fix(tui): address follow-up review nits

ui-tui/src/app/slash/commands/session.ts

@@ -21,7 +21,7 @@ const GLOBAL_MODEL_FLAG_RE = /(?:^|\s)--global(?:\s|$)/
 const persistedModelArg = (arg: string) => {
   const trimmed = arg.trim()
 
-  return GLOBAL_MODEL_FLAG_RE.test(trimmed) ? trimmed : `${trimmed} --global`
+  return !trimmed || GLOBAL_MODEL_FLAG_RE.test(trimmed) ? trimmed : `${trimmed} --global`
 }
 
 export const sessionCommands: SlashCommand[] = [
@@ -73,7 +73,7 @@ export const sessionCommands: SlashCommand[] = [
         return
       }
 
-      if (!arg) {
+      if (!arg.trim()) {
         return patchOverlayState({ modelPicker: true })
       }
 

ui-tui/src/app/useSubmission.ts

@@ -51,24 +51,29 @@ export function useSubmission(opts: UseSubmissionOptions) {
   const typingIdleTimer = useRef<ReturnType<typeof setTimeout> | null>(null)
 
   useEffect(() => {
-    if (composerState.input || composerState.inputBuf.length) {
-      if (getUiState().busy) {
-        turnController.boostStreamingForTyping()
-      }
-
-      if (typingIdleTimer.current) {
-        clearTimeout(typingIdleTimer.current)
-      }
-
-      typingIdleTimer.current = setTimeout(() => {
-        typingIdleTimer.current = null
-        turnController.relaxStreaming()
-      }, TYPING_IDLE_MS)
+    if (typingIdleTimer.current) {
+      clearTimeout(typingIdleTimer.current)
+      typingIdleTimer.current = null
     }
 
+    if (!composerState.input && !composerState.inputBuf.length) {
+      turnController.relaxStreaming()
+      return
+    }
+
+    if (getUiState().busy) {
+      turnController.boostStreamingForTyping()
+    }
+
+    typingIdleTimer.current = setTimeout(() => {
+      typingIdleTimer.current = null
+      turnController.relaxStreaming()
+    }, TYPING_IDLE_MS)
+
     return () => {
       if (typingIdleTimer.current) {
         clearTimeout(typingIdleTimer.current)
+        typingIdleTimer.current = null
       }
     }
   }, [composerState.input, composerState.inputBuf])