diff --git a/workspace-server/internal/handlers/workspace_abilities.go b/workspace-server/internal/handlers/workspace_abilities.go
index 71fa48f97..c2ba7d0ee 100644
--- a/workspace-server/internal/handlers/workspace_abilities.go
+++ b/workspace-server/internal/handlers/workspace_abilities.go
@@ -51,7 +51,12 @@ func PatchAbilities(c *gin.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 {
+	).Scan(&exists); err != nil {
+		log.Printf("PatchAbilities: workspace existence check for %s: %v", id, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "internal error"})
+		return
+	}
+	if !exists {
 		c.JSON(http.StatusNotFound, gin.H{"error": "workspace not found"})
 		return
 	}
diff --git a/workspace-server/internal/handlers/workspace_abilities_test.go b/workspace-server/internal/handlers/workspace_abilities_test.go
new file mode 100644
index 000000000..10d3c7a08
--- /dev/null
+++ b/workspace-server/internal/handlers/workspace_abilities_test.go
@@ -0,0 +1,265 @@
+package handlers
+
+// workspace_abilities_test.go — regression tests for PATCH /workspaces/:id/abilities.
+//
+// The handler toggles 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. These tests cover the uncredentialed unit-path (AdminAuth
+// middleware is tested separately).
+
+import (
+	"bytes"
+	"database/sql"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/gin-gonic/gin"
+)
+
+// validUUID is a stable test workspace ID that passes uuid.Parse validation.
+const validUUID = "00000000-0000-0000-0000-000000000001"
+
+// buildAbilitiesCtx wires a gin.Context for PATCH /workspaces/:id/abilities.
+func buildAbilitiesCtx(id string, body string) (*httptest.ResponseRecorder, *gin.Context) {
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: id}}
+	c.Request = httptest.NewRequest("PATCH", "/workspaces/"+id+"/abilities",
+		bytes.NewBufferString(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+	return w, c
+}
+
+// -------- Happy path --------
+
+// PatchAbilities writes broadcast_enabled=true and returns 200.
+func TestPatchAbilities_BroadcastEnabled_200(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT EXISTS\(SELECT 1 FROM workspaces WHERE id = \$1 AND status != 'removed'\)`).
+		WithArgs(validUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"exists"}).AddRow(true))
+	mock.ExpectExec(`UPDATE workspaces SET broadcast_enabled = \$2, updated_at = now\(\) WHERE id = \$1`).
+		WithArgs(validUUID, true).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w, c := buildAbilitiesCtx(validUUID, `{"broadcast_enabled":true}`)
+	PatchAbilities(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 sqlmock expectations: %v", err)
+	}
+}
+
+// PatchAbilities writes broadcast_enabled=false and returns 200.
+func TestPatchAbilities_BroadcastEnabledFalse_200(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT EXISTS\(SELECT 1 FROM workspaces WHERE id = \$1 AND status != 'removed'\)`).
+		WithArgs(validUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"exists"}).AddRow(true))
+	mock.ExpectExec(`UPDATE workspaces SET broadcast_enabled = \$2, updated_at = now\(\) WHERE id = \$1`).
+		WithArgs(validUUID, false).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w, c := buildAbilitiesCtx(validUUID, `{"broadcast_enabled":false}`)
+	PatchAbilities(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 sqlmock expectations: %v", err)
+	}
+}
+
+// PatchAbilities writes talk_to_user_enabled=true and returns 200.
+func TestPatchAbilities_TalkToUserEnabled_200(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT EXISTS\(SELECT 1 FROM workspaces WHERE id = \$1 AND status != 'removed'\)`).
+		WithArgs(validUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"exists"}).AddRow(true))
+	mock.ExpectExec(`UPDATE workspaces SET talk_to_user_enabled = \$2, updated_at = now\(\) WHERE id = \$1`).
+		WithArgs(validUUID, true).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w, c := buildAbilitiesCtx(validUUID, `{"talk_to_user_enabled":true}`)
+	PatchAbilities(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 sqlmock expectations: %v", err)
+	}
+}
+
+// Both ability flags in the same request are each written with their own UPDATE.
+func TestPatchAbilities_BothFields_200(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT EXISTS\(SELECT 1 FROM workspaces WHERE id = \$1 AND status != 'removed'\)`).
+		WithArgs(validUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"exists"}).AddRow(true))
+	// broadcast_enabled written first
+	mock.ExpectExec(`UPDATE workspaces SET broadcast_enabled = \$2, updated_at = now\(\) WHERE id = \$1`).
+		WithArgs(validUUID, true).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	// talk_to_user_enabled written second
+	mock.ExpectExec(`UPDATE workspaces SET talk_to_user_enabled = \$2, updated_at = now\(\) WHERE id = \$1`).
