fix(ui): avoid mobile prompt focus on switch

Stops auto-focusing the prompt on phone session switches and scopes type-to-focus to the active visible prompt, disabling it on coarse pointers.

packages/ui/src/App.tsx

@@ -143,6 +143,31 @@ const App: Component = () => {
     onCleanup(() => document.removeEventListener("fullscreenchange", syncBrowserFullscreenState))
   })
 
+  onMount(() => {
+    if (typeof window === "undefined") return
+    const vv = window.visualViewport
+    if (!vv) return
+
+    const updateKeyboardOffset = () => {
+      // visualViewport shrinks when the OSK is visible. Use the delta as a bottom inset.
+      const inset = Math.max(0, window.innerHeight - vv.height - vv.offsetTop)
+      document.documentElement.style.setProperty("--keyboard-offset", `${Math.floor(inset)}px`)
+    }
+
+    const schedule = () => requestAnimationFrame(updateKeyboardOffset)
+    schedule()
+    vv.addEventListener("resize", schedule)
+    vv.addEventListener("scroll", schedule)
+    window.addEventListener("orientationchange", schedule)
+
+    onCleanup(() => {
+      vv.removeEventListener("resize", schedule)
+      vv.removeEventListener("scroll", schedule)
+      window.removeEventListener("orientationchange", schedule)
+      document.documentElement.style.removeProperty("--keyboard-offset")
+    })
+  })
+
   // If the user exits browser fullscreen via browser UI, restore chrome.
   let lastBrowserFullscreen = false
   createEffect(() => {
@@ -471,7 +496,7 @@ const App: Component = () => {
           </div>
         </Dialog.Portal>
       </Dialog>
-      <div class="h-screen w-screen flex flex-col">
+      <div class="h-screen w-screen flex flex-col" style={{ height: "100dvh", "padding-bottom": "var(--keyboard-offset, 0px)" }}>
         <Show
           when={!hasInstances()}
           fallback={

packages/ui/src/components/instance/instance-shell2.tsx

@@ -823,6 +823,7 @@ const InstanceShell2: Component<InstanceShellProps> = (props) => {
                           instanceId={props.instance.id}
                           instanceFolder={props.instance.folder}
                           escapeInDebounce={props.escapeInDebounce}
+                          isPhoneLayout={isPhoneLayout()}
                           showSidebarToggle={showEmbeddedSidebarToggle()}
                           onSidebarToggle={() => setLeftOpen(true)}
                           forceCompactStatusLayout={showEmbeddedSidebarToggle()}

packages/ui/src/components/prompt-input.tsx

@@ -176,15 +176,26 @@ export default function PromptInput(props: PromptInputProps) {
     ),
   )
 
-  onMount(() => {
+  const isCoarsePointer = () => {
+    if (typeof window === "undefined") return false
+    return Boolean(window.matchMedia?.("(pointer: coarse)")?.matches)
+  }
+
+  createEffect(() => {
+    // Scope global "type-to-focus" behavior to the active, visible prompt only.
+    if (typeof document === "undefined") return
+    if (isCoarsePointer()) return
+    if (props.isActive === false) return
+    if (props.disabled) return
+
     const handleGlobalKeyDown = (e: KeyboardEvent) => {
-      const activeElement = document.activeElement as HTMLElement
+      const activeElement = document.activeElement as HTMLElement | null
 
       const isInputElement =
         activeElement?.tagName === "INPUT" ||
         activeElement?.tagName === "TEXTAREA" ||
         activeElement?.tagName === "SELECT" ||
-        activeElement?.isContentEditable
+        Boolean(activeElement?.isContentEditable)
 
       if (isInputElement) return
 
@@ -192,16 +203,25 @@ export default function PromptInput(props: PromptInputProps) {
       if (isModifierKey) return
 
       const isSpecialKey =
-        e.key === "Tab" || e.key === "Enter" || e.key.startsWith("Arrow") || e.key === "Backspace" || e.key === "Delete"
+        e.key === "Tab" ||
+        e.key === "Enter" ||
+        e.key.startsWith("Arrow") ||
+        e.key === "Backspace" ||
+        e.key === "Delete"
       if (isSpecialKey) return
 
