diff --git a/src/client/index.ts b/src/client/index.ts
index 1c9305c..1d43976 100644
--- a/src/client/index.ts
+++ b/src/client/index.ts
@@ -90,7 +90,7 @@ function apply(ctx: ClientCtx): void {
   ctx.slots.inject('conversation.input.overlay', () => {
     return ctx.slots.register(
       { name: 'conversation.input.overlay', id: 'context-modal', order: 10, locale: NS,
-        inject: (sessionId: string) => ({ hooks: { contextModal: modalStoreOf(sessionId) } }) },
+        inject: (sessionId = '') => ({ hooks: { contextModal: modalStoreOf(sessionId) } }) },
       props => h(ContextModal, props),
     )
   })
diff --git a/src/client/services.ts b/src/client/services.ts
index 58b1e6e..8825e5b 100644
--- a/src/client/services.ts
+++ b/src/client/services.ts
@@ -30,14 +30,14 @@ export interface SlotRegistration {
   locale?: string
   label?: () => string
   /** optional business face factory; a `hooks` compartment binds selector hooks onto props. */
-  inject?: (sessionId: string) => unknown
+  inject?: (sessionId?: string) => unknown
 }
 
 export interface SlotsService {
   inject(name: string, callback: () => unknown): unknown
   register(
     registration: SlotRegistration,
-    component: (props: { sessionId?: string }) => unknown,
+    component: (props: { sessionId?: string } & Record<string, unknown>) => unknown,
   ): unknown
 }