}`
+	c.Request = httptest.NewRequest("POST", "/workspaces/"+senderID+"/broadcast", bytes.NewBufferString(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+
+	handler.Broadcast(c)
+
+	if w.Code != http.StatusOK {
+		t.Errorf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet expectations: %v", err)
+	}
+}