-      if (e.key.length === 1 && textareaRef && !props.disabled) {
+      const textarea = textareaRef
-        textareaRef.focus()
+      if (!textarea || textarea.disabled) return
+
+      // In session cache mode inactive panes are display:none; avoid stealing focus.
+      if (textarea.offsetParent === null) return
+
+      if (e.key.length === 1) {
+        textarea.focus()
       }
     }
 
     document.addEventListener("keydown", handleGlobalKeyDown)
-
     onCleanup(() => {
       document.removeEventListener("keydown", handleGlobalKeyDown)
     })
@@ -435,7 +455,7 @@ export default function PromptInput(props: PromptInputProps) {
                 onFocus={() => setIsFocused(true)}
                 onBlur={() => setIsFocused(false)}
                 disabled={props.disabled}
-                rows={expandState() === "expanded" ? 15 : 4}
+                rows={expandState() === "expanded" ? 15 : 3}
                 spellcheck={false}
                 autocorrect="off"
                 autoCapitalize="off"

packages/ui/src/components/prompt-input/types.ts

@@ -17,6 +17,9 @@ export interface PromptInputProps {
   instanceId: string
   instanceFolder: string
   sessionId: string
+
+  // Used to scope global "type-to-focus" behavior.
+  isActive?: boolean
   onSend: (prompt: string, attachments: Attachment[]) => Promise<void>
   onRunShell?: (command: string) => Promise<void>
   disabled?: boolean

packages/ui/src/components/session/session-view.tsx

@@ -28,6 +28,7 @@ interface SessionViewProps {
   instanceId: string
   instanceFolder: string
   escapeInDebounce: boolean
+  isPhoneLayout?: boolean
   showSidebarToggle?: boolean
   onSidebarToggle?: () => void
   forceCompactStatusLayout?: boolean
@@ -76,6 +77,9 @@ export const SessionView: Component<SessionViewProps> = (props) => {
       (isActive) => {
         if (!isActive) return
 
+        // On phones, focusing the prompt on session switch is disruptive (it raises the OSK).
+        if (props.isPhoneLayout) return
+
         // Don't steal focus from other inputs (command palette, dialogs, selectors, etc.)
         if (typeof document === "undefined") return
         const activeEl = document.activeElement as HTMLElement | null
@@ -314,17 +318,18 @@ export const SessionView: Component<SessionViewProps> = (props) => {
                 </Show>
 
               <PromptInput
-               instanceId={props.instanceId}
+                instanceId={props.instanceId}
-               instanceFolder={props.instanceFolder}
+                instanceFolder={props.instanceFolder}
-               sessionId={activeSession.id}
+                sessionId={activeSession.id}
-               onSend={handleSendMessage}
+                isActive={props.isActive}
-               onRunShell={handleRunShell}
+                onSend={handleSendMessage}
-               escapeInDebounce={props.escapeInDebounce}
+                onRunShell={handleRunShell}
-               isSessionBusy={sessionBusy()}
+                escapeInDebounce={props.escapeInDebounce}
-               disabled={sessionNeedsInput()}
+                isSessionBusy={sessionBusy()}
-               onAbortSession={handleAbortSession}
+                disabled={sessionNeedsInput()}
-               registerPromptInputApi={registerPromptInputApi}
+                onAbortSession={handleAbortSession}
-               />
+                registerPromptInputApi={registerPromptInputApi}
+                />
             </div>
           )
         }}

packages/ui/src/styles/messaging/prompt-input.css

@@ -295,7 +295,33 @@
   }
 
   .prompt-input {
-    padding-bottom: 1.5rem;
+    /* Prevent iOS Safari input zoom + keep input compact. */
+    font-size: 16px;
+    padding-bottom: 0.75rem;
+  }
+}
+
+@media (max-width: 1279px) {
+  :root {
+    --prompt-input-compact-height: 104px;
+  }
+
+  .prompt-input-wrapper {
+    min-height: var(--prompt-input-compact-height);
+  }
+
+  .prompt-input-field-container {
+    min-height: var(--prompt-input-compact-height);
+    height: var(--prompt-input-compact-height);
+  }
+
+  .prompt-input-field {
+    height: var(--prompt-input-compact-height);
+  }
+
+  .prompt-input-field-container.is-expanded,
+  .prompt-input-field.is-expanded {
+    height: auto;
   }
 }
 
@@ -307,9 +333,9 @@
 
 @media (max-width: 640px) {
   .prompt-input {
-    min-height: 64px;
+    min-height: 0;
     padding: 0.5rem 0.75rem;
-    padding-bottom: 2.25rem;
+    padding-bottom: 0.75rem;
   }
 
   .prompt-input-wrapper {