+		WithArgs(validUUID, false).
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w, c := buildAbilitiesCtx(validUUID, `{"broadcast_enabled":true,"talk_to_user_enabled":false}`)
+	PatchAbilities(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 sqlmock expectations: %v", err)
+	}
+}
+
+// -------- Input validation --------
+
+// Empty body (neither field) → 400.
+func TestPatchAbilities_NoAbilityFields_400(t *testing.T) {
+	setupTestDB(t)
+	setupTestRedis(t)
+
+	w, c := buildAbilitiesCtx(validUUID, `{}`)
+	PatchAbilities(c)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400, got %d: %s", w.Code, w.Body.String())
+	}
+}
+
+// Non-JSON body → 400.
+func TestPatchAbilities_InvalidJSON_400(t *testing.T) {
+	setupTestDB(t)
+	setupTestRedis(t)
+
+	w, c := buildAbilitiesCtx(validUUID, `not json at all`)
+	PatchAbilities(c)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400, got %d: %s", w.Code, w.Body.String())
+	}
+}
+
+// Invalid (non-UUID) workspace ID → 400.
+func TestPatchAbilities_InvalidWorkspaceID_400(t *testing.T) {
+	setupTestDB(t)
+	setupTestRedis(t)
+
+	w, c := buildAbilitiesCtx("not-a-uuid", `{"broadcast_enabled":true}`)
+	PatchAbilities(c)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400, got %d: %s", w.Code, w.Body.String())
+	}
+}
+
+// -------- Database errors --------
+
+// Workspace does not exist → 404.
+func TestPatchAbilities_WorkspaceNotFound_404(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT EXISTS\(SELECT 1 FROM workspaces WHERE id = \$1 AND status != 'removed'\)`).
+		WithArgs(validUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"exists"}).AddRow(false))
+
+	w, c := buildAbilitiesCtx(validUUID, `{"broadcast_enabled":true}`)
+	PatchAbilities(c)
+
+	if w.Code != http.StatusNotFound {
+		t.Errorf("expected 404, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet sqlmock expectations: %v", err)
+	}
+}
+
+// DB error on existence check → 500.
+func TestPatchAbilities_DBErrorOnExistsCheck_500(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT EXISTS\(SELECT 1 FROM workspaces WHERE id = \$1 AND status != 'removed'\)`).
+		WithArgs(validUUID).
+		WillReturnError(sql.ErrConnDone)
+
+	w, c := buildAbilitiesCtx(validUUID, `{"broadcast_enabled":true}`)
+	PatchAbilities(c)
+
+	if w.Code != http.StatusInternalServerError {
+		t.Errorf("expected 500, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet sqlmock expectations: %v", err)
+	}
+}
+
+// DB error on broadcast_enabled UPDATE → 500.
+func TestPatchAbilities_DBErrorOnBroadcastUpdate_500(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT EXISTS\(SELECT 1 FROM workspaces WHERE id = \$1 AND status != 'removed'\)`).
+		WithArgs(validUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"exists"}).AddRow(true))
+	mock.ExpectExec(`UPDATE workspaces SET broadcast_enabled = \$2, updated_at = now\(\) WHERE id = \$1`).
+		WithArgs(validUUID, true).
+		WillReturnError(sql.ErrConnDone)
+
+	w, c := buildAbilitiesCtx(validUUID, `{"broadcast_enabled":true}`)
+	PatchAbilities(c)
+
+	if w.Code != http.StatusInternalServerError {
+		t.Errorf("expected 500, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet sqlmock expectations: %v", err)
+	}
+}
+
+// DB error on talk_to_user_enabled UPDATE → 500.
+func TestPatchAbilities_DBErrorOnTalkToUserUpdate_500(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+
+	mock.ExpectQuery(`SELECT EXISTS\(SELECT 1 FROM workspaces WHERE id = \$1 AND status != 'removed'\)`).
+		WithArgs(validUUID).
+		WillReturnRows(sqlmock.NewRows([]string{"exists"}).AddRow(true))
+	mock.ExpectExec(`UPDATE workspaces SET talk_to_user_enabled = \$2, updated_at = now\(\) WHERE id = \$1`).
+		WithArgs(validUUID, true).
+		WillReturnError(sql.ErrConnDone)
+
+	w, c := buildAbilitiesCtx(validUUID, `{"talk_to_user_enabled":true}`)
+	PatchAbilities(c)
+
+	if w.Code != http.StatusInternalServerError {
+		t.Errorf("expected 500, got %d: %s", w.Code, w.Body.String())
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet sqlmock expectations: %v", err)
+	}
+}